Solution Processed CZTS Thin Films and its Simulation Study for Solar Cell Applications with ZnTe as the Buffer Layer

The use of ZnTe as the buffer layer in the Cu 2 ZnSnS 4 (CZTS) based solar cells showed the improvement in overall efficiency. It may also reduce the overall cost of these cells as both the layers (absorbing and buffer) are having eco-friendly and earth abundant constitutes. The sol-gel spin coating method is used for the deposition of CZTS thin films on the corning glass substrates. The X-ray diffraction studies showed the peaks corresponding to (112), (200), (220) and (312) planes which confirmed the formation of essential kesterite phase. The optical band gap of the deposited films was found around 1.9 eV by UV-visible spectrophotometer. The optimum thickness of the absorber layer was investigated based on the performance of ZnO:Al/ZnO/ZnTe/CZTS/Mo cell structure by using AMPS-1D simulation tool, while the tool was moulded by the investigated data from the sol-gel deposited CZTS thin films. The efficiency of solar cell was found to be increased till 22.64% with increment in the thickness of absorber buffer layer up to 2500 nm and beyond this it starts to decrease. In addition to this, it was also analysed that the current density is improved with operating temperature as it is one of the requirements in the high solar radiation areas where the temperature rise more than 50 ᵒ C in summer.