A Pressure Dependent Comparative Study of Elastic, Electronic, Optical and Photocatalytic Properties of CsPbX₃ (X= Cl, Br, I): A DFT Study for Optoelectronic Applications

A systematic hydrostatic pressure dependence of the elastic, electronic, optical and photocatalytic properties of CsPbX₃ (X = C, Br and I) has been evaluated based on ab initio simulations. This study reveals that the mechanical stability sustain up to 25 GPa for Cl and I contained perovskites but Br contain sustains stability up to 75 GPa. It is also found that the mechanical properties of CsPbX₃ perovskites are ductile under ambient conditions and their ductility has been significantly improved (decreases) with pressure. The electronic properties suggested that CsPbX₃ perovskites have a direct energy band gap that decreases with increasing applied pressure due to structural change. The band gap becomes zero at 20, 15 and 10 GPa which insights the transportation of crystal structure. Absorption peak of CsPbX₃ perovskites is radically changed toward the lower photon energy region with the applied pressure. The photoconductivity, reflectivity, and dielectric constant have an increasing tendency under pressure. CsPbI₃ is the best photocatalyst for hydrogen evolution reaction and CsPbBr₃ is the most stable photocatalyst due to its nearly balanced oxidation and reduction potentials, but CaPbCl₃ is better for O₂ production. These findings would be beneficial for experimental study and suggest that pressure has a significant role on the physical properties of CsPbX₃ perovskites that might be promising for optoelectronic, photonic and hydrogen production along with biodegradation of polluted and waste materials.