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HL: Fachverband Halbleiterphysik

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

HL 32.3: Vortrag

Mittwoch, 29. März 2023, 15:30–15:45, GÖR 226

Modeling of the photoluminescence of geminate pairs using a hopping based Monte Carlo simulation — •Maik Schwuchow, Angela Thränhardt, Carsten Deibel, and Sibylle Gemming — TU Chemnitz, Institut für Physik, 09126 Chemnitz, Deutschland

The investigation of the transport and recombination characteristics of optically excited charge carriers in organic materials is an on-going research topic. Studying the underlying effects is crucial for understanding and improving practical applications, e.g. organic solar cells (OSCs). A main step in the process of free charge carrier generation in OSCs is the formation of geminate pairs, so called charge transfer complexes, consisting of spatially separated, Coulomb-bound charges. The radiative recombination of geminate pairs yields a photoluminescence (PL) decay ∝ t^−3/2 (t is time) on long time scales which arises due to a combination of thermally activated diffusion and attractive Coulomb interaction. While a continuous drift-diffusion model is able to theoretically explain this experimentally observed decay, weak molecular interaction and disorder are known to cause charge carrier localization. Therefore, a hopping model, based on tunneling between localized states, is usually more appropriate to describe charge transport in organic materials. We simulate the diffusion and recombination of hopping charge carriers using the Monte Carlo method and investigate the influence of different parameters, e.g. temperature and energetic disorder, on the PL data and the asymptotic slope.