Band-like Electron Transport with Record-High Mobility in the TCNQ family

Abstract

In highest quality organic single-crystal field-effect transistors, electron transport occurs in the band-like regime, with the carrier mobility increasing upon lowering temperature. Neither the microscopic nature of this regime, nor why it occurs only in a small number of materials is currently understood. Here, comparative studies of closely related materials, exhibiting high-quality reproducible transport properties are needed. We performed a study of electron transport in single-crystals of different TCNQ (tetracyanoquinodimethane) molecules, combined with band structure calculations. We show that F2-TCNQ devices exhibit very high electron mobility and an unprecedented increase in mobility upon cooling, whereas in TCNQ and F4-TCNQ the mobility is substantially lower and decreases upon cooling. We analyze the crystal and electronic structures of these materials and find that F2-TCNQ crystals are indeed ideal to achieve outstanding transport properties. Our analysis also shows that to understand the difference between the three materials, studying their band structure is not sufficient, and that the electron-phonon coupling needs to be investigated as well. Besides the outstanding transport properties of F2-TCNQ, a key result of our work is the identification of the Fx-TCNQ family as a paradigm to investigate the most fundamental aspects of electronic transport in organic crystals.

References in corpus (5)

• A Higher-Accuracy van der Waals Density Functional
• Metallic conduction at organic charge-transfer interfaces
• Band-Like Electron Transport in Organic Transistors and Implication of the Molecular Structure for Performance Optimization
• High Electron Mobility in Vacuum and Ambient for PDIF-CN2 Single-Crystal Transistors
• Electronic transport and quantum localization effects in organic semiconductors

Cited by in corpus (9)

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• On dynamical localization corrections to band transport
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• Microstructural control suppresses thermal activation of electron transport at room temperature in polymer transistors
• Tuning the charge transfer in Fx-TCNQ/rubrene single-crystal interfaces
• Charge transfer, band-like transport, and magnetic ions at F16CoPc/rubrene interfaces
• Exact solution of electronic transport in semiconductors dominated by scattering on polaronic impurities
• Spin-conserving Boltzmann theory for carriers and excitons in organic semiconductors
• Freeing electrons from extrinsic and intrinsic disorder yields band-like transport in n-type organic semiconductors