9% efficiency: CIGS on Cu substrate

The CIS Solartechnik is aiming at an industrial roll to roll process for the production of CIGS solar cells on metal substrates. For today we can report about a success concerning the efficiency. We are able to process ClGS solar cells on both Cu and stainless steel substrates with an efficiency of 9%. The absorber is synthesised by annealing the electrodeposited stacked metal layers of Cu, In and Ga. Se is added prior to the annealing by evaporation. The fabrication of high-efficiency CIGS absorber layers by mostly electrochemical methods is a challenge per se. The most challenging step, however, in realising cells on Cu substrates is to insert a barrier on top of the substrate which prevents the Cu from diffusion into the CIGS layer during annealing. In addition, this layer has to have good adhesion to both the CIGS layer and the Cu substrate.