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HL: Fachverband Halbleiterphysik

HL 32: Organic Electronics and Photovoltaics II (joint session CPP/HL)

HL 32.2: Vortrag

Mittwoch, 29. März 2023, 15:15–15:30, GÖR 226

What determines the Recombination Order in Organic Solar Cells? — •Kathrin Brocker, Jana Seiler, Dorothea Scheunemann, Clemens Göhler, and Martijn Kemerink — Institute for Molecular Systems Engineering and Advanced Materials, Heidelberg University

Organic Solar Cells provide an interesting and low-cost alternative to conventional inorganic photovoltaics. Upon illumination, excitons are created that separate into free electrons and holes at the donor-acceptor-interface and can be extracted to deliver electricity. The opposing loss mechanism is the recombination of charge carriers, which happens in the bulk both prior to and after charge separation. To understand these processes, the recombination order is crucially important. Experimentally, orders around or above 2 are typically found. Surprisingly, kinetic Monte Carlo (kMC) simulations that otherwise accurately reproduce experimental observations, yield values closer to 1. Here, we investigate the factors that might lead to higher recombination orders. Apart from the influence of morphology and contacts, special focus is laid on the effect of charge carrier delocalisation, which is shown to facilitate charge carrier separation and increase the fraction of bimolecular recombination. Simulation results are compared to experimental data obtained via the Steady State Bias Assisted Charge Extraction (BACE) method on P3HT:PCBM and PM6:Y6 solar cells.