Polarization-mediated multi-state infrared system for fine temperature regulation

Abstract

Passive radiative cooling has been spotlighted as a promising energy-saving cooling technology owing to its energy-free and zero-carbon emission for addressing global energy and climate crises. Although radiative cooling can significantly save cooling energy in hot weather, it inevitably accompanies undesirable cooling in cold weather resulting from a single-state of strong thermal emission. Dual-state emitters have recently been developed for self-adaptive thermoregulation, but they still exhibit energy loss in moderate weather. Herein, we report a “continuous” temperature-regulation system by introducing an infrared (IR) polarization valve as the energy-balancing channel. The proposed scheme controls the emitter temperature simply by the in-plane rotation of the IR polarizer as if closing and opening the valve, which presents heating/cooling capabilities of −17 to 51 W/m2 and an energy-saving of >20 GJ/year compared with the conventional emitters in all climate zones. Outdoor experiments demonstrate the precise temperature regulation with the range of ΔTcool >2 °C. This proof-of-concept demonstration in the outdoors verifies our approach’s reliability, suggesting its applicability in residential buildings, farms, and electronic devices.