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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 17: Poster Session I

CPP 17.21: Poster

Monday, March 27, 2023, 18:00–20:00, P3

Calculation of intra-molecular transition rates depending on structural parameters with DFTB — •Fabian Teichert, Robin Silligmann, Florian Günther, and Angela Thränhardt — Institute of Physics, Chemnitz University of Technology, Chemnitz, Germany

Organic semiconductors become increasingly important for electronic applications. The large number of organic materials and their combinations make it useful to investigate properties like current-voltage characteristics using simulations in order to find suitable material combinations for applications. We investigate the transition rates of electrons between two organic molecules, expecially between thiophene, zinc porphyrin and PCBM. For this, we calculate HOMO and LUMO states and energies, reorganisation energies and Hamiltonian coupling matrices with DFTB using the software dftb+. Based on these results, the transition rates are computed using Marcus theory for charge transfer. We present result for two systems: (1) two thiophene molecules and (2) zinc porphyrin and PCBM. We show reorganisation energies, Hamiltonian coupling constants and transition rates dependent on the structural configuration. E.g. the thiophene molecules are shifted and rotated against each other. The final goal of our work is to obtain the statistical distribution of all the results due to the statistical fluctuation of the structure. This is suitable as input for subsequent Monte-Carlo hopping simulations, which can be used to describe the large-scale transport of charges within organic materials for e.g. solar cell applications.