Investigations on Cu3SnS4 thin films prepared by spray pyrolysis

Thin films of Cu3SnS4, a promising absorber material for thin film heterojunction solar cells, are deposited using spray pyrolysis technique. The films are deposited at 360 degrees C, 390 degrees C and 420 degrees C to study the effect of substrate temperature on the growth of these films. The thickness of the films is found to be similar to 0.6 mu m. Films deposited at 420 degrees C are found to contain Cu3SnS4 as the dominant phase with CuS and Cu2SnS3 as the secondary phases. These films are annealed at 500 degrees C and 550 degrees C in sulfur atmosphere to improve the crystallinity and sulfur content in the films. With increase in the annealing temperature, the crystallinity is found to increase and the films annealed at 550 degrees C are found to be near-stoichiometric, cubic Cu3SnS4. The crystallite size is evaluated to be similar to 40 nm and the direct optical band gap of these films is found to be 1.75 eV. (C) 2014 Elsevier B. V. All rights reserved.