Cost-effective solar cells containing copper indium chalcogenides prepared by SILAR method

CuInSe2 (CISe) and CuIn(Se1−x S x )2 (CISeS) thin films have been prepared using successive ionic layer adsorption and reaction method (SILAR) to produce CuSe and In2Se3, which were subsequently heated in appropriated conditions. Glass, TCO, and TCO/TiO2 were used as substrates. A duplex layer of TiO2 had been deposited by spray-pyrolysis and doctor blade. The thermal treatment leading to the formation of the chalcogenide was carried out in two different atmospheres. The first treatment was an annealing step under argon atmosphere, where CISe is obtained. The second consisted of a sulfurization process, where sulfur powder is melted and the vapor mixed into the argon flux. The morphology and composition of the annealed films were characterized by GXRD, micro-Raman spectroscopy, and SEM/EDS. Raman spectra and EDS showed an almost complete replacement of the Se atoms by S atoms, leading to the formation of CuIn(Se1−x S x )2, with x = 0.8. Etching the films in KCN solution was necessary to dissolve residual secondary phases. Preliminary solar cell prototypes prepared with CISe and CISeS show a clear photo-response, although the photocurrent and open circuit potential are still low. This is a promising first result, showing that CuInSe2 and CuIn(Se1−x S x )2 prepared by SILAR can be used in solar cells.