Numerical study of thin films CIGS bilayer solar cells using SCAPS

In this paper we present a simulation study of thin films solar cells structure ZnO/CdS/CuIn(1-x)GaxSe2/CuIn(1-y)GaySe2 based on alternated CIGS absorber layers, using one dimensional simulator SCAPS-1D. We evaluated the open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF) and efficiency (η) of the structure as a function of band gaps and thicknesses of CIGS bi-layer. We found that the band gap Eg and thickness of the top absorber (CuIn(1-x)GaxSe2) strongly influence the performance of the solar cell. The efficiency of the CIGS solar cells with a second absorber layer can be increased if the band gap of this layer is equal to 1.38eV. The best efficiency is achieved with thicknesses of around 1100 nm and 600 nm respectively for top and bottom absorber layers is close to 22.5%.