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Schwarze M, Gaul C, Scholz R, Bussolotti F, Hofacker A, Schellhammer KS, Nell B, Naab BD, Bao Z, Spoltore D, Vandewal K, Widmer J, Kera S, Ueno N, Ortmann F, Leo K. Molecular parameters responsible for thermally activated transport in doped organic semiconductors. NATURE MATERIALS 2019; 18:242-248. [PMID: 30692647 DOI: 10.1038/s41563-018-0277-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 12/19/2018] [Indexed: 06/09/2023]
Abstract
Doped organic semiconductors typically exhibit a thermal activation of their electrical conductivity, whose physical origin is still under scientific debate. In this study, we disclose relationships between molecular parameters and the thermal activation energy (EA) of the conductivity, revealing that charge transport is controlled by the properties of host-dopant integer charge transfer complexes (ICTCs) in efficiently doped organic semiconductors. At low doping concentrations, charge transport is limited by the Coulomb binding energy of ICTCs, which can be minimized by systematic modification of the charge distribution on the individual ions. The investigation of a wide variety of material systems reveals that static energetic disorder induced by ICTC dipole moments sets a general lower limit for EA at large doping concentrations. The impact of disorder can be reduced by adjusting the ICTC density and the intramolecular relaxation energy of host ions, allowing an increase of conductivity by many orders of magnitude.
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Affiliation(s)
- Martin Schwarze
- Dresden Integrated Center for Applied Physics and Photonic Materials, Technische Universität Dresden, Dresden, Germany.
| | - Christopher Gaul
- Center for Advancing Electronics Dresden and Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, Germany
| | - Reinhard Scholz
- Dresden Integrated Center for Applied Physics and Photonic Materials, Technische Universität Dresden, Dresden, Germany
| | - Fabio Bussolotti
- Institute for Molecular Science, Department of Photo-Molecular Science, Myodaiji, Okazaki, Aichi, Japan
| | - Andreas Hofacker
- Dresden Integrated Center for Applied Physics and Photonic Materials, Technische Universität Dresden, Dresden, Germany
| | - Karl Sebastian Schellhammer
- Center for Advancing Electronics Dresden and Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, Germany
| | - Bernhard Nell
- Dresden Integrated Center for Applied Physics and Photonic Materials, Technische Universität Dresden, Dresden, Germany
| | - Benjamin D Naab
- Department of Chemical Engineering, Stanford University, Stanford, CA, USA
| | - Zhenan Bao
- Department of Chemical Engineering, Stanford University, Stanford, CA, USA
| | - Donato Spoltore
- Dresden Integrated Center for Applied Physics and Photonic Materials, Technische Universität Dresden, Dresden, Germany
| | - Koen Vandewal
- Dresden Integrated Center for Applied Physics and Photonic Materials, Technische Universität Dresden, Dresden, Germany
- Institute for Materials Research (IMO), Hasselt University, Diepenbeek, Belgium
| | - Johannes Widmer
- Dresden Integrated Center for Applied Physics and Photonic Materials, Technische Universität Dresden, Dresden, Germany
- Heliatek GmbH, Dresden, Germany
| | - Satoshi Kera
- Institute for Molecular Science, Department of Photo-Molecular Science, Myodaiji, Okazaki, Aichi, Japan
| | - Nobuo Ueno
- Graduate School of Advanced Integration Science, Chiba University, Chiba, Japan
| | - Frank Ortmann
- Center for Advancing Electronics Dresden and Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, Germany.
| | - Karl Leo
- Dresden Integrated Center for Applied Physics and Photonic Materials, Technische Universität Dresden, Dresden, Germany.
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Pollak M. On dynamical properties of electrons in Anderson-Mott insulators. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:105602. [PMID: 29393067 DOI: 10.1088/1361-648x/aaac94] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Properties of electrons in non-crystalline (alias disordered) systems has been a very active research topic for over half a century, since Anderson's ground breaking paper on localization. In strongly disordered systems electrons become Anderson and Mott localized. Interactions become important because screening by localized electrons is ineffective. Dynamical theories for such systems have long been controversial. Nevertheless one theory came to prominence in the literature and is often invoked and/or used. It is shown here that that theory is unsatisfactory in several aspects. It is based on the one-particle density of states, which turns out to be irrelevant to the problem it addresses. Another shortcoming is an implicit conjecture that interacting electrons move independently of each other. The theory is also in questionable agreement with experiment. It is shown that two other theories are free of those problems. They are useful for different types of studies, are compatible with each other and in agreement with experiment.
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Affiliation(s)
- M Pollak
- Department of Physics, University of California, Riverside, CA 93405, United States of America
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Chen TY, Lin TL, Chen CC, Chen CM, Chia-Fu C. Improved Catalytic Performance of Pt Supported on Multi-Wall Carbon Nanotubes as Cathode for Direct Methanol Fuel Cell Applications Prepared by Dual-Stepped Surface Thiolation Processes. J CHIN CHEM SOC-TAIP 2013. [DOI: 10.1002/jccs.200900178] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Pollak M. Non-ergodic behaviour of Anderson insulators with and without Coulomb interactions. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/13642818408238844] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- M. Pollak
- a Department of Physics , University of California , Riverside , California , 92521 , U.S.A
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Affiliation(s)
- M. Pollak
- a Department of Physics , University of California , Riverside , California , 92521 , USA
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