Issue 30, 2019

Ultrafast spectroscopic investigation on fluorescent carbon nanodots: the role of passivation

Abstract

Disentangling the respective roles of the surface and core structures in the photocycle of carbon nanodots is a critical open problem in carbon nanoscience. While the need of passivating carbon dot surfaces to obtain efficiently emitting nanoparticles is very well-known in the literature, it is unclear if passivation introduces entirely new surface emitting states, or if it stabilizes existing states making them fluorescent. In this multi-technique femtosecond spectroscopy study, the relaxation dynamics of non-luminescent (non-passivated) carbon dots are directly compared with their luminescent (passivated) counterparts. Non-passivated dots are found to host emissive states, albeit very short-lived and practically incapable of steady-state fluorescence. In contrast, the passivation procedure gives birth to a distinctive new manifold of emitting states, localized on the surface of the dots, and capable of intense, tunable, long-lived fluorescence. It turns out that these surface states are instantaneously populated by photo-excitation, and their subsequent dynamics are entirely independent of core electronic transitions. The experiments reveal the lack of any crosstalk between core- and surface states, at least for certain common types of carbon dots, and open a new perspective on the mechanisms by which surface passivation governs the fluorescence properties of these nanoparticles.

Graphical abstract: Ultrafast spectroscopic investigation on fluorescent carbon nanodots: the role of passivation

Supplementary files

Article information

Article type
Paper
Submitted
30 May 2019
Accepted
09 Jul 2019
First published
09 Jul 2019

Phys. Chem. Chem. Phys., 2019,21, 16459-16467

Ultrafast spectroscopic investigation on fluorescent carbon nanodots: the role of passivation

A. Sciortino, M. Gazzetto, M. L. Soriano, M. Cannas, S. Cárdenas, A. Cannizzo and F. Messina, Phys. Chem. Chem. Phys., 2019, 21, 16459 DOI: 10.1039/C9CP03063H

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