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Morris CD, Qian EK, Meza PE, Sangwan VK, Malliakas CD, Hersam MC, Kanatzidis MG. Nanotube Structure of AsPS 4-xSe x ( x = 0, 1). Inorg Chem 2024; 63:4915-4924. [PMID: 38440871 DOI: 10.1021/acs.inorgchem.3c03952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2024]
Abstract
Single-wall nanotubes of isostructural AsPS4-xSex (x = 0, 1) are grown from solid-state reaction of stoichiometric amounts of the elements. The structure of AsPS4 was determined using single-crystal X-ray diffraction and refined in space group P 1 ¯ . The infinite, single-walled AsPS4 nanotubes have an outer diameter of ≈1.1 nm and are built of corner-sharing PS4 tetrahedra and AsS3 trigonal pyramids. Each nanotube is nearly hexagonal, but the ≈3.4 Å distance between S atoms on adjacent nanotubes allows them to easily slide past one another, resulting in the loss of long-range order. Substituting S with Se disrupted the crystallization of the nanotubes, resulting in amorphous products that precluded the determination of the structure for AsPS3Se. 31P solid-state NMR spectroscopy indicated a single unique tetrahedral P environment in AsPS4 and five different P environments all with different degrees of Se substitution in AsPS3Se. Optical absorption spectroscopy revealed an energy band gap of 2.7 to 2.4 eV for AsPS4 and AsPS3Se, respectively. Individual AsPS4 microfibers showed a bulk conductivity of 3.2 × 10-6 S/cm and a negative photoconductivity effect under the illumination of light (3.06 eV) in ambient conditions. Thus, intrinsic conductivity originates from hopping through empty trap states along the length of the AsPS4 nanotubes.
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Affiliation(s)
- Collin D Morris
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Eric K Qian
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Patricia E Meza
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Christos D Malliakas
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Mark C Hersam
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, Illinois 60208, United States
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2
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Shi J, Arpaci S, Lopez-Dominguez V, Sangwan VK, Mahfouzi F, Kim J, Athas JG, Hamdi M, Aygen C, Arava H, Phatak C, Carpentieri M, Jiang JS, Grayson MA, Kioussis N, Finocchio G, Hersam MC, Khalili Amiri P. Electrically Controlled All-Antiferromagnetic Tunnel Junctions on Silicon with Large Room-Temperature Magnetoresistance. Adv Mater 2024:e2312008. [PMID: 38501999 DOI: 10.1002/adma.202312008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Revised: 02/11/2024] [Indexed: 03/20/2024]
Abstract
Antiferromagnetic (AFM) materials are a pathway to spintronic memory and computing devices with unprecedented speed, energy efficiency, and bit density. Realizing this potential requires AFM devices with simultaneous electrical writing and reading of information, which are also compatible with established silicon-based manufacturing. Recent experiments have shown tunneling magnetoresistance (TMR) readout in epitaxial AFM tunnel junctions. However, these TMR structures are not grown using a silicon-compatible deposition process, and controlling their AFM order required external magnetic fields. Here it is shown three-terminal AFM tunnel junctions based on the noncollinear antiferromagnet PtMn3 , sputter-deposited on silicon. The devices simultaneously exhibit electrical switching using electric currents, and electrical readout by a large room-temperature TMR effect. First-principles calculations explain the TMR in terms of the momentum-resolved spin-dependent tunneling conduction in tunnel junctions with noncollinear AFM electrodes.
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Affiliation(s)
- Jiacheng Shi
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Sevdenur Arpaci
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
- Applied Physics Program, Northwestern University, Evanston, IL, 60208, USA
| | - Victor Lopez-Dominguez
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
- Institute of Advanced Materials (INAM), Universitat Jaume I, Castellón, 12006, Spain
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Farzad Mahfouzi
- Department of Physics and Astronomy, California State University Northridge, Northridge, CA, 91330, USA
| | - Jinwoong Kim
- Department of Physics and Astronomy, California State University Northridge, Northridge, CA, 91330, USA
| | - Jordan G Athas
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Mohammad Hamdi
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Can Aygen
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Hanu Arava
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Charudatta Phatak
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Mario Carpentieri
- Department of Electrical and Information Engineering, Politecnico di Bari, Bari, 70125, Italy
| | - Jidong S Jiang
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Matthew A Grayson
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
- Applied Physics Program, Northwestern University, Evanston, IL, 60208, USA
| | - Nicholas Kioussis
- Department of Physics and Astronomy, California State University Northridge, Northridge, CA, 91330, USA
| | - Giovanni Finocchio
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, Messina, 98166, Italy
| | - Mark C Hersam
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
- Applied Physics Program, Northwestern University, Evanston, IL, 60208, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
- Department of Chemistry, Northwestern University, Evanston, IL, 60208, USA
| | - Pedram Khalili Amiri
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
- Applied Physics Program, Northwestern University, Evanston, IL, 60208, USA
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3
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Smyth CM, Cain JM, Boehm A, Ohlhausen JA, Lam MN, Yan X, Liu SE, Zeng TT, Sangwan VK, Hersam MC, Chou SS, Ohta T, Lu TM. Direct Characterization of Buried Interfaces in 2D/3D Heterostructures Enabled by GeO 2 Release Layer. ACS Appl Mater Interfaces 2024; 16:2847-2860. [PMID: 38170963 DOI: 10.1021/acsami.3c12849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Inconsistent interface control in devices based on two-dimensional materials (2DMs) has limited technological maturation. Astounding variability of 2D/three-dimensional (2D/3D) interface properties has been reported, which has been exacerbated by the lack of direct investigations of buried interfaces commonly found in devices. Herein, we demonstrate a new process that enables the assembly and isolation of device-relevant heterostructures for buried interface characterization. This is achieved by implementing a water-soluble substrate (GeO2), which enables deposition of many materials onto the 2DM and subsequent heterostructure release by dissolving the GeO2 substrate. Here, we utilize this novel approach to compare how the chemistry, doping, and strain in monolayer MoS2 heterostructures fabricated by direct deposition vary from those fabricated by transfer techniques to show how interface properties differ with the heterostructure fabrication method. Direct deposition of thick Ni and Ti films is found to react with the monolayer MoS2. These interface reactions convert 50% of MoS2 into intermetallic species, which greatly exceeds the 10% conversion reported previously and 0% observed in transfer-fabricated heterostructures. We also measure notable differences in MoS2 carrier concentration depending on the heterostructure fabrication method. Direct deposition of thick Au, Ni, and Al2O3 films onto MoS2 increases the hole concentration by >1012 cm-2 compared to heterostructures fabricated by transferring MoS2 onto these materials. Thus, we demonstrate a universal method to fabricate 2D/3D heterostructures and expose buried interfaces for direct characterization.
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Affiliation(s)
| | - John M Cain
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Alex Boehm
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - James A Ohlhausen
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Mila Nhu Lam
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Xiaodong Yan
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Stephanie E Liu
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Thomas T Zeng
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Stanley S Chou
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Taisuke Ohta
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Tzu-Ming Lu
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
- Center for Integrated Nanotechnologies (CINT), Sandia National Laboratories, Albuquerque, New Mexico 87123, United States
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4
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Yan X, Zheng Z, Sangwan VK, Qian JH, Wang X, Liu SE, Watanabe K, Taniguchi T, Xu SY, Jarillo-Herrero P, Ma Q, Hersam MC. Moiré synaptic transistor with room-temperature neuromorphic functionality. Nature 2023; 624:551-556. [PMID: 38123805 DOI: 10.1038/s41586-023-06791-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Accepted: 10/26/2023] [Indexed: 12/23/2023]
Abstract
Moiré quantum materials host exotic electronic phenomena through enhanced internal Coulomb interactions in twisted two-dimensional heterostructures1-4. When combined with the exceptionally high electrostatic control in atomically thin materials5-8, moiré heterostructures have the potential to enable next-generation electronic devices with unprecedented functionality. However, despite extensive exploration, moiré electronic phenomena have thus far been limited to impractically low cryogenic temperatures9-14, thus precluding real-world applications of moiré quantum materials. Here we report the experimental realization and room-temperature operation of a low-power (20 pW) moiré synaptic transistor based on an asymmetric bilayer graphene/hexagonal boron nitride moiré heterostructure. The asymmetric moiré potential gives rise to robust electronic ratchet states, which enable hysteretic, non-volatile injection of charge carriers that control the conductance of the device. The asymmetric gating in dual-gated moiré heterostructures realizes diverse biorealistic neuromorphic functionalities, such as reconfigurable synaptic responses, spatiotemporal-based tempotrons and Bienenstock-Cooper-Munro input-specific adaptation. In this manner, the moiré synaptic transistor enables efficient compute-in-memory designs and edge hardware accelerators for artificial intelligence and machine learning.
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Affiliation(s)
- Xiaodong Yan
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - Zhiren Zheng
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - Justin H Qian
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - Xueqiao Wang
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Stephanie E Liu
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Takashi Taniguchi
- International Center for Material Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Su-Yang Xu
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | | | - Qiong Ma
- Department of Physics, Boston College, Chestnut Hill, MA, USA.
- CIFAR Azrieli Global Scholars Program, CIFAR, Toronto, Ontario, Canada.
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA.
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, USA.
- Department of Chemistry, Northwestern University, Evanston, IL, USA.
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5
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Liu C, Yang Y, Chen H, Xu J, Liu A, Bati ASR, Zhu H, Grater L, Hadke SS, Huang C, Sangwan VK, Cai T, Shin D, Chen LX, Hersam MC, Mirkin CA, Chen B, Kanatzidis MG, Sargent EH. Bimolecularly passivated interface enables efficient and stable inverted perovskite solar cells. Science 2023; 382:810-815. [PMID: 37972154 DOI: 10.1126/science.adk1633] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 10/06/2023] [Indexed: 11/19/2023]
Abstract
Compared with the n-i-p structure, inverted (p-i-n) perovskite solar cells (PSCs) promise increased operating stability, but these photovoltaic cells often exhibit lower power conversion efficiencies (PCEs) because of nonradiative recombination losses, particularly at the perovskite/C60 interface. We passivated surface defects and enabled reflection of minority carriers from the interface into the bulk using two types of functional molecules. We used sulfur-modified methylthio molecules to passivate surface defects and suppress recombination through strong coordination and hydrogen bonding, along with diammonium molecules to repel minority carriers and reduce contact-induced interface recombination achieved through field-effect passivation. This approach led to a fivefold longer carrier lifetime and one-third the photoluminescence quantum yield loss and enabled a certified quasi-steady-state PCE of 25.1% for inverted PSCs with stable operation at 65°C for >2000 hours in ambient air. We also fabricated monolithic all-perovskite tandem solar cells with 28.1% PCE.
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Affiliation(s)
- Cheng Liu
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
| | - Yi Yang
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
| | - Hao Chen
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON M5S 1A4, Canada
| | - Jian Xu
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON M5S 1A4, Canada
| | - Ao Liu
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
| | - Abdulaziz S R Bati
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
| | - Huihui Zhu
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
| | - Luke Grater
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON M5S 1A4, Canada
| | - Shreyash Sudhakar Hadke
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Chuying Huang
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Tong Cai
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
- International Institute for Nanotechnology, Northwestern University, Evanston, IL 60208, USA
| | - Donghoon Shin
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
- International Institute for Nanotechnology, Northwestern University, Evanston, IL 60208, USA
| | - Lin X Chen
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
| | - Mark C Hersam
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Chad A Mirkin
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
- International Institute for Nanotechnology, Northwestern University, Evanston, IL 60208, USA
| | - Bin Chen
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
| | | | - Edward H Sargent
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON M5S 1A4, Canada
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL 60208, USA
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6
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Rangnekar SV, Sangwan VK, Jin M, Khalaj M, Szydłowska BM, Dasgupta A, Kuo L, Kurtz HE, Marks TJ, Hersam MC. Electroluminescence from Megasonically Solution-Processed MoS 2 Nanosheet Films. ACS Nano 2023; 17:17516-17526. [PMID: 37606956 DOI: 10.1021/acsnano.3c06034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/23/2023]
Abstract
Due to their superior optoelectronic properties, monolayer two-dimensional (2D) transition metal dichalcogenides (TMDs) have attracted significant attention for electroluminescent devices. However, challenges in isolating optoelectronically active TMD monolayers using scalable liquid phase exfoliation have precluded electroluminescence in large-area, solution-processed TMD films. Here, we overcome these limitations and demonstrate electroluminescence from molybdenum disulfide (MoS2) nanosheet films by employing a monolayer-rich MoS2 ink produced by electrochemical intercalation and megasonic exfoliation. Characteristic monolayer MoS2 photoluminescence and electroluminescence spectral peaks at 1.88-1.90 eV are observed in megasonicated MoS2 films, with the emission intensity increasing with film thickness over the range 10-70 nm. Furthermore, employing a vertical light-emitting capacitor architecture enables uniform electroluminescence in large-area devices. These results indicate that megasonically exfoliated MoS2 monolayers retain their direct bandgap character in electrically percolating thin films even following multistep solution processing. Overall, this work establishes megasonicated MoS2 inks as an additive manufacturing platform for flexible, patterned, and miniaturized light sources that can likely be expanded to other TMD semiconductors.
