G.Yin / HZB | The SiO2 nanoparticles (black) have been imprinted directly on the Molybdenum substrate (purple) which corresponds to the back contact of the solar cell. On top of this structured substrate the ultrathin CIGSe layer (red) was grown at HZB, and subsequently all the other layers and contacts needed for the solar cell. Since all layers are extremely thin, even the top layer is showing deformations according to the pattern of the nanoparticles.