Chemistry Reference
In-Depth Information
0
0.5
1
0.5
1
300
300
(a)
(b)
150
150
300
300
(c)
(d)
150
150
0
1
0.5
1
0.5
ω/
(eV)
Fig. 6. Low frequency optical conductivity for (a) pure Graphene, (b) Graphene-TCNE,
(c) Graphene-TCNQ and (d) Graphene-TTF. The solid and dashed lines in conductiv-
ity profiles correspond to the majority and minority spins respectively. The lines are
broadened with Gaussian functions of width 0.05 eV (From reference 45b).
5. Summary
In this chapter, we have presented emerging results on the effect of external
doping induced by the deposition of a few metal clusters and donor/acceptor
molecules in the modification of the intriguing electronic structure of pris-
tine 2D graphene using first-principles density functional theory level of
calculations. Our results show that the nature of the external dopants has
a significant effect in tuning the electronic structure of graphene through
charge transfer mechanisms. The presence of dopant metal clusters opens
up a small band gap between the valence and conduction bands, and thus
offers a possibile semi-metal to perfectly metallic transition. Interestingly,
we find typical half-metallic behavior for graphene@Pd
40
nanocomposite
which has potential applications in spintronic device fabrication. We have
also shown that the presence of organic donor or acceptor molecules on
graphene can significantly change the electronic properties, in particular
the characteristic Raman spectra of graphene. For all cases, the magnitude
of adsorption energies are found to be moderate, suggesting physisorption
process. Similar to the metal cluster dopants, in molecular cases also we
find that there is an effective charge transfer, the signature of which is found
