Thermo‐Optically Designed Scalable Photonic Films with High Thermal Conductivity for Subambient and Above‐Ambient Radiative Cooling

Abstract

Radiative cooling is a promising passive cooling technology that reflects sunlight and emits heat to deep space without any energy consumption. Current research mainly focuses on cooling non‐heat‐generating objects (e.g., water) to a deep subambient temperature under sunlight. Toward real‐world applications, however, cooling outdoor objects that generate tremendous heat and have a temperature higher than ambient (e.g., communication base stations and data centres) remains a challenge. Herein, a scalable photonic film is prepared by introducing 2D dielectric nanoplates with high backward scattering efficiency into a polymer using a simulation aided thermo‐optical design. It is demonstrated that the dielectric nanoplates can break the trade‐off between optical reflection and thermal dissipation of conventional radiative coolers. The photonic film exhibits superior solar reflectance (98%) and has a stronger heat dissipation ability compared to the matrix. It exhibits ≈4 °C subambient cooling performance under direct sunlight and ≈9 °C cooling performance at night. Moreover, it also demonstrates remarkable above‐ambient cooling performance by reducing the underlying heater temperature of ≈18 °C in comparison with traditional polymers under sunlight. The dielectric nanoplates reported here provide an innovative strategy for applications related to light management beyond subambient and above‐ambient radiative cooling.

Vapor–Liquid Transition‐Based Broadband Light Modulation for Self‐Adaptive Thermal Management

“…To achieve highly efficient solar radiation modulation, we explored various coating materials, liquids, and fabrication methods. First, SiO 2 particles were selected as the optimal materials for the porous coating because they do not absorb sunlight, [ 19 ] have a low refractive index (beneficial for finding a matching liquid), and exhibit high mid‐infrared emissivity (Figure S3a,b, Supporting Information). Second, the liquid used in the STMD should follow the refractive index matching mechanism.…”

A Dual‐Mode Infrared Asymmetric Photonic Structure for All‐Season Passive Radiative Cooling and Heating

“…In recent years, several approaches have been considered to mitigate the overcooling problem, such as dynamic modulation of thermal emissivity (smart chromism, metamaterial, phase-changing material, etc. ), [19][20][21][22][23][24][25][26] control of solar absorption, [4,27] and dual-mode architectures with contrastive emissivity on opposite sides. [28][29][30] Nevertheless, they are still subject to another thermal limitation: counter radiations.…”

Switchable Radiative Cooling from Temperature-Responsive Thermal Resistance Modulation

“…Though air-conditioning is a prevalent solution to satisfy the requirement, , the demand for electricity greatly increases because of the extensive use of air-conditioning; worse yet, it produces vast quantities of greenhouse and ozone-depleting gases, causing global warming . Fortunately, radiative cooling technologies are an attractive solution for reducing building energy consumption by providing a path to dissipate heat from buildings through the atmospheric transmittance window (ATW, 8–13 μm) into ultracold universe in the absence of energy input. − …”