Regensburg 2019 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 8: Transport and theory of electronic structure

HL 8.6: Talk

Monday, April 1, 2019, 16:15–16:30, H33

Explaining Charge Mobility Regimes in Amorphous Materials — •Markus Krammer¹, Chris Groves², and Karin Zojer¹ — ¹Institute of Solid State Physics, NAWI Graz, Graz University of Technology, Austria — ²Department of Engineering, Durham University, United Kingdom

Charge mobility in amorphous materials like disordered organic semiconductors is commonly evaluated assuming hopping transport, where charges are viewed to migrate via hopping between localised states. The charge motion is governed by a complex interplay of energetic disorder, electric field, interactions, temperature, and other parameters. While state-of-the-art simulation techniques like kinetic Monte Carlo or Master equation (ME) account well for this complex interplay, it is desirable to distinguish between field- and charge density related mobility regimes and transitions between them from a more fundamental point of view. We developed a new simulation technique providing this fundamental view. The technique is reminiscent of ME with the benefit that it can directly incorporate correlations and interactions. The separation of field- and charge density related effects included in our new technique allows to interpret the corresponding evolution of the mobility. We will explore the mobility regimes from the perspective of steady state charge densities and occupation statistics. With simulations containing one charge carrier, we will explain the ideas behind our technique and discuss the reasons for the field dependence of the mobility. By increasing the number of charge carriers, the charge density dependence of the mobility will be elucidated.