Theoretical investigation of structural, electronic, elastic, and optical properties of rubidium-based perovskites RbSrX3 (X = Cl, Br) for optoelectronic device applications – A DFT study

The search for environment-friendly lead-free halide perovskites is an emerging research area due to their crucial application in the field of photovoltaics and optoelectronics. So, in this current work, the structural, electronic, elastic, thermal, and optical properties of rubidium-based cubic halide perovskites RbSrX3 (X = Cl, Br) are investigated by the full potential linearized augmented plane wave (FP-LAPW) method in the context of density functional theory (DFT). The Generalized Gradient Approximation (GGA) of Perdew-Burke-Ernzerhof (PBE) is implemented as the exchange-correlation potential. The structural stability of these compounds in the cubic phase is studied and the values of their formation energies and ionic filling fraction (IFF) have been assessed. The band structure and DOS plots reveal a wide indirect bandgap at zero pressure. The elastic constants of these compounds are evaluated, and from Blackman's and Every's diagrams, they are found to be elastically stable with a ductile and anisotropic nature. The optical parameters of these compounds imply that they show good response in the ultraviolet region. Thus, by experimentally synthesizing these compounds their potential application in the development of optoelectronic devices working in UV range can be assessed.