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Won T, Kumagai S, Kasuya N, Yamashita Y, Watanabe S, Okamoto T, Takeya J. Individual and synergetic charge transport properties at the solid and electrolyte interfaces of a single ultrathin single crystal of organic semiconductors. Phys Chem Chem Phys 2023; 25:14496-14501. [PMID: 37190947 DOI: 10.1039/d3cp00782k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The chemical structures and morphologies of organic semiconductors (OSCs) and gate dielectrics have been widely investigated to improve the electrical performances of organic thin-film transistors (OTFTs) because the charge transport therein is a phenomenon at the semiconductor-dielectric interfaces. Here, solid and ionic gel gate dielectrics were adopted on the lower and upper surfaces, respectively, of a single, two molecule-thick single crystals of p-type OSCs to study the charge transport properties at individual interfaces between the morphologically compatible OSC surface and different gate dielectrics. Using the four-probe method, the solid and ionic gel interfaces were found to exhibit hole mobilities of 9.3 and 2.2 cm2 V-1 s-1, respectively, which revealed the crucial impact of the gate dielectric materials on the interfacial charge transport. Interestingly, when gate biases are applied through both dielectrics, i.e., under the solid/ionic gel dual-gate transistor operation, the hole mobility at the solid gate interface is improved up to 14.7 cm2 V-1 s-1, which is 1.5 times greater than that assessed without the ionic gel gate. This improvement can be attributed to the electric double layer formed at the ionic gel/uniform crystal surface, which provides a close-to-ideal charge transport interface through dramatic trap-filling. Therefore, the present dual-gate transistor technique will be promising for investigating the intrinsic charge-transport capabilities of OSCs.
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Affiliation(s)
- Taehyun Won
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
| | - Shohei Kumagai
- Material Innovation Research Center (MIRC) and Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - Naotaka Kasuya
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
- Material Innovation Research Center (MIRC) and Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - Yu Yamashita
- Material Innovation Research Center (MIRC) and Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
- MANA, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba 205-0044, Japan
| | - Shun Watanabe
- Material Innovation Research Center (MIRC) and Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - Toshihiro Okamoto
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
- Material Innovation Research Center (MIRC) and Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - Jun Takeya
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
- Material Innovation Research Center (MIRC) and Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
- MANA, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba 205-0044, Japan
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2
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Ding D, Qu Z, Han X, Han C, Zhuang Q, Yu XL, Niu R, Wang Z, Li Z, Gan Z, Wu J, Lu J. Multivalley Superconductivity in Monolayer Transition Metal Dichalcogenides. NANO LETTERS 2022; 22:7919-7926. [PMID: 36173038 DOI: 10.1021/acs.nanolett.2c02947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
In transition metal dichalcogenides (TMDs), Ising superconductivity with an antisymmetric spin texture on the Fermi surface has attracted wide interest due to the exotic pairing and topological properties. However, it is not clear whether the Q valley with a giant spin splitting is involved in the superconductivity of heavily doped semiconducting 2H-TMDs. Here by taking advantage of a high-quality monolayer WS2 on hexagonal boron nitride flakes, we report an ionic-gating induced superconducting dome with a record high critical temperature of ∼6 K, accompanied by an emergent nonlinear Hall effect. The nonlinearity indicates the development of an additional high-mobility channel, which (corroborated by first principle calculations) can be ascribed to the population of Q valleys. Thus, multivalley population at K and Q is suggested to be a prerequisite for developing superconductivity. The involvement of Q valleys also provides insights to the spin textured Fermi surface of Ising superconductivity in the large family of transition metal dichalcogenides.