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Affiliation(s)
- Sonal V Rangnekar
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Mengru Jin
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Maryam Khalaj
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Beata M Szydłowska
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Anushka Dasgupta
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Lidia Kuo
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Heather E Kurtz
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Tobin J Marks
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, Illinois 60208, United States
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7
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Bradshaw NP, Hirani Z, Kuo L, Li S, Williams NX, Sangwan VK, Chaney LE, Evans AM, Dichtel WR, Hersam MC. Aerosol-Jet-Printable Covalent Organic Framework Colloidal Inks and Temperature-Sensitive Nanocomposite Films. Adv Mater 2023; 35:e2303673. [PMID: 37288981 DOI: 10.1002/adma.202303673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 06/02/2023] [Indexed: 06/09/2023]
Abstract
With molecularly well-defined and tailorable 2D structures, covalent organic frameworks (COFs) have emerged as leading material candidates for chemical sensing, storage, separation, and catalysis. In these contexts, the ability to directly and deterministically print COFs into arbitrary geometries will enable rapid optimization and deployment. However, previous attempts to print COFs have been restricted by low spatial resolution and/or post-deposition polymerization that limits the range of compatible COFs. Here, these limitations are overcome with a pre-synthesized, solution-processable colloidal ink that enables aerosol jet printing of COFs with micron-scale resolution. The ink formulation utilizes the low-volatility solvent benzonitrile, which is critical to obtaining homogeneous printed COF film morphologies. This ink formulation is also compatible with other colloidal nanomaterials, thus facilitating the integration of COFs into printable nanocomposite films. As a proof-of-concept, boronate-ester COFs are integrated with carbon nanotubes (CNTs) to form printable COF-CNT nanocomposite films, in which the CNTs enhance charge transport and temperature sensing performance, ultimately resulting in high-sensitivity temperature sensors that show electrical conductivity variation by 4 orders of magnitude between room temperature and 300 °C. Overall, this work establishes a flexible platform for COF additive manufacturing that will accelerate the incorporation of COFs into technologically significant applications.
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Affiliation(s)
- Nathan P Bradshaw
- Department of Materials Science and Engineering, 2220 Campus Drive, Evanston, IL, 60208, USA
| | - Zoheb Hirani
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Lidia Kuo
- Department of Materials Science and Engineering, 2220 Campus Drive, Evanston, IL, 60208, USA
| | - Siyang Li
- Department of Materials Science and Engineering, 2220 Campus Drive, Evanston, IL, 60208, USA
| | - Nicholas X Williams
- Department of Materials Science and Engineering, 2220 Campus Drive, Evanston, IL, 60208, USA
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, 2220 Campus Drive, Evanston, IL, 60208, USA
| | - Lindsay E Chaney
- Department of Materials Science and Engineering, 2220 Campus Drive, Evanston, IL, 60208, USA
| | - Austin M Evans
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - William R Dichtel
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Mark C Hersam
- Department of Materials Science and Engineering, 2220 Campus Drive, Evanston, IL, 60208, USA
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
- Department of Electrical and Computer Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
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8
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Rawat A, Clark L, Zhang C, Cavin J, Sangwan VK, Toth PS, Janáky C, Ananth R, Goldfine E, Bedzyk MJ, Weiss EA, Rondinelli JM, Hersam MC, Meletis EI, Rajeshwar K. Solution Combustion Synthesis and Characterization of Magnesium Copper Vanadates. Inorg Chem 2023. [PMID: 37260199 DOI: 10.1021/acs.inorgchem.3c00452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Magnesium vanadate (MgV2O6) and its alloys with copper vanadate were synthesized via the solution combustion technique. Phase purity and solid solution formation were confirmed by a variety of experimental techniques, supported by electronic structure simulations based on density functional theory (DFT). Powder X-ray diffraction combined with Rietveld refinement, laser Raman spectroscopy, diffuse reflectance spectroscopy, and high-resolution transmission electron microscopy showed single-phase alloy formation despite the MgV2O6 and CuV2O6 end members exhibiting monoclinic and triclinic crystal systems, respectively. DFT-calculated optical band gaps showed close agreement in the computed optical bandgaps with experimentally derived values. Surface photovoltage spectroscopy, ambient-pressure photoemission spectroscopy, and Kelvin probe contact potential difference (work function) measurements confirmed a systematic variation in the optical bandgap modification and band alignment as a function of stoichiometry in the alloy composition. These data indicated n-type semiconductor behavior for all the samples which was confirmed by photoelectrochemical measurements.
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Affiliation(s)
- Abhishek Rawat
- Department of Chemistry & Biochemistry, The University of Texas at Arlington, Arlington, Texas 76019, United States
| | - Laura Clark
- Department of Mechanical and Aerospace Engineering, The University of Texas at Arlington, Arlington, Texas 76019, United States
| | - Chuzhong Zhang
- Department of Materials Science and Engineering, The University of Texas at Arlington, Arlington, Texas 76019, United States
| | - John Cavin
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Peter S Toth
- Department of Physical Chemistry and Materials Science, University of Szeged, Rerrich Square 1, Szeged H-6720, Hungary
| | - Csaba Janáky
- Department of Physical Chemistry and Materials Science, University of Szeged, Rerrich Square 1, Szeged H-6720, Hungary
| | - Riddhi Ananth
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Elise Goldfine
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Michael J Bedzyk
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Emily A Weiss
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - James M Rondinelli
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Efstathios I Meletis
- Department of Materials Science and Engineering, The University of Texas at Arlington, Arlington, Texas 76019, United States
| | - Krishnan Rajeshwar
- Department of Chemistry & Biochemistry, The University of Texas at Arlington, Arlington, Texas 76019, United States
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9
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Burke DW, Dasari RR, Sangwan VK, Oanta AK, Hirani Z, Pelkowski CE, Tang Y, Li R, Ralph DC, Hersam MC, Barlow S, Marder SR, Dichtel WR. Synthesis, Hole Doping, and Electrical Properties of a Semiconducting Azatriangulene-Based Covalent Organic Framework. J Am Chem Soc 2023. [PMID: 37216443 DOI: 10.1021/jacs.2c12371] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Two-dimensional covalent organic frameworks (2D COFs) containing heterotriangulenes have been theoretically identified as semiconductors with tunable, Dirac-cone-like band structures, which are expected to afford high charge-carrier mobilities ideal for next-generation flexible electronics. However, few bulk syntheses of these materials have been reported, and existing synthetic methods provide limited control of network purity and morphology. Here, we report transimination reactions between benzophenone-imine-protected azatriangulenes (OTPA) and benzodithiophene dialdehydes (BDT), which afforded a new semiconducting COF network, OTPA-BDT. The COFs were prepared as both polycrystalline powders and thin films with controlled crystallite orientation. The azatriangulene nodes are readily oxidized to stable radical cations upon exposure to an appropriate p-type dopant, tris(4-bromophenyl)ammoniumyl hexachloroantimonate, after which the network's crystallinity and orientation are maintained. Oriented, hole-doped OTPA-BDT COF films exhibit electrical conductivities of up to 1.2 × 10-1 S cm-1, which are among the highest reported for imine-linked 2D COFs to date.
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Affiliation(s)
- David W Burke
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Raghunath R Dasari
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Alexander K Oanta
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Zoheb Hirani
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Chloe E Pelkowski
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Yongjian Tang
- Department of Physics, Cornell University, Ithaca, New York 14853, United States
| | - Ruofan Li
- Department of Physics, Cornell University, Ithaca, New York 14853, United States
| | - Daniel C Ralph
- Department of Physics, Cornell University, Ithaca, New York 14853, United States
| | - Mark C Hersam
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Stephen Barlow
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
- Renewable & Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Seth R Marder
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
- Renewable & Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80303, United States
- Departments of Chemistry and of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - William R Dichtel
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
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10
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Yan X, Qian JH, Sangwan VK, Hersam MC. Progress and Challenges for Memtransistors in Neuromorphic Circuits and Systems. Adv Mater 2022; 34:e2108025. [PMID: 34813677 DOI: 10.1002/adma.202108025] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 11/07/2021] [Indexed: 06/13/2023]
Abstract
Due to the increasing importance of artificial intelligence (AI), significant recent effort has been devoted to the development of neuromorphic circuits that seek to emulate the energy-efficient information processing of the brain. While non-volatile memory (NVM) based on resistive switches, phase-change memory, and magnetic tunnel junctions has shown potential for implementing neural networks, additional multi-terminal device concepts are required for more sophisticated bio-realistic functions. Of particular interest are memtransistors based on low-dimensional nanomaterials, which are capable of electrostatically tuning memory and learning behavior at the device level. Herein, a conceptual overview of the memtransistor is provided in the context of neuromorphic circuits. Recent progress is surveyed for memtransistors and related multi-terminal NVM devices including dual-gated floating-gate memories, dual-gated ferroelectric transistors, and dual-gated van der Waals heterojunctions. The different materials systems and device architectures are classified based on the degree of control and relative tunability of synaptic behavior, with an emphasis on device concepts that harness the reduced dimensionality, weak electrostatic screening, and phase-changes properties of nanomaterials. Finally, strategies for achieving wafer-scale integration of memtransistors and multi-terminal NVM devices are delineated, with specific attention given to the materials challenges for practical neuromorphic circuits.
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Affiliation(s)
- Xiaodong Yan
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Justin H Qian
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
- Department of Chemistry, Northwestern University, Evanston, IL, 60208, USA
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11
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Schwinn MC, Rafiq S, Lee C, Bland MP, Song TW, Sangwan VK, Hersam MC, Chen LX. Charge Transfer Dynamics and Interlayer Exciton Formation in MoS2/VOPc Mixed Dimensional Heterojunction. J Chem Phys 2022; 157:184701. [DOI: 10.1063/5.0107791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Mixed-dimensional van der Waals heterojunctions involve interfacing materials with different dimensionalities, such as a 2D transition metal dichalcogenide (TMD) and a 0D organic semiconductor. These heterojunctions have shown unique interfacial properties not found in either individual components. Here, we use femtosecond transient absorption to reveal photoinduced charge transfer and interlayer exciton formation in a mixed-dimensional heterojunction between monolayer MoS2 and vanadyl phthalocyanine (VOPc). We find that hole transfer occurs from the MoS2 valence band to VOPc in ~710 fs, while electron transfer occurs from VOPc excited state to MoS2 conduction band in less than 100 fs. This ultrafast electron or hole transfer results in the formation of an interlayer exciton across the interface. Additionally, we observe the emergence of a new absorption band that is formed only in the heterojunction and assign it to the formation of delocalized hybrid states between the VOPc and MoS2 layers. By directly exciting this band, an interlayer exciton forms that is not limited by electron or hole transfer times. These interlayer excitons across the interface lead to longer-lived charge-separated states of up to 2.5 ns, longer than in each individual layer of this heterojunction. Thus, the longer charge-separated state along with ultrafast charge transfer times provide promising results for photovoltaic and optoelectronic device applications.
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Affiliation(s)
- Madison C. Schwinn
- 1 Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States2 Graduate Program in Applied Physics, Northwestern University, Evanston, Illinois 60201, United States3 Chemical Science and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, Unit-ed States, United States of America
| | | | - Changmin Lee
- Department of Chemistry, Northwestern University, United States of America
| | - Matthew P Bland
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States, United States of America
| | - Thomas W Song
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States, United States of America
| | - Vinod K Sangwan
- Materials Science and Engineering, Northwestern University, United States of America
| | - Mark C. Hersam
- Materials Science and Engineering, Northwestern University, United States of America
| | - Lin X. Chen
- Argonne National Laboratory, United States of America
- Northwestern University
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12
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Kuo L, Sangwan VK, Rangnekar SV, Chu TC, Lam D, Zhu Z, Richter LJ, Li R, Szydłowska BM, Downing JR, Luijten BJ, Lauhon LJ, Hersam MC. All-Printed Ultrahigh-Responsivity MoS 2 Nanosheet Photodetectors Enabled by Megasonic Exfoliation. Adv Mater 2022; 34:e2203772. [PMID: 35788996 DOI: 10.1002/adma.202203772] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 06/23/2022] [Indexed: 06/15/2023]
Abstract
Printed 2D materials, derived from solution-processed inks, offer scalable and cost-effective routes to mechanically flexible optoelectronics. With micrometer-scale control and broad processing latitude, aerosol-jet printing (AJP) is of particular interest for all-printed circuits and systems. Here, AJP is utilized to achieve ultrahigh-responsivity photodetectors consisting of well-aligned, percolating networks of semiconducting MoS2 nanosheets and graphene electrodes on flexible polyimide substrates. Ultrathin (≈1.2 nm thick) and high-aspect-ratio (≈1 μm lateral size) MoS2 nanosheets are obtained by electrochemical intercalation followed by megasonic atomization during AJP, which not only aerosolizes the inks but also further exfoliates the nanosheets. The incorporation of the high-boiling-point solvent terpineol into the MoS2 ink is critical for achieving a highly aligned and flat thin-film morphology following AJP as confirmed by grazing-incidence wide-angle X-ray scattering and atomic force microscopy. Following AJP, curing is achieved with photonic annealing, which yields quasi-ohmic contacts and photoactive channels with responsivities exceeding 103 A W-1 that outperform previously reported all-printed visible-light photodetectors by over three orders of magnitude. Megasonic exfoliation coupled with properly designed AJP ink formulations enables the superlative optoelectronic properties of ultrathin MoS2 nanosheets to be preserved and exploited for the scalable additive manufacturing of mechanically flexible optoelectronics.
