Due to the global understanding and the requirements on the use of renewable energy sources, solar energy has been lacoated in the focus of many research centers. The decline in the price of building next to the efficiency is the goal important of the solar cell industry. The application of thin film technology in these cells that used from photovoltaic effects is one way to reduce prices. Among these thin films, Cu‌(In Ga)‌Se has the highest efficiency and cost-effective among the thin films. In this paper the CIGS nanostructures solar cells is simulated by using Comsol and Sivaco-Tcad softwares and then to increase the efficiency, width and thickness of the ZnO: Al are optimized. The maximum efficiency is obtained 19.1% with Comsol in optimized thickness, and 19.702% with T-CAD software in 0.3 mm of thickness for this layer. Then, by optimizing the width of the layer in this optimized thickness, efficiency at 3‌mm width increase to 19.9%.