Dresden 2020 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 19: Focus Session: When theory meets experiment: Hybrid halide perovskites for applications beyond solar II (joint session HL/CPP)

HL 19.4: Talk

Monday, March 16, 2020, 16:15–16:30, POT 251

Double Peak Emission in Lead Halide Perovskites by Self-Absorption — •Konstantin Schötz¹, Abdelrahman M. Askar², Wei Peng³, Dominik Seeberger¹, Tanaji P. Gujar¹, Mukundan Thelakkat¹, Sven Huettner¹, Osman M. Bakr³, Karthik Shankar², Anna Köhler¹, and Fabian Panzer¹ — ¹Universität Bayreuth, Bayreuth, Germany — ²University of Alberta, Edmonton, Canada — ³King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia

Despite the rapidly increasing efficiencies of perovskite solar cells, the optoelectronic properties of this material class are not completely understood. Especially when measured photoluminescence (PL) spectra consist of multiple peaks, their origin is still debated. In this work, we investigate in detail double peak PL spectra of halide perovskite thin films and single crystals with different material compositions. By different optical spectroscopic approaches and quantitative models, we demonstrate that the additional PL peak results from an extensive self-absorption effect, whose impact is intensified by strong internal reflections. This self-absorption accounts for the unusual temperature dependence of the additional PL peak and it implies that absorption until far into the Urbach tail of the perovskite is important. The strong internal reflections entail that even for thin films self-absorption can have a significant contribution to the PL spectrum. Our results allow for a clear assignment of the PL peaks by differentiating between optical effects and actual electronic transitions, which is necessary for understanding the optoelectronic properties of halide perovskites.