Development of Rear Passivated Laser Grooved Buried Contact (LGBC) Laser Fired Contact (LFC) Silicon Solar Cells Using Thin Wafers

Abstract

The cost per watt peak of solar modules must be reduced to ensure long term commercial viability. Manufacturing costs can be reduced by using thinner silicon wafers. Thin wafers are also advantageous in that they have lower bulk recombination. However, as wafer thickness is reduced, surface recombination becomes a limiting factor for cell efficiency. The advantages of thin cells can be exploited by incorporating a good rear passivation. The FP7 funded project ‘20Plμs’, aims to produce well passivated 20% efficiency solar cells on 100μm Cz monocrystalline wafers.In this paper we describe the integration of a AlOx/SiOx rear passivating layer into a high efficiency LGBC solar cell structure fabricated using 100μm and 160μm thick industry standard Cz Si. These cells have significantly higher open circuit voltages (Voc) and short-circuit current densities (Jsc) than standard LGBC cells and hence show potential for higher cell efficiencies.