Environmental Surface Stability of the MAPbBr3 Single Crystal

Organic–inorganic halide perovskites have emerged as a promising semiconductor family because of their remarkable performance in optoelectronic devices. On the other hand, the stability of perovskites remains a critical issue. In this work, we report a quantitative and systematic investigation of in situ cleaved MAPbBr3 single-crystal degradation processes in X-ray, N2, O2, and H2O environments. The high-quality crystals were monitored by high-resolution X-ray photoelectron spectroscopy with careful control of the exposure time and pressure. The detailed electronic structure and compositional changes of the crystal were tracked throughout the different exposures, and these studies provided insights into the various degradation mechanisms. We identified that ∼10% of the surface MAPbBr3 degraded to metallic lead under X-rays in vacuum, while N2 could protect the sample from the degradation for 9 h under the same condition. Other measurements showed that while the surface was not sensitive to pure O2, it was...