Surface Termination—A Key Factor to Influence Electronic and Optical Properties of CsSnI₃

Despite great efforts devoted to the unusual optoelectronic properties for the bulk inorganic halide perovskites, overcoming the surface effects and bringing about selective growth in the specified surface termination are still a challenge. In this paper, we investigate the electronic structures, effective masses, carrier mobility, and optical properties of γ-CsSnI 3 with different terminations by employing density functional theory calculations. The calculated results show that the range of values of hole mobility is from 370.50 to 584.39 cm 2 /V s. Our results are close to the experimental data 400 cm 2 /V s. Moreover, we further predicted that the perfect CsI termination may exhibit better photovoltaic characteristics than the SnI 2 termination. On the basis of the stability of different surfaces and surface vacancies, an appropriate condition was obtained to suppress the I vacancies and promote the growth of perfect CsI-termination surface. This work also indicates that the electronic and optical properties of inorganic halide perovskites are tuned by selecting the proper surface, which is an important technique in the design of other optoelectronic devices.