Enhanced optoelectronic properties of Ca and S-doped HgSe (Hg1−xCaxSxSe1−x) compounds for photovoltaic applications

In optoelectronics, dopants play a crucial role in modulating material properties, as they directly influence the structural characteristics. This study investigates the structural, electronic, and optical properties of Hg${}_{1-x}$Ca${}_x$Se${}_{1-x}$S${}_x$ compounds at various Ca and S concentrations ($x=0.0,0.25,0.50,0.75,1$), using density functional theory (DFT) with the GGA-PBE approach. While semiconductor materials like HgSe are crucial for optoelectronic applications, the combined effects of Ca and S substitution are not well explored. This presents a gap in understanding how these dopants affect the material’s properties, especially in the visible spectrum. Our study addresses this by systematically analyzing the effects of Ca and S doping on the structure, band gap, and optical properties. We find that increasing Ca and S content widens the direct band gap at the $\Gamma$-point. The compounds also exhibit strong absorption, low reflectivity, and low loss function, enhancing their suitability in photovoltaic and optoelectronic applications than the state of the art. This work provides key insights into optimizing Hg${}_{1-x}$Ca${}_x$Se${}_{1-x}$S${}_x$ for next-generation devices.