Monolithic Perovskite/Silicon-Heterojunction Tandem Solar Cells with Nanocrystalline Si/SiOx Tunnel Junction

Abstract

Perovskite/silicon tandem solar cells have strong potential for high efficiency and low cost photovoltaics. In monolithic (two-terminal) configurations, one key element is the interconnection region of the two subcells, which should be designed for optimal light management and prevention of parasitic p/n junctions. We investigated monolithic perovskite/silicon-heterojunction (SHJ) tandem solar cells with a p/n nanocrystalline silicon/silicon-oxide recombination junction for improved infrared light management. This design can additionally provide for resilience to shunts and simplified cell processing. We probed modified SHJ solar cells, made from double-side polished n-type Si wafers, which included the proposed front-side p/n tunnel junction with the p-type film simultaneously functioning as selective charge transport layer for the SHJ bottom cell, trying different thicknesses for the n-type layer. Full tandem devices were then tested, by applying a planar n-i-p mixed-cation mixed-halide perovskite top cell, fabricated via low temperature solution methods to be compatible with the processed Si wafer. We demonstrate the feasibility of this tandem cell configuration over a 1 cm2 area with negligible J-V hysteresis and a VOC ~1.8 V, matching the sum of the VOC-s contributed by the two components.