Hot Carrier extraction with plasmonic broadband absorbers

TL;DR

This paper demonstrates a broadband plasmonic nanostructure system that significantly enhances hot carrier extraction efficiency across a wide spectral range, advancing applications in photo-catalysis, photovoltaics, and photodetection.

Contribution

It introduces a layered nanoparticle assembly achieving broad-band light absorption and models the physics of hot-electron generation and separation in these structures.

Findings

40-fold increase in photon-to-electron conversion efficiency

Broadband light absorption localized on nanoparticle layer

Efficient hot carrier extraction occurs where photon energy exceeds Schottky barrier and absorption overlap

Abstract

Hot charge carrier extraction from metallic nanostructures is a very promising approach for applications in photo-catalysis, photovoltaics and photodetection. One limitation is that many metallic nanostructures support a single plasmon resonance thus restricting the light-to-charge-carrier activity to a spectral band. Here we demonstrate that a monolayer of plasmonic nanoparticles can be assembled on a multi-stack layered configuration to achieve broad-band, near-unit light absorption, which is spatially localised on the nanoparticle layer. We show that this enhanced light absorbance leads to $\sim$ 40-fold increases in the photon-to-electron conversion efficiency by the plasmonic nanostructures. We developed a model that successfully captures the essential physics of the plasmonic hot-electron charge generation and separation in these structures. This model also allowed us to establish that efficient hot carrier extraction is limited to spectral regions where the photons possessing energies higher than the Schottky junctions and the localised light absorption of the metal nanoparticles overlap.