Process Development of Silicon Heterojunction Interdigitated Back-Contacted (SHJ-IBC) Solar Cells Bonded to Glass

In imec’s i2-module concept, silicon heterojunction interdigitated back-contacted (SHJ-IBC) solar cells are fabricated on monocrystalline foils bonded to glass. The proposed technology allows for cell processing on thin wafers mechanically supported by the glass, increasing the yield of processing such thin wafers. A process sequence for SHJ-IBC cell fabrication that can be applied to bonded thin foils is described. We investigated and optimized individual process steps on thick wafers. Then the developed steps were integrated into a process flow to fabricate solar cells on wafers with different thicknesses and bonding agents. On wafers with a thickness of 190 μm, functional cells with efficiencies of 22.6% and 21.7% were made on freestanding and silicone bonded wafers, respectively. On thin wafers of 57 μm, our best SHJ-IBC cell on an EVA bonded wafer exhibits excellent Voc of 740 mV and efficiency of 20.0%, which demonstrates the high potential of the i2-module concept.