Nanowire UVC LEDs on graphene

Offentlig prosjektsammendrag

In the proposed project CrayoNano AS will develop UVC LEDs based on AlGaN nanowires (NWs) on graphene. The AlGaN NWs will be used as the UV emitting material, whereas graphene will be used both as a substrate for the NW growth and a UV transparent electrode. This may offer a breakthrough in the making of high-efficiency UVC LEDs and allow disinfection and sterilization treatments on a much larger scale than is possible today. Existing UVC LEDs have a wall plug efficiency (WPE) of only 3-6%. Environmentally unfriendly mercury bulbs are therefore used instead in almost all UV applications. The UV LED market, and in particular UVC LEDs, is immature with inefficient and very high prices compared to blue GaN LEDs and the potential for technological advancements are huge. This is mainly due to the very high cost of AlN substrate that is needed to achieve close lattice-match with AlGaN, and the lack of transparent electrodes for UVC light. For the UVC LED to be useful for sterilization and disinfection, it needs to emit in the deep UV range of 265 nm to 280 nm where it kills bacteria and other microbes by directly attacking their DNA at its peak absorption. However, a sudden drop in the performance (efficiency and lifetime) of standard thin film UV LEDs at an emission wavelength < 350 nm is of major concern for its use in such applications today. Today, the UVC market is therefore totally dominated by traditional mercury bulbs. This research project will therefore focus on solving and optimizing key material challenges in the active AlGaN nanowire UV emitters in order to reach UVC wavelengths (<280 nm) and optimize the efficiency beyond state-of-the-art on the market today. This project will form the technical basis to develop and commercialize novel nanomaterials-based UVC LEDs that could result in cheaper and more compact handheld devices for water and tool disinfection in especially medical applications.