Photoelectrochemical performance of spray-deposited Fe-doped ZnS0.2Se0.8 thin films

Binary and ternary II–VI group semiconductor compounds are materials with potential use in various optoelectronic applications, including photoelectrochemical (PEC) solar cells. Thin films of ZnS_0.2Se_0.8 with various Fe-doping concentrations were successfully deposited on fluorine-doped tin oxide-coated glass substrates at a deposition temperature of 275 °C using the chemical spray pyrolysis. PEC cells with Fe:ZnS_0.2Se_0.8 thin film/1 M polysulphide/C (graphite) configurations were designed, and the effect of Fe doping on the PEC performance was studied. The results showed that Fe doping in ZnS_0.2Se_0.8 enhanced the performance of the PEC cells significantly. The optimum concentration was 0.20 mol%. The flat band potential and junction barrier height were maximum at this concentration, with values of −1.18 V and 0.27 eV, respectively. The junction ideality factors of the 0.20 mol% Fe-doped ZnS_0.2Se_0.8 thin film-based PEC cell in the dark and under illumination were found to be 1.21 and 1.17, respectively. The photovoltaic power output characteristics were boosted by Fe doping with a concentration of 0.20 mol%, with the open circuit voltage being 320 mV and the short circuit current being 1.48 mA cm⁻². The solar-to-electrical conversion and the fill factor of the 0.20 mol% Fe-doped ZnS_0.2Se_0.8 thin film-based PEC cells were superior, with values of 2.84% and 0.60, respectively. A PEC cell with a 0.20 mol% Fe-doped ZnS_0.2Se_0.8 photosensitive thin film had the highest spectral sensitivity, at a wavelength of 375 nm, with an optical band gap of 3.30 eV.