16% thin‐film epitaxial silicon solar cells on 70‐cm 2 area with 30‐µm active layer, porous silicon back reflector, and Cu‐based top‐contact metallization

We demonstrate the use of a copper‐based metallization scheme for the specific application of thin‐film epitaxial silicon wafer equivalent (EpiWE) solar cells with rear chemical vapor deposition emitter and conventional POCl 3 emitter. Thin‐film epitaxial silicon wafer equivalent cells are consisting of high‐quality epitaxial active layer of only 30 µm, beneath which a highly reflective porous silicon multilayer stack is embedded. By combining Cu‐plating metallization and narrow finger lines with an epitaxial cell architecture including the porous silicon reflector, a J sc exceeding 32 mA/cm 2 was achieved. We report on reproducible cell efficiencies of >16% on >70‐cm 2 cells with rear epitaxial chemical vapor deposition emitters and Cu contacts. Copyright © 2011 John Wiley & Sons, Ltd.