Dresden 2017 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 55: Focus: Static and Dynamic Disorder Phenomena on the Transport in Organic Semiconductors I

CPP 55.5: Vortrag

Donnerstag, 23. März 2017, 12:00–12:15, ZEU 222

Revisiting the Concept of Carrier Heating in Hopping Transport — •Markus Krammer1, Chris Groves2, and Karin Zojer11Institute of Solid State Physics, NAWI Graz, Graz University of Technology, Austria — 2School of Engineering and Computing Science, Durham University, United Kingdom

Charges can be viewed to migrate through amorphous materials like disordered organic semiconductors due to hopping between localised states. This motion is governed by a complex interplay of energetic disorder, electric field, interactions, temperature and other parameters. The concept of carrier heating holds the promise of being able to conveniently predict field-dependent steady state charge carrier densities (SSCCD).[1] The SSCCD can be described with a Fermi Dirac distribution such that the impact of an electric field manifests in an effective temperature; provided that electric field and interactions are weak enough. As the conditions for the validity of this concept are still debated [2], we provide here the exact analytical SSCCD for arbitrary field strengths and low charge carrier densities. We demonstrate that the carrier heating effect originates from a modification of the energetic disorder rather than from an effective temperature. By virtue of numerical Kinetic Monte Carlo simulations, the limits of the effective temperature approximation and the field dependence of the effective temperature are revealed.

[1] B. I. Shklovskii et al. in Transport, Correlation and Structural Defects, by H. Fritzsche, World Scientific, Singapore (1990), p. 161

[2] S. D. Baranovskii, Phys. Status Solidi B, 251, 487-525 (2014)

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