Influence of triangle wave pulse on the properties of Cu2ZnSnS4 thin films prepared by single step electrodeposition

Quaternary chalcogenide Cu2SnZnS4 (CZTS) thin films were synthesized onto Mo-coated glass substrates using electrochemical deposition with different triangle wave pulse times (τ). The effects of the triangle wave pulse time on the structural, morphological, chemical and optical properties of the CZTS thin films were investigated. X-ray diffraction showed that the as-grown CZTS thin films are single phase, with a kesterite structure, strong preferential orientation along the (112) plane and a crystal size ranging from 23 to 36 nm. FESEM images show that homogeneous, smooth, uniform, and densely packed grains could be formed, although the grain size and surface roughness depended on the triangle wave pulse time. UV-vis spectroscopy showed that the CZTS film had an optical absorption coefficient over 104 cm−1 in the visible region and optical band gaps of the various films ranged from 1.36 to 1.47 eV, suggesting that CZTS films can be useful absorbent layers in thin film solar cells. Solar cells were fabricated with SLG/Mo/CZTS/CdS/ZnO/ITO structures, and the best conversion efficiency obtained was 1.66% with Voc=571 mV, FF=40.4 and Jsc=7.22 mA/cm2.