Ultrafast exciton relaxation in size-controlled and well-dispersed graphene nanoflakes

Sébastien Quistrebert; Daniel Medina-Lopez; Stéphane Campidelli; Jean-Sébastien Lauret; Elsa Cassette

doi:10.1117/12.3016966

11 June 2024 Ultrafast exciton relaxation in size-controlled and well-dispersed graphene nanoflakes

Sébastien Quistrebert, Daniel Medina-Lopez, Stéphane Campidelli, Jean-Sébastien Lauret, Elsa Cassette

Author Affiliations +

Proceedings Volume PC12992, Advances in Ultrafast Condensed Phase Physics IV; PC129920M (2024) https://doi.org/10.1117/12.3016966
Event: SPIE Photonics Europe, 2024, Strasbourg, France

Abstract

Graphene nanostructures, such as Graphene Quantum Dots (G-QDs), Graphene Nanoribbons (G-NRs) and Carbon Nanotubes (C-NTs), combine the unique mechanical and electronical transport properties of sp2- hybridized carbon materials and the optical properties of direct semiconductors provided by the optical gap resulting from the reduction of dimensionally. Here we use transient absorption of 30 fs temporal resolution with polarization-controlled configuration to probe the hot exciton relaxation (internal conversion, Sn→S1) in rectangular G-QDs of various lateral lengths. We selectively excite the different samples at the second optically active electronic transition and, thought the appearance of a photo-induced emission signal at the energy corresponding to the bandedge and red-shifted vibrational replica (i.e. at the position of the steady-state photoluminescence peaks), the dynamics of relaxation were unveiled. The resulting relaxation times range from 100 fs to 175 fs. These results allowed to discuss the mechanism of relaxation, with the effect of the length of the graphene nanoflakes and of the fluence excitation.

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Citation Download Citation

Sébastien Quistrebert, Daniel Medina-Lopez, Stéphane Campidelli, Jean-Sébastien Lauret, and Elsa Cassette "Ultrafast exciton relaxation in size-controlled and well-dispersed graphene nanoflakes", Proc. SPIE PC12992, Advances in Ultrafast Condensed Phase Physics IV, PC129920M (11 June 2024); https://doi.org/10.1117/12.3016966

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