Nano Lett. 2015 Jan 14;15(1):753-8. doi: 10.1021/nl504462e. Epub 2014 Dec 30.

Doubling absorption in nanowire solar cells with dielectric shell optical antennas.

Nano letters

Sun-Kyung Kim, Xing Zhang, David J Hill, Kyung-Deok Song, Jin-Sung Park, Hong-Gyu Park, James F Cahoon

PMID: 25546325 DOI: 10.1021/nl504462e

Abstract

Semiconductor nanowires (NWs) often exhibit efficient, broadband light absorption despite their relatively small size. This characteristic originates from the subwavelength dimensions and high refractive indices of the NWs, which cause a light-trapping optical antenna effect. As a result, NWs could enable high-efficiency but low-cost solar cells using small volumes of expensive semiconductor material. Nevertheless, the extent to which the antenna effect can be leveraged in devices will largely determine the economic viability of NW-based solar cells. Here, we demonstrate a simple, low-cost, and scalable route to dramatically enhance the optical antenna effect in NW photovoltaic devices by coating the wires with conformal dielectric shells. Scattering and absorption measurements on Si NWs coated with shells of SiN(x) or SiO(x) exhibit a broadband enhancement of light absorption by ∼ 50-200% and light scattering by ∼ 200-1000%. The increased light-matter interaction leads to a ∼ 80% increase in short-circuit current density in Si photovoltaic devices under 1 sun illumination. Optical simulations reproduce the experimental results and indicate the dielectric-shell effect to be a general phenomenon for groups IV, II-VI, and III-V semiconductor NWs in both lateral and vertical orientations, providing a simple route to approximately double the efficiency of NW-based solar cells.

Keywords: FDTD simulation; Solar energy; optical antenna; photovoltaic device; silicon nanowires

Publication Types

• Journal Article
• Research Support, Non-U.S. Gov't
• Research Support, U.S. Gov't, Non-P.H.S.