Modulating the optoelectronic characteristics of ZnS through transition metals doping: insights from density functional theory

The optoelectronic properties of ZnS doped with transition metals (Cu, Cd, Ag, and Au) are systematically investigated by applying first-principles computations based on the density functional theory (DFT). Various doping concentrations for Cu (5%, 10%, 20%), Cd (5%, 10%, 15%, 20%), Ag (5%, 15%), and Au (5%, 15%, 20%) are explored to examine their impact on the properties of ZnS. Our analysis confirms that all doped structures exhibit direct band gap semiconducting behavior. Notably, the band gap energy decreases with the incorporation of Cd, Ag, and Au, while an increase in Cu content results in a wider band gap. This work also evaluates how these transition metals influence the absorption coefficient, the dielectric constant, the refractive index, and the extinction coefficient of ZnS, providing a comprehensive insight into their effects. Our findings show a good agreement with existing experimental and theoretical data, offering a deep understanding of the optoelectronic properties of doped ZnS semiconductors. This investigation underlines the significance of doping in tailoring the properties of ZnS for enhanced optoelectronic applications, laying the groundwork for further experimental validation and theoretical analysis.