The simulation of high efficiency CIGS, i.e., Copper Indium Gallium Selenide cells is the main objective of this thesis. We used SCAPS software for creating a model and basic analysis of the solar cell configuration. An Efficiency calculation was performed by using a baseline model in the SCAPS1D-software. As a first step, a multi-layer absorber structure was added with a graded Ga concentration with varying absorber layer thickness. With this, the electric field increased internally, thus helping to increase the output voltage of the cell. As second and third steps, the temperature and the bandgap was varied. In the final simulation of the CIGS solar cell, an efficiency of 16.33 % could be achieved. A change in temperature from 300 K to 400 K resulted in a drop of efficiency, while a simulated variation in the bandgap and electron affinity resulted in a CIGS solar cell with an efficiency of 22.87 %.