title: Gap-plasmon based broadband absorbers for enhanced hot-electron and photocurrent generation.
abstract: 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 450-850 nm 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.
authors.affiliation: College of Physics, Optoelectronics and Energy, Collaborative Innovation Center of Suzhou Nano Science and Jiangsu Key Laboratory of Thin Films, Soochow University, Suzhou 215006, China.
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Lu
authors.affiliation: College of Physics, Optoelectronics and Energy, Collaborative Innovation Center of Suzhou Nano Science and Jiangsu Key Laboratory of Thin Films, Soochow University, Suzhou 215006, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Dong
authors.affiliation: School of Physics and National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China.
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Centre for Nano Optics, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark.
authors.forename: Anders
authors.initials: A
authors.lastname: Pors
authors.affiliation: School of Physics and National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China.
authors.forename: Zhenlin
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Centre for Nano Optics, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark.
authors.forename: Sergey I
authors.initials: SI
authors.lastname: Bozhevolnyi