Solution-processed Cd free kesterite Cu2ZnSnS4 thin film solar cells with vertically aligned ZnO nanorod arrays

In order to development of non-toxic thin film photovoltaic devices the ZnO/ZnS are quite attractive as window/buffer layer due to its suitable semiconductor properties and abundant availability. We report CZTS based solar cells devices of layer configuration ITO/ZnO (NR's)/ZnS/CZTS/Au. The vertically aligned ZnO nanorod arrays have been grown using hydrothermal technique, whereas the ZnS and CZTS thin films has been deposited by chemical bath deposition and solution processing method respectively. In proposed device architecture ZnO nanorods arrays/ZnS films work as window/buffer layer and CZTS as photo active layer respectively. The nanostructured ZnS/ZnO array provides improved light harvesting behaviour compared to a thin film configuration. The prepared Cd free CZTS/ZnS/ZnO NR device exhibit a solar energy conversion efficiency of 3.63%, which is the highest efficiency yet reported for nanostructured ZnS/ZnO superstrate CZTS solar cells from best of our knowledge.