Fluoropolymer Drops Graphene’s Resistance

By laminating graphene with a fluoropolymer layer, researchers have made flexible, transparent, and highly conductive films (ACS Nano, DOI: 10.1021/nn3010137). The films could find use as the transparent electrodes needed in organic light-emitting diodes, solar cells, and video displays, the researchers say. Electronics manufacturers currently use indium tin oxide (ITO) to make transparent electrodes. But to build foldable displays and solar cells, researchers want to replace this expensive material with cheaper, more flexible graphene. One major hurdle is graphene’s relatively high electrical resistance. To increase its conductance, Barbaros Özyilmaz of the National University of Singapore and colleagues used spin-coating to add a fluorinated copolymer layer to graphene. This fluoropolymer has dipolar charges on its surface that facilitate electron transfer back and forth to graphene, decreasing graphene’s resistance from about 500 ohms to 120 ohms; ITO’s resistance is about 100 ohms. Unlike previous methods to improve graphene’s conductance, this doping method is permanent and doesn’t damage the material, Özyilmaz says.