LAUSR

High voltage is an obstacle when applying electrohydrodynamics technology. Nanomaterials are good candidates for its extraordinary electrical properties and heat‐conducting characteristics. An originally designed ionic wind cooling system was secured with graphene using the dip‐coating method to study the cooling effect for the high‐power light‐emitting diodes. The experiment results indicated that the graphene on the needles' surface acted as new emitting electrode with a smaller curvature radius. The corona discharge current density increased, and the ionic wind inception voltage decreased, because of the high aspect ratios and the field emission characteristic of graphene. The maximum ionic wind volume velocity was improved by 41.3% when the discharge gap was 10 mm, which was attributed to the local electric field enhancement and the electron field emission effect that the graphene had. The best cooling performance was obtained when the needles and the heat sink were both coated with graphene. The junction temperature decreased 21%, and the luminous flux increased 5.6% at the discharge gap of 15 mm, taking the electrostatic screening effect into consideration.