Colourful phase change material-incorporated flexible film for efficient passive radiative cooling

Abstract

Passive radiative cooling (PRC) involves the emission of thermal radiation into cold space and the reflection of solar radiation, which aims to cool and lower the temperature of objects. However, currently most radiative coolers have a white appearance which restricts their potential applications. We develop a coloured bilayer radiative cooling membrane using polyvinylidene fluoride/tetraethoxysilane (PVDF/TEOS) fibres, with incorporation of phase change materials (PCMs) and active dyes through a simple and large-area electrospinning process. In comparison to traditional emitters, PCM-incorporated colourful coolers provide energy storage capacity and colourful appearances. Our phase-transition-based colourful flexible film (PCFF) achieves a total solar reflectance of 0.81 and a mid-infrared (MIR) (8-13 μm) emissivity of 0.85 with superior mechanical strength and good hydrophobicity. We experimentally demonstrate that our PCFF can significantly reduce the temperature of objects exposed to direct sunlight, with a cooling effect of up to 9 ℃ compared to commercial fabrics of similar materials and colours. Our work provides a promising starting point for the design and manufacture of colourful and flexible thermal control films.

Self-Cleaning Red-Toned Perylene Poly(aryl ether) Film with Superior NIR Reflectance for Passive Radiative Cooling

“…PVDF is a popular choice for reflective film fabrication for the intrinsic low surface energy and ease in processing. 32 Addition of pigment is a commonly adopted approach to prepare the color matrix, 33 but issues like compatibility, dispersion, use of solvent, and precipitation of dye pigment upon prolong storage are unavoidable. Attaching perylene directly onto the mainchain endows the polymerized product with the desired coloration and avoids the issues mentioned, not to mention the obvious advantages of processing a single matrix over a multicomponent system.…”