Optimization of the CIGS solar cell by adding a heavily doped layer and an intrinsic layer at absorber layer

Solar conversion efficiency of CIGS solar cells is investigated in this work. It is found that the efficiency can be improved if heavily doped layer is added to intrinsic absorber layer in CIGS solar cells. On the other hand, the presence of an interface between the high and low doped regions behaves like a p–n junction. As a result, an electric field for the minority electrons is created that decreases surface recombination in rear surface. In order to improve the parameters of CIGS solar cell, we investigated the effect of different thicknesses and doping concentrations of i-layer and p+ layer in the absorber layer. Finally, it had been found that the ZnO/CdS/i-CIGS/p+-CIGS structure in which at the thickness of i and p+ layers with 10 nm and 2.99 µm will have an efficiency ≈3.1 % higher than that of the basic CIGS cell.