Structural, mechanical, and optoelectronic properties of potassium-doped mixed halide perovskites Cs0.5K0.5SnX3 (X = Cl, Br, I): a first-principles study

The structural, mechanical, and optoelectronic properties of potassium-doped mixed halide perovskites Cs0.5K0.5SnX3 (X = Cl, Br, I) have been systematically delved into within the density functional theory (DFT) framework. Structural stability was confirmed through the ground state energy $${(E}_{o})$$ ( E o ) and Born’s mechanical stability criteria, indicating that all compounds retain a stable cubic phase. Mechanical analysis, including Poisson ( $${\varvec{\upsilon}}$$ υ ) and Pough’s ratios $$(B/G)$$ ( B / G ) suggests the significant ductility, making them suitable for device fabrication. Electronic structure calculations reveal that the bandgap can be tuned via halide substitution, impacting their potential for optoelectronic applications. Optical properties such as absorption, reflectivity, and optical conductivity demonstrate enhanced light-harvesting capabilities, particularly for Cs0.5K0.5SnI3. These findings highlight the potential of potassium-doped tin-based perovskites as promising candidates for photovoltaics, light-emitting diodes, and optical sensors. Graphical abstract