Spectroscopic ellipsometry study of CsPbBr <sub>3</sub> perovskite thin films prepared by vacuum evaporation
Chen Chen, Dan Wu, Meng Yuan, Chao Yu, Jian Zhang, Chuannan Li, Yu Duan
Abstract
Abstract CsPb X 3 ( X = Cl, Br, or I) perovskite thin films can be fabricated by vacuum evaporation (VE) with high reproducibility and good film-forming ability. To design optical devices based on CsPb X 3 thin films, precise optical constants are required. As only a few optical and dielectric properties of perovskites obtained by VE have been reported, we have comprehensively studied the complex reflective index and complex dielectric function of CsPbBr 3 perovskite VE films. Spectroscopic ellipsometry combined with x-ray diffraction and scanning electron microscopy revealed that the three-oscillator model precisely describes the optical constants. Therefore, the wavelength-dependent optical constants of a material can be empirically determined. Time-resolved photoluminescence of a designed CsPbBr 3 -light-emitting device with a Fabry–Perot cavity and agreement of its dielectric properties with reported data confirmed the existence of a microcavity effect and accurately predicted the electric field intensity distribution and cavity length. This methodology also enables the composition of perovskite to be monitored, which contains a fraction that is desirable for optimizing the performance of optical electronics.