Effects of Zn doping concentration on the optical and photovoltaic properties of Zn x Pb 1−x S thin film-based solar cell prepared by chemical spray pyrolysis

The metal dopants in PbS thin films make a significant impact on its optical and electronic transport properties that make it useful for photovoltaic and other optoelectronic applications. The photovoltaic properties of Zn-doped nanostructured PbS thin films synthesized from zinc acetate, lead acetate, and thiourea as an absorber layer prepared using chemical spray pyrolysis were investigated. Rutherford backscattering spectroscopy (RBS), X-ray diffraction (XRD), and UV–visible spectrophotometry techniques were used to obtain stoichiometry, thickness, structural, and optical properties of the thin films before fabrication of Zn–PbS/CdS solar cell. The RBS revealed the stoichiometry ratio as ZnxPb1−xS and thickness range of 189.05–251.64 (1015 atoms/cm2). The inclusion of the Zn dopant drastically reduced the concentration of lead from the initial 40.93–14.95%. Optical analysis of the films gave high optical absorption and relatively low reflectance from visible toward the NIR region. An increase in energy bandgap was observed with Zn dopants inclusion from 0.53 to 1.65 eV, which fits the path of the solar radiation for maximum absorption. Photovoltaic properties revealed from the J–V measurement confirmed that Zn-doped sample 6% ZnAcet thin film solar cell gave a maximum short-circuit current density (Jsc) of 17.30 mA/cm2, open-circuit (Voc) 390 mV, fill factor (FF) 0.48, and conversion efficiency (η) of 2.7%.