Simultaneous Oxygen and Light Exposure Induced degradation of MAPbBr₃

In this work, we investigated oxygen and light induced the degradation on methylammonium lead bromide (MAPbBr₃) single crystal by using X-ray photoelectron spectroscopy (XPS). The elemental core level spectra show substantial surface degradation during the exposure. It was found that the with light the oxygen degradation process of the MAPbBr₃ was substantially accelerated. Quantitative analysis showed that Carbon, Bromine and Nitrogen lost 52%, 56% and 90% of their initial concentration respectively at 10¹² Langmuir of oxygen exposure. It further showed that ~11% of the perovskite’s Pb degraded to metallic Pb at 10⁹ Langmuir. We observed that the new metallic Pb component faded away and the oxygen peak started to form after 10¹¹ L, which indicates the oxidation of metallic Pb with the increase of the oxygen pressure.