# Hot-Carrier Generation in Bimetallic Janus Nanoparticles

## TL;DR

This paper studies how bimetallic Janus nanoparticles generate hot carriers under light, which could improve nanoscale devices for energy and sensing.

## Contribution

A novel atomistic modeling approach is used to study hot-carrier generation in bimetallic Janus nanoparticles.

## Key findings

- Ag–Au Janus nanoparticles show the highest hot-carrier generation rate under solar illumination.
- Dumbbell-shaped nanoparticles exhibit increased hot-carrier generation with larger neck sizes due to enhanced electric fields.
- Maximum hot-carrier generation occurs when light polarization is perpendicular to the metal interface.

## Abstract

Energetic electrons and holes generated from the decay
of localized
surface plasmons in metallic nanoparticles can be harnessed in nanoscale
devices for photocatalysis, photovoltaics or sensing. In this work,
we study the generation of such hot carriers in bimetallic Janus nanoparticles
composed of Au, Ag and Cu using a recently developed atomistic modeling
approach that combines a solution of the macroscopic Maxwell equation
with large-scale quantum-mechanical tight-binding models. We first
analyze spherical Janus nanoparticles whose unique hot-carrier spectrum
can be associated with the spectra of the two hemispheres and the
interface coupling and find that under solar illumination the Ag–Au
system exhibits the highest hot-carrier generation rate. For dumbbell-shaped
Janus nanoparticles, we observe a significant increase in hot-carrier
generation with increasing neck size. This is caused by a dramatic
enhancement of the electric field in the neck region. We also study
the dependence of hot-carrier generation on the light polarization
and find that the largest generation rates are obtained when the electric
field is perpendicular to the interface between the two metals due
to the maximal dipole coupling with the electric field. The insights
from our study will guide the experimental design of efficient hot-carrier
devices based on bimetallic Janus nanoparticles.