Letter pubs.acs.org/JPCL
Cite This: J. Phys. Chem. Lett. 2018, 9, 2062−2069
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,‡ and Gerd Bacher*,† †
Werkstoffe der Elektrotechnik and CENIDE, University of Duisburg-Essen, Bismarckstraße 81, 47057 Duisburg, Germany Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States § Nanoparticle Process Technology and CENIDE, University of Duisburg-Essen, Lotharstraße 1, 47057 Duisburg, Germany ∥ Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195-1700, United States ‡
S Supporting Information *
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.
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photoluminescence intensity upon photoexcitation of halide perovskite semiconductors, whereas an agreement on the mechanistic origin of the different light-soaking effects has not been reached yet.36 For instance, using a white light source with a power density of
