Flexible highly thermal conductive hybrid film for efficient radiative cooling

Abstract

Radiative cooling is highly significant for carbon neutrality and sustainable development. Rapid development has been made for materials of radiative heat dissipation, applicable to sub-ambient and above-ambient cooling. However, scalable and low-cost approach for radiative cooling materials coupled with high thermal conductivity need to be further explored. Here, we present a design strategy for flexible highly thermal conductive hybrid film towards efficient radiative cooling. The proposed thermal conductive radiative cooler (TCRC) consists of interconnected polyvinylidene difluoride (PVDF) fibrous frameworks and randomly dispersed hexagonal boron nitride (h-BN) nanoplates via electrospinning and hot-pressing processes. Synergistic effects of spectral and thermal conductive properties endow the film with a high solar reflectivity of 0.92 in 250–2500 nm and a broadband mid-infrared (MIR) emissivity of 0.93 in 4–16 μm, while the thermal conductivity reaches over 10 W m−1 K−1. The radiative cooler demonstrates excellent above-ambient cooling performance (∼11 °C) with an effective cooling power of ∼80 W m−2, comparable to the most advanced reports. Besides, the film exhibits superior mechanical strength of 33 MPa and hydrophobicity with 140° contact angle. This work opens up a new avenue of radiative cooling for devices working under both above-ambient conditions.