Bifacial inversion layer solar cells with multicrystalline silicon substrates

The fabrication of MIS inversion-layer solar cells with bifacial sensitivity on low-cost multicrystalline silicon (Wacker Silso) is presented. A rear-side configuration consisting of a coarse-gridded ohmic contact and a plasma silicon nitride film, which acts as a passivating and optical coating film, was used. The thickness dependence of the solar cell data in the range from 385 mu m down to 130 mu m is presented for both front and back illumination and confirmed by theoretical calculations. An AM1 efficiency of 13.5% for the front side and 7.8% for the rear side was obtained from a 140- mu m-thick bifacial multicrystalline MIS-IL solar cell without grain boundary passivation. From the thickness dependence of the quantum efficiency under back illumination, a diffusion length of 115 mu m was obtained.