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Affiliation(s)
- Lidia Kuo
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Sonal V Rangnekar
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Ting-Ching Chu
- Applied Physics Graduate Program, Northwestern University, Evanston, IL, 60208, USA
| | - David Lam
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Zhehao Zhu
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Lee J Richter
- National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Ruipeng Li
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Beata M Szydłowska
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Julia R Downing
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Benjamin J Luijten
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Lincoln J Lauhon
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
- Department of Chemistry, Northwestern University, Evanston, IL, 60208, USA
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
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13
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Lam D, Lebedev D, Kuo L, Sangwan VK, Szydłowska BM, Ferraresi F, Söll A, Sofer Z, Hersam MC. Liquid-Phase Exfoliation of Magnetically and Optoelectronically Active Ruthenium Trichloride Nanosheets. ACS Nano 2022; 16:11315-11324. [PMID: 35714054 DOI: 10.1021/acsnano.2c04888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
α-RuCl3 is a layered transition metal halide that possesses a range of exotic magnetic, optical, and electronic properties including fractional excitations indicative of a proximate Kitaev quantum spin liquid (QSL). While previous reports have explored these properties on idealized single crystals or mechanically exfoliated samples, the scalable production of α-RuCl3 nanosheets has not yet been demonstrated. Here, we perform liquid-phase exfoliation (LPE) of α-RuCl3 through an electrochemically assisted approach, which yields ultrathin, electron-doped α-RuCl3 nanosheets that are then assembled into electrically conductive large-area thin films. The crystalline integrity of the α-RuCl3 nanosheets following LPE is confirmed through a wide range of structural and chemical analyses. Moreover, the physical properties of the LPE α-RuCl3 nanosheets are investigated through electrical, optical, and magnetic characterization methods, which reveal a structural phase transition at 230 K that is consistent with the onset of Kitaev paramagnetism in addition to an antiferromagnetic transition at 2.6 K. Intercalated ions from the electrochemical LPE protocol favorably alter the optical response of the α-RuCl3 nanosheets, enabling large-area Mott insulator photodetectors that operate at telecommunications-relevant infrared wavelengths near 1.55 μm. These photodetectors show a linear photocurrent response as a function of incident power, which suggests negligible trap-mediated recombination or photothermal effects, ultimately resulting in a photoresponsivity of ≈2 mA/W.
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Affiliation(s)
- David Lam
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Dmitry Lebedev
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Lidia Kuo
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Beata M Szydłowska
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Filippo Ferraresi
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Aljoscha Söll
- Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague 6, Czech Republic
| | - Zdeněk Sofer
- Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague 6, Czech Republic
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, Illinois 60208, United States
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14
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Kim SM, Kim S, Ling L, Liu SE, Jin S, Jung YM, Kim M, Park HH, Sangwan VK, Hersam MC, Lee HS. Linear and Symmetric Li-Based Composite Memristors for Efficient Supervised Learning. ACS Appl Mater Interfaces 2022; 14:5673-5681. [PMID: 35043617 DOI: 10.1021/acsami.1c24562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Emerging energy-efficient neuromorphic circuits are based on hardware implementation of artificial neural networks (ANNs) that employ the biomimetic functions of memristors. Specifically, crossbar array memristive architectures are able to perform ANN vector-matrix multiplication more efficiently than conventional CMOS hardware. Memristors with specific characteristics, such as ohmic behavior in all resistance states in addition to symmetric and linear long-term potentiation/depression (LTP/LTD), are required in order to fully realize these benefits. Here, we demonstrate a Li-based composite memristor (LCM) that achieves these objectives. The LCM consists of three phases: Li-doped TiO2 as a Li reservoir, Li4Ti5O12 as the insulating phase, and Li7Ti5O12 as the metallic phase, where resistive switching correlates with the change in the relative fraction of the metallic and insulating phases. The LCM exhibits a symmetric and gradual resistive switching behavior for both set and reset operations during a full bias sweep cycle. This symmetric and linear weight update is uniquely enabled by the symmetric bidirectional migration of Li ions, which leads to gradual changes in the relative fraction of the metallic phase in the film. The optimized LCM in ANN simulation showed that exceptionally high accuracy in image classification is realized in fewer training steps compared to the nonlinear behavior of conventional memristors.
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Affiliation(s)
- Su-Min Kim
- Department of Materials Science & Engineering, Kangwon National University, 1 Kangwondaehak-gil, Chuncheon, Gangwon24341, Korea
| | - Sungkyu Kim
- HMC, Department of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul05006, Republic of Korea
| | - Leo Ling
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, Illinois60208, United States
| | - Stephanie E Liu
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois60208, United States
| | - Sila Jin
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University, 1 Kangwondaehak-gil, Chuncheon, Gangwon24341, Korea
| | - Young Mee Jung
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University, 1 Kangwondaehak-gil, Chuncheon, Gangwon24341, Korea
- Institute of Quantum Convergence Technology, Kangwon National University, 1 Kangwondaehak-gil, Chuncheon, Gangwon 24341, Korea
| | - Minjae Kim
- Department of Materials Science and Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul03772, Republic of Korea
| | - Hyung-Ho Park
- Department of Materials Science and Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul03772, Republic of Korea
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois60208, United States
| | - Mark C Hersam
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, Illinois60208, United States
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois60208, United States
- Department of ChemistryNorthwestern University, Evanston, Illinois60208, United States
| | - Hong-Sub Lee
- Department of Materials Science & Engineering, Kangwon National University, 1 Kangwondaehak-gil, Chuncheon, Gangwon24341, Korea
- Institute of Quantum Convergence Technology, Kangwon National University, 1 Kangwondaehak-gil, Chuncheon, Gangwon 24341, Korea
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15
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Kim SE, Lee JG, Ling L, Liu SE, Lim HK, Sangwan VK, Hersam MC, Lee HS. Sodium-Doped Titania Self-Rectifying Memristors for Crossbar Array Neuromorphic Architectures. Adv Mater 2022; 34:e2106913. [PMID: 34773720 DOI: 10.1002/adma.202106913] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 11/11/2021] [Indexed: 06/13/2023]
Abstract
Memristors integrated into a crossbar-array architecture (CAA) are promising candidates for nonvolatile memory elements in artificial neural networks. However, the relatively low reliability of memristors coupled with crosstalk and sneak currents in CAAs have limited the realization of the full potential of this technology. Here, high-reliability Na-doped TiO2 memristors grown in situ by atomic layer deposition (ALD) are demonstrated, where reversible Na migration underlies the resistive-switching mechanism. By employing ALD growth with an aqueous NaOH reactant in deionized water, uniform implantation of Na dopants is achieved in the crystallized TiO2 thin films at 250 °C without post-annealing. The resulting Na-doped TiO2 memristors show electroforming-free and self-rectifying resistive-switching behavior, and they are ideally suited for selectorless CAAs. Effective addressing of selectorless nodes is demonstrated via electrical measurement of individual memristors in a 6 × 6 crossbar using a read current of less than 1 µA with negligible sneak current at or below the noise level of ≈100 pA. Finally, the long-term potentiation and depression synaptic behavior from these Na-doped TiO2 memristors achieves greater than 99.1% accuracy for image-recognition tasks using a convolutional neural network based on the selectorless of crossbar arrays.
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Affiliation(s)
- Sung-Eun Kim
- Department of Materials Science and Engineering, Kangwon National University, 1 Kangwondaehak-gil, Chuncheon, Gangwon, 24341, Korea
| | - Jin-Gyu Lee
- Department of Materials Science and Engineering, Kangwon National University, 1 Kangwondaehak-gil, Chuncheon, Gangwon, 24341, Korea
| | - Leo Ling
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Stephanie E Liu
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Hyung-Kyu Lim
- Department of Chemical Engineering, Interdisciplinary Program in Advanced Functional Materials and Devices Development, Kangwon National University, 1 Kangwondaehak-gil, Chuncheon, Gangwon, 24341, Korea
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Mark C Hersam
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
- Department of Chemistry, Northwestern University, Evanston, IL, 60208, USA
| | - Hong-Sub Lee
- Department of Materials Science and Engineering, Kangwon National University, 1 Kangwondaehak-gil, Chuncheon, Gangwon, 24341, Korea
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16
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Amsterdam SH, Stanev TK, Wang L, Zhou Q, Irgen-Gioro S, Padgaonkar S, Murthy AA, Sangwan VK, Dravid VP, Weiss EA, Darancet P, Chan MKY, Hersam MC, Stern NP, Marks TJ. Mechanistic Investigation of Molybdenum Disulfide Defect Photoluminescence Quenching by Adsorbed Metallophthalocyanines. J Am Chem Soc 2021; 143:17153-17161. [PMID: 34613735 DOI: 10.1021/jacs.1c07795] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Lattice defects play an important role in determining the optical and electrical properties of monolayer semiconductors such as MoS2. Although the structures of various defects in monolayer MoS2 are well studied, little is known about the nature of the fluorescent defect species and their interaction with molecular adsorbates. In this study, the quenching of the low-temperature defect photoluminescence (PL) in MoS2 is investigated following the deposition of metallophthalocyanines (MPcs). The quenching is found to significantly depend on the identity of the phthalocyanine metal, with the quenching efficiency decreasing in the order CoPc > CuPc > ZnPc, and almost no quenching by metal-free H2Pc is observed. Time-correlated single photon counting (TCSPC) measurements corroborate the observed trend, indicating a decrease in the defect PL lifetime upon MPc adsorption, and the gate voltage-dependent PL reveals the suppression of the defect emission even at large Fermi level shifts. Density functional theory modeling argues that the MPc complexes stabilize dark negatively charged defects over luminescent neutral defects through an electrostatic local gating effect. These results demonstrate the control of defect-based excited-state decay pathways via molecular electronic structure tuning, which has broad implications for the design of mixed-dimensional optoelectronic devices.
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Affiliation(s)
- Samuel H Amsterdam
- Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Teodor K Stanev
- Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
| | - Luqing Wang
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States.,Department of Materials Science and Engineering and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Qunfei Zhou
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States.,Department of Materials Science and Engineering and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Shawn Irgen-Gioro
- Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Suyog Padgaonkar
- Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Akshay A Murthy
- Department of Materials Science and Engineering and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Vinod K Sangwan
- Department of Materials Science and Engineering and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Vinayak P Dravid
- Department of Materials Science and Engineering and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States.,Northwestern University Atomic and Nanoscale Characterization Experimental (NUANCE) Center, Evanston, Illinois 60208, United States
| | - Emily A Weiss
- Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States.,Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States.,Department of Materials Science and Engineering and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Pierre Darancet
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States.,Northwestern Argonne Institute of Science and Engineering, Evanston, Illinois 60208, United States
| | - Maria K Y Chan
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States.,Northwestern Argonne Institute of Science and Engineering, Evanston, Illinois 60208, United States
| | - Mark C Hersam
- Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States.,Department of Materials Science and Engineering and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States.,Department of Electrical and Computer Engineering and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Nathaniel P Stern
- Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
| | - Tobin J Marks
- Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States.,Department of Materials Science and Engineering and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
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17
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Yuan J, Liu SE, Shylendra A, Gaviria Rojas WA, Guo S, Bergeron H, Li S, Lee HS, Nasrin S, Sangwan VK, Trivedi AR, Hersam MC. Reconfigurable MoS 2 Memtransistors for Continuous Learning in Spiking Neural Networks. Nano Lett 2021; 21:6432-6440. [PMID: 34283622 DOI: 10.1021/acs.nanolett.1c00982] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Artificial intelligence and machine learning are growing computing paradigms, but current algorithms incur undesirable energy costs on conventional hardware platforms, thus motivating the exploration of more efficient neuromorphic architectures. Toward this end, we introduce here a memtransistor with gate-tunable dynamic learning behavior. By fabricating memtransistors from monolayer MoS2 grown on sapphire, the relative importance of the vertical field effect from the gate is enhanced, thereby heightening reconfigurability of the device response. Inspired by biological systems, gate pulses are used to modulate potentiation and depression, resulting in diverse learning curves and simplified spike-timing-dependent plasticity that facilitate unsupervised learning in simulated spiking neural networks. This capability also enables continuous learning, which is a previously underexplored cognitive concept in neuromorphic computing. Overall, this work demonstrates that the reconfigurability of memtransistors provides unique hardware accelerator opportunities for energy efficient artificial intelligence and machine learning.
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Affiliation(s)
- Jiangtan Yuan
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Stephanie E Liu
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Ahish Shylendra
- Department of Electrical and Computer Engineering, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - William A Gaviria Rojas
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Silu Guo
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Hadallia Bergeron
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Shaowei Li
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Hong-Sub Lee
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Shamma Nasrin
- Department of Electrical and Computer Engineering, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Amit Ranjan Trivedi
- Department of Electrical and Computer Engineering, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, Illinois 60208, United States
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18
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Gaviria Rojas WA, Beck ME, Sangwan VK, Guo S, Hersam MC. Ohmic-Contact-Gated Carbon Nanotube Transistors for High-Performance Analog Amplifiers. Adv Mater 2021; 33:e2100994. [PMID: 34270835 DOI: 10.1002/adma.202100994] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 04/14/2021] [Indexed: 06/13/2023]
Abstract
The growing demand for ubiquitous data collection has driven the development of sensing technologies with local data processing. As a result, solution-processed semiconductors are widely employed due to their compatibility with low-cost additive manufacturing on a wide range of substrates. However, to fully realize their potential in sensing applications, high-performance scalable analog amplifiers must be realized. Here, ohmic-contact-gated transistors (OCGTs) based on solution-processed semiconducting single-walled carbon nanotubes are introduced to address this unmet need. This new device concept enables output current saturation in the short-channel limit without compromising output current drive. The resulting OCGTs are used in common-source amplifiers to achieve the highest width-normalized output current (≈30 µA µm-1 ) and length-scaled signal gain (≈230 µm-1 ) to date for solution-processed semiconductors. The utility of these amplifiers for emerging sensing technologies is demonstrated by the amplification of complex millivolt-scale analog biological signals including the outputs of electromyography, photoplethysmogram, and accelerometer sensors. Since the OCGT design is compatible with other solution-processed semiconducting materials, this work establishes a general route to high-performance, solution-processed analog electronics.
