Electronic Structure and Chemical Nature of Oxygen Dopant States in Carbon Nanotubes

详细信息    查看全文

• 作者：Xuedan Ma ; Lyudmyla Adamska ; Hisato Yamaguchi ; Sibel Ebru Yalcin ; Sergei Tretiak ; Stephen K. Doorn ; Han Htoon
• 刊名：ACS Nano
• 出版年：2014
• 出版时间：October 28, 2014
• 年：2014
• 卷：8
• 期：10
• 页码：10782-10789
• 全文大小：544K
• ISSN：1936-086X

文摘

We performed low temperature photoluminescence (PL) studies on individual oxygen-doped single-walled carbon nanotubes (SWCNTs) and correlated our observations to electronic structure simulations. Our experiment reveals multiple sharp asymmetric emission peaks at energies 50鈥?00 meV red-shifted from that of the E₁₁ bright exciton peak. Our simulation suggests an association of these peaks with deep trap states tied to different specific chemical adducts. In addition, oxygen doping is also observed to split the E₁₁ exciton into two or more states with an energy splitting <40 meV. We attribute these states to dark states that are brightened through defect-induced symmetry breaking. While the wave functions of these brightened states are delocalized, those of the deep-trap states are strongly localized and pinned to the dopants. These findings are consistent with our experimental observation of asymmetric broadening of the deep trap emission peaks, which can result from interaction between pinned excitons and one-dimensional phonons. Exciton pinning also increases the sensitivity of the deep traps to the local dielectric environment, leading to a large inhomogeneous broadening. Observations of multiple spectral features on single nanotubes indicate the possibility of different chemical adducts coexisting on a given nanotube.

Keywords:

carbon nanotubes; electronic structure; oxygen doping; photoluminescence; exciton localization