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Bandgap engineering of graphene by molecular self-assembly

Final Report Summary - BENGRAS (Bandgap engineering of graphene by molecular self-assembly)


Executive Summary:

1. Summary of the project objective:

The ultimate goal of this project is to study band gap engineering of graphene induced by physisorption and/or chemisorption of self-assembled monolayers (figure 1). The areas of nano-science and nanotechnology are rapidly emerging with the strong focus on the development of so-called smart materials – functional nanostructured system capable of being remotely activated to carry out specific functions and tasks. Such devices will likely need to be supported on surface characterized by a large surface to volume ratio and will require a “bottom-up’ chemical approach, a role for which molecular self-assembly appears to be one of the ideal approaches. Graphene, a single atomic layer of graphite, has enormous potential for use in electronic transistors because of the unique electric properties and the reduced dimensionality. A prerequisite for the use of graphene in electric devices is the ability to control its electronic band structures (e.g. band-gap) and the availability of methods permitting such control in a flexible and technologically achievable manner. This can be accomplished by applying the knowledge from supramolecular chemistry in designing molecules with specific electronic structure, which through the process of either physisorption and/or chemisorption are able to carefully tune the work function, carrier type and concentration of the system. The additional benefit of this method is that the generated two-dimensional molecular network be extended to a scale of over micrometers to millimeters, finally making graphene suitable for practical applications. However, this approach has not yet been exploited and remains its experimental /analytical infancy.

The main objectives of this project constitute three work packages;

1: generation of large-scale molecular network on graphene surface using (a) physisorbed and/or chemisorbed molecular self-assembled network.
2: Building up (super-resolution) vibrational microscopy, combined with scanning probe microscope, such as atomic force microscope.
3: characterization of electric/vibrational properties of graphene modified by molecular self-assembled network.

2. The work performed since the beginning of the project

- Installation of nanoscopic techniques to investigate band structure of graphene (confocal Raman microscopy combined with atomic force microscope).
- Raman spectroscopy on donor molecule – graphene mixture

3. The main results:

A home-built Raman microscope has been combined with AFM in this project in order to correlate spectroscopic future of graphene with their morphology. Raman spectra of individual graphene nano-ribbon were resolved clearly using the newly installed Raman mapping system.

Tetracyanoquinodimethan (TCQ) is known as an electron rich molecule acting as donor (n-doping) molecule. According to the Raman mapping of this mixture, TCQ aggregate well with graphene sheet. Significant change in the ratio between G- and D-band of graphene has been observed after adding TCQ, suggesting doping effect of TCQ on graphene sheets.

4. The expected final results and their potential impact

BENGRAS will award the fellow with a unique, challenging and engaging opportunity to communicate the research results obtained in the project directly to the general public and by doing so, contribute to growing awareness among the general population about the importance of fundamental research and the role of Marie Curie Actions program in the support and promotion of science.

BENGRAS is focused on the designing of functional nanomaterials based on graphene, a material that has been recently discovered and has been popularised through the award of the Nobel Prize in Physics in 2010 to A. Geim and K. Novoselov. While there is little doubt that some general knowledge is shared to non-scientific population about new materials available for the future of humanity including ‘small’ nanotubes, buckyballs, carbon sheets, etc., it is certain that the public is lacking awareness and critical information about the importance of such materials for the development of present-day and future technologies for new smart device applications, superior every-day materials and, as means that potentially can solve our environmental problems.

The fellow will address this problem and present BENGRAS as: a) The project based on the ‘real’ use of newly discovered ‘nano’-materials (i.e. graphene) and, b) The project, which plays the major role in bridging the gap between chemistry and material science from both the fundamental and applied applications viewpoints.

Nanostructured multi-compositional materials are expected to make significant impacts in the emerging areas of molecular electronics, photovoltaics and photonics. It is therefore of vital importance to ensure that the general public is aware about the real and tangible benefits the research in such materials conveys and, about the importance of continuation of government funding including EU Marie Curie Actions program supporting such research pursuits.