Zheng Yu, Han Yulun, Weight Braden M, Lin Zhiwei, Gifford Brendan J, Zheng Ming, Kilin Dmitri, Kilina Svetlana, Doorn Stephen K, Htoon Han, Tretiak Sergei
Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND, 58102, USA.
Nat Commun. 2022 Aug 1;13(1):4439. doi: 10.1038/s41467-022-31921-0.
Incorporating fluorescent quantum defects in the sidewalls of semiconducting single-wall carbon nanotubes (SWCNTs) through chemical reaction is an emerging route to predictably modify nanotube electronic structures and develop advanced photonic functionality. Applications such as room-temperature single-photon emission and high-contrast bio-imaging have been advanced through aryl-functionalized SWCNTs, in which the binding configurations of the aryl group define the energies of the emitting states. However, the chemistry of binding with atomic precision at the single-bond level and tunable control over the binding configurations are yet to be achieved. Here, we explore recently reported photosynthetic protocol and find that it can control chemical binding configurations of quantum defects, which are often referred to as organic color centers, through the spin multiplicity of photoexcited intermediates. Specifically, photoexcited aromatics react with SWCNT sidewalls to undergo a singlet-state pathway in the presence of dissolved oxygen, leading to ortho binding configurations of the aryl group on the nanotube. In contrast, the oxygen-free photoreaction activates previously inaccessible para configurations through a triplet-state mechanism. These experimental results are corroborated by first principles simulations. Such spin-selective photochemistry diversifies SWCNT emission tunability by controlling the morphology of the emitting sites.
通过化学反应将荧光量子缺陷引入半导体单壁碳纳米管（SWCNT）的侧壁是一种可预测地改变纳米管电子结构并开发先进光子功能的新兴途径。诸如室温单光子发射和高对比度生物成像等应用已通过芳基功能化的SWCNT取得进展，其中芳基的结合构型决定了发射态的能量。然而，在单键水平上以原子精度进行结合的化学方法以及对结合构型的可调控制尚未实现。在这里，我们探索了最近报道的光合协议，发现它可以通过光激发中间体的自旋多重性来控制量子缺陷（通常称为有机色心）的化学结合构型。具体而言，光激发的芳烃与SWCNT侧壁反应，在溶解氧存在下经历单重态途径，导致芳基在纳米管上的邻位结合构型。相比之下，无氧光反应通过三重态机制激活了以前无法获得的对位构型。这些实验结果得到了第一性原理模拟的证实。这种自旋选择性光化学通过控制发射位点的形态使SWCNT发射可调性多样化。
