The goal of this research work was to carry out a Density Functional Theory (DFT) calculation to study the effect of C and Mn on the electronic and optical properties of pure wurtzite ZnS at 25% and 50% dopant concentrations. The study was carried out using Full Potential Linearized Augmented Plane Wave

(FP-LAPW) method using the WIEN2k code package. Our investigation found that using C as dopant element we can get reduced direct band-gap with increased

optical absorption which indicates the possible use of C doped ZnS as the absorption layer in solar cell.