Berlin 2024 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 42: Perovskite and Photovoltaics II (joint session HL/KFM)

HL 42.3: Talk

Thursday, March 21, 2024, 10:00–10:15, EW 203

Combining transient photoluminescence and transient surface photovoltage experiments: insights from drift-diffusion modeling — •Orestis Karalis, Hannes Hempel, and Thomas Unold — Helmholtz-Zentrum Berlin, Berlin, Deutschland

The combination of transient surface photovoltage (trSPV) and transient photoluminescence (trPL) can help to distinguish charge transfer and recombination at the interfaces between photo-absorbers and charge-selective layers (I. Levine, 2021). This distinction is particularly crucial for the optimization of halide perovskite solar cells, as their power conversion efficiency is mainly limited by interfacial losses. However rate-equation models previously employed for trSPV (I. Levine, 2021) or trPL (F.Staub, 2016) are unable to simultaneously describe both experiments, which raises concerns about the validity of their findings. To address this limitation, we perform drift-diffusion modeling utilizing the open-source SIMsalabim algorithm (M. Koopmans, 2022). Our investigation reveals that strong charging of the sample with repetitive pulsed illumination, a factor overlooked in previous models, can strongly change the shape of the transients. Based on the improved model, we explore the impact of various parameters, such as charge-transfer velocity, bulk trap density, energy level alignment between absorber and charge transport layer, on the trPL and trSPV transients, as well as on overall solar cell performance. Finally, comparison of these simulations allows a simple phenomenological interpretation of trPL and trSPV. This insight can serve as a valuable guide in the pursuit of optimizing halide perovskite solar cells.

Keywords: interfaces; non-radiative losses; charge extraction; surface photovoltage; photoluminescence