Improving the solar cell performance of electrodeposited Cu2ZnSn(S,Se)4 by varying the Cu/(Zn + Sn) ratio

Cu2ZnSn(S,Se)4 (CZTSSe) thin films with controlled composition, phase, and uniformity were fabricated by sulfo-selenization of stack layer electro-deposited Cu-Sn-Zn precursors. In order to reduce the detrimental bubble phenomenon, Triton X-100 surfactant assisted deposition of the zinc layer was conducted. The effects of Triton X-100 addition on the surface morphology, composition, and solar cell properties were investigated. The results indicated that the addition of Triton X-100 boosted the solar cell performance by many folds. Along with studying the effect of Triton X-100 addition, the composition of the film was finely controlled by varying the deposition time of the Cu layer. Cu poor and Zn rich composition with a Cu/(Zn + Sn) ratio of 0.82 was achieved. The prepared films were characterized by X-ray diffraction, scanning electron microscopy, X-ray fluorescence spectroscopy, and Raman spectroscopy to investigate the structural, morphological, and compositional properties. The highest solar cell performance of approximately 6.06% was achieved for the film in which the Cu-layer was deposited for 15 min.