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Affiliation(s)
- William A Gaviria Rojas
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Megan E Beck
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Silu Guo
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
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19
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Evans AM, Giri A, Sangwan VK, Xun S, Bartnof M, Torres-Castanedo CG, Balch HB, Rahn MS, Bradshaw NP, Vitaku E, Burke DW, Li H, Bedzyk MJ, Wang F, Brédas JL, Malen JA, McGaughey AJH, Hersam MC, Dichtel WR, Hopkins PE. Thermally conductive ultra-low-k dielectric layers based on two-dimensional covalent organic frameworks. Nat Mater 2021; 20:1142-1148. [PMID: 33737728 DOI: 10.1038/s41563-021-00934-3] [Citation(s) in RCA: 67] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 01/18/2021] [Indexed: 06/12/2023]
Abstract
As the features of microprocessors are miniaturized, low-dielectric-constant (low-k) materials are necessary to limit electronic crosstalk, charge build-up, and signal propagation delay. However, all known low-k dielectrics exhibit low thermal conductivities, which complicate heat dissipation in high-power-density chips. Two-dimensional (2D) covalent organic frameworks (COFs) combine immense permanent porosities, which lead to low dielectric permittivities, and periodic layered structures, which grant relatively high thermal conductivities. However, conventional synthetic routes produce 2D COFs that are unsuitable for the evaluation of these properties and integration into devices. Here, we report the fabrication of high-quality COF thin films, which enable thermoreflectance and impedance spectroscopy measurements. These measurements reveal that 2D COFs have high thermal conductivities (1 W m-1 K-1) with ultra-low dielectric permittivities (k = 1.6). These results show that oriented, layered 2D polymers are promising next-generation dielectric layers and that these molecularly precise materials offer tunable combinations of useful properties.
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Affiliation(s)
- Austin M Evans
- Department of Chemistry, Northwestern University, Evanston, IL, USA
| | - Ashutosh Giri
- Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA, USA
- Department of Mechanical, Industrial and Systems Engineering, University of Rhode Island, Kingston, RI, USA
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - Sangni Xun
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA
- Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, GA, USA
- College of Environmental Science and Engineering, Hunan University, Changsha, People's Republic of China
| | - Matthew Bartnof
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
| | | | - Halleh B Balch
- Department of Physics, University of California Berkeley, Berkeley, CA, USA
- Kavli Energy NanoScience Institute, University of California Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Matthew S Rahn
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - Nathan P Bradshaw
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - Edon Vitaku
- Department of Chemistry, Northwestern University, Evanston, IL, USA
| | - David W Burke
- Department of Chemistry, Northwestern University, Evanston, IL, USA
| | - Hong Li
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, AZ, USA
| | - Michael J Bedzyk
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
- Department of Physics and Astronomy, Northwestern University, Evanston, IL, USA
| | - Feng Wang
- Department of Physics, University of California Berkeley, Berkeley, CA, USA
- Kavli Energy NanoScience Institute, University of California Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Jean-Luc Brédas
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, AZ, USA
| | - Jonathan A Malen
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Alan J H McGaughey
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Mark C Hersam
- Department of Chemistry, Northwestern University, Evanston, IL, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, USA
- Simpson Querrey Institute, Northwestern University, Evanston, IL, USA
| | - William R Dichtel
- Department of Chemistry, Northwestern University, Evanston, IL, USA.
| | - Patrick E Hopkins
- Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA, USA.
- Department of Physics, University of Virginia, Charlottesville, VA, USA.
- Department of Materials Science and Engineering, University of Virginia, Charlottesville, VA, USA.
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20
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Gish JT, Lebedev D, Stanev TK, Jiang S, Georgopoulos L, Song TW, Lim G, Garvey ES, Valdman L, Balogun O, Sofer Z, Sangwan VK, Stern NP, Hersam MC. Ambient-Stable Two-Dimensional CrI 3 via Organic-Inorganic Encapsulation. ACS Nano 2021; 15:10659-10667. [PMID: 34101433 DOI: 10.1021/acsnano.1c03498] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Two-dimensional transitional metal halides have recently attracted significant attention due to their thickness-dependent and electrostatically tunable magnetic properties. However, this class of materials is highly reactive chemically, which leads to irreversible degradation and catastrophic dissolution within seconds in ambient conditions, severely limiting subsequent characterization, processing, and applications. Here, we impart long-term ambient stability to the prototypical transition metal halide CrI3 by assembling a noncovalent organic buffer layer, perylenetetracarboxylic dianhydride (PTCDA), which templates subsequent atomic layer deposition (ALD) of alumina. X-ray photoelectron spectroscopy demonstrates the necessity of the noncovalent organic buffer layer since the CrI3 undergoes deleterious surface reactions with the ALD precursors in the absence of PTCDA. This organic-inorganic encapsulation scheme preserves the long-range magnetic ordering in CrI3 down to the monolayer limit as confirmed by magneto-optical Kerr effect measurements. Furthermore, we demonstrate field-effect transistors, photodetectors, and optothermal measurements of CrI3 thermal conductivity in ambient conditions.
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Affiliation(s)
- J Tyler Gish
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Dmitry Lebedev
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Teodor K Stanev
- Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
| | - Shizhou Jiang
- Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Leonidas Georgopoulos
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Thomas W Song
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Gilhwan Lim
- Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
| | - Ethan S Garvey
- Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
| | - Lukáš Valdman
- Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague 6, Czech Republic
| | - Oluwaseyi Balogun
- Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Zdeněk Sofer
- Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague 6, Czech Republic
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Nathaniel P Stern
- Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, Illinois 60208, United States
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21
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Islam SM, Sangwan VK, Bruce Buchholz D, Wells SA, Peng L, Zeng L, He Y, Hersam MC, Ketterson JB, Marks TJ, Bedzyk MJ, Grayson M, Kanatzidis MG. Amorphous to Crystal Phase Change Memory Effect with Two-Fold Bandgap Difference in Semiconducting K 2Bi 8Se 13. J Am Chem Soc 2021; 143:6221-6228. [PMID: 33856803 DOI: 10.1021/jacs.1c01484] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Chalcogenide-based phase change memory (PCM) is a key enabling technology for optical data storage and electrical nonvolatile memory. Here, we report a new phase change chalcogenide consisting of a 3D network of ionic (K···Se) and covalent bonds (Bi-Se), K2Bi8Se13 (KBS). Thin films of amorphous KBS deposited by DC sputtering are structurally and chemically homogeneous and exhibit a surface roughness of 5 nm. The KBS film crystallizes upon heating at ∼483 K. The optical bandgap of the amorphous film is about 1.25 eV, while its crystalline phase has a bandgap of ∼0.65 eV shows 2-fold difference between the two states. The bulk electrical conductivity of the amorphous and crystalline film is ∼7.5 × 10-4 and ∼2.7 × 10-2 S/cm, respectively. We have demonstrated a phase change memory effect in KBS by Joule heating in a technologically relevant vertical memory cell architecture. Upon Joule heating, the vertical device undergoes switching from its amorphous to crystalline state of KBS at 1-1.5 V (∼50 kV/cm), increasing conductivity by a factor of ∼40. Besides the large electrical and optical contrast in the crystalline and amorphous KBS, its elemental cost-effectiveness, stoichiometry, fast crystallization kinetics, as determined by the ratio of the glass transition and melting temperature, Tg/Tm ∼ 0.5, as well as the scalable synthesis of the thin film determine that KBS is a promising PC material for next general phase change memory.
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Affiliation(s)
- Saiful M Islam
- Department of Chemistry, Physics and Atmospheric Sciences, Jackson State University, Jackson, Mississippi 39217, United States.,Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - D Bruce Buchholz
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Spencer A Wells
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Lintao Peng
- Graduate Program in Applied Physics, Northwestern University, Evanston, Illinois 60208, United States
| | - Li Zeng
- Graduate Program in Applied Physics, Northwestern University, Evanston, Illinois 60208, United States
| | - Yihui He
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Mark C Hersam
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.,Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States.,Graduate Program in Applied Physics, Northwestern University, Evanston, Illinois 60208, United States.,Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, Illinois 60208, United States
| | - John B Ketterson
- Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, Illinois 60208, United States.,Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
| | - Tobin J Marks
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.,Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States.,Graduate Program in Applied Physics, Northwestern University, Evanston, Illinois 60208, United States
| | - Michael J Bedzyk
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States.,Graduate Program in Applied Physics, Northwestern University, Evanston, Illinois 60208, United States.,Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
| | - Matthew Grayson
- Graduate Program in Applied Physics, Northwestern University, Evanston, Illinois 60208, United States.,Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, Illinois 60208, United States
| | - Mercouri G Kanatzidis
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.,Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
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22
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Li G, Zhang X, Jones LO, Alzola JM, Mukherjee S, Feng LW, Zhu W, Stern CL, Huang W, Yu J, Sangwan VK, DeLongchamp DM, Kohlstedt KL, Wasielewski MR, Hersam MC, Schatz GC, Facchetti A, Marks TJ. Systematic Merging of Nonfullerene Acceptor π-Extension and Tetrafluorination Strategies Affords Polymer Solar Cells with >16% Efficiency. J Am Chem Soc 2021; 143:6123-6139. [PMID: 33848146 DOI: 10.1021/jacs.1c00211] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The end-capping group (EG) is the essential electron-withdrawing component of nonfullerene acceptors (NFAs) in bulk heterojunction (BHJ) organic solar cells (OSCs). To systematically probe the impact of two frequent EG functionalization strategies, π-extension and halogenation, in A-DAD-A type NFAs, we synthesized and characterized four such NFAs: BT-BIC, LIC, L4F, and BO-L4F. To assess the relative importance of these strategies, we contrast these NFAs with the baseline acceptors, Y5 and Y6. Up to 16.6% power conversion efficiency (PCE) in binary inverted OSCs with BT-BO-L4F combining π-extension and halogenation was achieved. When these two factors are combined, the effect on optical absorption is cumulative. Single-crystal π-π stacking distances are similar for the EG strategies of π-extension. Increasing the alkyl substituent length from BT-L4F to BT-BO-L4F significantly alters the packing motif and eliminates the EG core interactions of BT-L4F. Electronic structure computations reveal some of the largest NFA π-π electronic couplings observed to date, 103.8 meV in BT-L4F and 47.5 meV in BT-BO-L4F. Computed electronic reorganization energies, 132 and 133 meV for BT-L4F and BT-BO-L4F, respectively, are also lower than Y6 (150 meV). BHJ blends show preferential π-face-on orientation, and both fluorination and π-extension increase NFA crystallinity. Femto/nanosecond transient absorption spectroscopy (fs/nsTA) and integrated photocurrent device analysis (IPDA) indicate that π-extension modifies the phase separation to enhance film ordering and carrier mobility, while fluorination suppresses unimolecular recombination. This systematic study highlights the synergistic effects of NFA π-extension and fluorination in affording efficient OSCs and provides insights into designing next-generation materials.
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Affiliation(s)
- Guoping Li
- Department of Chemistry, the Center for Light Energy Activated Redox Processes (LEAP), and the Materials Research Center (MRC), Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Xiaohua Zhang
- Department of Chemistry, the Center for Light Energy Activated Redox Processes (LEAP), and the Materials Research Center (MRC), Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.,State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China (UESTC), Chengdu, Sichuan 610054, P.R. China
| | - Leighton O Jones
- Department of Chemistry, the Center for Light Energy Activated Redox Processes (LEAP), and the Materials Research Center (MRC), Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Joaquin M Alzola
- Department of Chemistry, the Center for Light Energy Activated Redox Processes (LEAP), and the Materials Research Center (MRC), Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Subhrangsu Mukherjee
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Liang-Wen Feng
- Department of Chemistry, the Center for Light Energy Activated Redox Processes (LEAP), and the Materials Research Center (MRC), Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Weigang Zhu
- Department of Chemistry, the Center for Light Energy Activated Redox Processes (LEAP), and the Materials Research Center (MRC), Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.,Tianjin Key Laboratory of Molecular Optoelectronic Sciences (TJ-MOS), Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, China
| | - Charlotte L Stern
- Department of Chemistry, the Center for Light Energy Activated Redox Processes (LEAP), and the Materials Research Center (MRC), Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Wei Huang
- Department of Chemistry, the Center for Light Energy Activated Redox Processes (LEAP), and the Materials Research Center (MRC), Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Junsheng Yu
- State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China (UESTC), Chengdu, Sichuan 610054, P.R. China
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Dean M DeLongchamp
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Kevin L Kohlstedt
- Department of Chemistry, the Center for Light Energy Activated Redox Processes (LEAP), and the Materials Research Center (MRC), Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Michael R Wasielewski
- Department of Chemistry, the Center for Light Energy Activated Redox Processes (LEAP), and the Materials Research Center (MRC), Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Mark C Hersam
- Department of Chemistry, the Center for Light Energy Activated Redox Processes (LEAP), and the Materials Research Center (MRC), Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.,Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - George C Schatz
- Department of Chemistry, the Center for Light Energy Activated Redox Processes (LEAP), and the Materials Research Center (MRC), Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Antonio Facchetti
- Department of Chemistry, the Center for Light Energy Activated Redox Processes (LEAP), and the Materials Research Center (MRC), Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.,Flexterra Corporation, 8025 Lamon Avenue, Skokie, Illinois 60077, United States
| | - Tobin J Marks
- Department of Chemistry, the Center for Light Energy Activated Redox Processes (LEAP), and the Materials Research Center (MRC), Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.,Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
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23
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Amsterdam SH, LaMountain T, Stanev TK, Sangwan VK, López-Arteaga R, Padgaonkar S, Watanabe K, Taniguchi T, Weiss EA, Marks TJ, Hersam MC, Stern NP. Tailoring the Optical Response of Pentacene Thin Films via Templated Growth on Hexagonal Boron Nitride. J Phys Chem Lett 2021; 12:26-31. [PMID: 33296212 DOI: 10.1021/acs.jpclett.0c03132] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The optoelectronic properties of organic thin films are strongly dependent on their molecular orientation and packing, which in turn is sensitive to the underlying substrate. Hexagonal boron nitride (hBN) and other van der Waals (vdW) materials are known to template different organic thin film growth modalities from conventional inorganic substrates such as SiO2. Here, the morphology and temperature-dependent optical properties of pentacene films grown on hBN are reported. Pentacene deposited on hBN forms large-grain films with a molecular π-face-on orientation unlike the dendritic edge-on thin-film phase on SiO2. Pentacene/hBN films exhibit a 40 meV lower free exciton emission than pentacene/SiO2 and an unconventional emission energy temperature dependence. Time-resolved photoluminescence (PL) decay measurements show a long-lived signal in the π-face-on phase related to delayed emission from triplet-triplet fusion. This work demonstrates that growth on vdW materials provides a pathway for controlling optoelectronic functionality in molecular thin films.
