8 / 16
Page 69
Research & Reviews: Journal of Material Sciences | ISSN: 2321-6212 | Volume 6
Theoretical, Materials and Condensed Matter Physics
5
th
International Conference on
November 26-28, 2018 | Los Angeles, USA
Quenching of photoluminescence in graphene hybrids
Mahi R Singh
The University of Western Ontario, Canada
R
ecently there is a considerable interest to study the plasmonic properties of graphene hybrids. Graphene was invented theoretically
byWallace in 1947. He predicted that graphene is a gapless NS and has an indirect band gap. Later,Wallace and I foundmore gapless
materials such as Cd3AS2, HgTe which have direct band gaps. We showed that the optical energy absorption/emission is stronger in
the direct bandgap materials than indirect band materials. Recently graphene-like nanostructures such as germanene and silicanes
have been invented. Here, we investigate the quenching of photoluminescence in a quantum dot (QD)-metallic nanoparticles and
metallic graphene film (QD-MN-G) hybrid systemdeposited on a dielectric material such as Si. The surface plasmon polaritons (SPPs)
are calculated solving the Maxwell equations for the graphene and the dielectric heterostructure in the quasi-static approximation.
QDs have excitons which interact with SPPs of the graphene-dielectric heterostructure. Photoluminescence (PL) of QD is found by
using the quantum density matrix method in the presence of exciton-SPP coupling. Numerical simulations for the PL spectrum in
the QD is performed for (QD-MN-G) hybrid system. It is found that when the exciton energy of the QD is in resonant with the SPP
energy the intensity of the photoluminescence is quenched. The PL quenching occurs is due to the transfer of photon energy from
the QD to the graphene film and MNP due to the exciton-SPP coupling. Furthermore, when the exciton energy is non-resonant with
the SPP energy the PL quenching disappears. The energy transfer from the QDs to the graphene film can be switched ON and OFF
by mismatching the resonant energies of excitons and polaritons. The mismatching of energies can be achieved by applying external
pump lasers or stress and strain fields. Recently Dong et al. and Zeng et al. have measured the PL spectrum of QDs in QD-G hybrid
and QD-MN-G hybrid, respectively. In both experiments, they have observed the PL quenching. We have compared our theory with
these experiments and found a good agreement between theory and experiments. These are interesting findings and they can be used
to fabricate switches and sensors by using graphene nanocomposites.
msingh@uwo.caRes. Rev. J Mat. Sci. 2018, Volume 6
DOI: 10.4172/2321-6212-C10-042