A simple passivation technique for the edge area of silicon solar cells improves the efficiency

Abstract The efficiency of silicon solar cells (SC) can strongly be degraded by localized defects especially at the edge of SC (e.g. scratches) which are introduced during the production of the SC and may cause local shunts. A new optimized chemical etching procedure has been developed which allows a very effective passivation of shunts at the SC edges without reducing the surface area, i.e. without a reduction of the Isc current. In contrast to other techniques like plasma etching (“coin staking”) or cutting off the edges, this procedure could be implemented cheaply in a large-scale production. The newly developed passivation method always leads to an improvement in the efficiency η of slightly or severely degraded SCs which is typically around 10–30%, but can be as large as 100%, while good SCs are totally unaffected with respect to η but still showing an improvement of the leakage current.