Dielectric Engineering of Hot-Carrier Generation by Quantized Plasmons in Embedded Silver Nanoparticles.

Lara Román Castellanos,Ortwin Hess,Johannes Lischner

doi:10.1021/acs.jpcc.0c07617

Lara Román Castellanos, Ortwin Hess + Show 1 more

Open Access

https://doi.org/10.1021/acs.jpcc.0c07617

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Abstract

Understanding and controlling properties of plasmon-induced hot carriers is a key step toward next-generation photovoltaic and photocatalytic devices. Here, we uncover a route to engineering hot-carrier generation rates of silver nanoparticles by designed embedding in dielectric host materials. Extending our recently established quantum-mechanical approach to describe the decay of quantized plasmons into hot carriers we capture both external screening by the nanoparticle environment and internal screening by silver d-electrons through an effective electron–electron interaction. We find that hot-carrier generation can be maximized by engineering the dielectric host material such that the energy of the localized surface plasmon coincides with the highest value of the nanoparticle joint density of states. This allows us to uncover a path to control the energy of the carriers and the amount produced, for example, a large number of relatively low-energy carriers are obtained by embedding in strongly screening environments.

Highlights

Understanding and controlling light−matter interactions at the nanoscale is important for increasing the efficiency of photovoltaic and photocatalytic devices.[1−3] In this context, localized surface plasmons (LSP) in metallic nanoparticles provide a unique platform because the LSP decay generates energetic or “hot” carriers that can be harnessed to induce chemical reactions[4] or overcome interfacial barriers.[5]
We have developed a quantum-mechanical approach for describing hot carriers resulting from the decay of localized surface plasmons in small silver nanoparticles that are embedded in dielectric media
Dielectric screening by the nanoparticle environment and by Ag d-electrons is taken into account by means of an effective electron−electron interaction, which is used to calculate electron−electron interaction matrix elements and electron−plasmon couplings

Summary

Introduction

Understanding and controlling light−matter interactions at the nanoscale is important for increasing the efficiency of photovoltaic and photocatalytic devices.[1−3] In this context, localized surface plasmons (LSP) in metallic nanoparticles provide a unique platform because the LSP decay generates energetic or “hot” carriers that can be harnessed to induce chemical reactions[4] or overcome interfacial barriers.[5]. It is well known that the dielectric properties of the nanoparticle environment modify the LSP frequency,[18] influence interfacial transport barriers, and protect the nanoparticle from oxidation,[19] but not much is known about their effect on hot-carrier generation rates. The dielectric environment modifies the effective interaction between conduction electrons in the nanoparticle. To approximate this screened interaction, several groups have modeled the environment as a linear polarizable medium, solved the corresponding Maxwell equations for a point charge in this system, and used the result to study the changes in the photoabsorption behavior of the nanoparticle induced by the environment.[14,20,21] By treating the nanoparticle itself as a polarizable medium, this approach can be extended to capture the dielectric screening by bound charges in the material, such as d-band electrons in silver

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