Aspect ratio controls hot-carrier generation in gold nanobricks

TL;DR

This study investigates how the aspect ratio of gold nanobricks influences hot-carrier generation, revealing that shape and polarization significantly affect energetic electron production for applications in photocatalysis and sensing.

Contribution

We introduce a combined Maxwell and tight-binding simulation approach to analyze hot-carrier generation in gold nanobricks, highlighting the role of aspect ratio and polarization.

Findings

Flatter nanobricks produce more energetic electrons regardless of polarization.

Elongated nanobricks' hot-carrier generation depends strongly on light polarization.

Aspect ratio can be tuned to optimize hot-carrier properties for specific applications.

Abstract

Energetic or "hot" electrons and holes generated from the decay of localized surface plasmons in metallic nanoparticles have great potential for applications in photocatalysis, photovoltaics, and sensing. Here, we study the generation of hot carriers in brick-shaped gold nanoparticles using a recently developed modelling approach that combines a solution to Maxwell's equation with large-scale tight-binding simulations to evaluate Fermi's Golden Rule. We find that hot-carrier generation depends sensitively on the aspect ratio of the nanobricks with flatter bricks producing a large number of energetic electrons irrespective of the light polarization. In contrast, the hot-carrier generation rates of elongated nanobricks exhibits a strong dependence on the light polarization. The insights resulting from our calculations can be harnessed to design nanobricks that produce hot carriers with properties tailored to specific device applications.