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Affiliation(s)
- Dongdong Ding
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Zhuangzhuang Qu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Xiangyan Han
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Chunrui Han
- Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Quan Zhuang
- Shenzhen Institute for Quantum Science and Engineering (SIQSE), Southern University of Science and Technology, Shenzhen 518055, China
- Inner Mongolia Key Laboratory of Carbon Nanomaterials, Nano Innovation Institute (NII), Inner Mongolia Minzu University, Tongliao 028000, China
| | - Xiang-Long Yu
- Shenzhen Institute for Quantum Science and Engineering (SIQSE), Southern University of Science and Technology, Shenzhen 518055, China
- International Quantum Academy, Shenzhen 518048, China
| | - Ruirui Niu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Zhiyu Wang
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Zhuoxian Li
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Zizhao Gan
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Jiansheng Wu
- Shenzhen Institute for Quantum Science and Engineering (SIQSE), Southern University of Science and Technology, Shenzhen 518055, China
- International Quantum Academy, Shenzhen 518048, China
| | - Jianming Lu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
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3
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He T, Frisbie CD. Sub-Band Filling, Mott-like Transitions, and Ion Size Effects in C 60 Single Crystal Electric Double Layer Transistors. ACS NANO 2022; 16:4823-4830. [PMID: 35243860 DOI: 10.1021/acsnano.2c00222] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Electric double layer transistors (EDLTs) based on C60 single crystals and ionic liquid gates display pronounced peaks in sheet conductance versus gate-induced charge. Sheet conductance is maximized at electron densities near 0.5 e/C60 and is suppressed near 1 e/C60. The conductance suppression depends markedly on the choice of ionic liquid cation, with small cations favoring activated transport and essentially a complete shutdown of conductance at ∼1 e/C60 and larger cations favoring band-like transport, higher overall conductances at all charge densities up to 1.7 e/C60, and weaker suppression at 1 e/C60. Displacement current measurements on C60 EDLTs with small cations show clear evidence of sub-band filling at 1 e/C60, which correlates very well with the minimum in the C60 sheet conductance. Overall, the data suggest a significant Mott-Hubbard-like energy gap opens up in the surface density of states for C60 crystals gated with small cations. The causes of this energy gap may include both electron-electron repulsion and electron-cation attraction at the crystal/ionic liquid interface. The energy gap suppresses the insulator-to-metal transition in C60 EDLTs, but it can be manipulated by choice of electrolyte.
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Affiliation(s)
- Tao He
- State Key Laboratory of Crystal Materials, Shandong University, 250100, Jinan, Shandong, People's Republic of China
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - C Daniel Frisbie
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
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4
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Schweicher G, Garbay G, Jouclas R, Vibert F, Devaux F, Geerts YH. Molecular Semiconductors for Logic Operations: Dead-End or Bright Future? ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1905909. [PMID: 31965662 DOI: 10.1002/adma.201905909] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 11/18/2019] [Indexed: 05/26/2023]
Abstract
The field of organic electronics has been prolific in the last couple of years, leading to the design and synthesis of several molecular semiconductors presenting a mobility in excess of 10 cm2 V-1 s-1 . However, it is also started to recently falter, as a result of doubtful mobility extractions and reduced industrial interest. This critical review addresses the community of chemists and materials scientists to share with it a critical analysis of the best performing molecular semiconductors and of the inherent charge transport physics that takes place in them. The goal is to inspire chemists and materials scientists and to give them hope that the field of molecular semiconductors for logic operations is not engaged into a dead end. To the contrary, it offers plenty of research opportunities in materials chemistry.
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Affiliation(s)
- Guillaume Schweicher
- Laboratoire de chimie des polymères, Faculté des Sciences, Université Libre de Bruxelles (ULB) Boulevard du Triomphe, Brussels, 1050, Belgium
- Optoelectronics Group, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Guillaume Garbay
- Laboratoire de chimie des polymères, Faculté des Sciences, Université Libre de Bruxelles (ULB) Boulevard du Triomphe, Brussels, 1050, Belgium
| | - Rémy Jouclas
- Laboratoire de chimie des polymères, Faculté des Sciences, Université Libre de Bruxelles (ULB) Boulevard du Triomphe, Brussels, 1050, Belgium
| | - François Vibert
- Laboratoire de chimie des polymères, Faculté des Sciences, Université Libre de Bruxelles (ULB) Boulevard du Triomphe, Brussels, 1050, Belgium
| | - Félix Devaux
- Laboratoire de chimie des polymères, Faculté des Sciences, Université Libre de Bruxelles (ULB) Boulevard du Triomphe, Brussels, 1050, Belgium
| | - Yves H Geerts
- Laboratoire de chimie des polymères, Faculté des Sciences, Université Libre de Bruxelles (ULB) Boulevard du Triomphe, Brussels, 1050, Belgium
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5
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Greenberg BL, Robinson ZL, Ayino Y, Held JT, Peterson TA, Mkhoyan KA, Pribiag VS, Aydil ES, Kortshagen UR. Metal-insulator transition in a semiconductor nanocrystal network. SCIENCE ADVANCES 2019; 5:eaaw1462. [PMID: 31467972 PMCID: PMC6707780 DOI: 10.1126/sciadv.aaw1462] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 07/15/2019] [Indexed: 06/01/2023]
Abstract
Many envisioned applications of semiconductor nanocrystals (NCs), such as thermoelectric generators and transparent conductors, require metallic (nonactivated) charge transport across an NC network. Although encouraging signs of metallic or near-metallic transport have been reported, a thorough demonstration of nonzero conductivity, σ, in the 0 K limit has been elusive. Here, we examine the temperature dependence of σ of ZnO NC networks. Attaining both higher σ and lower temperature than in previous studies of ZnO NCs (T as low as 50 mK), we observe a clear transition from the variable-range hopping regime to the metallic regime. The critical point of the transition is distinctly marked by an unusual power law close to σ ∝ T 1/5. We analyze the critical conductivity data within a quantum critical scaling framework and estimate the metal-insulator transition (MIT) criterion in terms of the free electron density, n, and interparticle contact radius, ρ.
