Dual plasmonic nanostructures for switching polarity of hot electron-induced photocurrent

We report on the experimental investigation of polarity-switchable hot electron-induced photocurrents in dual-plasmonic nanostructures, consisting of two layers of gold nanoparticles (AuNPs) separated by a TiO₂ film. Hot electrons generated through the non-radiative decay of the localized surface plasmon resonances supported by the top and bottom layers of AuNPs can be simultaneously injected into the TiO₂ film in opposite directions and counteract each other. As a result, the polarity and magnitude of the net photocurrents can be tailored by controlling the population of hot electrons either generated from or collected by the two layers of AuNPs. We believe the wavelength-dependent photocurrent polarity switching could be useful for biosensors with a direct electrical readout and photoconversion applications.