Double peak emission in lead halide perovskites by self-absorption

Konstantin Schötz, Abdelrahman M. Askar, Wei Peng, Dominik Seeberger, Tanaji P. Gujar, Mukundan Thelakkat, Anna Köhler, Sven Huettner, Osman Bakr, Karthik Shankar, Fabian Panzer

Research output: Contribution to journalArticlepeer-review

54 Scopus citations

Abstract

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 perovskite's Urbach tail is important. The 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 electronic transitions, which is a necessary requirement for understanding the optoelectronic properties of halide perovskites.
Original languageEnglish (US)
Pages (from-to)2289-2300
Number of pages12
JournalJournal of Materials Chemistry C
Volume8
Issue number7
DOIs
StatePublished - Jan 7 2020

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: KoS acknowledges financial support from the German National Science Foundation (Project KO 3973/2-1 and GRK 1640). AK, SH and MT acknowledges support by the Bavarian State Ministry of Science, Research, and the Arts for the Collaborative Research Network ‘‘Solar Technologies go Hybrid’’. KaS acknowledges financial support from NSERC (grant number 06630) and NRC (grant number A1-014009). WP and OMB acknowledge the financial support of KAUST. Furthermore, we thank Daniel Niesner and Laura Herz for fruitful discussions, and Yu Zhong for the help with film characterizations.

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