Experimental and numerical insights into Co-doped ZnS buffer layers for high-efficiency solar cells

This study explores the influence of cobalt (Co) doping concentration on the structural, morphological, optical, and electrical properties of zinc sulfide (ZnS) thin films. Both undoped and Co-doped ZnS thin films were successfully deposited on glass substrates using an economical and scalable ultrasonic-assisted chemical vapor deposition (Mist CVD) technique at a substrate temperature of 450 °C. A comprehensive characterization was performed using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, atomic force microscopy, UV–Vis spectrophotometry, and Hall effect measurements. To assess their device relevance, SCAPS-1D simulations were performed by incorporating ZnS:Co as buffer layers in thin-film solar cells. The results show that 4 % Co doping enhances the optoelectronic properties and achieves the highest simulated efficiency of 14.50 %. These findings demonstrate that controlled Co incorporation is a promising route for tailoring ZnS thin films toward efficient buffer layers in photovoltaic devices.