Fabrication of High-Efficient Si-Based Solar Cells Using Tapered ZnO Nanorods as Antireflection Layers

We have hydrothermally synthesized highly-textured ZnO NRs on ZnO-seeded n(+)-p-Si substrates, and investigated the dependence of growth time on the morphological and optical properties of ZnO NRs. The tips of the ZnO NRs are changed from flat tops to tapered shapes with increasing the growth time. The subtle changes in the shape of NR tips result in significantly improved antireflection properties due to the elimination of interference fringes in the visible and near-infrared region, leading to enhanced photocurrent output. By introducing the ZnO NRs as antireflection layers, a high PCE of similar to 14.1% can be realized for the tapered 1.2 mu m-ZnO NRs/ZnO/n(+)-p-Si solar cells, which is by far superior to that of the control solar device (similar to 9.2%).