Growth of Cu2ZnSnS4 thin films on transparent conducting glass substrates by the solvothermal method

Abstract

In this study, a facile solvothermal method was proposed to grow Cu2ZnSnS4 (CZTS) thin films directly on transparent conductive fluorine-doped tin oxide (FTO) substrates. In the solvothermal fabrication process, precursors of hexadecyl trimethyl ammonium bromide, copper (II) chloride dihydrate, tin (II) chloride dehydrate, zinc (II) chloride, thiourea and ethanol were used. The morphology, crystallographic structure, chemical composition and optical band gap of CZTS thin films were investigated using scanning electronic microscope (SEM), X-ray diffraction (XRD), Raman spectroscopy, energy dispersive spectrometry (EDS) and UV–vis–NIR spectrophotometer, respectively. It is revealed that Cu2ZnSnS4 thin films are in kesterite phase, composed of a large number of uniform sphere-like particles with an average diameter of about 530nm. The optical band gap is found to be 1.51eV. It is believed that both the similar tetragonal structure and small lattice mismatch between the FTO substrate and Cu2ZnSnS4 play a key role in promoting the epitaxial nucleation and growth of the Cu2ZnSnS4 thin films on FTO substrates.