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Optical fingerprint of non-covalently functionalized transition metal dichalcogenides

Maja Feierabend (Institutionen för fysik, Kondenserade materiens teori (Chalmers)) ; Ermin Malic (Institutionen för fysik, Kondenserade materiens teori (Chalmers)) ; A. Knorr ; Gunnar Berghäuser (Institutionen för fysik, Kondenserade materiens teori (Chalmers))
Journal of Physics-Condensed Matter (0953-8984). Vol. 29 (2017), 38, p. Article no 384003 .
[Artikel, refereegranskad vetenskaplig]

Atomically thin transition metal dichalcogenides (TMDs) hold promising potential forapplications in optoelectronics. Due to their direct band gap and the extraordinarily strong Coulomb interaction, TMDs exhibit efficient light-matter coupling and tightly bound excitons. Moreover, large spin orbit coupling in combination with circular dichroism allows for spin and valley selective optical excitation. As atomically thin materials, they are very sensitive to changes in the surrounding environment. This motivates a functionalization approach, where external molecules are adsorbed to the materials surface to tailor its optical properties. Here, we apply the density matrix theory to investigate the potential of non-covalently functionalized monolayer TMDs. Considering exemplary molecules with a strong dipole moment, we predict spectral redshifts and the appearance of an additional side peak in the absorption spectrum of functionalized TMDs. We show that the molecular characteristics, e.g. coverage, orientation and dipole moment, crucially influence the optical properties of TMDs, leaving a unique optical fingerprint in the absorption spectrum. Furthermore, we find that the molecular dipole moments open a channel for coherent intervalley coupling between the high-symmetry K and K' points which may create new possibilities for spin-valleytronics application.

Nyckelord: Graphene, Spectroscopy, Disulfide, transition metal dichalcogenides, excitonic absorption spectrum, functionalization

Denna post skapades 2017-09-12.
CPL Pubid: 251840


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