Journal Article

Photo-induced halide redistribution in organic–inorganic perovskite films

Ginger, David S., Zhang, Wei, Burlakov, Victor M., Leijtens, Tomas, Bulović, Vladimir, Stranks, Samuel D., Snaith, Henry J., deQuilettes, Dane W., Graham, Daniel J., Osherov, Anna

2016

Overview

Organic–inorganic perovskites such as CH 3 NH 3 PbI 3 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 CH 3 NH 3 PbI 3 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 CH 3 NH 3 PbI 3 films under illumination.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 140/125 / 639/301/299 / 639/624/1075/401 / 639/766/400 / Ammonia / anomalous hysteresis / Calcium Compounds - chemistry / Calcium Compounds - radiation effects / CH3NH3PbI3 / diffusion / electron / Halides / Humanities and Social Sciences / Iodides - chemistry / Iodides - radiation effects / Iodine / Iodine - chemistry / Iodine - radiation effects / Lead - chemistry / Lead - radiation effects / lead-iodide / Lifetime / Light / Luminescent Measurements - methods / Mass spectrometry / MATERIALS SCIENCE / Methylamines - chemistry / Methylamines - radiation effects / Microscopy / Microscopy, Confocal - methods / multidisciplinary / Oxides - chemistry / Oxides - radiation effects / photoluminescence / recombination / Science / Science (multidisciplinary) / Scientific imaging / single-crystals / Solar cells / Spectrometry, Mass, Secondary Ion - methods / thin-films / Titanium - chemistry / Titanium - radiation effects