High-performance radiative cooling film with excellent thermostability and mechanical property realized by self-assembled nanoparticles

Radiative cooling as a new zero-energy cooling technology is promising for cooling highly integrated, miniaturized and flexible electronic devices. However, it's a challenge to combine outstanding cooling performance with excellent thermostability and mechanical properties for flexible radiative cooling films. Herein, a novel strategy to fabricate a high-performance SiO2-doped colorless polyimide (CPI)/Ag flexible film for efficient radiative cooling via controllable self-assembled SiO2 nanoparticles is demonstrated. The film has high solar reflectivity (96.58%, 0.4–2.5 μm) and mid-infrared emissivity (91.24%,5–20 μm). A maximum cooling temperature of 7 °C below ambient and 10 °C lower than the bare aluminum device is achieved under direct sunlight. More importantly, the thermostability (Tg∼331 °C) and tensile strength (78 MPa) broaden its applicability. The strong interfacial interaction between the uniformly distributed tiny self-assembled nanoparticles and matrix plays crucial roles in enhancing radiative cooling performance, thermostability and mechanical properties. This work provides an effective strategy to realize efficient radiative cooling for electronic devices.