Optimization of Cd1−yZnyS buffer layer in Cu(In,Ga)Se2 based thin film solar cells

SCAPS one-dimensional simulation program was used to investigate the performance of thin film photovoltaic solar cells based on Cu(In,Ga)Se2. First, the effect of CdS buffer layer thickness on the CdS/CIGS solar cell output parameters was carried out and its optimum value was determined. Subsequently, Cd1−yZnyS was introduced as alternative for CdS buffer layer and the influence of Zn content (y value) on cell performance was investigated. The optimum value of Zn content was found at 0.2, corresponding to a conversion efficiency of around 21.32%. At the end, the optimum thickness of new buffer layer was found out. Results show that CdZnS/CIGS cell with 28 nm-thick of Cd0.8Zn0.2S have 21.67% conversion efficiency with acceptable VOC and JSC values.