Solution Processed Cu(In,Ga)(S,Se)₂ Solar Cells with 15.25% Efficiency by Surface Sulfurization

Cu(In,Ga)(S,Se)2 (CIGSSe) is considered as a promising absorber for solar cells due to its excellent electrical and optical properties. However, there are numerous defects on the surface of the CIGSSe film, leading to dramatic carrier recombination at the heterointerface, which hinders further efficiency improvement of CIGSSe solar cells. Therefore, an effective interface defect passivation strategy is urgently needed to further boost the device performance. In this work, we employ a facile and effective method to passivate interface defects by a thioacetamide induced surface sulfurization process. The thioacetamide treatment could introduce S into the CIGSSe surface, while realizing well-controlled S incorporation. After sulfurization, the interface carrier recombination was decreased and carrier separation was more efficient. Consequently, we obtained a device efficiency of 15.25% with an increased open-circuit voltage (VOC) of 0.650 V and a fill factor (FF) of 72.21%.