Influence of precursor thin films stacking order on the properties of Cu_2ZnSnS_4 thin films fabricated by electrochemical deposition method

摘要

We fabricated Cu_2ZnSnS_4 (CZTS) thin films by electrochemically depositing precursor stacks on Mo-coated glass in a variety of orders: Cu/Sn/Cu/Zn, Cu/Zn/Cu/Sn, Zn/Cu/Sn/Cu, and Sn/Cu/Zn/Cu. Using Raman spectroscopy and X-ray diffraction, we found that for all stacking orders the annealed film was composed of a single CZTS phase with good crystallinity and strong (112) orientation. For the Cu/Sn/Cu/Zn stack, field-emission scanning electron microscopy revealed a homogeneous, compact surface morphology and large columnar grains. This stack also had an optical absorption coefficient of ＞10~4 cm~(-1) and an optical band gap of 1.51 eV. We fabricated a solar cell with the structure SLG substrate/Mo/Cu_2ZnSnS_4/CdS/i-ZnO Al:ZnO/Al, which achieved a conversion efficiency of 2.3%.