Scalable Flexible Hybrid Membranes with Photonic Structures for Daytime Radiative Cooling

Passive radiative cooling technology can cool down an object by reflecting solar light and radiating heat simultaneously. However, photonic radiators generally require stringent and nanoscale-precision fabrication, which greatly restricts mass production and renders them less attractive for large-area applications. A simple, inexpensive, and scalable electrospinning method is demonstrated for fabricating a high-performance flexible hybrid membrane radiator (FHMR) that consists of polyvinylidene fluoride/tetraethyl orthosilicate fibers with numerous nanopores inside and SiO2 microspheres randomly distributed across its surface. Even without silver back-coating, a 300 mu m thick FHMR has an average infrared emissivity >0.96 and reflects approximate to 97% of solar irradiance. Moreover, it exhibits great flexibility and superior strength. The daytime cooling performance this device is experimentally demonstrated with an average radiative cooling power of 61 W m(-2) and a temperature decrease up to 6 degrees C under a peak solar intensity of 1000 W m(-2). This performance is comparable to those of state-of-the-art devices.