Evidence for edge state photoluminescence in graphene quantum dots

ORAL

Abstract

For a practical realization of graphene-based logic devices, opening of a band gap in graphene is crucial and has proved challenging. To this end, several synthesis techniques including unzipping of carbon nanotubes, chemical vapor deposition and other bottom-up fabrication techniques have been pursued for the bulk production of graphene nanoribbons (GNRs) and graphene quantum dots (GQDs). However, only a limited progress has been made towards a fundamental understanding of the electronic and optical properties of GQDs. In particular, the origin of strong photoluminescence (PL) in GQDs, which has been attributed to the presence of emissive surface traps and/or the edge states in GQD, remains inconclusive to date. Here, we experimentally show that the PL is independent of the functional groups attached to the GQDs. Following a series of annealing experiments, we further show that the PL in GQDs originates from the edge states, and an edge-passivation subsequent to synthesis quenches PL. These results are consistent with comparative studies on other carbon nanostructures such as GNRs and carbon nano-onions.

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Authors

  • Kiran Lingam

    Dept. of Physics and Astronomy, Clemson University, Clemson, SC USA 29634, Department of Physics, Clemson University, Clemson, SC 29634, Department of Physics and Astronomy, Clemson University, Clemson, SC 29634

  • R.S. Sai Siddhardha

    Department of Physics, Clemson University, Clemson, SC 29634, Department of Physics and Astronomy, Clemson University, Clemson SC, USA 29634, Dept. of Physics and Astronomy, Clemson University, Clemson, SC USA 29634, Department of Physics and Astronomy, Clemson University, Clemson, SC, United States 29634, Sri Sathya Sai Institute of Higher Learning, India, Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, Sri Sathya Sai Institute of Higher Learning

  • Haijun Qian

    Advanced Materials Research Laboratories, Clemson University, Anderson, SC USA 29625, Electron Microscope facility, Clemson research park, Clemson University, Anderson, SC USA 29625.

  • Steve Serkiz

    Savannah River National Laboratory, Savannah River National Laboratory, Aiken, SC USA 29808

  • Apparao M. Rao

    Department of Physics and Astronomy, Clemson University, Clemson SC, USA 29634, Clemson University, Dept. of Physics and Astronomy, Clemson University, Clemson, SC USA 29634, Department of Physics and Astronomy, Clemson University, Clemson, SC, United States 29634, Department of Physics and Astronomy, Clemson University, Clemson, SC 29634