I am a PhD student in the theory group at the Max Planck Institute for Polymer Research since February 2012.
My field of research is in material science, I am in particular interested in charge transport in organic semiconductors at high charge carrier densities, a situation occurring in organic light emitting diodes and field effect transistors.
I studied Physics (Diplom Oct. 2011) and Mathematics (B.Sc. Nov. 2009) at RWTH Aachen University and QMUL London. My final year project in Physics was in the field of Density Functional Theory in the group of Prof. Bluegel (Peter Gruenberg Institut) at Forschungszentrum Juelich. Here I developed a scheme allowing fully-relativistic Green function calculations for potentials of arbitrary shape within the Korringa-Kohn-Rostoker method.
Simulations of organic light emitting diodes
P. Kordt, P. Bobbert, R. Coehoorn, F. May, C. Lennartz, D. Andrienko
Finite-size scaling of charge carrier mobility in disordered organic semiconductors
P. Kordt, T. Speck, D. Andrienko
Phys. Rev. B,
Simulations of charge transport in amorphous semiconductors are often performed in microscopically sized systems. As a result charge carrier mobilities become system-size dependent. We propose a simple method for extrapolating a macroscopic nondispersive mobility from the system-size dependence of a microscopic one. The method is validated against a temperature-based extrapolation [A. Lukyanov and D. Andrienko Phys. Rev. B 82 193202 (2010)]. In addition we provide an analytic estimate of system sizes required to perform nondispersive charge transport simulations in systems with finite charge carrier density derived from a truncated Gaussian distribution. This estimate is not limited to lattice models or specific rate expressions.
Modeling of spatially correlated energetic disorder in organic semiconductors
P. Kordt, D. Andrienko
J. Chem. Theory Comput.,
Modeling of organic light emitting diodes: from molecular to device properties
P. Kordt, J. M. van der Holst, M. Al Helwi, W. Kowalsky, F. May, A. Badinski, C. Lennartz, D. Andrienko
Adv. Funct. Mater.,
In this chapter we describe the current state of the art of microscopic charge transport simulations in partially ordered and disordered organic semiconductors including simulations of atomistic morphologies evaluation of electronic couplings driving forces charge transfer rates and charge carrier mobilities. Special attention is paid to finite-size effects long-range interactions and charge localization.
Molecular scale simulation of hole mobility and current densities in amorphous tridecane
M. Unge, Ch. Toernkvist, P. Kordt, D. Andrienko
IEEE Conference Publications,
The hole mobility of amorphous tridecane (a model of amorphous polyethylene) is simulated using a parameter-free approach which combines density functional theory molecular dynamics and kinetic Monte Carlo methods. We observe large variations of the current density in the samples typical to materials with large energetic disorder. The obtained mobility values are of the same order of magnitude as the highest experimentally reported values. By introducing carbonyl groups we assess the effect of material oxidation and find that the mobility is reduced by an order of magnitude already at moderate concentrations of these groups.
Parameter-free continuous drift-diffusion models of amorphous organic semiconductors
P. Kordt, S. Stodtmann, A. Badinski, M. Al Helwi, C. Lennartz, D. Andrienko
Phys. Chem. Chem. Phys.,
Parametrization of extended Gaussian disorder models from microscopic charge transport simulations
P. Kordt, O. Stenzel, B. Baumeier, V. Schmidt, D. Andrienko
J. Chem. Theory Comput.,
Simulations of organic semiconducting devices using drift-diffusion equations are vital for the understanding of their functionality as well as for the optimization of their performance. Input parameters for these equations are usually determined from experiments and do not provide a direct link to the chemical structures and material morphology. Here we demonstrate how such a parametrization can be performed by using atomic-scale (microscopic) simulations. To do this a stochastic network model parametrized on atomistic simulations is used to tabulate charge mobility in a wide density range. After accounting for finite-size effects at small charge densities the data is fitted to the uncorrelated and correlated extended Gaussian disorder models. Surprisingly the uncorrelated model reproduces the results of microscopic simulations better than the correlated one compensating for spatial correlations present in a microscopic system by a large lattice constant. The proposed method retains the link to the material morphology and the underlying chemistry and can be used to formulate structure-property relationships or optimize devices prior to compound synthesis.