Electronic band structure, mechanical and optical characteristics of new lead-free halide perovskites for solar cell applications based on DFT computation

Recently, photovoltaic solar cells have been revolutionized by adopting ABX(3) halide perovskite materials as photoabsorbers. In the recent past, lead halide perovskites have attracted significant research interest. However, owing to its toxicity, alternative lead-free materials are currently being actively sought. In this work, we report the computational results of the structural, electronic, optical and elastic properties of the unexplored lead-free halide fluoroperovskite material ASiF(3) (A = Li, Na, K and Rb) by means of first-principles calculations. The computed energetic and elastic properties assert that the formation of the ASiF(3) cubic systems is energetically favourable and mechanically stable. According to the results, LiSiF3 and NaSiF3 are indirect bandgap semiconductors, which are not appropriate for solar cell applications. The calculated elastic, electronic and optical properties indicate that KSiF3 and RbSiF3 alloys are isotropic and exhibit high ductility. They have reasonable direct bandgaps, a small effective mass and good light absorption, making them suitable for single-junction photovoltaic cells and other optoelectronic applications in the visible and UV regions of the electromagnetic spectrum.