Optical, structural and photoelectrochemical properties of CdS1−xSex semiconductor films produced by chemical bath deposition

• The solid solutions of CdS1−xSex thin films were prepared.
• The growth mechanism of CdS1−xSex thin films was investigated.
• The band gap can be adjusted successively via changing the S/Se ratio.
• The photocurrents were greatly depended on the absorption of thin films.
• The annealed CdSe film got the highest photo-to-current efficiency.

A series of CdS1−xSex thin films have been deposited on fluorine doped tin oxide (FTO) coated glass substrates by chemical bath deposition. The influences of S/Se ratio in the precursor solution and annealing treatment on the structural, morphological, compositional, optical, and photoelectrochemical properties of the films were investigated. X-ray diffraction patterns revealed that the hexagonal cadmium cyanamide and the solid solutions of CdS1−xSex were formed. The morphological and compositional studies indicated that the thin film was composed of cadmium cyanamide sheets in the upper layer and CdS1−xSex spherical grains in the underlying layer. The optical absorption studies revealed that the band gap of unannealed and annealed films varied from 2.4 eV to 1.94 eV and from 2.35 eV to 1.67 eV as x increased from 0 to 1, respectively. The photo responses well agreed with the optical absorption of these films. The annealed CdSe shows the best photoresponse with a photon-to-current efficiency of 1.69% at 0.27 V (versus SCE).