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Affiliation(s)
| | - Zachary L. Robinson
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, USA
| | - Yilikal Ayino
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, USA
| | - Jacob T. Held
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, USA
| | - Timothy A. Peterson
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, USA
| | - K. Andre Mkhoyan
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, USA
| | - Vlad S. Pribiag
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, USA
| | - Eray S. Aydil
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, USA
| | - Uwe R. Kortshagen
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN, USA
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6
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Ren X, Wang Y, Xie Z, Xue F, Leighton C, Frisbie CD. Gate-Tuned Insulator-Metal Transition in Electrolyte-Gated Transistors Based on Tellurene. NANO LETTERS 2019; 19:4738-4744. [PMID: 31181883 DOI: 10.1021/acs.nanolett.9b01827] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Tellurene is a recently discovered 2D material with high hole mobility and air stability, rendering it a good candidate for future applications in electronics, optoelectronics, and energy devices. However, the physical properties of tellurene remain poorly understood. In this paper, we report on the fabrication and characterization of high-performance electrolyte-gated transistors (EGTs) based on solution-grown tellurene flakes <30 nm in thickness. Both Hall measurements and resistance-temperature behavior down to 2 K are recorded at multiple gate voltages, and an electronic phase diagram is generated. The results show that it is possible to cross the insulator-metal transition in tellurene EGTs by tuning gate voltage, achieving mobility up to ∼500 cm2 V-1 s-1. In particular, a truly metallic 2D state is observed at gate-induced hole densities >1 × 1013 cm-2, as confirmed by the temperature dependence of resistance and magnetoresistance measurements. Wide-range tuning of the electronic ground state of tellurene is thus achievable in EGTs, opening up new opportunities to realize electrical control of its physical properties.
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7
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Leighton C. Electrolyte-based ionic control of functional oxides. NATURE MATERIALS 2019; 18:13-18. [PMID: 30542099 DOI: 10.1038/s41563-018-0246-7] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 11/12/2018] [Indexed: 05/23/2023]
Abstract
The use of electrolyte gating to electrically control electronic, magnetic and optical properties of materials has seen strong recent growth, driven by the potential of the many devices and applications that such control may enable. Contrary to initial expectations of a purely electrostatic response based on electron or hole doping, electrochemical mechanisms based on the motion of ions are now understood to be common, suggesting promising new electrical control concepts.
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Affiliation(s)
- Chris Leighton
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, USA.
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8
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Ren X, Frisbie CD, Leighton C. Anomalous Cooling-Rate-Dependent Charge Transport in Electrolyte-Gated Rubrene Crystals. J Phys Chem Lett 2018; 9:4828-4833. [PMID: 30066562 DOI: 10.1021/acs.jpclett.8b01751] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Although electrolyte gating has been demonstrated to enable control of electronic phase transitions in many materials, long sought-after gate-induced insulator-metal transitions in organic semiconductors remain elusive. To better understand limiting factors in this regard, here we report detailed wide-range resistance-temperature ( R- T) measurements at multiple gate voltages on ionic-liquid-gated rubrene single crystals. Focusing on the previously observed high-bias regime where conductance anomalously decreases with increasing bias magnitude, we uncover two surprising (and related) features. First, distinctly cooling-rate-dependent transport is detected for the first time. Second, power law R- T is observed over a significant T window, which is highly unusual in an insulator. These features are discussed in terms of electronic disorder at the rubrene/ionic liquid interface influenced by (i) cooling-rate-dependent structural order in the ionic liquid and (ii) the intriguing possibility of a gate-induced glassy short-range charge-ordered state in rubrene. These results expose new physics at the gated rubrene surface, pointing to exciting new directions in the field.
