title: Monolayer graphene dispersion and radiative cooling for high power LED.
abstract: Molecular fan, a radiative cooling by thin film, has been developed and its application for compact electronic devices has been evaluated. The enhanced surface emissivity and heat dissipation efficiency of the molecular fan coating are shown to correlate with the quantization of lattice modes in active nanomaterials. The highly quantized G and 2D bands in graphene are achieved by our dispersion technique, and then incorporated in an organic-inorganic acrylate emulsion to form a coating assembly on heat sinks (for LED and CPU). This water-based dielectric layer coating has been formulated and applied on metal core printed circuit boards. The heat dissipation efficiency and breakdown voltage are evaluated by a temperature-monitoring system and a high-voltage breakdown tester. The molecular fan coating on heat dissipation units is able to decrease the equilibrium junction temperature by 29.1 ° C, while functioning as a dielectric layer with a high breakdown voltage (>5 kV). The heat dissipation performance of the molecular fan coating applied on LED devices shows that the coated 50 W LED gives an enhanced cooling of 20% at constant light brightness. The schematics of monolayer graphene dispersion, undispersed graphene platelet, and continuous graphene sheet are illustrated and discussed to explain the mechanisms of radiative cooling, radiative/non-radiative, and non-radiative heat re-accumulation.
authors.affiliation: Department of Chemistry and Biochemistry, Northern Illinois University, Dekalb, IL 60115, USA.
authors.forename: Tun-Jen
authors.initials: TJ
authors.lastname: Hsiao
authors.forename: Tsehaye
authors.initials: T
authors.lastname: Eyassu
authors.forename: Kimberly
authors.initials: K
authors.lastname: Henderson
authors.forename: Taesam
authors.initials: T
authors.lastname: Kim
authors.forename: Chhiu-Tsu
authors.initials: CT
authors.lastname: Lin