Environmental Surface Stability of the MAPbBr3 Single Crystal

5 years ago

Environmental Surface Stability of the MAPbBr3 Single Crystal

Haotong Wei, Benjamin R. Ecker, Jinsong Huang, Congcong Wang, Yongli Gao

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 susceptible to H₂O exposure within the top 0.37 nm and a reaction threshold of ∼10⁸ 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.

Publisher URL: http://dx.doi.org/10.1021/acs.jpcc.7b12740

DOI: 10.1021/acs.jpcc.7b12740