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Affiliation(s)
- Xinglong Ren
- Department of Chemical Engineering and Materials Science , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - C Daniel Frisbie
- Department of Chemical Engineering and Materials Science , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Chris Leighton
- Department of Chemical Engineering and Materials Science , University of Minnesota , Minneapolis , Minnesota 55455 , United States
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9
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Choi HH, Cho K, Frisbie CD, Sirringhaus H, Podzorov V. Critical assessment of charge mobility extraction in FETs. NATURE MATERIALS 2017; 17:2-7. [PMID: 29255225 DOI: 10.1038/nmat5035] [Citation(s) in RCA: 257] [Impact Index Per Article: 36.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Affiliation(s)
- Hyun Ho Choi
- Department of Physics, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA
- Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, South Korea
| | - Kilwon Cho
- Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, South Korea
| | - C Daniel Frisbie
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, USA
| | - Henning Sirringhaus
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Vitaly Podzorov
- Department of Physics, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA
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10
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Bisri SZ, Shimizu S, Nakano M, Iwasa Y. Endeavor of Iontronics: From Fundamentals to Applications of Ion-Controlled Electronics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1607054. [PMID: 28582588 DOI: 10.1002/adma.201607054] [Citation(s) in RCA: 177] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Revised: 02/16/2017] [Indexed: 05/28/2023]
Abstract
Iontronics is a newly emerging interdisciplinary concept which bridges electronics and ionics, covering electrochemistry, solid-state physics, electronic engineering, and biological sciences. The recent developments of electronic devices are highlighted, based on electric double layers formed at the interface between ionic conductors (but electronically insulators) and various electronic conductors including organics and inorganics (oxides, chalcogenide, and carbon-based materials). Particular attention is devoted to electric-double-layer transistors (EDLTs), which are producing a significant impact, particularly in electrical control of phase transitions, including superconductivity, which has been difficult or impossible in conventional all-solid-state electronic devices. Besides that, the current state of the art and the future challenges of iontronics are also reviewed for many applications, including flexible electronics, healthcare-related devices, and energy harvesting.
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Affiliation(s)
- Satria Zulkarnaen Bisri
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Sunao Shimizu
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Masaki Nakano
- Quantum Phase Electronic Center (QPEC) and Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Yoshihiro Iwasa
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan
- Quantum Phase Electronic Center (QPEC) and Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
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11
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Xu H, Zhu Q, Lv Y, Deng K, Deng Y, Li Q, Qi S, Chen W, Zhang H. Flexible and Highly Photosensitive Electrolyte-Gated Organic Transistors with Ionogel/Silver Nanowire Membranes. ACS APPLIED MATERIALS & INTERFACES 2017; 9:18134-18141. [PMID: 28488860 DOI: 10.1021/acsami.7b04470] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Flexible and low-voltage photosensors with high near-infrared (NIR) sensitivity are critical for realization of interacting humans with robots and environments by thermal imaging or night vision techniques. In this work, we for the first time develop an easy and cost-effective process to fabricate flexible and ultrathin electrolyte-gated organic phototransistors (EGOPTs) with high transparent nanocomposite membranes of high-conductivity silver nanowire (AgNW) networks and large-capacitance iontronic films. A high responsivity of 1.5 × 103 A·W1-, high sensitivity of 7.5 × 105, and 3 dB bandwidth of ∼100 Hz can be achieved at very low operational voltages. Experimental studies in temporal photoresponse characteristics reveal the device has a shorter photoresponse time at lower light intensity since strong interactions between photoexcited hole carriers and anions induce extra long-lived trap states. The devices, benefiting from fast and air-stable operations, provide the possibility of the organic photosensors for constructing cost-effective and smart optoelectronic systems in the future.