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Affiliation(s)
- Samuel H Amsterdam
- Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Trevor LaMountain
- Applied Physics Program, Northwestern University, Evanston, Illinois 60208, United States
| | - Teodor K Stanev
- Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
| | - Vinod K Sangwan
- Department of Materials Science and Engineering and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Rafael López-Arteaga
- Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Suyog Padgaonkar
- Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Emily A Weiss
- Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
- Applied Physics Program, Northwestern University, Evanston, Illinois 60208, United States
- Department of Materials Science and Engineering and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Tobin J Marks
- Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
- Department of Materials Science and Engineering and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Mark C Hersam
- Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
- Applied Physics Program, Northwestern University, Evanston, Illinois 60208, United States
- Department of Materials Science and Engineering and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
- Department of Electrical Engineering and Computer Science and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Nathaniel P Stern
- Applied Physics Program, Northwestern University, Evanston, Illinois 60208, United States
- Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
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24
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Zhu W, Spencer AP, Mukherjee S, Alzola JM, Sangwan VK, Amsterdam SH, Swick SM, Jones LO, Heiber MC, Herzing AA, Li G, Stern CL, DeLongchamp DM, Kohlstedt KL, Hersam MC, Schatz GC, Wasielewski MR, Chen LX, Facchetti A, Marks TJ. Crystallography, Morphology, Electronic Structure, and Transport in Non-Fullerene/Non-Indacenodithienothiophene Polymer:Y6 Solar Cells. J Am Chem Soc 2020; 142:14532-14547. [PMID: 32698577 DOI: 10.1021/jacs.0c05560] [Citation(s) in RCA: 89] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Emerging nonfullerene acceptors (NFAs) with crystalline domains enable high-performance bulk heterojunction (BHJ) solar cells. Thermal annealing is known to enhance the BHJ photoactive layer morphology and performance. However, the microscopic mechanism of annealing-induced performance enhancement is poorly understood in emerging NFAs, especially regarding competing factors. Here, optimized thermal annealing of model system PBDB-TF:Y6 (Y6 = 2,2'-((2Z,2'Z)-((12,13-bis(2-ethylhexyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2″,3'':4',5']thieno[2',3':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]-thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile) decreases the open circuit voltage (VOC) but increases the short circuit current (JSC) and fill factor (FF) such that the resulting power conversion efficiency (PCE) increases from 14 to 15% in the ambient environment. Here we systematically investigate these thermal annealing effects through in-depth characterizations of carrier mobility, film morphology, charge photogeneration, and recombination using SCLC, GIXRD, AFM, XPS, NEXAFS, R-SoXS, TEM, STEM, fs/ns TA spectroscopy, 2DES, and impedance spectroscopy. Surprisingly, thermal annealing does not alter the film crystallinity, R-SoXS characteristic size scale, relative average phase purity, or TEM-imaged phase separation but rather facilitates Y6 migration to the BHJ film top surface, changes the PBDB-TF/Y6 vertical phase separation and intermixing, and reduces the bottom surface roughness. While these morphology changes increase bimolecular recombination (BR) and lower the free charge (FC) yield, they also increase the average electron and hole mobility by at least 2-fold. Importantly, the increased μh dominates and underlies the increased FF and PCE. Single-crystal X-ray diffraction reveals that Y6 molecules cofacially pack via their end groups/cores, with the shortest π-π distance as close as 3.34 Å, clarifying out-of-plane π-face-on molecular orientation in the nanocrystalline BHJ domains. DFT analysis of Y6 crystals reveals hole/electron reorganization energies of as low as 160/150 meV, large intermolecular electronic coupling integrals of 12.1-37.9 meV rationalizing the 3D electron transport, and relatively high μe of 10-4 cm2 V-1 s-1. Taken together, this work clarifies the richness of thermal annealing effects in high-efficiency NFA solar cells and tasks for future materials design.
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Affiliation(s)
| | | | - Subhrangsu Mukherjee
- Material Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, United States
| | | | | | | | | | | | - Michael C Heiber
- Material Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, United States
| | - Andrew A Herzing
- Material Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, United States
| | | | | | - Dean M DeLongchamp
- Material Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, United States
| | | | | | | | | | - Lin X Chen
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Antonio Facchetti
- Flexterra Corporation, 8025 Lamon Avenue, Skokie, Illinois 60077, United States
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25
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Abstract
Memristive and nanoionic devices have recently emerged as leading candidates for neuromorphic computing architectures. While top-down fabrication based on conventional bulk materials has enabled many early neuromorphic devices and circuits, bottom-up approaches based on low-dimensional nanomaterials have shown novel device functionality that often better mimics a biological neuron. In addition, the chemical, structural and compositional tunability of low-dimensional nanomaterials coupled with the permutational flexibility enabled by van der Waals heterostructures offers significant opportunities for artificial neural networks. In this Review, we present a critical survey of emerging neuromorphic devices and architectures enabled by quantum dots, metal nanoparticles, polymers, nanotubes, nanowires, two-dimensional layered materials and van der Waals heterojunctions with a particular emphasis on bio-inspired device responses that are uniquely enabled by low-dimensional topology, quantum confinement and interfaces. We also provide a forward-looking perspective on the opportunities and challenges of neuromorphic nanoelectronic materials in comparison with more mature technologies based on traditional bulk electronic materials.
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Affiliation(s)
- Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA.
- Department of Chemistry, Northwestern University, Evanston, IL, USA.
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, USA.
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26
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Li S, Zhong C, Henning A, Sangwan VK, Zhou Q, Liu X, Rahn MS, Wells SA, Park HY, Luxa J, Sofer Z, Facchetti A, Darancet P, Marks TJ, Lauhon LJ, Weiss EA, Hersam MC. Molecular-Scale Characterization of Photoinduced Charge Separation in Mixed-Dimensional InSe-Organic van der Waals Heterostructures. ACS Nano 2020; 14:3509-3518. [PMID: 32078300 DOI: 10.1021/acsnano.9b09661] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Layered indium selenide (InSe) is an emerging two-dimensional semiconductor that has shown significant promise for high-performance transistors and photodetectors. The range of optoelectronic applications for InSe can potentially be broadened by forming mixed-dimensional van der Waals heterostructures with zero-dimensional molecular systems that are widely employed in organic electronics and photovoltaics. Here, we report the spatially resolved investigation of photoinduced charge separation between InSe and two molecules (C70 and C8-BTBT) using scanning tunneling microscopy combined with laser illumination. We experimentally and computationally show that InSe forms type-II and type-I heterojunctions with C70 and C8-BTBT, respectively, due to an interplay of charge transfer and dielectric screening at the interface. Laser-excited scanning tunneling spectroscopy reveals a ∼0.25 eV decrease in the energy of the lowest unoccupied molecular orbital of C70 with optical illumination. Furthermore, photoluminescence spectroscopy and Kelvin probe force microscopy indicate that electron transfer from InSe to C70 in the type-II heterojunction induces a photovoltage that quantitatively matches the observed downshift in the tunneling spectra. In contrast, no significant changes are observed upon optical illumination in the type-I heterojunction formed between InSe and C8-BTBT. Density functional theory calculations further show that, despite the weak coupling between the molecular species and InSe, the band alignment of these mixed-dimensional heterostructures strongly differs from the one suggested by the ionization potential and electronic affinities of the isolated components. Self-energy-corrected density functional theory indicates that these effects are the result of the combination of charge redistribution at the interface and heterogeneous dielectric screening of the electron-electron interactions in the heterostructure. In addition to providing specific insight for mixed-dimensional InSe-organic van der Waals heterostructures, this work establishes a general experimental methodology for studying localized charge transfer at the molecular scale that is applicable to other photoactive nanoscale systems.
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Affiliation(s)
- Shaowei Li
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3108, United States
| | - Chengmei Zhong
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3108, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Alex Henning
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3108, United States
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3108, United States
| | - Qunfei Zhou
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Northwestern Argonne Institute for Science and Engineering, Evanston, Illinois 60208, United States
| | - Xiaolong Liu
- Applied Physics Graduate Program, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Matthew S Rahn
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3108, United States
| | - Spencer A Wells
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3108, United States
| | - Hong Youl Park
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3108, United States
| | - Jan Luxa
- Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague 6, Czech Republic
| | - Zdeněk Sofer
- Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague 6, Czech Republic
| | - Antonio Facchetti
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Pierre Darancet
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Northwestern Argonne Institute for Science and Engineering, Evanston, Illinois 60208, United States
| | - Tobin J Marks
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Lincoln J Lauhon
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3108, United States
| | - Emily A Weiss
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3108, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, United States
- Applied Physics Graduate Program, Northwestern University, Evanston, Illinois 60208-3113, United States
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27
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de Moraes ACM, Obrzut J, Sangwan VK, Downing JR, Chaney LE, Patel D, Elmquist RE, Hersam MC. Elucidating Charge Transport Mechanisms in Cellulose-Stabilized Graphene Inks. J Mater Chem C Mater 2020; 8:10.1039/D0TC03309J. [PMID: 34131488 PMCID: PMC8201474 DOI: 10.1039/d0tc03309j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Solution-processed graphene inks that use ethyl cellulose as a polymer stabilizer are blade-coated into large-area thin films. Following blade-coating, the graphene thin films are cured to pyrolyze the cellulosic polymer, leaving behind an sp2-rich amorphous carbon residue that serves as a binder in addition to facilitating charge transport between graphene flakes. Systematic charge transport measurements, including temperature-dependent Hall effect and non-contact microwave resonant cavity characterization, reveal that the resulting electrically percolating graphene thin films possess high mobility (≈ 160 cm2 V-1 s-1), low energy gap, and thermally activated charge transport, which develop weak localization behavior at cryogenic temperatures.
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Affiliation(s)
- Ana C M de Moraes
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Jan Obrzut
- Materials Science and Engineering Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Julia R Downing
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Lindsay E Chaney
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Dinesh Patel
- Quantum Measurements Division, Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Randolph E Elmquist
- Quantum Measurements Division, Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
- Department of Medicine, Northwestern University, Evanston, IL 60208, USA
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL 60208, USA
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28
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Sangwan VK, Zhu M, Clark S, Luck KA, Marks TJ, Kanatzidis MG, Hersam MC. Low-Frequency Carrier Kinetics in Perovskite Solar Cells. ACS Appl Mater Interfaces 2019; 11:14166-14174. [PMID: 30896169 DOI: 10.1021/acsami.9b03884] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Hybrid organic-inorganic halide perovskite solar cells have emerged as leading candidates for third-generation photovoltaic technology. Despite the rapid improvement in power conversion efficiency (PCE) for perovskite solar cells in recent years, the low-frequency carrier kinetics that underlie practical roadblocks such as hysteresis and degradation remain relatively poorly understood. In an effort to bridge this knowledge gap, we perform here correlated low-frequency noise (LFN) and impedance spectroscopy (IS) characterization that elucidates carrier kinetics in operating perovskite solar cells. Specifically, we focus on planar cell geometries with a SnO2 electron transport layer and two different hole transport layers-namely, poly(triarylamine) (PTAA) and spiro-OMeTAD. PTAA and spiro-OMeTAD cells with moderate PCEs of 5-12% possess a Lorentzian feature at ∼200 Hz in LFN measurements that corresponds to a crossover from electrode to dielectric polarization. In comparison, spiro-OMeTAD cells with high PCEs (>15%) show 4 orders of magnitude lower LFN amplitude and are accompanied by a cyclostationary process. Through a systematic study of more than a dozen solar cells, we establish a correlation with noise amplitude, PCE, and fill factor. Overall, this work establishes correlated LFN and IS as an effective methodology for quantifying low-frequency carrier kinetics in perovskite solar cells, thereby providing new physical insights that can rationally guide ongoing efforts to improve device performance, reproducibility, and stability.
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Affiliation(s)
| | - Menghua Zhu
- Wuhan National Laboratory for Optoelectronics (WNLO) , Huazhong University of Science and Technology (HUST) , Wuhan 430074 , China
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29
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Seo JWT, Zhu J, Sangwan VK, Secor EB, Wallace SG, Hersam MC. Fully Inkjet-Printed, Mechanically Flexible MoS 2 Nanosheet Photodetectors. ACS Appl Mater Interfaces 2019; 11:5675-5681. [PMID: 30693759 DOI: 10.1021/acsami.8b19817] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Solution-processed two-dimensional materials offer a scalable route toward next-generation printed devices. In this report, we demonstrate fully inkjet-printed photodetectors using molybdenum disulfide (MoS2) nanosheets as the active material and graphene as the electrodes. Percolating films of semiconducting MoS2 with high electrical conductivity are achieved with an ethyl cellulose-based ink formulation. Two classes of photodetectors are fabricated, including thermally annealed devices on glass with fast photoresponse of 150 μs and photonically annealed devices on flexible polyimide with high photoresponsivity exceeding 50 mA/W. The photonically annealed photodetector also reduces the curing time to milliseconds and maintains functionality over 500 bending cycles.
