Exciton dynamics in luminescent carbon nanodots: Electron–hole exchange interaction
- 387 Downloads
The electron–hole exchange interaction significantly influences the optical properties of excitons and radiative decay. However, exciton dynamics in luminescent carbon dots (Cdots) is still not clear. In this study, we have developed a simple and efficient one-step strategy to synthesize luminescent Cdots using the pyrolysis of oleylamine. The sp2 clusters of a few aromatic rings are responsible for the observed blue photoluminescence. The size of these clusters can be tuned by controlling the reaction time, and the energy gap between the π–π* states of the sp2 domains decreases as the sp2 cluster size increases. More importantly, the strong electron–hole exchange interaction results in the splitting of the exciton states of the sp2 clusters into the singlet-bright and triplet-dark states with an energy difference ΔE, which decreases with increasing sp2 cluster size owing to the reduction of the confinement energy and the suppression of the electron–hole exchange interaction.
Keywordscarbon dots photoluminescence pyrolysis electron–hole exchange interaction energy splitting
Unable to display preview. Download preview PDF.
- Pan, J.; Utama, M. I. B.; Zhang, Q.; Liu, X. F.; Peng, B.; Wong, L. M.; Sum, T. C.; Wang, S. J.; Xiong, Q. H. Composition-tunable vertically aligned CdSxSe1-x nanowire arrays via van der waals epitaxy: Investigation of optical properties and photocatalytic behavior. Adv. Mater. 2012, 24, 4151–4156.CrossRefGoogle Scholar
- Kisner, A. Ultrathin Gold Nanowires: Chemistry, Electrical Characterization and Application to Sense Cellular Biology; Forschungszentrum Jülich, Zentralbibliothek: Jülich, 2012.Google Scholar
- Yang, D. X.; Velamakanni, A.; Bozoklu, G.; Park, S.; Stoller, M.; Piner, R. D.; Stankovich, S.; Jung, I.; Field, D. A.; Ventrice, C. A. Jr. et al. Chemical analysis of graphene oxide films after heat and chemical treatments by X-ray photoelectron and micro-Raman spectroscopy. Carbon 2009, 47, 145–152.CrossRefGoogle Scholar
- Labeau, O.; Tamarat, P.; Lounis, B. Temperature dependence of the luminescence lifetime of single CdSe/ZnS quantum dots. Phys. Rev. Lett. 2003, 90, 257404.Google Scholar
- Brovelli, S.; Schaller, R. D.; Crooker, S. A.; García-Santamaría, F.; Chen, Y.; Viswanatha, R.; Hollingsworth, J. A.; Htoon, H.; Klimov, V. I. Nano-engineered electron–hole exchange interaction controls exciton dynamics in core–shell semiconductor nanocrystals. Nat. Commun. 2011, 2, 280.CrossRefGoogle Scholar