Analysis of absorber layer properties effect on CIGS solar cell performance using SCAPS

This paper shows a numerical simulation and analysis of a copper–indium–gallium–diselenide (CIGS) solar cell performance. The Solar Cell Capacitance Simulator (SCAPS) software is used for multiple measurements. The impacts of absorber layer band gap and thickness variation on the cell's output parameters were extensively simulated. In this study, the CIGS band gap and electron affinity are first defined and formulated as mathematical functions of gallium (Ga) content (“x”). Then these new functions can predict the absorber layer band gap at different “x” and used to simulate and study of the cell performance. The analysis made from this numerical simulation has revealed the optimum energy band gap of the absorber layer to be 1.2 eV corresponding to x = 0.3. Subsequently, the cell efficiency is innovatively formulated as a function of Ga content in the absorber layer. The effect of absorber layer thickness on cell performance has also been simulated and its range was found to be between 2 μm and 3 μm and it is for the cell with low and optimum absorber layer band gap. Nevertheless, the cell with wide absorber layer band gap will increase the absorber layer thickness thus will cause reduction in cell efficiency.