An Optimized Self-Adaptive Thermal Radiation Turn-Down Coating with Vanadium Dioxide Nanowire Array

TL;DR

This paper presents a novel VO2 nanowire array metasurface that self-adaptively switches thermal radiative properties, enhancing cooling efficiency for solar cells and electronic devices through a simple, high-performance design.

Contribution

It introduces a new, easy-to-fabricate VO2 nanowire array metasurface with superior turn-down thermal radiative properties for cooling applications.

Findings

Achieves high reflectance at low temperatures and high emissivity at high temperatures.

Demonstrates superior turn-down figure-of-merit compared to previous VO2 metasurfaces.

Utilizes a sub-wavelength nanowire array effective medium for switching mechanisms.

Abstract

High performance metasurfaces for thermal radiative cooling applications can be identified using computational optimization methods. This work has identified an easy-to-fabricate temperature phase transition VO2 nanowire array laid atop dielectric BaF2 Fabry-Perot cavity-on-metal with total coating thickness of 2 um. This optimized structure has ability to self-adaptively switch between high reflectance at low temperature to high emissivity at high temperature in the broad thermal infrared spectrum. This design demonstrates exceptional turn-down figure-of-merit compared to previously realized configurations utilizing VO2 metasurfaces and multilayers. The mechanism is achieved with a sub-wavelength nanowire array effective medium that switches between anti-reflecting gradient coating and Fabry-Perot interference. This thin metasurface coating could impact self-cooling of the solar cells, batteries, and electrical devices where risk presents at high temperatures.