Cu2SnS3 based thin film solar cells from chemical spray pyrolysis

Abstract A simple and eco-friendly method for solution processing of Cu2SnS3 p-type semiconductor absorbers using a water-based precursor solution is presented. Cu2SnS3 layers were processed by chemical spray pyrolysis deposition of the precursor solution onto Mo-coated glass substrates at 350 °C. The as-prepared layers were placed inside a graphite susceptor with S and SnS powders and were annealed in a tube furnace at 550 °C. The impact of the annealing step on structural, morphological and device characteristics of the prepared layers was studied. The as-prepared layers were crack-free with fine grains and dominant tetragonal Cu2SnS3 structure. A denser and compact Cu2SnS3 layer with larger grains was formed upon annealing accompanied by a structural phase transition from the tetragonal polymorph to the monoclinic phase. The as-prepared Cu2SnS3 layers showed no photovoltaic activity, whereas the annealed layers showed a device efficiency of 0.65%. A short air annealing of the complete Cu2SnS3 device at 250 °C improved the overall device performance and increased the device efficiency to 1.94%. Mechanical removal of shunt paths led to Cu2SnS3 device with 2.28% efficiency.