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2008
Conference Paper
Titel
High-efficiency back-contact back-junction silicon solar cell research at Fraunhofer ISE
Abstract
In this paper we present the Fraunhofer ISE approach to high-efficiency back-contact back-junction (BC-BJ) solar cell design and processing. An industrially feasible processing sequence for manufacturing of the BC-BJ solar cells was developed. The best efficiency of 21.3 % was achieved on 1 ohm cm n-type FZ Si. The cell features a phosphorus-doped front-surface field. Local recombination losses called electrical shading were indentified as one of the main cell loss mechanism. In the case of base resistivity of 1 ohm cm the increased recombination over the BSF and undiffused gap areas is responsible for 3.3 % reduction of IQE. This causes around 0.7 % absolute efficiency loss. A novel cell structure with locally overcompensated boron emitters is proposed as a solution to reducing the carrier recombination over the base areas.