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30
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Zhong C, Sangwan VK, Kang J, Luxa J, Sofer Z, Hersam MC, Weiss EA. Hot Carrier and Surface Recombination Dynamics in Layered InSe Crystals. J Phys Chem Lett 2019; 10:493-499. [PMID: 30642181 DOI: 10.1021/acs.jpclett.8b03543] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Layered indium selenide (InSe) is a van der Waals solid that has emerged as a promising material for high-performance ultrathin solar cells. The optoelectronic parameters that are critical to photoconversion efficiencies, such as hot carrier lifetime and surface recombination velocity, are however largely unexplored in InSe. Here, these key photophysical properties of layered InSe are measured with femtosecond transient reflection spectroscopy. The hot carrier cooling process is found to occur through phonon scattering. The surface recombination velocity and ambipolar diffusion coefficient are extracted from fits to the pump energy-dependent transient reflection kinetics using a free carrier diffusion model. The extracted surface recombination velocity is approximately an order of magnitude larger than that for methylammonium lead-iodide perovskites, suggesting that surface recombination is a principal source of photocarrier loss in InSe. The extracted ambipolar diffusion coefficient is consistent with previously reported values of InSe carrier mobility.
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Affiliation(s)
- Chengmei Zhong
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
| | - Vinod K Sangwan
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
| | - Joohoon Kang
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
| | - Jan Luxa
- Department of Inorganic Chemistry , University of Chemistry and Technology Prague , Technicka 5 , 166 28 Prague 6, Czech Republic
| | - Zdeněk Sofer
- Department of Inorganic Chemistry , University of Chemistry and Technology Prague , Technicka 5 , 166 28 Prague 6, Czech Republic
| | - Mark C Hersam
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
| | - Emily A Weiss
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
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31
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Chen Y, Huang W, Sangwan VK, Wang B, Zeng L, Wang G, Huang Y, Lu Z, Bedzyk MJ, Hersam MC, Marks TJ, Facchetti A. Polymer Doping Enables a Two-Dimensional Electron Gas for High-Performance Homojunction Oxide Thin-Film Transistors. Adv Mater 2019; 31:e1805082. [PMID: 30499146 DOI: 10.1002/adma.201805082] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Revised: 10/10/2018] [Indexed: 05/04/2023]
Abstract
High-performance solution-processed metal oxide (MO) thin-film transistors (TFTs) are realized by fabricating a homojunction of indium oxide (In2 O3 ) and polyethylenimine (PEI)-doped In2 O3 (In2 O3 :x% PEI, x = 0.5-4.0 wt%) as the channel layer. A two-dimensional electron gas (2DEG) is thereby achieved by creating a band offset between the In2 O3 and PEI-In2 O3 via work function tuning of the In2 O3 :x% PEI, from 4.00 to 3.62 eV as the PEI content is increased from 0.0 (pristine In2 O3 ) to 4.0 wt%, respectively. The resulting devices achieve electron mobilities greater than 10 cm2 V-1 s-1 on a 300 nm SiO2 gate dielectric. Importantly, these metrics exceed those of the devices composed of the pristine In2 O3 materials, which achieve a maximum mobility of ≈4 cm2 V-1 s-1 . Furthermore, a mobility as high as 30 cm2 V-1 s-1 is achieved on a high-k ZrO2 dielectric in the homojunction devices. This is the first demonstration of 2DEG-based homojunction oxide TFTs via band offset achieved by simple polymer doping of the same MO material.
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Affiliation(s)
- Yao Chen
- Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
- Key Laboratory of Green Chemistry and Technology (Ministry of Education), College of Chemistry, Sichuan University, Chengdu, 610064, P. R. China
| | - Wei Huang
- Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Binghao Wang
- Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Li Zeng
- Applied Physics Program and the Materials Research Center, Northwestern University, 2220 Campus Drive, Evanston, IL, 60208, USA
| | - Gang Wang
- Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Yan Huang
- Key Laboratory of Green Chemistry and Technology (Ministry of Education), College of Chemistry, Sichuan University, Chengdu, 610064, P. R. China
| | - Zhiyun Lu
- Key Laboratory of Green Chemistry and Technology (Ministry of Education), College of Chemistry, Sichuan University, Chengdu, 610064, P. R. China
| | - Michael J Bedzyk
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
- Applied Physics Program and the Materials Research Center, Northwestern University, 2220 Campus Drive, Evanston, IL, 60208, USA
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Tobin J Marks
- Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
- Department of Materials Science and Engineering and the Argonne Northwestern Solar Energy Research Center (ANSER), Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Antonio Facchetti
- Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
- Flexterra Inc., 8025 Lamon Avenue, Skokie, IL, 60077, USA
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32
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Wells SA, Henning A, Gish JT, Sangwan VK, Lauhon LJ, Hersam MC. Suppressing Ambient Degradation of Exfoliated InSe Nanosheet Devices via Seeded Atomic Layer Deposition Encapsulation. Nano Lett 2018; 18:7876-7882. [PMID: 30418785 DOI: 10.1021/acs.nanolett.8b03689] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
With exceptional charge carrier mobilities and a direct bandgap at most thicknesses, indium selenide (InSe) is an emerging layered semiconductor that has generated significant interest for electronic and optoelectronic applications. However, exfoliated InSe nanosheets are susceptible to rapid degradation in ambient conditions, thus limiting their technological potential. In addition to morphological changes upon ambient exposure, the mobilities and current modulation on/off ratios of InSe transistors, as well as the responsivities of InSe photodetectors, decrease by over 3 orders of magnitude within 12 h of ambient exposure. In an effort to mitigate these deleterious effects, here we present an encapsulation scheme based on seeded atomic layer deposition that provides pinhole-free growth of alumina without compromising the intrinsic electronic properties of the underlying InSe. In particular, this encapsulation provides reproducible InSe field-effect transistor characteristics and InSe photodetector responsivities in excess of 107 A/W following ambient exposure for time periods on the order of months. Because atomic layer deposition is a highly scalable and manufacturable process, this work will accelerate ongoing efforts to integrate InSe nanosheets into electronic and optoelectronic technologies.
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Affiliation(s)
- Spencer A Wells
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
| | - Alex Henning
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
| | - J Tyler Gish
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
| | - Vinod K Sangwan
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
| | - Lincoln J Lauhon
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
| | - Mark C Hersam
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
- Department of Electrical Engineering and Computer Science , Northwestern University , Evanston , Illinois 60208 , United States
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33
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Islam SM, Sangwan VK, Li Y, Kang J, Zhang X, He Y, Zhao J, Murthy A, Ma S, Dravid VP, Hersam MC, Kanatzidis MG. Abrupt Thermal Shock of (NH 4) 2Mo 3S 13 Leads to Ultrafast Synthesis of Porous Ensembles of MoS 2 Nanocrystals for High Gain Photodetectors. ACS Appl Mater Interfaces 2018; 10:38193-38200. [PMID: 30299078 DOI: 10.1021/acsami.8b12406] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Ultrafast synthesis of high-quality transition-metal dichalcogenide nanocrystals, such as molybdenum disulfide (MoS2), is technologically relevant for large-scale production of electronic and optoelectronic devices. Here, we report a rapid solid-state synthesis route for MoS2 using the chemically homogeneous molecular precursor, (NH4)2Mo3S13·H2O, resulting in nanoparticles with estimated size down to 25 nm only in 10 s at 1000 °C. Despite the extreme nonequilibrium conditions, the resulting porous MoS2 nanoparticles remain aggregated to preserve the form of the original rod shape bulk morphology of the molecular precursor. This ultrafast synthesis proceeds through the rapid decomposition of the precursor and rearrangement of Mo and S atoms coupled with simultaneous efficient release of massive gaseous species, to create nanoscale porosity in the resulting isomorphic pseudocrystals, which are composed of the MoS2 nanoparticles. Despite the very rapid escape of massive amounts of NH3, H2O, H2S, and S gases from the (NH4)2Mo3S13·H2O mm sized crystals, they retain their original shape as they convert to MoS2 rather than undergo explosive destruction from the rapid escape process of the gases. The obtained pseudocrystals are made of aggregated MoS2 nanocrystals exhibit a Brunauer-Emmett-Teller surface area of ∼35 m2/g with an adsorption average pore width of ∼160 Å. The nanoporous MoS2 crystals are solution processable by dispersing in ethanol and water and can be cast into large-area uniform composite films. Photodetectors fabricated from these films show more than 2 orders of magnitude higher conductivity (∼6.25 × 10-6 S/cm) and photoconductive gain (20 mA/W) than previous reports of MoS2 composite films. The optoelectronic properties of this nanoporous MoS2 imply that the shallow defects that originate from the ultrafast synthesis act as sensitizing centers that increase the photocurrent gain via two-level recombination kinetics.
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Affiliation(s)
- Saiful M Islam
- Department of Chemistry, Physics and Atmospheric Sciences , Jackson State University , Jackson , Mississippi 39217 , United States
| | | | | | | | | | | | | | | | - Shulan Ma
- College of Chemistry , Beijing Normal University , Beijing 100875 , China
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34
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Kang J, Wells SA, Sangwan VK, Lam D, Liu X, Luxa J, Sofer Z, Hersam MC. Solution-Based Processing of Optoelectronically Active Indium Selenide. Adv Mater 2018; 30:e1802990. [PMID: 30095182 DOI: 10.1002/adma.201802990] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 07/23/2018] [Indexed: 05/24/2023]
Abstract
Layered indium selenide (InSe) presents unique properties for high-performance electronic and optoelectronic device applications. However, efforts to process InSe using traditional liquid phase exfoliation methods based on surfactant-assisted aqueous dispersions or organic solvents with high boiling points compromise electronic properties due to residual surface contamination and chemical degradation. Here, these limitations are overcome by utilizing a surfactant-free, low boiling point, deoxygenated cosolvent system. The resulting InSe flakes and thin films possess minimal processing residues and are structurally and chemically pristine. When employed in photodetectors, individual InSe nanosheets exhibit a maximum photoresponsivity of ≈5 × 107 A W-1 , which is the highest value of any solution-processed monolithic semiconductor to date. Furthermore, the surfactant-free cosolvent system not only stabilizes InSe dispersions but is also amenable to the assembly of electronically percolating InSe flake arrays without posttreatment, which enables the realization of ultrahigh performance thin-film photodetectors. This surfactant-free, deoxygenated cosolvent approach can be generalized to other layered materials, thereby presenting additional opportunities for solution-processed thin-film electronic and optoelectronic technologies.
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Affiliation(s)
- Joohoon Kang
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Spencer A Wells
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - David Lam
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Xiaolong Liu
- Applied Physics Graduate Program, Northwestern University, Evanston, IL, 60208, USA
| | - Jan Luxa
- Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague 6, Czech Republic
| | - Zdeněk Sofer
- Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague 6, Czech Republic
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
- Applied Physics Graduate Program, Northwestern University, Evanston, IL, 60208, USA
- Department of Chemistry, Electrical Engineering and Computer Science, Northwestern University, Evanston, IL, 60208, USA
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35
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Senanayak SP, Sangwan VK, McMorrow JJ, Everaerts K, Chen Z, Facchetti A, Hersam MC, Marks TJ, Narayan KS. Self-Assembled Photochromic Molecular Dipoles for High-Performance Polymer Thin-Film Transistors. ACS Appl Mater Interfaces 2018; 10:21492-21498. [PMID: 29847908 DOI: 10.1021/acsami.8b05401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The development of high-performance multifunctional polymer-based electronic circuits is a major step toward future flexible electronics. Here, we demonstrate a tunable approach to fabricate such devices based on rationally designed dielectric super-lattice structures with photochromic azobenzene molecules. These nanodielectrics possessing ionic, molecular, and atomic polarization are utilized in polymer thin-film transistors (TFTs) to realize high-performance electronics with a p-type field-effect mobility (μFET) exceeding 2 cm2 V-1 s-1. A crossover in the transport mechanism from electrostatic dipolar disorder to ionic-induced disorder is observed in the transistor characteristics over a range of temperatures. The facile supramolecular design allows the possibility to optically control the extent of molecular and ionic polarization in the ultrathin nanodielectric. Thus, we demonstrate a 3-fold increase in the capacitance from 0.1 to 0.34 μF/cm2, which results in a 200% increase in TFT channel current.
