The Role of Oxygen in the Degradation of Methylammonium Lead Trihalide Perovskite Photoactive Layers Article Swipe
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· 2015
· Open Access
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· DOI: https://doi.org/10.1002/anie.201503153
· OA: W2132808501
In this paper we report on the influence of light and oxygen on the stability of CH 3 NH 3 PbI 3 perovskite‐based photoactive layers. When exposed to both light and dry air the mp‐Al 2 O 3 /CH 3 NH 3 PbI 3 photoactive layers rapidly decompose yielding methylamine, PbI 2 , and I 2 as products. We show that this degradation is initiated by the reaction of superoxide (O 2 − ) with the methylammonium moiety of the perovskite absorber. Fluorescent molecular probe studies indicate that the O 2 − species is generated by the reaction of photoexcited electrons in the perovskite and molecular oxygen. We show that the yield of O 2 − generation is significantly reduced when the mp‐Al 2 O 3 film is replaced with an mp‐TiO 2 electron extraction and transport layer. The present findings suggest that replacing the methylammonium component in CH 3 NH 3 PbI 3 to a species without acid protons could improve tolerance to oxygen and enhance stability.
