Wen Dong

Gap-plasmon based broadband absorbers for enhanced hot-electron and photocurrent generation

Plasmonic hot-electron generation has recently come into focus as a new scheme for solar energy conversion. So far, however, due to the relatively narrow bandwidth of the surface plasmon resonances and the insufficient resonant light absorption, most of plasmonic photocatalysts show narrow-band spectral responsivities and small solar energy conversion efficiencies. Here we experimentally demonstrate that a three-layered nanostructure, consisting of a monolayer gold-nanoparticles and a gold film separated by a TiO2 gap layer (Au-NPs/TiO2/Au-film), is capable of near-completely absorbing light within the whole visible region. We show that the Au-NPs/TiO2/Au-film device can take advantage of such strong and broadband light absorption to enhance the generation of hot electrons and thus the photocurrent under visible irradiation. As compared to conventional plasmonic photocatalysts such as Au-NPs/TiO2 nanostructures, a 5-fold-enhanced incident photon-to-current conversion efficiency is achieved within the entire wavelength range 450–850u2009nm in the Au-NPs/TiO2/Au-film device. Simulations show good agreements with the experimental results, demonstrating that only the plasmon-induced losses contribute to the enhanced photocurrent generation of the Au-NPs/TiO2/Au-film device.

Reflectivity behavior of two-dimensional ordered array of metallodielectric composite particles at large incidence angles

Optical reflectance of a two-dimensional (2D) metallodielectric (MD) photonic crystal composed of hexagonal array of close-packed silver-shell polystyrene-core composite particles has been studied at off-normal incidence under both P and S polarizations. A dramatic change in reflectivity behavior of the 2D MD film from a 2D colloidal crystal template and a homogeneous silver film has been observed. The phenomenon of strong reflectance bands of the 2D MD film was explained as a selective coupling of the incident light with surface plasmon of the 2D textured structure via the 2D grating.

The effect of annealing on the photoluminescence of layered perovskite H{sub 1.77}[Sr{sub 0.8}Bi{sub 0.21}Ta{sub 2}O{sub 7}] powders

Abstract The microstructural and luminescent properties of H 1.77 [Sr 0.8 Bi 0.21 Ta 2 O 7 ] powders under different dehydrating conditions were investigated. The powders were obtained by protonating Bi 2 SrTa 2 O 9 powders in 3xa0M aqueous HCl solution, and were dehydrated by a post-annealing in air from 250 to 700xa0°C. The photoluminescence was enhanced for all dehydrated powders, especially for the sample annealed at 400xa0°C. The thermogravimetric analysis showed that there is an obvious dehydration temperature range from 200 to 400xa0°C, which was corresponding to the changing of the microstructure and photoluminescence in the same temperature range. The mechanism behind the experimental results was discussed.