Low-Temperature Refractive Index Dispersion in MAPbI₃ Halide Perovskite Single Crystal

Abstract

The refractive index is one of the main optical parameters of any semiconductor medium, including halide perovskites. To model devices, such as laser cavities, it is important to know not only the absolute value of the refractive index but also its spectral behavior, the dispersion. In this work, the refractive index dispersion n(E) in the MAPbI 3 (MA + = CH 3 NH 3 + ) halide perovskite single crystal is determined in the temperature range from 4 to 88 K by studying the interference of light in a microcavity. It has been shown that in the most practically important transparency region of the material, the dispersion of the refractive index is determined not only by the excitonic transition located nearby but also by higher-lying interband transitions.