Intelligent regulation of VO2-PDMS-driven radiative cooling

Abstract

Passive radiative cooling, radiating energy from objects to the outer space through the Earth's atmospheric window, offers promising solutions for passive building cooling and renewable energy harvesting. However, static passive radiative cooling systems with a fixed thermal emissivity cannot automatically regulate emission in response to varying ambient temperature. Here, we propose an intelligent cooling system composed of nanoporous polyethylene, which acts as a solar reflector and a nanograting radiative cooler using the phase-transition material vanadium dioxide (VO2) and polydimethylsiloxane (PDMS). The top reflector enables the cooling system to reflect solar irradiation during the daytime, and the bottom cooler plays the role of switching radiative cooling in the spectrum band (8 μm < λ < 13 μm) due to the phase transition characteristic of VO2, contributing to the temperature of radiative cooler near a critical temperature. Meanwhile, continuous stretching of the material can achieve dynamic radiative cooling via deformation of the elastic PDMS substrate to realize different desired cooling temperatures. The proposed VO2-PDMS-driven radiative cooling system can not only intelligently switch between “on” and “off” radiative cooling modes but also adjust thermal comfort in its on mode in response to changes in the ambient temperature. This work has a great potential to be applied in the intelligent temperature regulation of buildings, vehicles, and utilities.