Plasmon Enhanced Solar-to-Fuel Energy Conversion

TL;DR

This paper demonstrates how plasmonic nanostructures can be engineered to concentrate sunlight near photoelectrodes, enhancing solar-to-fuel energy conversion efficiency despite the limitations of earth-abundant materials.

Contribution

It introduces a method to utilize plasmonic resonances and interference effects to improve light concentration at the reactive surface of photoelectrodes made from inexpensive materials.

Findings

Spectral features in photocurrent spectra match electromagnetic simulations.

Surface plasmon excitations significantly enhance light concentration.

The approach enables optimization of photochemical processes using plasmonics.

Abstract

Future generations of photoelectrodes for solar fuel generation must employ inexpensive, earth-abundant absorber materials in order to provide a large-scale source of clean energy. These materials tend to have poor electrical transport properties and exhibit carrier diffusion lengths which are significantly shorter than the absorption depth of light. As a result, many photo-excited carriers are generated too far from a reactive surface, and recombine instead of participating in solar-to-fuel-conversion. We demonstrate that plasmonic resonances in metallic nanostructures and multi-layer interference effects can be engineered to strongly concentrate sunlight close to the electrode/liquid interface, precisely where the relevant reactions take place. By comparing spectral features in the enhanced photocurrent spectra to full-field electromagnetic simulations, the contribution of surface plasmon excitations is verified. These results open the door to the optimization of a wide variety of photochemical processes by leveraging the rapid advances in the field of plasmonics.