Photo-induced halide redistribution in organic–inorganic perovskite films

By D. deQuilettes, Wei Zhang, Victor M. Burlakov, D. J. Graham, T. Leijtens, A. Osherov, Vladimir Bulovic, H. Snaith, David S. Ginger, S. Stranks. Nature Communications, 2016

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Organic–inorganic perovskites such as CH3NH3PbI3 are promising materials for a variety of optoelectronic applications, with certified power conversion efficiencies in solar cells already exceeding 21%. Nevertheless, state-of-the-art films still contain performance-limiting non-radiative recombination sites and exhibit a range of complex dynamic phenomena under illumination that remain poorly understood. Here we use a unique combination of confocal photoluminescence (PL) microscopy and chemical imaging to correlate the local changes in photophysics with composition in CH3NH3PbI3 films under illumination. We demonstrate that the photo-induced ‘brightening’ of the perovskite PL can be attributed to an order-of-magnitude reduction in trap state density. By imaging the same regions with time-of-flight secondary-ion-mass spectrometry, we correlate this photobrightening with a net migration of iodine. Our work provides visual evidence for photo-induced halide migration in triiodide perovskites and reveals the complex interplay between charge carrier populations, electronic traps and mobile halides that collectively impact optoelectronic performance. Visual evidence for photo-induced ionic migration in perovskite films without contacts is lacking. Here, the authors use a unique combination of confocal photoluminescence microscopy and chemical imaging to correlate the local changes in photophysics with composition in CH3NH3PbI3films under illumination.

Subfields: Electrical and Electronic Engineering, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/19858ee9bd751cebdfcb2a15a2ee66a960a25609

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