Fabrication and investigation of optoelectronic properties of graphene-1d nanostructure hybrid films
Due to low electron-phonon scattering, graphene has excellent transport properties with high charge carrier mobilities. In addition, single layer graphene absorbs about 2.3% of visible light. The combination of these unique properties makes graphene an excellent candidate for transparent conductive films (TCF). Chemical vapor deposition (CVD) of hydrocarbon gases on metal surfaces allows scaling graphene films to large sizes that can be transferred onto arbitrary substrates. These features open the possibility to replace indium tin oxide (ITO) by graphene as the TCF, particularly for flexible and large-area device applications. However, the sheet resistance of CVD-grown monolayer graphene is significantly higher than ITO-based TCFs. The charge carrier mobility in these graphene films is much lower than mechanically exfoliated graphene, as well as theoretically calculated values. Defects influence the transport properties of CVD-grown graphene. Large-area CVD-grown graphene is a polycrystalline material with topological defects such as dislocations and grain boundaries. Depending on the detailed atomic structure, these defects can disrupt the sp2 delocalization of π electrons in graphene and effectively scatter the charge carriers. Elimination of the detrimental effect of line defects can be achieved through the integration of CVD-grown graphene with one dimensional (1D) nanostructures. In our research studies, we investigate new methods of fabrication and optoelectronic properties of graphene-1D nanostructure composites. Ag, Cu and Au nanowires and single-walled and multi-walled carbon nanotubes have been assembled with graphene in order to obtain hybrid transparent conductive films with improved electrical conductivity and high optical transmittance comparable with commercially available indium tin oxide films.
Our recently developed methods allow easy integration of 2D graphene with 1D nanoconductors. Current research studies are focused on investigation of mechanical, thermal and environmental stability of the graphene-based composites and their potential for applications in a wide range of optoelectronic devices.
SEM image of Ag nanowire/reduced graphene oxide (rG-O) hybrid films. Flexible rG-O films on top of nanowires provide additional 2D platforms for charge transport. This can explain the improved electrical conductivity of the hybrid films.