Low-Temperature Single Carbon Nanotube Spectroscopy of sp3 Quantum Defects
Low-Temperature Single Carbon Nanotube Spectroscopy of sp3 Quantum Defects
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DOI：
10.1021/acsnano.7b03022
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发表时间：
2017-11-01
期刊：
影响因子：
17.1
通讯作者：
Htoon, Han
中科院分区：
文献类型：
--
作者：
He, Xiaowei;Gifford, Brendan J.;Htoon, Han
为了揭示芳基官能化（6，5）单壁碳纳米管（SWCNTs）sp（3）缺陷的化学构型和电子结构之间的关系，我们进行了低温单纳米管光致发光（PL）光谱研究，并将我们的观察与量子化学模拟相关联。我们观察到尖锐的发射峰从个别缺陷的网站，是在一个非常广泛的，1000-1350 nm，光谱范围内蔓延。我们的模拟使我们能够将这种光谱多样性归因于六种化学和能量上不同的缺陷态的发生，这些缺陷态是由单价芳基的化学结合构型的拓扑变化引起的。PL发射效率和缺陷态的谱线宽度都受到局部介电环境的强烈影响。用聚芴聚合物包裹单壁碳纳米管提供了与环境的最佳隔离，并产生了具有270 μ eV的近分辨率有限光谱线宽度的最亮发射，以及与局部声学声子相关的光谱分辨发射翼。依赖于泵浦的研究进一步表明，缺陷态能够发射单个的，尖锐的，孤立的PL峰超过3个数量级的泵浦功率增加，二能级系统的一个关键特性和高纯度的单光子发射的重要先决条件。这些发现指出了sp（3）缺陷在开发能够在电信波长下操作的室温量子光源中的巨大潜力，因为缺陷态的发射可以通过使用较大直径的SWCNT容易地扩展到该范围。
Aiming to unravel the relationship between chemical configuration and electronic structure of sp(3) defects of aryl-functionalized (6,5) single-walled carbon nanotubes (SWCNTs), we perform low-temperature single nanotube photoluminescence (PL) spectroscopy studies and correlate our observations with quantum chemistry simulations. We observe sharp emission peaks from individual defect sites that are spread over an extremely broad, 1000-1350 nm, spectral range. Our simulations allow us to attribute this spectral diversity to the occurrence of six chemically and energetically distinct defect states resulting from topological variation in the chemical binding configuration of the monovalent aryl groups. Both PL emission efficiency and spectral line width of the defect states are strongly influenced by the local dielectric environment. Wrapping the SWCNT with a polyfluorene polymer provides the best isolation from the environment and yields the brightest emission with near-resolution limited spectral line width of 270 mu eV, as well as spectrally resolved emission wings associated with localized acoustic phonons. Pump-dependent studies further revealed that the defect states are capable of emitting single, sharp, isolated PL peaks over 3 orders of magnitude increase in pump power, a key characteristic of two level systems and an important prerequisite for single-photon emission with high purity. These findings point to the tremendous potential of sp(3) defects in development of room temperature quantum light sources capable of operating at telecommunication wavelengths as the emission of the defect states can readily be extended to this range via use of larger diameter SWCNTs.