Functionalization of carbon nanotubes (CNT) by organic surfactants, conjugated polymers, or biomolecules promises improvement of their working functions for future CNT-based optoelectronic and photovoltaic devices. Using the combination of the molecular mechanics and density functional theory, we have investigated morphology, the electronic structure, and optical properties of CNTs covalently or non-covalently functionalized by organic molecules. We have found that non-covalent functionalization, when a nanotube and a molecule interact weakly via pi-pi stacking, as in the case of functionalization by single strand DNA and conjugated polymers, only slightly perturbs the electronic structure of the system resulting on insignificant red-shifting and broadening of the first and second optical bands of CNTs. In contrast, covalent functionalization introduces chemical defects locally destroying conjugation in the nanotube. Such defects change optical selection rules of excitonic transitions. As a result, the lowest state becomes optically allowed promising increase in photoluminescence of such functionalized CNTs.

Covalently and noncovalently functionalized carbon nanotubes: Modeling of morphologies and optical properties

243rd National Meeting (2012)

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