A Comprehensive First Principle Investigation of Ti-Doped Ca(Hf1–xTix)S3 Alloys: Implications on Electronic Structure and Stability with Hubbard Correction

This study investigates the potential of Ca(Hf_1–xTi_x)S₃ chalcogenide perovskite alloys (orthorhombic phase) for optoelectronic applications. Density functional theory (DFT) calculations explore the influence of titanium (Ti) doping (x = 0, 0.25, 0.50, 0.75, 1.00) on the material’s structural, thermodynamic, electronic, and optical properties. The calculations confirm the structural and thermodynamic stability of the alloys through tolerance factor and formation energy calculations. Interestingly, Ti doping is found to influence the bulk modulus and its derivative, affecting the material’s compressibility and hardness. A crucial finding is the decrease in bandgap with increasing Ti concentration, falling within the optimal range for efficient light absorption (1.0–1.6 eV). This suggests that Ti doping can enhance the optoelectronic properties of Ca(Hf_1–xTi_x)S₃. Furthermore, all studied compositions (x = 0, 0.25, 0.50, 0.75, 1.00) exhibit favorable light absorption across the visible to ultraviolet spectrum, making them promising candidates for solar cells and other optoelectronic devices.