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Zeng BF, Wang G, Qian QZ, Chen ZX, Zhang XG, Lu ZX, Zhao SQ, Feng AN, Shi J, Yang Y, Hong W. Selective Fabrication of Single-Molecule Junctions by Interface Engineering. Small 2020; 16:e2004720. [PMID: 33155382 DOI: 10.1002/smll.202004720] [Citation(s) in RCA: 14] [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] [Received: 08/03/2020] [Revised: 09/14/2020] [Indexed: 06/11/2023]
Abstract
Recent progress in addressing electrically driven single-molecule behaviors has opened up a path toward the controllable fabrication of molecular devices. Herein, the selective fabrication of single-molecule junctions is achieved by employing the external electric field. For molecular junctions with methylthio (-SMe), thioacetate (-SAc), amine (-NH2 ), and pyridyl (-PY), the evolution of their formation probabilities along with the electric field is extracted from the plateau analysis of individual single-molecule break junction traces. With the increase of the electric field, the SMe-anchored molecules show a different trend in the formation probability compared to the other molecular junctions, which is consistent with the density functional theory calculations. Furthermore, switching from an SMe-anchored junction to an SAc-anchored junction is realized by altering the electric field in a mixed solution. The results in this work provide a new approach to the controllable fabrication and modulation of single-molecule junctions and other bottom-up nanodevices at molecular scales.
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Affiliation(s)
- Biao-Feng Zeng
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, College of Chemistry and Chemical Engineering and State Key Laboratory of Physical Chemistry of Solid Surfaces, IKKEM, iChEM, Xiamen University, Xiamen, 361005, China
| | - Gan Wang
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, College of Chemistry and Chemical Engineering and State Key Laboratory of Physical Chemistry of Solid Surfaces, IKKEM, iChEM, Xiamen University, Xiamen, 361005, China
| | - Qiao-Zan Qian
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, College of Chemistry and Chemical Engineering and State Key Laboratory of Physical Chemistry of Solid Surfaces, IKKEM, iChEM, Xiamen University, Xiamen, 361005, China
| | - Zhi-Xin Chen
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, College of Chemistry and Chemical Engineering and State Key Laboratory of Physical Chemistry of Solid Surfaces, IKKEM, iChEM, Xiamen University, Xiamen, 361005, China
| | - Xia-Guang Zhang
- School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Zhi-Xing Lu
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, College of Chemistry and Chemical Engineering and State Key Laboratory of Physical Chemistry of Solid Surfaces, IKKEM, iChEM, Xiamen University, Xiamen, 361005, China
| | - Shi-Qiang Zhao
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, College of Chemistry and Chemical Engineering and State Key Laboratory of Physical Chemistry of Solid Surfaces, IKKEM, iChEM, Xiamen University, Xiamen, 361005, China
| | - An-Ni Feng
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, College of Chemistry and Chemical Engineering and State Key Laboratory of Physical Chemistry of Solid Surfaces, IKKEM, iChEM, Xiamen University, Xiamen, 361005, China
| | - Jia Shi
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, College of Chemistry and Chemical Engineering and State Key Laboratory of Physical Chemistry of Solid Surfaces, IKKEM, iChEM, Xiamen University, Xiamen, 361005, China
| | - Yang Yang
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, College of Chemistry and Chemical Engineering and State Key Laboratory of Physical Chemistry of Solid Surfaces, IKKEM, iChEM, Xiamen University, Xiamen, 361005, China
| | - Wenjing Hong
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, College of Chemistry and Chemical Engineering and State Key Laboratory of Physical Chemistry of Solid Surfaces, IKKEM, iChEM, Xiamen University, Xiamen, 361005, China
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Akaike K. Distributions of Potential and Contact-Induced Charges in Conventional Organic Photovoltaics. Materials (Basel) 2020; 13:E2411. [PMID: 32456312 PMCID: PMC7288283 DOI: 10.3390/ma13102411] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 05/15/2020] [Accepted: 05/22/2020] [Indexed: 12/11/2022]
Abstract
The interfaces of dissimilar materials play central roles in photophysical events in organic photovoltaics (OPVs). Depth profiles of electrostatic potential and contact-induced charges determine the energy-level lineup of the frontier orbitals at electrode/organic and organic heterointerfaces. They are critical for the elementary processes in an OPV cell, such as generation and diffusion of free carriers. A simple electrostatic model describes the energetics in organic heterojunctions supported by an electrode, and experiments via photoelectron spectroscopy and the Kelvin probe method validate the potential distribution in the stacking direction of the device. A comparative study has clarified the significance of Fermi-level pinning and resulting electrostatic fields in determining the energy-level alignment. In this review, we discuss how parameters of device constituents affect the distributions of potential and the dark charges in conventional OPVs comprising metallophthalocyanine and C60 as donor and acceptor, respectively. The results of previous studies, together with additional numerical simulations, suggest that a number of the factors influence the depth profiles of the dark charge and potential, such as the work function of bottom materials, layer thickness, structural inhomogeneity at interfaces, top electrode, and stacking sequence.
