Negative field-dependent charge mobility in crystalline organic semiconductors with delocalized transport

Autor: Paul Heremans, Alexander Mityashin, Cedric Rolin, Egon Pavlica, Andrey Kadashchuk, Anna Köhler, Ivan I. Fishchuk, Gvido Bratina, Jan Genoe, Robby Janneck, Fei Tong
Rok vydání: 2018
Předmět:
Zdroj: Chemical Papers. 72:1685-1695
ISSN: 1336-9075
2585-7290
Popis: © 2018, Institute of Chemistry, Slovak Academy of Sciences. Charge-carrier mobility has been investigated by time-of-flight (TOF) transient photocurrent in a lateral transport configuration in highly crystalline thin films of 2,7-dioctyl[1]benzothieno [3,2-b][1] benzothiophene (C 8 -BTBT) grown by a zone-casting alignment technique. High TOF mobility has been revealed that it is consistent with the delocalized nature of the charge transport in this material, yet it featured a positive temperature dependence at T≥295K. Moreover, the mobility was surprisingly found to decrease with electric field in the high-temperature region. These observations are not compatible with the conventional band-transport mechanism. We have elaborated an analytic model based on effective-medium approximation to rationalize the puzzling findings. The model considers the delocalized charge transport within the energy landscape formed by long-range transport band-edge variations in imperfect organic crystalline materials and accounts for the field-dependent effective dimensionality of charge transport percolative paths. The results of the model calculations are found to be in good agreement with experimental data. ispartof: CHEMICAL PAPERS vol:72 issue:7 pages:1685-1695 ispartof: location:CZECH REPUBLIC, Prague status: published
Databáze: OpenAIRE
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