Photon energy conversion via localized surface plasmons in ZnO/Ag/ZnO nanostructures

Localized surface plasmons mediated photon energy conversion in ZnO/Ag/ZnO nanostructures has been investigated. Ag nano islands immersed in ZnO cause a great enhancement of visible light emission where silicon solar cells have maximum response, compared to that of ZnO single layer or Ag/ZnO bilayer structures. It is found that the visible light emission enhancement ratio increases with the thickness of the ZnO capping layer and an enhancement ratio of tenfold for 100 nm ZnO is realized. Furthermore, the intensity and peak wavelength of visible light emission are also influenced by the sizes of Ag islands. The observation of photoluminescence from ZnO/Ag/ZnO nanostructures is interpreted with theoretical calculation of localized surface plasmon resonance. The observed large enhancement of visible light emission may have potential applications in high efficiency solar cells by conversion of ultraviolet to visible light.