Performance of Cu2ZnSn(S,Se)4 solar cells by adding H3BO3 in the precursor solution

In this work, Cu 2 ZnSn(S,Se) 4 thin films were prepared by sol-gel methods based on dimethyl sulfoxide solutions with H 3 BO 3 additive. The morphological, structural, compositional and photovoltaic properties of the Cu 2 ZnSn(S,Se) 4 thin films were investigated. We found that the formation of voids, cracks and fine-grain layers were suppressed effectively with slight H 3 BO 3 . Based on the decrease of these micro defects, the series resistance decreased and shunt resistance increased largely. And the band gap of CZTSSe solar cells broaden from 1.031 eV to 1.064 eV. The best solar cell showed an open-circuit voltage of 440.1 mV, short-circuit current density of 28.15 mA/cm 2 , fill factor of 58.81% and power conversion efficiency of 7.27% under air mass 1.5 (100 mW/cm 2 ) illumination.