Overview on Recent Improvement for Industrially Applicable PERL-Type Si Solar Cell Processing

An industrially applicable process flow for the formation of rear side passivated solar cells has been suggested by IMEC in 2005. Since then considerable improvements in solar cell efficiencies have been obtained with that type of process. In parallel simplifications and cost reductions were needed to bring it to production. IMEC’s Industrial Affiliate Programme (IIAP) offers industrial partners the possibility to actively join development efforts with IMEC and other partners sending residents to work at IMEC as part of a research team. Selected development results of this IIAP are presented here. On large area homogeneous emitter CZ-Si solar cells FhG-SE Cal-Lab confirmed solar cell efficiencies of 20.0 and 20.3% for screen printed Ag and reliable plated Cu front contacts, respectively. Fill factors of 80% have been achieved for fully screen printed (front and rear) solar cells with low cost rear side dielectric stack layers. Cu plated contacts show reliable module data in IEC test conditions. Latest results with average solar cell efficiencies of 20.4% over the length of a CZ-Si ingot with top efficiencies of 20.6% are just an intermediate step. IMEC sees a road to >21% efficient i-PERL solar cells in production.