Eco-friendly and non-toxic thin film solar cell employing spray pyrolysed p-CZTS and n-SnS:Cu—a novel approach

n-Type SnS:Cu thin films are fabricated using chemical spray pyrolysis and are used successfully for solar cell device fabricationwith the configuration ITO/CZTS/SnS:Cu/ZnO:Al/Ag for the first time. The device has high open-circuit voltage (V_oc) of 810 mV, short circuit current density (J_sc) of 0.87 mA/cm², fill factor (FF) of 51% and an efficiency of 0.36%. Similar device structure is not reported so far. Even though the J_sc obtained is less, we could achieve a good V_oc and FF value which are comparable with the parameters obtained for well established solar devices. The structural, morphological, electrical and optical properties of SnS:Cu films used for the cell fabrication are studied using X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, Scanning electron microscopy, Hall measurements and UV-Vis-NIR spectroscopy. The oxygen concentration is decreased from 49 to 8% as the Sulfur concentration is increased and hence proved that adjustment of precursor ratio is a very effective method to control the oxygen content of the samples, which is a determining factor in the performance of the device. This work suggests an easily adoptable method for preparing n-type SnS:Cu thin films favorable for device fabrication by varying tin to sulphur ratio.