A strong antireflective solar cell prepared by tapering silicon nanowires

OPTICS EXPRESS 18(S3) A286-A292

https://doi.org/10.1364/OE.18.00A286

Jin-Young Jung, Zhongyi Guo, Sang-Won Jee, Han-Don Um, Kwang-Tae Park, and Jung-Ho Lee

Abstract

Vertically aligned silicon nanowires (SiNWs) were cost-effectively formed on a four-inch silicon wafer using a simple room temperature approach, i.e., metal-assisted electroless etching. Tapering the NWs by post-KOH dipping achieved separation of each NW from the bunched NW, resulting in a strong enhancement of broadband optical absorption. As electroless etching time increases, the optical crossover feature was observed in the tradeoff between enhanced light trapping (by graded-refractive index during initial tapering) and deteriorated reflectance (by decreasing the areal density of NWs during later tapering). Compared to the bunched SiNWs, tapered NW solar cells demonstrated superior photovoltaic characteristics, such as a short circuit current of 17.67 mA/cm2 and a cell conversion efficiency of ~6.56% under 1.5 AM illumination.