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 MAPbBr(3) single-crystal degradation processes in X-ray, N-2, O-2, 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 similar to 10% of the surface MAPbBr(3) degraded to metallic lead under X-rays in vacuum, while N-2 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 O-2, it was susceptible to H2O exposure within the top 0.37 nm and a reaction threshold of similar to 10(8) Langmuir was found. Below the threshold, H2O acted only as an n-type dopant; above it, the surface began to decompose. These observations highlight possible future directions to improve the material stability by environmental control.