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Affiliation(s)
- Kouki Akaike
- National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8565, Japan
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Cowan AJ, Hardwick LJ. Advanced Spectroelectrochemical Techniques to Study Electrode Interfaces Within Lithium-Ion and Lithium-Oxygen Batteries. Annu Rev Anal Chem (Palo Alto Calif) 2019; 12:323-346. [PMID: 31038984 DOI: 10.1146/annurev-anchem-061318-115303] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Lithium battery technologies have revolutionized mobile energy storage, but improvements in the technology are still needed. Critical to delivering new light weight, high capacity, safe devices is an improved understanding of the dynamic processes occurring at the electrode-electrolyte interfaces. Therefore, alongside advances in materials there has been a parallel progression in advanced characterization methods. Herein, recent developments for operando spectro-electrochemical techniques centered on Raman, infrared, and sum frequency generation are described within the context of lithium-ion and non-aqueous lithium-oxygen battery research. In particular, shell-isolated nanoparticles for enhanced Raman spectroscopy (SHINERS), surface-enhanced infrared absorption spectroscopy (SEIRAS), and near-field infrared are explained and critically evaluated, and future opportunities discussed. The aim is to introduce the wider community to the developing range of methodologies and tools now available in the hope that it encourages greater usage across the sector.
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Affiliation(s)
- Alexander J Cowan
- Department of Chemistry, Stephenson Institute for Renewable Energy, University of Liverpool, Liverpool L69 7ZD, United Kingdom;
| | - Laurence J Hardwick
- Department of Chemistry, Stephenson Institute for Renewable Energy, University of Liverpool, Liverpool L69 7ZD, United Kingdom;
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Abstract
Ferroelectric materials are used in many applications of modern technologies including information storage, transducers, sensors, tunable capacitors, and other novel device concepts. In many of these applications, the ferroelectric properties, such as switching voltages, piezoelectric constants, or stability of nanodomains, are crucial. For any application, even for material characterization, the material itself needs to be interfaced with electrodes. On the basis of the structural, chemical, and electronic properties of the interfaces, the measured material properties can be determined by the interface. This is also true for surfaces. However, the importance of interfaces and surfaces and their effect on experiments are often neglected, which results in many dramatically different experimental results for nominally identical samples. Therefore, it is crucial to understand the role of the interface and surface properties on internal bias fields and the domain switching process. Here, the nanoscale ferroelectric switching process and the stability of nanodomains for Pb(Zr,Ti)O3 thin films are investigated by using scanning probe microscopy. Interface and surface properties are modulated through the selection/redesign of electrode materials as well as tuning the surface-near oxygen vacancies, which both can result in changes of the electric fields acting across the sample, and consequently this controls the measured ferroelectric and domain retention properties. By understanding the role of surfaces and interfaces, ferroelectric properties can be tuned to eliminate the problem of asymmetric domain stability by combining the effects of different electrode materials. This study forms an important step toward integrating ferroelectric materials in electronic devices.
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Affiliation(s)
- Nina Balke
- Oak Ridge National Laboratory , 1 Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
| | - Ramamoorthy Ramesh
- University of California at Berkeley , 210 Hearst Memorial Mining Building, Berkeley, California 94720, United States
| | - Pu Yu
- Tsinghua University, and Collaborative Innovation Center of Quantum Matter , Beijing 100084, China
- RIKEN Center for Emergent Matter Science (CEMS) , Wako, Saitama 351-0198, Japan
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Bilby D, Frieberg B, Kramadhati S, Green P, Kim J. Design considerations for electrode buffer layer materials in polymer solar cells. ACS Appl Mater Interfaces 2014; 6:14964-14974. [PMID: 25116039 DOI: 10.1021/am502673e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Electrode buffer layers in polymer-based photovoltaic devices enable highly efficient devices. In the absence of buffer layers, we show that diode rectification is lost in ITO/P3HT:PCBM/Ag (ITO = indium tin oxide; P3HT = poly(3-hexylthiophene); PCBM = phenyl C61-butyric acid methyl ester) devices due to nonselective charge injection through the percolated phase pathways of a bulk heterojunction active layer. Charge-selective injection, and thus rectification and device function, can be regained by placing thin, polymeric buffer layers that break the direct electrode-active layer contact. Additionally, we show that strong active layer-buffer layer interactions lead to unwanted vertical phase separation and a kinked current-voltage curve. Device function is regained, increasing power conversion efficiency from 3.6% to 7.2%, by placing a noninteracting layer between the buffer and active layer. These results guide the design and selection of future polymeric electrode buffer layers for efficient polymer solar cell devices.
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Affiliation(s)
- David Bilby
- Materials Science and Engineering, ‡Macromolecular Science and Engineering, and ∥Chemical Engineering, University of Michigan , Ann Arbor, 48109, United States
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