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Affiliation(s)
- Haihua Xu
- Department of Biomedical and Engineering, School of Medicine, ‡Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, and §National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen University , Shenzhen 518060, China
| | - QingQing Zhu
- Department of Biomedical and Engineering, School of Medicine, ‡Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, and §National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen University , Shenzhen 518060, China
| | - Ying Lv
- Department of Biomedical and Engineering, School of Medicine, ‡Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, and §National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen University , Shenzhen 518060, China
| | - Kan Deng
- Department of Biomedical and Engineering, School of Medicine, ‡Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, and §National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen University , Shenzhen 518060, China
| | - Yinghua Deng
- Department of Biomedical and Engineering, School of Medicine, ‡Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, and §National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen University , Shenzhen 518060, China
| | - Qiaoliang Li
- Department of Biomedical and Engineering, School of Medicine, ‡Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, and §National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen University , Shenzhen 518060, China
| | - Suwen Qi
- Department of Biomedical and Engineering, School of Medicine, ‡Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, and §National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen University , Shenzhen 518060, China
| | - Wenwen Chen
- Department of Biomedical and Engineering, School of Medicine, ‡Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, and §National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen University , Shenzhen 518060, China
| | - Huisheng Zhang
- Department of Biomedical and Engineering, School of Medicine, ‡Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, and §National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen University , Shenzhen 518060, China
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12
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Bâldea I. Vibrational Frequencies of Fractionally Charged Molecular Species: Benchmarking DFT Results against ab Initio Calculations. J Phys Chem A 2017; 121:2282-2287. [PMID: 28257195 DOI: 10.1021/acs.jpca.6b12946] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recent advances in nano/molecular electronics and electrochemistry made it possible to continuously tune the fractional charge q of single molecules and to use vibrational spectroscopic methods to monitor such changes. Approaches to compute vibrational frequencies ω(q) of fractionally charged species based on the density functional theory (DFT) are faced with an important issue: the basic quantity used in these calculations, the total energy, should exhibit piecewise linearity with respect to the fractional charge, but approximate, commonly utilized exchange correlation functionals do not obey this condition. In this paper, with the aid of a simple and representative example, we benchmark results for ω(q) obtained within the DFT against ab initio methods, namely, coupled cluster singles and doubles and also second- and third-order Møller-Plesset perturbation) expansions. These results indicate that, in spite of missing the aforementioned piecewise linearity, DFT-based values ω(q) can reasonably be trusted.
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Affiliation(s)
- Ioan Bâldea
- Theoretische Chemie, Universität Heidelberg , Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany.,Institute of Space Sciences, National Institute of Lasers, Plasma and Radiation Physics , RO 077125 Bucharest-Măgurele, Romania
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13
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Bâldea I. Vibrational properties of fractionally charged molecules and their relevance for molecular electronics and electrochemistry. Chem Phys 2017. [DOI: 10.1016/j.chemphys.2016.08.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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14
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Sun L, Park SS, Sheberla D, Dincă M. Measuring and Reporting Electrical Conductivity in Metal-Organic Frameworks: Cd 2(TTFTB) as a Case Study. J Am Chem Soc 2016; 138:14772-14782. [PMID: 27766856 DOI: 10.1021/jacs.6b09345] [Citation(s) in RCA: 164] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Electrically conductive metal-organic frameworks (MOFs) are emerging as a subclass of porous materials that can have a transformative effect on electronic and renewable energy devices. Systematic advances in these materials depend critically on the accurate and reproducible characterization of their electrical properties. This is made difficult by the numerous techniques available for electrical measurements and the dependence of metrics on device architecture and numerous external variables. These challenges, common to all types of electronic materials and devices, are especially acute for porous materials, whose high surface area make them even more susceptible to interactions with contaminants in the environment. Here, we use the anisotropic semiconducting framework Cd2(TTFTB) (TTFTB4- = tetrathiafulvalene tetrabenzoate) to benchmark several common methods available for measuring electrical properties in MOFs. We show that factors such as temperature, chemical environment (atmosphere), and illumination conditions affect the quality of the data obtained from these techniques. Consistent results emerge only when these factors are strictly controlled and the morphology and anisotropy of the Cd2(TTFTB) single-crystal devices are taken into account. Most importantly, we show that depending on the technique, device construction, and/or the environment, a variance of 1 or even 2 orders of magnitude is not uncommon for even just one material if external factors are not controlled consistently. Differences in conductivity values of even 2 orders of magnitude should therefore be interpreted with caution, especially between different research groups comparing different compounds. These results allow us to propose a reliable protocol for collecting and reporting electrical properties of MOFs, which should help improve the consistency and comparability of reported electrical properties for this important new class of crystalline porous conductors.
