title: Solvatochromism Unravels the Emission Mechanism of Carbon Nanodots.
abstract: High quantum yield, photoluminescence tunability, and sensitivity to the environment are hallmarks that make carbon nanodots interesting for fundamental research and applications. Yet, the underlying electronic transitions behind their bright photoluminescence are strongly debated. Despite carbon-dot interactions with their environment should provide valuable insight into the emitting transitions, they have hardly been studied. Here, we investigate these interactions in a wide range of solvents to elucidate the nature of the electronic transitions. We find remarkable and systematic dependence of the emission energy and kinetics on the characteristics of the solvent, with strong response of the photoexcited dots to hydrogen bonding. These findings suggest that the fluorescence originates from the radiative recombination of a photoexcited electron migrated to surface groups with holes left in the valence band of the crystalline core. Furthermore, the results demonstrate the fluorescence tunability to inherently derive from dot-to-dot polydispersity, independent of solvent interactions.
authors.affiliation: Dipartimento di Fisica e Chimica, Università degli Studi di Palermo , Via Archirafi 36, 90123 Palermo, Italy.|Dipartimento di Fisica e Astronomia, Università degli Studi di Catania , Via Santa Sofia 64, 95123 Catania, Italy.
authors.forename: Alice
authors.initials: A
authors.lastname: Sciortino
authors.affiliation: Van der Waals-Zeeman Institute, Universiteit van Amsterdam , Science Park 904, 1098 XH Amsterdam, The Netherlands.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Marino
authors.affiliation: Van der Waals-Zeeman Institute, Universiteit van Amsterdam , Science Park 904, 1098 XH Amsterdam, The Netherlands.
authors.forename: Bart van
authors.initials: Bv
authors.lastname: Dam
authors.affiliation: Van der Waals-Zeeman Institute, Universiteit van Amsterdam , Science Park 904, 1098 XH Amsterdam, The Netherlands.
authors.forename: Peter
authors.initials: P
authors.lastname: Schall
authors.affiliation: Dipartimento di Fisica e Chimica, Università degli Studi di Palermo , Via Archirafi 36, 90123 Palermo, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Cannas
authors.affiliation: Dipartimento di Fisica e Chimica, Università degli Studi di Palermo , Via Archirafi 36, 90123 Palermo, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Messina