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Affiliation(s)
- Satyaprasad P Senanayak
- Chemistry and Physics of Materials Unit , Jawaharlal Nehru Centre for Advanced Scientific Research , Bangalore 560064 , India
- Optoelectronics Group , Cavendish Laboratory, University of Cambridge , JJ Thomson Avenue , Cambridge CB3 0HE , U.K
| | | | | | | | - Zhihua Chen
- Flexterra Inc. , 8025 Lamon Avenue , Skokie , Illinois 60077 , United States
| | - Antonio Facchetti
- Flexterra Inc. , 8025 Lamon Avenue , Skokie , Illinois 60077 , United States
| | | | | | - K S Narayan
- Chemistry and Physics of Materials Unit , Jawaharlal Nehru Centre for Advanced Scientific Research , Bangalore 560064 , India
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36
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Zhong C, Sangwan VK, Wang C, Bergeron H, Hersam MC, Weiss EA. Mechanisms of Ultrafast Charge Separation in a PTB7/Monolayer MoS 2 van der Waals Heterojunction. J Phys Chem Lett 2018; 9:2484-2491. [PMID: 29688016 DOI: 10.1021/acs.jpclett.8b00628] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Mixed-dimensional van der Waals heterojunctions comprising polymer and two-dimensional (2D) semiconductors have many characteristics of an ideal charge separation interface for optoelectronic and photonic applications. However, the photoelectron dynamics at polymer-2D semiconductor heterojunction interfaces are currently not sufficiently understood to guide the optimization of devices for these applications. This Letter reports a systematic exploration of the time-dependent photophysical processes that occur upon photoexcitation of a type-II heterojunction between the polymer PTB7 and monolayer MoS2. In particular, photoinduced electron transfer from PTB7 to electronically hot states of MoS2 occurs in less than 250 fs. This process is followed by a 1-5 ps exciton diffusion-limited electron transfer from PTB7 to MoS2 and a sub-3 ps photoinduced hole transfer from MoS2 to PTB7. The equilibrium between excitons and polaron pairs in PTB7 determines the charge separation yield, whereas the 3-4 ns lifetime of photogenerated carriers is probably limited by MoS2 defects.
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Affiliation(s)
- Chengmei Zhong
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208-3113 , United States
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208-3108 , United States
| | - Vinod K Sangwan
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208-3108 , United States
| | - Chen Wang
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208-3113 , United States
| | - Hadallia Bergeron
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208-3108 , United States
| | - Mark C Hersam
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208-3113 , United States
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208-3108 , United States
- Department of Electrical Engineering and Computer Science , Northwestern University , Evanston , Illinois 60208-3108 , United States
| | - Emily A Weiss
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208-3113 , United States
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208-3108 , United States
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37
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Henning A, Sangwan VK, Bergeron H, Balla I, Sun Z, Hersam MC, Lauhon LJ. Charge Separation at Mixed-Dimensional Single and Multilayer MoS 2/Silicon Nanowire Heterojunctions. ACS Appl Mater Interfaces 2018; 10:16760-16767. [PMID: 29682958 DOI: 10.1021/acsami.8b03133] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Layered two-dimensional (2-D) semiconductors can be combined with other low-dimensional semiconductors to form nonplanar mixed-dimensional van der Waals (vdW) heterojunctions whose charge transport behavior is influenced by the heterojunction geometry, providing a new degree of freedom to engineer device functions. Toward that end, we investigated the photoresponse of Si nanowire/MoS2 heterojunction diodes with scanning photocurrent microscopy and time-resolved photocurrent measurements. Comparison of n-Si/MoS2 isotype heterojunctions with p-Si/MoS2 heterojunction diodes under varying biases shows that the depletion region in the p-n heterojunction promotes exciton dissociation and carrier collection. We measure an instrument-limited response time of 1 μs, which is 10 times faster than the previously reported response times for planar Si/MoS2 devices, highlighting the advantages of the 1-D/2-D heterojunction. Finite element simulations of device models provide a detailed understanding of how the electrostatics affect charge transport in nanowire/vdW heterojunctions and inform the design of future vdW heterojunction photodetectors and transistors.
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Affiliation(s)
- Vinod K. Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA
| | - Mark C. Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA
- Department of Chemistry and Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, Illinois 60208, USA
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39
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Sangwan VK, Lee HS, Bergeron H, Balla I, Beck ME, Chen KS, Hersam MC. Multi-terminal memtransistors from polycrystalline monolayer molybdenum disulfide. Nature 2018; 554:500-504. [DOI: 10.1038/nature25747] [Citation(s) in RCA: 494] [Impact Index Per Article: 82.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 12/19/2017] [Indexed: 12/22/2022]
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40
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Sangwan VK, Beck ME, Henning A, Luo J, Bergeron H, Kang J, Balla I, Inbar H, Lauhon LJ, Hersam MC. Self-Aligned van der Waals Heterojunction Diodes and Transistors. Nano Lett 2018; 18:1421-1427. [PMID: 29385342 DOI: 10.1021/acs.nanolett.7b05177] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A general self-aligned fabrication scheme is reported here for a diverse class of electronic devices based on van der Waals materials and heterojunctions. In particular, self-alignment enables the fabrication of source-gated transistors in monolayer MoS2 with near-ideal current saturation characteristics and channel lengths down to 135 nm. Furthermore, self-alignment of van der Waals p-n heterojunction diodes achieves complete electrostatic control of both the p-type and n-type constituent semiconductors in a dual-gated geometry, resulting in gate-tunable mean and variance of antiambipolar Gaussian characteristics. Through finite-element device simulations, the operating principles of source-gated transistors and dual-gated antiambipolar devices are elucidated, thus providing design rules for additional devices that employ self-aligned geometries. For example, the versatility of this scheme is demonstrated via contact-doped MoS2 homojunction diodes and mixed-dimensional heterojunctions based on organic semiconductors. The scalability of this approach is also shown by fabricating self-aligned short-channel transistors with subdiffraction channel lengths in the range of 150-800 nm using photolithography on large-area MoS2 films grown by chemical vapor deposition. Overall, this self-aligned fabrication method represents an important step toward the scalable integration of van der Waals heterojunction devices into more sophisticated circuits and systems.
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Affiliation(s)
- Vinod K Sangwan
- Department of Materials Science and Engineering, ‡Department of Chemistry, and §Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States
| | - Megan E Beck
- Department of Materials Science and Engineering, ‡Department of Chemistry, and §Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States
| | - Alex Henning
- Department of Materials Science and Engineering, ‡Department of Chemistry, and §Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States
| | - Jiajia Luo
- Department of Materials Science and Engineering, ‡Department of Chemistry, and §Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States
| | - Hadallia Bergeron
- Department of Materials Science and Engineering, ‡Department of Chemistry, and §Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States
| | - Junmo Kang
- Department of Materials Science and Engineering, ‡Department of Chemistry, and §Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States
| | - Itamar Balla
- Department of Materials Science and Engineering, ‡Department of Chemistry, and §Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States
| | - Hadass Inbar
- Department of Materials Science and Engineering, ‡Department of Chemistry, and §Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States
| | - Lincoln J Lauhon
- Department of Materials Science and Engineering, ‡Department of Chemistry, and §Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States
| | - Mark C Hersam
- Department of Materials Science and Engineering, ‡Department of Chemistry, and §Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States
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Behranginia A, Yasaei P, Majee AK, Sangwan VK, Long F, Foss CJ, Foroozan T, Fuladi S, Hantehzadeh MR, Shahbazian-Yassar R, Hersam MC, Aksamija Z, Salehi-Khojin A. Direct Growth of High Mobility and Low-Noise Lateral MoS 2 -Graphene Heterostructure Electronics. Small 2017; 13:1604301. [PMID: 28626881 DOI: 10.1002/smll.201604301] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 04/24/2017] [Indexed: 05/28/2023]
Abstract
Reliable fabrication of lateral interfaces between conducting and semiconducting 2D materials is considered a major technological advancement for the next generation of highly packed all-2D electronic circuitry. This study employs seed-free consecutive chemical vapor deposition processes to synthesize high-quality lateral MoS2 -graphene heterostructures and comprehensively investigated their electronic properties through a combination of various experimental techniques and theoretical modeling. These results show that the MoS2 -graphene devices exhibit an order of magnitude higher mobility and lower noise metrics compared to conventional MoS2 -metal devices as a result of energy band rearrangement and smaller Schottky barrier height at the contacts. These findings suggest that MoS2 -graphene in-plane heterostructures are promising materials for the scale-up of all-2D circuitry with superlative electrical performance.
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Affiliation(s)
- Amirhossein Behranginia
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Poya Yasaei
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Arnab K Majee
- Electrical and Computer Engineering Department, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Fei Long
- Department of Mechanical Engineering, University of Michigan Tech, Houghton, MI, 49931, USA
| | - Cameron J Foss
- Electrical and Computer Engineering Department, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Tara Foroozan
- Department of Civil and Material Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Shadi Fuladi
- Department of Physics, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Mohammad Reza Hantehzadeh
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Reza Shahbazian-Yassar
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
- Department of Chemistry, Northwestern University, Evanston, IL, 60208, USA
| | - Zlatan Aksamija
- Electrical and Computer Engineering Department, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Amin Salehi-Khojin
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA
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Abstract
Exfoliation of single-layer graphene from bulk graphite and the subsequent discovery of exotic physics and emergent phenomena in the atomically thin limit has motivated the isolation of other two-dimensional (2D) layered nanomaterials. Early work on isolated 2D nanomaterial flakes has revealed a broad range of unique physical and chemical properties with potential utility in diverse applications. For example, the electronic and optical properties of 2D nanomaterials depend strongly on atomic-scale variations in thickness, enabling enhanced performance in optoelectronic technologies such as light emitters, photodetectors, and photovoltaics. Much of the initial research on 2D nanomaterials has relied on micromechanical exfoliation, which yields high-quality 2D nanomaterial flakes that are suitable for fundamental studies but possesses limited scalability for real-world applications. In an effort to overcome this limitation, solution-processing methods for isolating large quantities of 2D nanomaterials have emerged. Importantly, solution processing results in 2D nanomaterial dispersions that are amenable to roll-to-roll fabrication methods that underlie lost-cost manufacturing of thin-film transistors, transparent conductors, energy storage devices, and solar cells. Despite these advantages, solution-based exfoliation methods typically lack control over the lateral size and thickness of the resulting 2D nanomaterial flakes, resulting in polydisperse dispersions with heterogeneous properties. Therefore, post-exfoliation separation techniques are needed to achieve 2D nanomaterial dispersions with monodispersity in lateral size, thickness, and properties. In this Account, we survey the latest developments in solution-based separation methods that aim to produce monodisperse dispersions and thin films of emerging 2D nanomaterials such as graphene, boron nitride, transition metal dichalcogenides, and black phosphorus. First, we motivate the need for precise thickness control in 2D nanomaterials by reviewing thickness-dependent physical properties. Then we present a succinct survey of solution-based exfoliation methods that yield 2D nanomaterial dispersions in organic solvents and aqueous media. The Account subsequently focuses on separation methods, including a critical analysis of their relative strengths and weaknesses for 2D nanomaterials with different buoyant densities, van der Waals interactions, and chemical reactivities. Specifically, we evaluate sedimentation-based density gradient ultracentrifugation (sDGU) and isopycnic DGU (iDGU) for post-exfoliation 2D nanomaterial dispersion separation. The comparative advantages of sedimentation and isopycnic methods are presented in both aqueous and nonaqueous media for 2D nanomaterials with varying degrees of chemical reactivity. Finally, we survey methods for forming homogeneous thin films from 2D nanomaterial dispersions and emerging technologies that are likely to benefit from these structures. Overall, this Account provides not only an overview of the present state-of-the-art but also a forward-looking vision for the field of solution-processed monodisperse 2D nanomaterials.
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Affiliation(s)
- Joohoon Kang
- Department
of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Vinod K. Sangwan
- Department
of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Joshua D. Wood
- Department
of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Mark C. Hersam
- Department
of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Graduate
Program in Applied Physics, Northwestern University, Evanston, Illinois 60208, United States
- Department
of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Department
of Medicine, Northwestern University, Evanston, Illinois 60208, United States
- Department
of Electrical Engineering and Computer Science, Northwestern University, Evanston, Illinois 60208, United States
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43
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Chen KS, Xu R, Luu NS, Secor EB, Hamamoto K, Li Q, Kim S, Sangwan VK, Balla I, Guiney LM, Seo JWT, Yu X, Liu W, Wu J, Wolverton C, Dravid VP, Barnett SA, Lu J, Amine K, Hersam MC. Comprehensive Enhancement of Nanostructured Lithium-Ion Battery Cathode Materials via Conformal Graphene Dispersion. Nano Lett 2017; 17:2539-2546. [PMID: 28240911 DOI: 10.1021/acs.nanolett.7b00274] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Efficient energy storage systems based on lithium-ion batteries represent a critical technology across many sectors including consumer electronics, electrified transportation, and a smart grid accommodating intermittent renewable energy sources. Nanostructured electrode materials present compelling opportunities for high-performance lithium-ion batteries, but inherent problems related to the high surface area to volume ratios at the nanometer-scale have impeded their adoption for commercial applications. Here, we demonstrate a materials and processing platform that realizes high-performance nanostructured lithium manganese oxide (nano-LMO) spinel cathodes with conformal graphene coatings as a conductive additive. The resulting nanostructured composite cathodes concurrently resolve multiple problems that have plagued nanoparticle-based lithium-ion battery electrodes including low packing density, high additive content, and poor cycling stability. Moreover, this strategy enhances the intrinsic advantages of nano-LMO, resulting in extraordinary rate capability and low temperature performance. With 75% capacity retention at a 20C cycling rate at room temperature and nearly full capacity retention at -20 °C, this work advances lithium-ion battery technology into unprecedented regimes of operation.
