Through a comparison with transparent polymer composite films, we investigate the thermal property of transparent silver nanowire (AgNW) films that may be employed for heat sink in transparent electronic devices. To fabricate transparent polymer composite films and enhance their thermal property, poly(methyl methacrylate) (PMMA) solution featuring high transparency (∼90%) and thermal emissivity (0.9) is mixed with thermal conductive fillers such as aluminum nitride (AlN) and silicon carbide (SiC). It is observed that the thermal emissivity of the AgNW films is decreased as the sheet resistance is reduced. However, we have found that the AgNW film shows the most excellent heat dissipation property (53.7 • C) while maintaining relatively higher transparency (77.1% at 520 nm), followed by the PMMA:SiC and then PMMA:AlN films.

We investigate the thermal property of cover glasses with heat sink films and provide useful design guidelines of heat sinks for transparent organic light-emitting diodes (OLEDs). To this end, we inquire into the thermal effect of the thickness of cover glasses, Cu sheet or Cu strip lines attached to cover glasses, transparent metal meshes and polymer composite films fabricated on cover glasses, and their position (i.e., inner or outer surface of the cover glass). It is found that the heat sink property varies depending sensitively on the heat sink position and cover glass thickness. To enhance the heat transfer (sink) property, it is preferred to attach the heat sink to the inner surface of the cover glass without any air involved. If no heat sink is used, then thicker cover glasses are required to dissipate the Joule heat effectively. With high-transparency (>80%) metal meshes, we have achieved about 7% heat dissipation. The polymer composite films (poly (methyl methacrylate) (PMMA) binder mixed with cubic-boron nitride (c-BN) filler) show poor heat sink property due to difficulty in establishing an enough heat transfer pathway using a small amount of fillers.