Samsung has filed a patent application for graphene electronic devices, including graphene transistors, that are immune to moisture. Moisture has plagued graphene electronics, limiting the performance of devices.
In US Patent Application 20120313079, Samsung describes a graphene transistor in a standard configuration: bottom gate, insulator, graphene, and two electrodes. The graphene can be simply a sheet, or a nanoribbon that results in a band gap. The novelty of the invention is an insulating layer that prevents graphene from absorbing ambient moisture. The organic insulating layer contains a fluorine group polymer, which is hydrophobic, or water-repellant.
Graphene is known to be hydrophilic, meaning that it readily absorbs moisture from the environment. Moisture deteriorates the performance of graphene. The Samsung patent application includes graphs that show how a graphene device protected with a fluorine polymer performs essentially like an undoped sheet of graphene, with its properties preserved over a period of weeks. Surprisingly, the polymer protects the graphene even when it is placed underneath the sheet, with the top side of graphene exposed to air.
The discovery that a hydrophilic layer can be placed between the graphene and the insulator is indeed a novelty which shows once again the excellence of Samsung. Samsung has been patenting graphene for various electronic purposes, including touchpanels and magnetic memories.