期刊
NATURE CHEMISTRY
卷 5, 期 10, 页码 840-845出版社
NATURE PUBLISHING GROUP
DOI: 10.1038/NCHEM.1711
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资金
- University of Maryland
- Office of Naval Research [N000141110465]
- National Science Foundation [CAREER CHE-1055514]
- ARO MURI grant [W911NF-09-1-0541]
- Direct For Mathematical & Physical Scien
- Division Of Chemistry [1055514] Funding Source: National Science Foundation
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.
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