A comparative study of the mechanical stability, electronic, optical and photocatalytic properties of CsPbX (X = Cl, Br, I) by DFT calculations for optoelectronic applications.

Organic free Cs-based perovskite materials are potential candidates for electronic and optoelectronic applications. A systematic comparative study of the mechanical, electronic, optical, and photocatalytic properties of CsPbX (X = Cl, Br, I) was conducted using density functional theory to compare the applicability of these materials in optoelectronic, photocatalytic, and photovoltaic (PV) devices. We calculated structural and elastic properties to determine the better agreement of damage-tolerance and electronic and optical responses for suitable device applications. Optimized lattice parameters and elastic constants showed excellent agreement with the experimental data whereas some properties were found to be much better than other theoretical reports. CsPbBr is thermodynamically more stable and more ductile compared to the other two perovskites. The hydrostatic pressure dependent mechanical stability showed that CsPbCl and CsPbBr sustained stability under low applied pressure, whereas the stability of CsPbI was very high. The electronic band gap calculations showed that CsPbCl, CsPbBr and CsPbI are suitable for green, orange, and red emissions of optical spectra owing to the proper electronic band gaps. CsPbI can be shown as the best photocatalyst for the hydrogen evolution reaction and CsPbBr is the most stable photocatalyst due to its nearly balanced oxidation and reduction potentials, but CaPbCl is better for O production. The density of states and other optical properties have been reported in this study. Thus, our findings would be beneficial for experimental studies and can open a new window for efficient electronic, optoelectronic, and hydrogen production along with the biodegradation of polluted and waste materials.