CUED Publications database

Exciton-exciton annihilation and biexciton stimulated emission in graphene nanoribbons.

Soavi, G and Dal Conte, S and Manzoni, C and Viola, D and Narita, A and Hu, Y and Feng, X and Hohenester, U and Molinari, E and Prezzi, D and Müllen, K and Cerullo, G (2016) Exciton-exciton annihilation and biexciton stimulated emission in graphene nanoribbons. Nat Commun, 7. 11010-.

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Abstract

Graphene nanoribbons display extraordinary optical properties due to one-dimensional quantum-confinement, such as width-dependent bandgap and strong electron-hole interactions, responsible for the formation of excitons with extremely high binding energies. Here we use femtosecond transient absorption spectroscopy to explore the ultrafast optical properties of ultranarrow, structurally well-defined graphene nanoribbons as a function of the excitation fluence, and the impact of enhanced Coulomb interaction on their excited states dynamics. We show that in the high-excitation regime biexcitons are formed by nonlinear exciton-exciton annihilation, and that they radiatively recombine via stimulated emission. We obtain a biexciton binding energy of ≈ 250 meV, in very good agreement with theoretical results from quantum Monte Carlo simulations. These observations pave the way for the application of graphene nanoribbons in photonics and optoelectronics.

Item Type: Article
Subjects: UNSPECIFIED
Divisions: Div B > Electronics, Power & Energy Conversion
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 18:57
Last Modified: 19 Sep 2017 01:28
DOI: