Realization of bifunctional photothermal and radiative cooling based on self-adaptive VO2/PDMS metamaterial

Abstract

The integration of photothermal (PT) and radiative cooling (RC) for sustainable energy collection has garnered much attention. In this work, a novel polydimethylsiloxane (PDMS) metamaterial is first developed to achieve an efficient radiative cooling. A high reflection of 91.57 % is obtained in the solar band. The average emissivity in the first and second atmospheric windows is up to 93.62 % and 85.58 %, respectively. It can be well explained through the analysis of the electromagnetic power loss. Subsequently, the phase change material of VO2 is deposited in the top PDMS interval to yield adaptive switching between the solar and infrared bands. The patterned VO2/PDMS metamaterial switches from RC mode to PT mode when the temperature exceeds 341 K. Unlike the previous work, this new bifunctional mode operates flexibly during the daytime upon the external thermal stimuli. Finally, the cooling power with different non-radiative heat transfer coefficients is systematically investigated. These numerical results indicate that our patterned PDMS/VO2 metamaterial has great potential in the field of temperature-adaptive switching between PT and RC modes, improving the utilization efficiency of energy in dynamic environments.