Abstract:CZTSSe thin films were prepared using the sol-gel method, and the crystal morphology of the CZTSSe films were improved by Mg doping. The prepared films were characterized using techniques such as XRD, Raman spectroscopy, SEM, and UV-Vis spectroscopy. The results showed that Mg replaced Zn in the CZTSSe lattice, forming the CMZTSSe phase. As the Mg doping concentration increased, the grain size initially increased and then decreased.After Mg doping, no additional impurities are produced.When the Mg doping concentration was 0.1, the film exhibited the optimal crystal morphology, narrowest peak width, largest grain size, the best light absorption propertiessmoothest and most compact surface, which is favorable for use as an absorber layer in solar cells.