The Role of Excitation Energy in Photobrightening and Photodegradation of Halide Perovskite Thin Films

Wolf-Alexander Quitsch; Dane W deQuilettes; Oliver Pfingsten; Alexander Schmitz; Stevan Ognjanovic; Sarthak Jariwala; Susanne Koch; Markus Winterer; David S Ginger; Gerd Bacher

doi:10.1021/acs.jpclett.8b00212

The Role of Excitation Energy in Photobrightening and Photodegradation of Halide Perovskite Thin Films

J Phys Chem Lett. 2018 Apr 19;9(8):2062-2069. doi: 10.1021/acs.jpclett.8b00212. Epub 2018 Apr 10.

Affiliations

¹ Werkstoffe der Elektrotechnik and CENIDE , University of Duisburg-Essen , Bismarckstraße 81 , 47057 Duisburg , Germany.
² Department of Chemistry , University of Washington , Box 351700, Seattle , Washington 98195-1700 , United States.
³ Nanoparticle Process Technology and CENIDE , University of Duisburg-Essen , Lotharstraße 1 , 47057 Duisburg , Germany.
⁴ Department of Materials Science and Engineering , University of Washington , Seattle , Washington 98195-1700 , United States.

PMID: 29624057
DOI: 10.1021/acs.jpclett.8b00212

Abstract

We study the impact of excitation energy on the photostability of methylammonium lead triiodide (CH₃NH₃PbI₃ or MAPI) perovskite thin films. Light soaking leads to a transient increase of the photoluminescence efficiency at excitation wavelengths longer than 520 nm, whereas light-induced degradation occurs when exciting the films with wavelengths shorter than 520 nm. X-ray diffraction and extinction measurements reveal the light-induced decomposition of CH₃NH₃PbI₃ to lead iodide (PbI₂) for the high-energy excitation regime. We propose a model explaining the energy dependence of the photostability that involves the photoexcitation of residual PbI₂ species in the perovskite triggering the decomposition of CH₃NH₃PbI₃.