Scaling-up of CIS technology for thin-film solar modules

Abstract

The compound semiconductor Cu(Ga,In)Se2 (CIGS) and related compounds have demonstrated their high potential for high-efficiency thin-film solar cells up to levels approaching 18%. The Center for Solar Energy and Hydrogen Research (ZSW) and the University of Stuttgart (IPE) are working together on CIS upscaling. On the module basis, ZSW is collaborating with Phototronics Solartechnik GmbH/Putzbrunn as a manufacturer for a-Si modu les supporting module technology. With the aim of developing high-volume fabrication technologies, all the laboratory deposition techniques suitable for highest device performance are applied now also on the module level to avoid physical and chemical effects that could limit device performance to a low level. All film deposition techniques are developed for high-vacuum in-line fabrication on a large area, except for the buffer layer of CdS, and monolithic integration is realized by patterning steps. A key issue for the development of modules is upscaling of the CIGS absorber deposition. Films of CIGS are prepared by simultaneous thermal evaporation of the elements. Modules are prepared on substrate areas of 7 × 7, 10 × 10 ??? 30 × 30 cm2. Actual results of modules of these sizes are shown.