Synthesis of graphitic materials and its applications in nanoelectronics.

摘要

Single layer graphene is of great interest for electronic applications as an atomically thin, zero hand gap semiconductor. Experimental results have been sparse due to the difficulty of creating single layer samples. A new solution process for the large-scale production of single layer chemically converted graphene overcomes the formidable challenge and is able to deliver a uniform coating over the entire area of a wafer. By dispersing graphite oxide paper in pure hydrazine we are able to remove oxygen functionalities and restore the planar geometry of single sheets. The chemically converted graphene sheets produced have the largest area (up to 25 microm x 40 microm) of any yet reported chemically converted counterparts, making them far easier to process. Field effect devices are fabricated by conventional photolithography, displaying currents that are 3 orders of magnitude higher than any previously reported for chemically produced graphene. The size of these sheets enables a wide range of characterization techniques, including optical microscopy, SEM and AFM performed on the same specimen. This versatile solution process holds great promise for transparent conductors and nanoelectronics.;The facile synthesis of a nano-composite comprised of chemically converted graphene (CCG) and carbon nanotubes (CNTs) is also presented. This solution-based approach does not require surfactants, thus preserving the intrinsic electronic and mechanical properties of both components. By carefully controlling the nano-scale morphology and counter-ion formation of such hybrid materials, we are able to deliver high conductivities at very low optical densities on rigid and flexible substrates. We believe that this approach is inexpensive, massively scalable and does not suffer from several shortcomings of ITO. We present conductivity and optical data demonstrating comparable performance to ITO, less than 300 O/□ at 91% transmittance, and also a proof-of-principle application in a polymer solar cell. Through further modification, the graphene-CNTs composite may well suited for future solar applications and overcome the limited production of indium (In).