Spray pyrolysis deposition of copper indium disulfide thin films

Copper indium disulfide (CuInS2) thin films were successfully prepared from non-chlorinated starting materials on glass substrates by a spray pyrolysis deposition (SPD) method. The spray solutions were composed of water-ethanol (1:1 in volume) including copper acetate, indium acetylacetonate, and thiourea. The experimental parameters for the stoichiometric and well-crystallized CuInS2 thin film formation were determined as follows: spraying rate 1.0 ml/s, spraying period 0.5 s, substrate temperature 350degreesC, and S/(Cu + In) ratio of the spray solution 1.25. The dark brown CuInS2 thin film obtained was composed of rounded grains 1-3 mum in size with a direct band gap of 1.48 eV. The CuInS2/CdS heterojunction fabricated by the SPD method presented photovoltaic characteristics, though the current was only 5 muA.