Broadband light management using low-Q whispering gallery modes in spherical nanoshells.
Light trapping across a wide band of frequencies is important for applications such as solar cells and photodetectors. Here, we demonstrate a new approach to light management by forming whispering-gallery resonant modes inside a spherical nanoshell structure. The geometry of the structure gives rise to a low quality-factor, facilitating the coupling of light into the resonant modes and substantial enhancement of the light path in the active material, thus dramatically improving absorption. Using nanocrystalline silicon (nc-Si) as a model system, we observe broadband absorption enhancement across a large range of incident angles. The absorption of a single layer of 50-nm-thick spherical nanoshells is equivalent to a 1-μm-thick planar nc-Si film. This light-trapping structure could enable the manufacturing of high-throughput ultra-thin film absorbers in a variety of material systems that demand shorter deposition time, less material usage and transferability to flexible substrates.
Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA.
Yan
Y
Yao
Jie
J
Yao
Vijay Kris
VK
Narasimhan
Zhichao
Z
Ruan
Chong
C
Xie
Shanhui
S
Fan
Yi
Y
Cui
D004553:Electric Conductivity; D011211:Electric Power Supplies; D004867:Equipment Design; D008027:Light; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning / Q000379:methods; D057145:Nanoshells; D036103:Nanotechnology / Q000379:methods*; D055095:Optics and Photonics; D012825:Silicon / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry; D012993:Solar Energy; D013472:Sunlight; D013696:Temperature
D012822:Silicon Dioxide; D012825:Silicon