November 18, 2024
Journal Article
Local A-site phase segregation leads to Cs-rich regions showing accelerated photodegradation in mixed-cation perovskite semiconductor films
Abstract
We use hyperspectral photoluminescence microscopy to study compositional heterogeneity and its influence on the stability of mixed-cation (formamindinium (FA) and cesium) FA1-xCsxPb(I0.9Br0.1)3 lead halide perovskites with different Cs contents. We observe substantial microscale heterogeneity in the photoluminescence. By correlating photoluminescence maps with time-of-flight secondary ion mass spectrometry (ToF-SIMS) imaging, we show that the redder-photoluminescence regions of the perovskite film are associated with Cs-rich compositions. X-ray diffraction measurement and confocal Raman spectroscopy provide evidence for the presence of d-phase CsPbIxBr3-x in these regions. Photo-aging tests show that these Cs-rich clusters undergo faster photoluminescence decay than the rest of the film. These observations highlight the importance of local heterogeneities and their influence on the stability of halide perovskite semiconductors being studied for optoelectronics.Published: November 18, 2024