Self-Switching Dynamic Infrared Radiative Cooler Enabling Triple-Mode Temperature Regulation

Area of Science:

• Materials Science
• Nanotechnology
• Thermodynamics

Background:

• Passive radiative cooling provides zero-energy heat dissipation but static photonic structures are limited by fixed spectral properties.
• Different thermal environments require distinct infrared emission spectra, hindering the application of static coolers in multi-scenario settings.

Purpose of the Study:

• To propose a self-switching dynamic infrared radiative cooler (DIRC) capable of triple-mode temperature regulation.
• To achieve adaptive spectral conversion for sub-ambient, near-ambient, and above-ambient cooling applications.

Main Methods:

• Leveraging temperature-triggered directional migration of water molecules within a thermoresponsive hydrogel.
• Designing a DIRC that enables spectral conversion between selective and broadband infrared emission.
• Characterizing DIRC performance including emissivity, solar reflectivity, and spectral transition response times.

Main Results:

• The DIRC exhibits high broadband emissivity (94.1% across 2.5-25 µm) and selective emissivity (81.6% within 8-13 µm).
• Solar reflectivity remains stable at ≈90% during spectral conversion.
• Rapid, autonomous spectral transitions occur within 37.3-85.6 seconds across a 35-45 °C temperature range.

Conclusions:

• The DIRC achieves significant cooling performance: 9.5 °C sub-ambient, 7.0 °C near-ambient, and 6.9 °C above-ambient.
• This dynamic approach overcomes the limitations of static designs for single-scenario and weather-dependent applications.
• The DIRC offers a versatile strategy for triple-mode thermal regulation across a wide range of applications.