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Affiliation(s)
- Lei Sun
- Department of Chemistry, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Sarah S Park
- Department of Chemistry, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Dennis Sheberla
- Department of Chemistry, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Mircea Dincă
- Department of Chemistry, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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15
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Abstract
Organic (opto)electronic materials have received considerable attention due to their applications in thin-film-transistors, light-emitting diodes, solar cells, sensors, photorefractive devices, and many others. The technological promises include low cost of these materials and the possibility of their room-temperature deposition from solution on large-area and/or flexible substrates. The article reviews the current understanding of the physical mechanisms that determine the (opto)electronic properties of high-performance organic materials. The focus of the review is on photoinduced processes and on electronic properties important for optoelectronic applications relying on charge carrier photogeneration. Additionally, it highlights the capabilities of various experimental techniques for characterization of these materials, summarizes top-of-the-line device performance, and outlines recent trends in the further development of the field. The properties of materials based both on small molecules and on conjugated polymers are considered, and their applications in organic solar cells, photodetectors, and photorefractive devices are discussed.
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Affiliation(s)
- Oksana Ostroverkhova
- Department of Physics, Oregon State University , Corvallis, Oregon 97331, United States
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16
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Lodge TP, Ueki T. Mechanically Tunable, Readily Processable Ion Gels by Self-Assembly of Block Copolymers in Ionic Liquids. Acc Chem Res 2016; 19:2107-2114. [PMID: 27704769 DOI: 10.1021/acs.accounts.6b00308] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Room temperature ionic liquids are of great interest for many advanced applications, due to the combination of attractive physical properties with essentially unlimited tunability of chemical structure. High chemical and thermal stability, favorable ionic conductivity, and complete nonvolatility are just some of the most important physical characteristics that make ionic liquids promising candidates for emerging technologies. Examples include separation membranes, actuators, polymer gel electrolytes, supercapacitors, ion batteries, fuel cell membranes, sensors, printable plastic electronics, and flexible displays. However, in these and other applications, it is essential to solidify the ionic liquid, while retaining the liquid state properties of interest. A broadly applicable solidification strategy relies on gelation by addition of suitable triblock copolymers with the ABA architecture, producing ion gels or ionogels. In this paradigm, the A end blocks are immiscible with the ionic liquid, and consequently self-assemble into micellar cores, while some fraction of the well-solvated B midblocks bridge between micelles, forming a percolating network. The chemical structures of the A and B repeat units, the molar mass of the blocks, and the concentration of the copolymer in the ionic liquid are all independently tunable to attain desired property combinations. In particular, the modulus of the resulting ion gel can be readily varied between 100 Pa and 1 MPa, with little sacrifice of the transport properties of the ionic liquid, such as ionic conductivity or gas diffusivity. Suitable A blocks can impart thermoreversible gelation (with solidification either on heating or cooling) or even photoreversible gelation. By virtue of the nonvolatility of ionic liquids, a wide range of processing strategies can be employed directly to prepare ion gels in thin or thick film forms, including solvent casting, spin coating, aerosol jet printing, photopatterning, and transfer printing. For higher modulus ion gels it is even possible to employ a manual "cut and stick" strategy for easy device fabrication. Ion gels prepared from common triblock copolymers, for example, with A = polystyrene and B = poly(ethylene oxide) or poly(methyl methacrylate), in imidazolium based ionic liquids provide exceptional performance in membranes for separating CO2 from N2 or CH4. The same materials also are the best available gate dielectrics for printed plastic electronics, because their high capacitance endows organic transistors with milliamp output currents for sub-1 V applied bias, with switching speeds that can go well beyond 100 kHz, while being amenable to large area roll-to-roll printing. Incorporation of well-designed electroluminescent (e.g., Ru(bpy)3-based) or electrochromic (e.g., viologen-based) moieties into ion gels held between transparent electrodes yields flexible color displays operating with sub-1 V dc inputs.
