Record efficiencies for EFG and string ribbon solar cells

Solar cells have been processed on Edge-defined Film-fed Growth and String Ribbon silicon. Based on a standard process developed for different types of multicrystalline materials including evaporation of contacts and photolithography for front-contact formation, optimisations have been implemented to deal with the special needs of these low-cost ribbon materials. Especially a remote plasma hydrogenation step and a change from evaporated to screen-printed aluminium back-surface-field improved cell parameters drastically. Independently confirmed stable efficiencies of 16.7% (EFG) and 17.7% (String Ribbon) have been achieved on 4 cm(2) cells (full area). These values represent the highest stable efficiencies obtained for multicrystalline silicon ribbons so far. Copyright (C) 2003 John Wiley Sons, Ltd.