Density functional theory investigation of CsMnBrxI3-x (x = 0-3) halide perovskites for optoelectronic applications

As technology and industrialization quickly advance, global energy demand increases immensely, burdening energy systems to keep up. Renewable energy is a sustainable method to remedy the demand, in particular using solar energy, which is incredibly abundant and its implementation is rapidly increasing worldwide. In addition, optoelectronics have also yielded applications in thermophotovoltaics and photodetectors, with research utilizing mechanical flexibility, optical anisotropy, and exploring magnetic semiconductors in advancing the field of optoelectronics. Despite the popularity of lead (Pb) based perovskites as absorbers in optoelectronics, their toxicity and phase instability have moved interest towards Pb-free perovskites. This research performs a preliminary theoretical exploration of CsMnBr x I 3-x (x = 0, 1, 2, and 3) to assess their potential as candidate materials for optoelectronic applications. The Kohn-Sham framework of density functional theory (DFT) is used with spin-dependent generalized gradient approximations (SGGA) and Perdew–Burke–Ernzerhof (PBE) functional with linear combination of atomic orbitals (LCAO) basis set. The mixed halide compounds relaxed to lower-symmetry lattice structures. Although all examined compounds are generally soft and ductile, CsMnBrI 2 shear is soft. All bandgaps are direct and close to one electron volt, with the exception of the far narrower direct bandgap of CsMnBrI 2 . The optical properties of the four samples exhibit anisotropy in the perovskites, with CsMnBr 2 I as the most isotropic, but all exhibit high absorption and low reflectivity.