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Affiliation(s)
- Timothy P. Lodge
- Department of Chemistry and Department of Chemical Engineering & Materials Science, University of Minnesota, 207 Pleasant St SE, Minneapolis, Minnesota 55455, United States
| | - Takeshi Ueki
- National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
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17
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Walter J, Wang H, Luo B, Frisbie CD, Leighton C. Electrostatic versus Electrochemical Doping and Control of Ferromagnetism in Ion-Gel-Gated Ultrathin La0.5Sr0.5CoO3-δ. ACS NANO 2016; 10:7799-810. [PMID: 27479878 DOI: 10.1021/acsnano.6b03403] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Recently, electrolyte gating techniques employing ionic liquids/gels in electric double layer transistors have proven remarkably effective in tuning charge carrier density in a variety of materials. The ability to control surface carrier densities at levels above 10(14) cm(-2) has led to widespread use in the study of superconductivity, insulator-metal transitions, etc. In many cases, controversy remains over the doping mechanism, however (i.e., electrostatic vs electrochemical (e.g., redox-based)), and the technique has been less applied to magnetic materials. Here, we discuss ion gel gating of nanoscale 8-unit-cell-thick hole-doped La0.5Sr0.5CoO3-δ (LSCO) films, probing in detail the critical bias windows and doping mechanisms. The LSCO films, which are under compressive stress on LaAlO3(001) substrates, are metallic and ferromagnetic (Curie temperature, TC ∼ 170 K), with strong anomalous Hall effect and perpendicular magnetic anisotropy. Transport measurements reveal that negative gate biases lead to reversible hole accumulation (i.e., predominantly electrostatic operation) up to some threshold, whereas positive bias immediately induces irreversibility. Experiments in inert/O2 atmospheres directly implicate oxygen vacancies in this irreversibility, supported by atomic force microscopy and X-ray photoelectron spectroscopy. The results are thus of general importance, suggesting that hole- and electron-doped oxides may respond very differently to electrolyte gating. Reversible voltage control of electronic/magnetic properties is then demonstrated under hole accumulation, including resistivity, magnetoresistance, and TC. The sizable anomalous Hall coefficient and perpendicular anisotropy in LSCO provide a particularly powerful probe of magnetism, enabling direct extraction of the voltage-dependent order parameter and TC shift. The latter amounts to ∼7%, with potential for much stronger modulation at lower Sr doping.
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Affiliation(s)
- Jeff Walter
- Department of Chemical Engineering and Materials Science and ‡Characterization Facility, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Helin Wang
- Department of Chemical Engineering and Materials Science and ‡Characterization Facility, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Bing Luo
- Department of Chemical Engineering and Materials Science and ‡Characterization Facility, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - C Daniel Frisbie
- Department of Chemical Engineering and Materials Science and ‡Characterization Facility, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Chris Leighton
- Department of Chemical Engineering and Materials Science and ‡Characterization Facility, University of Minnesota , Minneapolis, Minnesota 55455, United States
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18
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Ovchinnikov D, Gargiulo F, Allain A, Pasquier DJ, Dumcenco D, Ho CH, Yazyev OV, Kis A. Disorder engineering and conductivity dome in ReS2 with electrolyte gating. Nat Commun 2016; 7:12391. [PMID: 27499375 PMCID: PMC4979068 DOI: 10.1038/ncomms12391] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 06/29/2016] [Indexed: 11/09/2022] Open
Abstract
Atomically thin rhenium disulphide (ReS2) is a member of the transition metal dichalcogenide family of materials. This two-dimensional semiconductor is characterized by weak interlayer coupling and a distorted 1T structure, which leads to anisotropy in electrical and optical properties. Here we report on the electrical transport study of mono- and multilayer ReS2 with polymer electrolyte gating. We find that the conductivity of monolayer ReS2 is completely suppressed at high carrier densities, an unusual feature unique to monolayers, making ReS2 the first example of such a material. Using dual-gated devices, we can distinguish the gate-induced doping from the electrostatic disorder induced by the polymer electrolyte itself. Theoretical calculations and a transport model indicate that the observed conductivity suppression can be explained by a combination of a narrow conduction band and Anderson localization due to electrolyte-induced disorder.
