Daytime sub-ambient radiative cooling with vivid structural colors mediated by coupled nanocavities

TL;DR

This paper introduces multilayered nanocavity structures that produce vivid structural colors for daytime radiative cooling, achieving high aesthetic appeal without compromising cooling efficiency, demonstrated through outdoor experiments.

Contribution

It presents a novel design of multilayered nanocavities that generate vivid structural colors with high cooling performance, surpassing previous color gamut and efficiency trade-offs.

Findings

Colorful radiative coolers show a 17.7% sRGB color gamut.

Outdoor experiments demonstrate temperature drops of 3.4 to 4.4°C.

The design enables aesthetic and efficient daytime cooling applications.

Abstract

Daytime radiative cooling is a promising passive cooling technology for combating global warming. Existing daytime radiative coolers usually show whitish colors due to their broadband high solar reflectivity, which severely impedes applications in real-life situations with aesthetic demands and effective display. However, there is a trade-off between vivid colors and high cooling performance because colors are often produced by absorption of visible light, decreasing net cooling power. To break this trade-off, we design multilayered structures with coupled nanocavities and produce structural colors with high cooling performance. Using this design, we can obtain colorful radiative coolers which show a larger color gamut (occupying 17.7% sRGB area) than reported ones. We further fabricate colorful multilayered radiative coolers (CMRCs) and demonstrate they have temperature drops of 3.4 - 4.4 degrees on average based on outdoor experiments. These CMRCs are promising in thermal management of electronic/optoelectronic devices and outdoor facilities.