Improvement of the efficiency of triple junction n–i–p solar cells with hot-wire CVD proto- and microcrystalline silicon absorber layers

Abstract

Hot-wire chemical vapour deposition (HWCVD) was applied for the deposition of intrinsic protocrystalline (proto-Si:H) and microcrystalline silicon (μc-Si:H) absorber layers in thin film solar cells. For a single junction μc-Si:H n–i–p cell on a Ag/ZnO textured back reflector (TBR) with a 2.0 μm i-layer, an 8.5% efficiency was obtained, which showed to be stable after 750 h of light-soaking. The short-circuit current density (Jsc) of this cell was 23.4 mA/cm2, with a high open-circuit voltage (Voc) and fill factor (FF) of 0.545 V and 0.67. Triple junction n–i–p cells were deposited using proto-Si:H, plasma-deposited proto-SiGe:H and μc-Si:H as top, middle and bottom cell absorber layers. With Ag/ZnO TBR's from our lab and United Solar Ovonic LLC, respective initial efficiencies of 10.45% (2.030 V, 7.8 mA/cm2, 0.66) and 10.50% (2.113 V, 7.4 mA/cm2, 0.67) were achieved.