The passive cooling and thermal properties of the dual functional film composed of Graphene and PDMS-TiO2: Application in the passive heat sink

In recent years, various macro and micro multilayer structures designed for thermal radiation wavelength have been developed to realize radiative cooling from daytime to nighttime. More and more record-breaking radiation cooling films have been developed and experimentally confirmed. At present, the way to use the cold energy generated by radiation cooling film is to use fluid for heat exchange. The cooling energy generated by the radiative cooler is usually transmitted to the demand side for interval cooling through the fluid channel manufactured on the back of the radiative cooling surface. However, the typical radiation cooling film has poor heat conduction characteristics, especially the radiation cooling film based on organic matter. In order to avoid this problems, a new passive cooling composite material with high thermal conductivity, a new passive heat sink, was prepared by combining Graphene film and PDMS based radiation cooling film. Like radiative cooling materials, Graphene/PDMS-TiO2 has a reflectivity of 95.5 % in the sunlight band and only 2 % in the atmospheric window band. The thermal conductivity of Graphene/PDMS-TiO2 is one order of magnitude higher than that of traditional RC. Compared with the most advanced high thermal conductivity RC, it can reduce the thermal resistance by twice. By resolving this critical thermal bottleneck, the Graphene/PDMS-TiO2 enables outdoor equipment with internal heat element, ranging from portable electronics and electronic equipment to massive data centers, to operate at lower temperatures without energy consumption and complex cooling structures. •A new passive cooling composite film high thermal conductivity was proposed.•Graphene/PDMS-TiO2 has a reflectivity of 95.5 % in the sunlight band.•It can reduce the thermal resistance by twice.