First-principles study on the crystal, elastic, electronic and photoelectric transport properties of three phases of CsPbBr 3

Abstract

To reveal the regulatory mechanism of crystal structure symmetry on the physicochemical properties of CsPbBr 3 perovskite, the electronic, elastic, and optical properties of its cubic (Pm3m), tetragonal (I4/mcm), and orthorhombic (Pbnm) phases were systematically investigated via first-principles density functional theory (DFT) calculations. The generalized gradient approximation parameterized by the Perdew-Burke-Ernzerhof functional (GGA-PBE) was adopted to describe the exchangecorrelation potential. The calculated band structures reveal that all three phases belong to direct band-gap semiconductors, with band gaps of 1.748 eV (cubic), 2.260 eV (tetragonal), and 2.301 eV (orthorhombic). As a common feature of GGA-PBE calculations, the obtained band gaps are evidently underestimated compared with available experimental results, which is widely reported in halide perovskite systems.All three polymorphs exhibit negative formation energies, indicating thermodynamic stability with respect to their constituent elements. All three CsPbBr 3 polymorphs comply with the Born mechanical stability criteria, demonstrating reliable structural robustness. By elucidating the intrinsic structure-property relationships of CsPbBr 3 , this work offers theoretical insights and data references that are expected to facilitate its structural design, property modulation, and applications in optoelectronics, photovoltaics, and laser detection.