Up-scaling and optimization of thin-film solar cells and modules based on amorphous and microcrystalline silicon

This paper reviews the status of the process development and up-scaling of thin-film solar cells and modules based on amorphous (a-Si:H) and microcrystalline (μc-Si:H) silicon at the Institute of Photovoltaics (IPV) on substrate areas up to 30×30 cm². Initial efficiencies of 10.6% and 10.7% were achieved for a-Si:H/μc-Si:H modules on 30×30 cm² and 10×10 cm² substrates, respectively. The latter ones yielded a stabilized efficiency of 10.1% which was independently confirmed by NREL. We address the process development for μc-Si:H solar cells in a high pressure regime using plasma excitation frequencies of 13.56 and 40.68 MHz. High deposition rates up to 15 Å/s could be achieved by applying high discharge powers at 40.68 MHz. We discuss technological aspects related to the up-scaling of the PECVD processes to areas of 1 m² and above which is the topic of a recently started German R&D project of Applied Films GmbH & Co. KG (AF), Forschungsund Applikationslabor Plasmatechnik GmbH (FAP) and the IPV.