A numerical study of high efficiency ultra-thin CdS/CIGS solar cells

This work aims to improve the performance of solar cells with structure SnO2/CdS/CIGS/Mo by using the solar cell capacitance simulator (SCAPS-1D). Our idea is to insert the SnS layer between the absorber layer CIGS and the Mo (molybdenum) back contact. A maximum conversion efficiency of 24.45% (V-OC = 0.78 V, J(SC) = 38.66 mA/cm(2), FF = 0.80) was achieved with 1 mu m-CIGS absorber layer, 50 nm-CdS buffer layer, 200 nm of ZnO window layer and 300 nm of SnS BSF layer. This study shows that ultra-thin CIGS solar cells with a BSF layer give better results compared to the work of Gloeckler (2005), which presented an efficiency of 19.62% (V-OC = 0.61 V, J(SC) = 39.23 mA/cm(2), FF = 0.81) with 3 mu m thickness of CIGS in the structure ZnO/CdS/CIGS/Mo. In addition to this, the cells' stability with temperature was studied and analysed.