Ultrafast Exciton Trapping at sp 3 Quantum Defects in Carbon Nanotubes
Ultrafast Exciton Trapping at sp 3 Quantum Defects in Carbon Nanotubes
复制标题
碳纳米管中 sp 3 量子缺陷的超快激子捕获
DOI：
10.1021/acsnano.9b06279
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发表时间：
2019
期刊：
影响因子：
17.1
通讯作者：
Ma, Xuedan
中科院分区：
文献类型：
--
作者：
Sykes, Matthew E.;Kim, Mijin;Wu, Xiaojian;Wiederrecht, Gary P.;Peng, Lintao;Wang, YuHuang;Gosztola, David J.;Ma, Xuedan
半导体单壁碳纳米管（SWCNT）由于其独特的光学和电学特性，构成了开发近红外生物传感器、单光子源和纳米激光器的理想平台。最近发现单壁碳纳米管的共价掺杂是增强其发射强度的有效方法。我们对共价掺杂 sp3 量子缺陷的单壁碳纳米管进行了泵浦探针研究，揭示了缺陷位点存在下截然不同的激子形成动力学和衰变机制。我们表明，在高掺杂的单壁碳纳米管中，缺陷位点处激子的超快俘获可以超过其他光动力过程，并导致量子缺陷的基态光漂白。我们对瞬态数据与动力学模型的拟合还揭示了获得高发光单壁碳纳米管而不造成不可逆损伤的量子缺陷密度的上限。这些发现不仅加深了我们对共价掺杂单壁碳纳米管光动力学的理解，而且还揭示了设计可用于生物、量子信息和纳米光子应用的明亮近红外发射器的关键信息。
Semiconducting single-walled carbon nanotubes (SWCNTs) constitute an ideal platform for developing near-infrared biosensors, single photon sources, and nanolasers due to their distinct optical and electrical properties. Covalent doping of SWCNTs has recently been discovered as an efficient approach in enhancing their emission intensities. We perform pump–probe studies of SWCNTs that are covalently doped withsp3quantum defects and reveal strikingly different exciton formation dynamics and decay mechanisms in the presence of the defect sites. We show that, in highly doped SWCNTs, ultrafast trapping of excitons at the defect sites can outpace other photodynamic processes and lead to ground-state photobleaching of the quantum defects. Our fitting of the transient data with a kinetic model also reveals an upper limit in the quantum defect density for obtaining highly luminescent SWCNTs without causing irreversible damage. These findings not only deepen our understanding of the photodynamics in covalently doped SWCNTs but also reveal critical information for the design of bright near-infrared emitters that can be utilized in biological, quantum information, and nanophotonic applications.