(Georgia Institute of Technology, 2003-05)
Damiani, Benjamin Mark; Nakayashiki, Kenta; Kim, Dong Seop; Yelundur, Vijay; Ostapenko, Sergei; Tarasov, Igor; Rohatgi, Ajeet
Light induced degradation (LID) in boron doped Czochralski (Cz) silicon with high oxygen content is known to degrade solar cell efficiency. Multicrystalline Si
crystals also have oxygen and use B doping, but LID effects are largely unknown. In this paper, ribbon, Cz, and cast multi-crystalline Si crystals with a resistivity of 1-3 Ωcm were investigated for LID. 15-16% efficient EFG, String Ribbon, and cast mc-Si solar cells, fabricated by manufacturable screen printed technology, show small but
measurable LID (0.2% absolute efficiency loss). In less than 15% efficient devices, LID was not detectable in ribbon Si crystals. However, >16% efficient photolithography ribbon Si degraded >0.5% absolute. Analysis of the bulk lifetime using photoluminescence mapping, after cell processing, supports the presence of LID in the good regions of the ribbon materials while the defective regions remained essentially unaffected.