Abstract
Semiconducting carbon nanotubes promise a broad range of potential applications in optoelectronics and imaging, but their photon-conversion efficiency is relatively low. Quantum theory suggests that nanotube photoluminescence is intrinsically inefficient because of low-lying 'dark' exciton states. Here we demonstrate the significant brightening of nanotube photoluminescence (up to 28-fold) through the creation of an optically allowed defect state that resides below the predicted energy level of the dark excitons. Emission from this new state generates a photoluminescence peak that is red-shifted by as much as 254 meV from the nanotube's original excitonic transition. We also found that the attachment of electron-withdrawing substituents to carbon nanotubes systematically drives this defect state further down the energy ladder. Our experiments show that the material's photoluminescence quantum yield increases exponentially as a function of the shifted emission energy. This work lays the foundation for chemical control of defect quantum states in low-dimensional carbon materials.
Original language | English (US) |
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Pages (from-to) | 840-845 |
Number of pages | 6 |
Journal | Nature chemistry |
Volume | 5 |
Issue number | 10 |
DOIs | |
State | Published - Oct 2013 |
Funding
We thank A. Brozena and J. Fourkas for helpful discussions and K. Gaskell for assistance with XPS experiments. This work was partially supported by the University of Maryland, the Office of Naval Research (N000141110465) and the National Science Foundation (CAREER CHE-1055514). G.C.S. and N.V. acknowledge support from ARO MURI grant #W911NF-09-1-0541.
ASJC Scopus subject areas
- General Chemistry
- General Chemical Engineering