Triple-functional n-type microcrystalline silicon oxide layers in hydrogenated amorphous silicon/microcrystalline silicon tandem solar cells

A novel tunnel recombination junction (TRJ) consisted of n type hydrogenated microcrystalline silicon oxide (n-mu c-SiOx:H) layer and p type hydrogenated nanocrystalline silicon oxide (p-nc-SiOx:H) layer was proposed in hydrogenated amorphous silicon/microcrystalline silicon (a-Si: H/mu c-Si: H) tandem solar cell. The absence of n-mu c-Si: H compared to conventional n-mu c-SiOx: H/n-mu c-Si: H/p-nc-SiOx: H TRJ reduced parasitic absorption. Meanwhile, the new TRJ indicated an ohmic contact, which is suitable for the tandem solar cell. The application of the new TRJ significantly improved the shortcircuit current (J(sc)) of bottom cell. Moreover, n-mu c-SiOx: H layer functioned as intermediate reflector layer to ensure high J(sc) of top cell. Initial conversion efficiency of optimized a-Si: H/mu c-Si: H tandem solar cell with novel TRJ based on as-grown MOCVDZnO: B (BZO) substrate reached up to 1 2.99%.