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 ASiF₃ (A = Li, Na, K and Rb) by means of first-principles calculations. The computed energetic and elastic properties assert that the formation of the ASiF₃ 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. (author)