Carbon nanorings are hoop-shaped, p-conjugated macrocycles which form the fundamental annular segments of single-walled carbon nanotubes (SWNTs). In a series of very recent reports1-2, we showed that the excited-state properties of these unique nanorings exhibit anomalous and extremely interesting optoelectronic properties, with excitation energies growing larger as a function of size (in contradiction with typical quantum confinement effects). In order to understand their unusual electronic properties, we carried out an extensive investigation of excitonic effects by analyzing electron-hole transition density matrices and exciton binding energies utilizing time-dependent density functional theory (TD-DFT). The transition density matrices allow a global view of electronic coherence during an electronic excitation, and the exciton binding energies give a quantitative measure of electron-hole interaction energies in the nanorings. Based on overall trends in exciton binding energies and their spatial delocalization, we find that excitonic effects play a vital role in understanding the unique photoinduced dynamics in these carbon nanoring systems.(1) Wong, B. M. J. Phys. Chem. C 2009 , 113, 21921.(2) Wong, B. M.; Lee, J. W. J. Phys. Chem. Lett. 2011 , 2, 2702.

Anomalous optoelectronic properties of carbon nanorings: Unusual excitonic and nanoscale effects

243rd National Meeting (2012)

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