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Affiliation(s)
- Kan-Sheng Chen
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Rui Xu
- Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Norman S Luu
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Ethan B Secor
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Koichi Hamamoto
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Qianqian Li
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Soo Kim
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Itamar Balla
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Linda M Guiney
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Jung-Woo T Seo
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Xiankai Yu
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Weiwei Liu
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Jinsong Wu
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Chris Wolverton
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Vinayak P Dravid
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Scott A Barnett
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Jun Lu
- Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Khalil Amine
- Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
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44
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Bettis Homan S, Sangwan VK, Balla I, Bergeron H, Weiss EA, Hersam MC. Ultrafast Exciton Dissociation and Long-Lived Charge Separation in a Photovoltaic Pentacene-MoS 2 van der Waals Heterojunction. Nano Lett 2017; 17:164-169. [PMID: 28073273 DOI: 10.1021/acs.nanolett.6b03704] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
van der Waals heterojunctions between two-dimensional (2D) layered materials and nanomaterials of different dimensions present unique opportunities for gate-tunable optoelectronic devices. Mixed-dimensional p-n heterojunction diodes, such as p-type pentacene (0D) and n-type monolayer MoS2 (2D), are especially interesting for photovoltaic applications where the absorption cross-section and charge transfer processes can be tailored by rational selection from the vast library of organic molecules and 2D materials. Here, we study the kinetics of excited carriers in pentacene-MoS2 p-n type-II heterojunctions by transient absorption spectroscopy. These measurements show that the dissociation of MoS2 excitons occurs by hole transfer to pentacene on the time scale of 6.7 ps. In addition, the charge-separated state lives for 5.1 ns, up to an order of magnitude longer than the recombination lifetimes from previously reported 2D material heterojunctions. By studying the fractional amplitudes of the MoS2 decay processes, the hole transfer yield from MoS2 to pentacene is found to be ∼50%, with the remaining holes undergoing trapping due to surface defects. Overall, the ultrafast charge transfer and long-lived charge-separated state in pentacene-MoS2 p-n heterojunctions suggest significant promise for mixed-dimensional van der Waals heterostructures in photovoltaics, photodetectors, and related optoelectronic technologies.
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Affiliation(s)
- Stephanie Bettis Homan
- Department of Chemistry and ‡Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Vinod K Sangwan
- Department of Chemistry and ‡Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Itamar Balla
- Department of Chemistry and ‡Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Hadallia Bergeron
- Department of Chemistry and ‡Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Emily A Weiss
- Department of Chemistry and ‡Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Mark C Hersam
- Department of Chemistry and ‡Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
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45
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Kang J, Sangwan VK, Wood JD, Liu X, Balla I, Lam D, Hersam MC. Layer-by-Layer Sorting of Rhenium Disulfide via High-Density Isopycnic Density Gradient Ultracentrifugation. Nano Lett 2016; 16:7216-7223. [PMID: 27700101 DOI: 10.1021/acs.nanolett.6b03584] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Isopycnic density gradient ultracentrifugation (iDGU) has been widely applied to sort nanomaterials by their physical and electronic structure. However, the commonly used density-gradient medium iodixanol has a finite maximum buoyant density that prevents the use of iDGU for high-density nanomaterials. Here, we overcome this limit by adding cesium chloride (CsCl) to iodixanol, thus increasing its maximum buoyant density to the point where the high-density two-dimensional nanomaterial rhenium disulfide (ReS2) can be sorted in a layer-by-layer manner with iDGU. The resulting aqueous ReS2 dispersions show photoluminescence at ∼1.5 eV, which is consistent with its direct bandgap semiconductor electronic structure. Furthermore, photocurrent measurements on thin films formed from solution-processed ReS2 show a spectral response that is consistent with optical absorbance and photoluminescence data. In addition to providing a pathway for effective solution processing of ReS2, this work establishes a general methodology for sorting high-density nanomaterials via iDGU.
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Affiliation(s)
- Joohoon Kang
- Department of Materials Science and Engineering, ‡Graduate Program in Applied Physics, §Department of Chemistry, ∥Department of Medicine and ⊥Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, ‡Graduate Program in Applied Physics, §Department of Chemistry, ∥Department of Medicine and ⊥Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States
| | - Joshua D Wood
- Department of Materials Science and Engineering, ‡Graduate Program in Applied Physics, §Department of Chemistry, ∥Department of Medicine and ⊥Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States
| | - Xiaolong Liu
- Department of Materials Science and Engineering, ‡Graduate Program in Applied Physics, §Department of Chemistry, ∥Department of Medicine and ⊥Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States
| | - Itamar Balla
- Department of Materials Science and Engineering, ‡Graduate Program in Applied Physics, §Department of Chemistry, ∥Department of Medicine and ⊥Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States
| | - David Lam
- Department of Materials Science and Engineering, ‡Graduate Program in Applied Physics, §Department of Chemistry, ∥Department of Medicine and ⊥Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States
| | - Mark C Hersam
- Department of Materials Science and Engineering, ‡Graduate Program in Applied Physics, §Department of Chemistry, ∥Department of Medicine and ⊥Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States
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46
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Arnold HN, Cress CD, McMorrow JJ, Schmucker SW, Sangwan VK, Jaber-Ansari L, Kumar R, Puntambekar KP, Luck KA, Marks TJ, Hersam MC. Tunable Radiation Response in Hybrid Organic-Inorganic Gate Dielectrics for Low-Voltage Graphene Electronics. ACS Appl Mater Interfaces 2016; 8:5058-5064. [PMID: 26882215 DOI: 10.1021/acsami.5b12259] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Solution-processed semiconductor and dielectric materials are attractive for future lightweight, low-voltage, flexible electronics, but their response to ionizing radiation environments is not well understood. Here, we investigate the radiation response of graphene field-effect transistors employing multilayer, solution-processed zirconia self-assembled nanodielectrics (Zr-SANDs) with ZrOx as a control. Total ionizing dose (TID) testing is carried out in situ using a vacuum ultraviolet source to a total radiant exposure (RE) of 23.1 μJ/cm(2). The data reveal competing charge density accumulation within and between the individual dielectric layers. Additional measurements of a modified Zr-SAND show that varying individual layer thicknesses within the gate dielectric tuned the TID response. This study thus establishes that the radiation response of graphene electronics can be tailored to achieve a desired radiation sensitivity by incorporating hybrid organic-inorganic gate dielectrics.
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Affiliation(s)
| | - Cory D Cress
- Electronics Science & Technology Division, U.S. Naval Research Laboratory , Washington, D.C. 20375, United States
| | | | - Scott W Schmucker
- Electronics Science & Technology Division, U.S. Naval Research Laboratory , Washington, D.C. 20375, United States
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47
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Jariwala D, Howell SL, Chen KS, Kang J, Sangwan VK, Filippone SA, Turrisi R, Marks TJ, Lauhon LJ, Hersam MC. Hybrid, Gate-Tunable, van der Waals p-n Heterojunctions from Pentacene and MoS2. Nano Lett 2016; 16:497-503. [PMID: 26651229 DOI: 10.1021/acs.nanolett.5b04141] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The recent emergence of a wide variety of two-dimensional (2D) materials has created new opportunities for device concepts and applications. In particular, the availability of semiconducting transition metal dichalcogenides, in addition to semimetallic graphene and insulating boron nitride, has enabled the fabrication of "all 2D" van der Waals heterostructure devices. Furthermore, the concept of van der Waals heterostructures has the potential to be significantly broadened beyond layered solids. For example, molecular and polymeric organic solids, whose surface atoms possess saturated bonds, are also known to interact via van der Waals forces and thus offer an alternative for scalable integration with 2D materials. Here, we demonstrate the integration of an organic small molecule p-type semiconductor, pentacene, with a 2D n-type semiconductor, MoS2. The resulting p-n heterojunction is gate-tunable and shows asymmetric control over the antiambipolar transfer characteristic. In addition, the pentacene/MoS2 heterojunction exhibits a photovoltaic effect attributable to type II band alignment, which suggests that MoS2 can function as an acceptor in hybrid solar cells.
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Affiliation(s)
- Deep Jariwala
- Department of Materials Science and Engineering and ‡Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Sarah L Howell
- Department of Materials Science and Engineering and ‡Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Kan-Sheng Chen
- Department of Materials Science and Engineering and ‡Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Junmo Kang
- Department of Materials Science and Engineering and ‡Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Vinod K Sangwan
- Department of Materials Science and Engineering and ‡Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Stephen A Filippone
- Department of Materials Science and Engineering and ‡Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Riccardo Turrisi
- Department of Materials Science and Engineering and ‡Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Tobin J Marks
- Department of Materials Science and Engineering and ‡Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Lincoln J Lauhon
- Department of Materials Science and Engineering and ‡Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Mark C Hersam
- Department of Materials Science and Engineering and ‡Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
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McMorrow JJ, Walker AR, Sangwan VK, Jariwala D, Hoffman E, Everaerts K, Facchetti A, Hersam MC, Marks TJ. Solution-Processed Self-Assembled Nanodielectrics on Template-Stripped Metal Substrates. ACS Appl Mater Interfaces 2015; 7:26360-26366. [PMID: 26479833 DOI: 10.1021/acsami.5b07744] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The coupling of hybrid organic-inorganic gate dielectrics with emergent unconventional semiconductors has yielded transistor devices exhibiting record-setting transport properties. However, extensive electronic transport measurements on these high-capacitance systems are often convoluted with the electronic response of the semiconducting silicon substrate. In this report, we demonstrate the growth of solution-processed zirconia self-assembled nanodielectrics (Zr-SAND) on template-stripped aluminum substrates. The resulting Zr-SAND on Al structures leverage the ultrasmooth (r.m.s. roughness <0.4 nm), chemically uniform nature of template-stripped metal substrates to demonstrate the same exceptional electronic uniformity (capacitance ∼700 nF cm(-2), leakage current <1 μA cm(-2) at -2 MV cm(-1)) and multilayer growth of Zr-SAND on Si, while exhibiting superior temperature and voltage capacitance responses. These results are important to conduct detailed transport measurements in emergent transistor technologies featuring SAND as well as for future applications in integrated circuits or flexible electronics.
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Affiliation(s)
| | | | | | | | | | | | - Antonio Facchetti
- Polyera Corporation , 8045 Lamon Avenue, Skokie, Illinois 60077, United States
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Sangwan VK, Jariwala D, Kim IS, Chen KS, Marks TJ, Lauhon LJ, Hersam MC. Gate-tunable memristive phenomena mediated by grain boundaries in single-layer MoS2. Nat Nanotechnol 2015; 10:403-6. [PMID: 25849785 DOI: 10.1038/nnano.2015.56] [Citation(s) in RCA: 249] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 02/23/2015] [Indexed: 05/09/2023]
Abstract
Continued progress in high-speed computing depends on breakthroughs in both materials synthesis and device architectures. The performance of logic and memory can be enhanced significantly by introducing a memristor, a two-terminal device with internal resistance that depends on the history of the external bias voltage. State-of-the-art memristors, based on metal-insulator-metal (MIM) structures with insulating oxides, such as TiO₂, are limited by a lack of control over the filament formation and external control of the switching voltage. Here, we report a class of memristors based on grain boundaries (GBs) in single-layer MoS₂ devices. Specifically, the resistance of GBs emerging from contacts can be easily and repeatedly modulated, with switching ratios up to ∼10(3) and a dynamic negative differential resistance (NDR). Furthermore, the atomically thin nature of MoS₂ enables tuning of the set voltage by a third gate terminal in a field-effect geometry, which provides new functionality that is not observed in other known memristive devices.
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Affiliation(s)
- Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA
| | - Deep Jariwala
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA
| | - In Soo Kim
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA
| | - Kan-Sheng Chen
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA
| | - Tobin J Marks
- 1] Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA [2] Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| | - Lincoln J Lauhon
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA
| | - Mark C Hersam
- 1] Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA [2] Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
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50
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Howell SL, Jariwala D, Wu CC, Chen KS, Sangwan VK, Kang J, Marks TJ, Hersam MC, Lauhon LJ. Investigation of band-offsets at monolayer-multilayer MoS₂ junctions by scanning photocurrent microscopy. Nano Lett 2015; 15:2278-84. [PMID: 25807012 DOI: 10.1021/nl504311p] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The thickness-dependent band structure of MoS2 implies that discontinuities in energy bands exist at the interface of monolayer (1L) and multilayer (ML) thin films. The characteristics of such heterojunctions are analyzed here using current versus voltage measurements, scanning photocurrent microscopy, and finite element simulations of charge carrier transport. Rectifying I-V curves are consistently observed between contacts on opposite sides of 1L/ML junctions, and a strong bias-dependent photocurrent is observed at the junction. Finite element device simulations with varying carrier concentrations and electron affinities show that a type II band alignment at single layer/multilayer junctions reproduces both the rectifying electrical characteristics and the photocurrent response under bias. However, the zero-bias junction photocurrent and its energy dependence are not explained by conventional photovoltaic and photothermoelectric mechanisms, indicating the contributions of hot carriers.
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Affiliation(s)
- Sarah L Howell
- †Department of Materials Science and Engineering, ‡Department of Chemistry, §Department of Medicine, and ∥Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Deep Jariwala
- †Department of Materials Science and Engineering, ‡Department of Chemistry, §Department of Medicine, and ∥Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Chung-Chiang Wu
- †Department of Materials Science and Engineering, ‡Department of Chemistry, §Department of Medicine, and ∥Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Kan-Sheng Chen
- †Department of Materials Science and Engineering, ‡Department of Chemistry, §Department of Medicine, and ∥Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Vinod K Sangwan
- †Department of Materials Science and Engineering, ‡Department of Chemistry, §Department of Medicine, and ∥Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Junmo Kang
- †Department of Materials Science and Engineering, ‡Department of Chemistry, §Department of Medicine, and ∥Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Tobin J Marks
- †Department of Materials Science and Engineering, ‡Department of Chemistry, §Department of Medicine, and ∥Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Mark C Hersam
- †Department of Materials Science and Engineering, ‡Department of Chemistry, §Department of Medicine, and ∥Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Lincoln J Lauhon
- †Department of Materials Science and Engineering, ‡Department of Chemistry, §Department of Medicine, and ∥Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
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