Modeling of structural, electronic, optical, and thermoelectric properties of CsPb(I1-xBrx)3 (x=0, 1, 2, 3) solid solutions by first principle approach

We report a systematic study of CsPb(I1-xBrx)3 halide perovskites with Br concentration of x = 0, 1, 2, 3 using density functional theory. The exchange and correlation has been treated with generalized gradient approximation (GGA) and GGA-modified-Becke-Johnson (GGA-mBJ) approximation. The estimation of the total energy and electronic structure confirm Pm-3m structure and semiconductor nature at the equilibrium lattice parameter. The calculated ground state properties are in good agreement with the available experimental and other theoretical findings. Further based on optical properties, the studied halide perovskites have good dielectric constant, high refractive index, optical conductivity, and absorption coefficient, therefore, suggested for photovoltaic and optoelectronic applications. Furthermore, these halide perovskites have excellent thermoelectric performances in terms of Seebeck coefficient, electrical conductivity, power factor, and figure of merit at room temperature as well as at high temperatures. The mixing of Br produces an increment in the power factor and henceforth figure of merit at a certain n-type doping. We report a figure of merit value for these perovskites in the range of 0.66-0.748 at room temperature and can be used in generators for the production of heat. The present study opens a scope for further applications of the studied materials.