Effect of solution concentration on the properties of Cu2ZnSnS4 nanocrystalline thin films prepared by microwave irradiation

In this paper, Cu2ZnSnS4 (CZTS) thin films were directly grown on the transparent conductive fluorine-doped tin oxide (FTO) substrates by microwave irradiation solution method. The influences of precursor concentration and thiourea concentration on the crystallographic structure, morphology and optical properties were studied using X-ray diffraction, Raman spectroscopy, scanning electronic microscope, transmission electron microscopy and UV–Vis spectrophotometer. Results revealed that the CZTS thin films were selectively deposited only on the conductive side of substrates. The CZTS thin films are in the kesterite structure with a little binary and ternary impurities phases and composed of sphere-like particles. The optical band gap of the CZTS thin films is in the range of 1.27–1.54 eV. The similar tetragonal structure between the FTO substrate and Cu2ZnSnS4, suitable electrical conductivity and surface roughness are critical to promoting the epitaxial nucleation and growth of the Cu2ZnSnS4 thin films on FTO substrates.