Required Material Properties for High-Efficiency CIGS Modules

Relatively high proven efficiencies of CIGS devices are often cited regarding its choice as a semiconductor for photovoltaic manufacturing. Module efficiency is an important parameter, as a number of factors in the cost per watt are driven downward by increasing efficiency. Some of these factors include materials costs, throughput for a given capital investment, and installation costs. Thus, realizing high-efficiency (e.g. 15%) large-area CIGS modules is key in both reducing cost per watt and differentiating the technology from other thin films. This paper discusses the material properties required of each layer of the CIGS device such that large-area CIGS modules can achieve efficiencies 15%, which is substantially higher than the current industrial state-of-the-art. The sensitivity of module performance to the important material parameters is quantified based on both experimental data and modeling. Necessary performance differences between small-area devices and large-area modules imposed by geometry are also quantified. Potential technical breakthroughs that may relax the requirements for each layer are discussed.