Electronic Structure and Optical Properties of Inorganic Pm3m and Pnma CsPbX3 (X = Cl, Br, I) Perovskite: A Theoretical Understanding from Density Functional Theory Calculations

• Published in: Materials Vol. 16; no. 18; p. 6232
• Main Authors: Ghaithan, Hamid M., Qaid, Saif M. H., Alahmed, Zeyad A., Bawazir, Huda S., Aldwayyan, Abdullah S.
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 15-09-2023; MDPI
• Subjects: Absorptivity; Approximation; Bromine; Chlorine; Crystal structure; Density functional theory; DFT calculation; electronic properties; Electronic structure; Energy gap; Energy levels; inorganic perovskite; Investigations; Light emitting diodes; Methods; Optical properties; Optoelectronics; Perovskites; Plane waves; Refractivity
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma16186232

In this study, we investigated the optoelectronic properties of cubic (Pm3m) and orthorhombic (Pnma) CsPbX3 (X = I, Br, and Cl). We utilized the full potential linear augmented plane wave method, which is implemented in the WIEN2k code, to facilitate the investigation. Different exchange potentials were used to analyze the optoelectronic behavior using the available density functional theory methods. Our findings revealed that CsPbX3 perovskites display direct band gaps at the R and Г points for cubic (Pm3m) and orthorhombic (Pnma) structures, respectively. Among the exchange potentials, the mBJ-GGA method provided the most accurate results. These outcomes concurred with the experimental results. In both Pm3m and Pnma structures, interesting changes were observed when iodide (I) was replaced with bromine (Br) and then chlorine (Cl). The direct band gap at the R and Г points shifted to higher energy levels. Similarly, when I was replaced with Br and Cl, there was a noticeable decrease in the absorption coefficient, dielectric constants, refractive index, and reflectivity, in addition to a band gap shift to higher energy levels.