Double peak emission in lead halide perovskites by self-absorption

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...

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Bibliographic Details
Published in:Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2020-02, Vol.8 (7), p.2289-23
Main Authors: Schötz, Konstantin, Askar, Abdelrahman M, Peng, Wei, Seeberger, Dominik, Gujar, Tanaji P, Thelakkat, Mukundan, Köhler, Anna, Huettner, Sven, Bakr, Osman M, Shankar, Karthik, Panzer, Fabian
Format: Article
Language:English
Subjects:
Absorption
Lead compounds
Metal halides
Optoelectronics
Perovskites
Photoluminescence
Photovoltaic cells
Single crystals
Solar cells
Temperature dependence
Thin films
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Summary: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. We demonstrate that the often observed double peak emission in lead halide perovskites is caused by an extensive self-absorption effect.
ISSN:2050-7526
2050-7534
DOI:10.1039/c9tc06251c