Schottky Junction Made from a Nanoporous Au and TiO2 Film for Plasmonic Photodetectors

Abstract

The generation, transfer, and collection of plasmon-derived hot electrons represent a distinctive pathway for the utilization of solar energy. Herein, we report the construction of a plasmonic photodetector from a metal/TiO2 Schottky junction, featuring using a solution-processed continuous nanoporous Au film (CNAuF) as the light absorption layer and an n-type TiO2 film as the electron acceptation layer. Because of its plasmon properties, the CNAuF can absorb broadband light in the visible region and in turn creates abundant hot electrons (via the decay of its plasmon). Using a CNAuF/TiO2 Schottky junction, these hot electrons can be collected into the TiO2 film to generate a steady-state photocurrent. As a result, the plasmonic photodetector constructed from the CNAuF/TiO2 Schottky junction delivers an appreciable photoresponse to visible light. Taking the photoresponse to 532 nm light as an example, this plasmonic photodetector delivers a high responsivity of 0.06 A/W, a specific detectivity of 3.9 × 109 Jones, and an external quantum efficiency of 13.8%, with a rise time and a decay time being 110 and 120 ms, respectively. The bottom-up nature of the solution-processed strategy offers great flexibility to tune the plasmonic nanostructure and in turn its optical properties, thereby creating many possibilities for the creation of next-generation plasmonic photoelectric devices and beyond.