Scalable colored sub-ambient radiative coolers based on a polymer-Tamm photonic structure

TL;DR

This paper presents a new polymer-Tamm photonic structure enabling scalable, colorful daytime radiative coolers that achieve sub-ambient cooling without electricity, with experimental demonstrations of temperature drops and large-scale manufacturing.

Contribution

It introduces a novel polymer-Tamm photonic design for colored radiative coolers, enabling scalable production and effective sub-ambient cooling in various colors.

Findings

Achieved 2.6-8.8°C cooling during daytime

Demonstrated scalable roll-to-roll fabrication of magenta cooler

Provided theoretical thresholds for sub-ambient cooling in different colors

Abstract

Daytime radiative coolers cool objects below the air temperature without any electricity input, while most of them are limited by a silvery or whitish appearance. Colored daytime radiative coolers (CDRCs) with diverse colors, scalable manufacture, and sub-ambient cooling have not been achieved. We introduce a polymer-Tamm photonic structure to enable a high infrared emittance and an engineered absorbed solar irradiance, governed by the quality factor (Q-factor). We theoretically determine the theoretical thresholds for sub-ambient cooling through yellow, magenta, and cyan CDRCs. We experimentally fabricate and observe a temperature drop of 2.6-8.8 degrees Celsius on average during daytime and 4.0-4.4degrees Celsius during nighttime. Furthermore, we demonstrate a scalable-manufactured magenta CDRC with a width of 60 cm and a length of 500 cm by a roll-to-roll deposition technique. This work provides guidelines for large-scale CDRCs and offers unprecedented opportunities for potential applications with energy-saving, aesthetic, and visual comfort demands.