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Affiliation(s)
- Dmitry Ovchinnikov
- Electrical Engineering Institute, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.,Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Fernando Gargiulo
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Adrien Allain
- Electrical Engineering Institute, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.,Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Diego José Pasquier
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Dumitru Dumcenco
- Electrical Engineering Institute, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.,Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Ching-Hwa Ho
- Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 106, Taiwan
| | - Oleg V Yazyev
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Andras Kis
- Electrical Engineering Institute, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.,Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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19
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Bâldea I. Invariance of molecular charge transport upon changes of extended molecule size and several related issues. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2016; 7:418-431. [PMID: 27335734 PMCID: PMC4901537 DOI: 10.3762/bjnano.7.37] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 02/24/2016] [Indexed: 06/06/2023]
Abstract
As a sanity test for the theoretical method employed, studies on (steady-state) charge transport through molecular devices usually confine themselves to check whether the method in question satisfies the charge conservation. Another important test of the theory's correctness is to check that the computed current does not depend on the choice of the central region (also referred to as the "extended molecule"). This work addresses this issue and demonstrates that the relevant transport and transport-related properties are indeed invariant upon changing the size of the extended molecule, when the embedded molecule can be described within a general single-particle picture (namely, a second-quantized Hamiltonian bilinear in the creation and annihilation operators). It is also demonstrates that the invariance of nonequilibrium properties is exhibited by the exact results but not by those computed approximately within ubiquitous wide- and flat-band limits (WBL and FBL, respectively). To exemplify the limitations of the latter, the phenomenon of negative differential resistance (NDR) is considered. It is shown that the exactly computed current may exhibit a substantial NDR, while the NDR effect is absent or drastically suppressed within the WBL and FBL approximations. The analysis done in conjunction with the WBLs and FBLs reveals why general studies on nonequilibrium properties require a more elaborate theoretical than studies on linear response properties (e.g., ohmic conductance and thermopower) at zero temperature. Furthermore, examples are presented that demonstrate that treating parts of electrodes adjacent to the embedded molecule and the remaining semi-infinite electrodes at different levels of theory (which is exactly what most NEGF-DFT approaches do) is a procedure that yields spurious structures in nonlinear ranges of current-voltage curves.
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Affiliation(s)
- Ioan Bâldea
- Theoretische Chemie, Universität Heidelberg, INF 229, 69120 Heidelberg, Germany
- Institute of Space Sciences, National Institute for Lasers, Plasma, and Radiation Physics, National Institute for Lasers, Plasma, and Radiation Physics, 077125, Bucharest-Măgurele, Romania
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20
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Bâldea I. Fractional molecular charge studied via molecular vibrational properties. Specific aspects in Jahn–Teller active molecular species. RSC Adv 2016. [DOI: 10.1039/c6ra21476b] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Jahn–Teller active and inactive vibrational modes are affected in a different manner by charge removal.
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Affiliation(s)
- Ioan Bâldea
- Theoretische Chemie
- Universität Heidelberg
- D-69120 Heidelberg
- Germany
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21
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Abstract
Recent advances in electrochemistry and nano- and molecular electronics made it possible to prepare and study molecular species having fractional charges (q ≠ 0, ±1, …) that can be continuously tuned by biases.
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Affiliation(s)
- Ioan Bâldea
- Theoretische Chemie
- Universität Heidelberg
- D-69120 Heidelberg
- Germany
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22
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Atallah TL, Gustafsson MV, Schmidt E, Frisbie CD, Zhu XY. Charge Saturation and Intrinsic Doping in Electrolyte-Gated Organic Semiconductors. J Phys Chem Lett 2015; 6:4840-4844. [PMID: 26588805 DOI: 10.1021/acs.jpclett.5b02336] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Electrolyte gating enables low voltage operation of organic thin film transistors, but little is known about the nature of the electrolyte/organic interface. Here we apply charge-modulation Fourier transform infrared spectroscopy, in conjunction with electrical measurements, on a model electrolyte gated organic semiconductor interface: single crystal rubrene/ion-gel. We provide spectroscopic signature for free-hole like carriers in the organic semiconductor and unambiguously show the presence of a high density of intrinsic doping of the free holes upon formation of the rubrene/ion-gel interface, without gate bias (Vg = 0 V). We explain this intrinsic doping as resulting from a thermodynamic driving force for the stabilization of free holes in the organic semiconductor by anions in the ion-gel. Spectroscopy also reveals the saturation of free-hole like carrier density at the rubrene/ion-gel interface at Vg < -0.5 V, which is commensurate with the negative transconductance seen in transistor measurements.
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Affiliation(s)
- Timothy L Atallah
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Martin V Gustafsson
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Elliot Schmidt
- Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - C Daniel Frisbie
- Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - X-Y Zhu
- Department of Chemistry, Columbia University , New York, New York 10027, United States
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