# Hot Electron Dynamics in Plasmonic Thermionic Emitters

## TL;DR

This paper demonstrates that plasmonic nanostructures can sustain high electronic temperatures for thermionic emission at lower lattice temperatures, enabling more efficient and thermally stable thermionic energy conversion.

## Contribution

It introduces a novel approach using resonant plasmonic absorption to achieve high electronic temperatures without high lattice temperatures, improving thermionic device performance.

## Key findings

- Plasmonic nanostructures enable steady-state high electronic temperatures at below 600 K.
- Optical thermometry confirms unique electron dynamics in these structures.
- Thermionic devices outperform other solar power conversion methods in efficiency and stability.

## Abstract

Thermionic converters generate electricity from thermal energy in a power cycle based on vacuum emission of electrons. While thermodynamically efficient, practical implementations are limited by the extreme temperatures required for electron emission (> 1500 K). Here, we show how metal nanostructures that support resonant plasmonic absorption enable an alternative strategy. High electronic temperatures required for efficient vacuum emission can be maintained during steady-state optical absorption while the lattice temperature remains within the range of thermal stability, below 600 K. We have also developed an optical thermometry technique based on anti-Stokes Raman spectroscopy that confirms these unique electron dynamics. Thermionic devices constructed from plasmonic absorbers show performance that can out-compete other strategies of concentrated solar power conversion in terms of efficiency and thermal stability.

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Source: https://tomesphere.com/paper/1905.01580