Dresden 2020 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 96: Organic Electronics and Photovoltaics IV

CPP 96.4: Talk

Thursday, March 19, 2020, 15:45–16:00, ZEU 260

Explaining Charge Mobility Regimes in Amorphous Materials: The correction energy concept — 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 transport in amorphous materials like organic semiconductors happens via hopping between localized states of profound energetic disorder. The charge mobility reflects how swiftly charges are transported through such an energy landscape. Evidently, it is desirable to predict mobility-limiting bottlenecks and roadblocks directly from analyzing the energy landscape. However, external electric fields and interactions with other charges are as relevant for transport as the landscape, so that mobility-limiting features can be quantified only after having fully simulated entire charge trajectories respecting those influences. We developed a new simulation technique to calculate the mobility, which further permits to predict and interpret the dependence of the mobility on the external electric field and the charge density based on the energy landscape. The key idea is to modify the energy landscape by local correction energies that account for the ability of the charges to explore the underlying local landscape in the presence of all other charges, external electric fields, and temperature. To demonstrate the appealing ease of interpreting our simulations, we will explain the reasons for the field and the charge carrier-density dependence of the mobility.