Si microwire solar cells: improved efficiency with a conformal SiO2 layer.

Seo, Kwanyong; Yu, Young J; Duane, Peter; Zhu, Wenqi; Park, Hyunsung; Wober, Munib; Crozier, Kenneth B · ACS Nano · 2013

basic_science · Level V

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Abstract

Silicon microwire arrays have attracted considerable attention recently due to the opportunity they present as highly efficient and cost-effective solar cells. In this study, we report on efficient Si microwire array solar cells with areas of 1 cm(2) and Air Mass 1.5 Global conversion efficiencies of up to 10.6%. These solar cells show an open-circuit voltage of 0.56 V, a short-circuit current density of 25.2 mA/cm(2), and a fill factor of 75.2%, with a silicon absorption region that is only 25 μm thick. In particular, the maximum overall efficiency of the champion device is improved from 8.71% to 10.6% by conformally coating the wires with a 200 nm thick SiO2 layer. Optical measurements reveal that the layer reduces reflection significantly over the entire visible range.