Study On Preparation And Performance Of Cu-Zn-Sn-Sulfur Compound Thin Films Absorbed Layers Prepared By Co-Sputtering

Thin Film Sloar Cells made of Cu-Zn-Sn-sulfur compound have become a hotspot in research of renewable energy in recent years owing to their distinct advantages (direct band gap about 1.45-1.51eV, absorption coefficient of about 104cm-1, non-toxic, resourceful, cheap and environment-friendly). In this thesis, based on Cu-Zn-Sn-sulfur compound, Cu2ZnSnS4 (CZTS) thin films were prepared by using magnetron Co-sputtering method, Cu2ZnSn(SSe)4 (CZTSSe) thin films were fabricated by selenylation technics at high temperature, and then their photoelectric properties were evaluated as thin film cell absorption layers.First, Cu-Zn-Sn-S precursors were prepared by magnetron co-sputtering, then CZTS thin films were obtained by annealing above precursors. The effects of experiment technological conditions were studied, the results indicate that the forbidden band width decreases gradually with the increasing of annealing temperature, the diffraction peak intensity increases gradually, and the CZTS film grow along the (112) preferential orientation. We can get ideal thin film absorption layers when ZnS, SnS, Cu2S sputtering target power is respectively 60,15 and 20W, annealing temperature is 540℃, sputtering time is 20minutes. And their compositions are Cu poor and Zn rich. The surface morphology of the film is uniform and dense. The absorption coefficient is beyond 104cm-1 within the scope of the visible light, its optical band gap figure is about 1.5eV.In order to optimize the performance of CZTS thin films further, solid Se powder is used as the source of selenium. CZTSSe thin films with Cu poor and Zn rich were successfully prepared by selenizing and annealing Cu-Zn-Sn-S precursors. According to all kinds of characterizations, compared to CZTS, the forbidden band width of CZTSSe is smaller, the uniformity of CZTSSe thin film is better, and the surface morphology is denser. The optical band gap decreases with the increase of amount of selenium powder. The optical band gaps of thin films are 1.20,1.18,1.16 and 1.13eV when the mass of Se powder are 0.002,0.004,0.006 and 0.008g, respectively. Their light absorptions in the ultraviolet visible light range are above5*104cm-1.