An Analytic Description of Transient Current in Disordered Organics for a Broad Range of Temperature and Electric Field by the Joint Application of Transport Level and Effective Temperature Concepts
Maxim Khan a, Vladimir Nikitenko a, Andrey Tyutnev b, Renat Ikhsanov b c
a National Research Nuclear University «MEPhI» (Moscow Engineering Physics Institute), Kashira Highway, 31, Moskva, Russian Federation
b National Research University Higher School of Economics, Myasnitskaya Ulitsa, 20, Moskva, Russian Federation
c P.N. Lebedev Physical Institute, Leninsky Avenue, 53, Moskva, Russian Federation
Proceedings of International Conference on Advances in Organic and Hybrid Electronic Materials (AOHM19)
Dubrovnik, Croatia, 2019 March 17th - 20th
Organizers: Alejandro Briseno, Thuc-Quyen Nguyen and Natalie Stingelin
Poster, Maxim Khan, 056
Publication date: 8th January 2019

Charge carrier transport in disordered organic semiconductors is the subject of intensive investigations due to growing applications of these materials in electronics. The combination of steady-state and time resolved measurements, like the well-known time-of-flight (TOF) technique [1], seems to be the most reliable way to obtain the information about the mobility and other parameters of disordered materials. The Monte-Carlo (MC) modelling of charge transport is a very pertinent, but the time-consuming, tool for the theoretical modelling of charge transport in disordered organics. Hence, an alternative approach, i.e. the analytic modeling of charge transport using simple heuristic models, like the transport energy [2] and effective temperature [3], employing MA or Marcus models, is promising. The first concept allows describing the hopping transport by the relatively simple formalism of the multiple-trapping model in the low-field limit, while the second provides a simple way to describe both the field and temperature dependence of mobility. Both these analytic tools used typically for the analysis of the mobility in quasi-equilibrium transport mode. The description of non-equilibrium transport [4], including dispersive mode, still considered as questionable.

We perform calculations of transient current in time-of-flight conditions, using both the concepts, transport energy and effective temperature, simultaneously. Our calculations provide good enough fitting for the results of MC modelling [1], in a very broad interval of electric field (from 106 to 2x108 V/m) and temperature (from 203 to 377 K), approving this approach [5]. This approach also allowed us to describe quite accurately the quasi-equilibrium mobility field and temperature dependence, using the same set of model parameters.

The authors acknowledge financial support of the Volkswagen foundation, grant “Understanding the dependence of charge transport on the morphology of organic semiconductor films”.

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