Numerical analysis of thin film Cu₂InGaSe₄ solar cells design

Working performance of the CIGS (Cu₂InGaSe₄) solar cells are extensively dependent on their thin film's composition structure, therefore, it is obvious to explore a suitable structural combination possibility for the better performing CIGS solar cell device. This work demonstrates a simulation study on CIGS solar cells with the varying layers thicknesses. The optimization of the ZnO:Al/ZnO/CdS/CIGS combination devices structure has been investigated using the SCAPS-1D software, with variable layer thicknesses of the ZnO:Al/ZnO/CdS/CIGS. Moreover, numerical simulation is used to optimize structure composition by varying the thicknesses of active layer (0.5, 1.0 and 1.5 µm), whereas other layers thicknesses are kept constant. The optimized results of different sets CIGS devices combinations revealed that, with the increasing thickness of the active layer, the overall performance parameters are enhanced. This simulation outcome reveals that, an optimal high efficient CIGS solar cell device can be fabricated with the thicknesses of the window layers 0.06 µm, 0.03 µm (ZnO:Al and ZnO), buffer layer 0.02 µm (CdS), absorber layer in the range of (CIGS) 0.5 µm to 4 µm and back contact layer 0.04 µm (Mo). Additionally, active layer dependency on doping levels and optical energy band gaps are also addressed.