Graphene Nanoplatelets Prepared by Electric Heating Acid-Treated Graphite in a Vacuum Chamber and Their Use as Additives in Organic Semiconductors

Graphene nanoplatelets (GNPs) were prepared from acid-treated expandable graphite using a novel method of electric heating the graphite in an evaporation chamber under high vacuum, followed by solvent exfoliation. Such prepared graphene nanoplatelets, the eGNPs, were compared to GNPs prepared from two conventional methods: thermal expansion in an isothermal oven followed by solvent exfoliation (oGNPs), and direct solvent exfoliation (sGNPs), using various characterization techniques including UV-vis spectroscopy, scanning electron microscopy, and atomic force microscopy. It was found that the eGNPs were very thin, with a thickness of 4-16 nm, and showed no oxidation. On the other hand, oGNPs exhibited much thicker sheets, upward of 40 nm, and the sGNPs showed a high degree of oxidation. Utilizing the high purity eGNPs as an additive in PQT-12 semiconductor layer has been shown to improve the mobility by a factor of 2 in thin-film transistor devices.