Gas–solid reaction for in situ deposition of Cu3SbS4 on a mesoporous TiO2 film

Abstract

Herein, a novel, facile, in situ gas–solid reaction method has been successfully employed for the deposition of famatinite (Cu₃SbS₄) semiconductor on a mesosporous TiO₂ film, where precursors CuCl₂ and SbCl₃ were first solution-coated on a TiO₂ substrate, followed by reaction with H₂S gas and further thermal annealing. Various precursor ratios, temperatures and heating atmospheres have been examined for the deposition. The phase-pure Cu₃SbS₄ has been obtained by coating a mixed solution of CuCl₂ and SbCl₃ at a molar ratio of 2.5 : 1, and annealing at 300 °C for 10 min in an H₂S atmosphere. The deposited Cu₃SbS₄ was uniformly distributed on the entire porous TiO₂ film with crystal grain sizes of about 3–4 nm. X-ray photoelectron spectroscopy (XPS) analysis revealed valence states of the synthetic samples for Cu⁺, Sb⁵⁺ and S²⁻, verifying phase-pure Cu₃SbS₄. The spectral absorption of the film ranges from 400 nm to 1000 nm with a band gap of ∼1.24 eV. The Cu₃SbS₄ film shows good and stable photoresponse performance, indicating its high potential as photovoltaic absorber.