Harnessing the Advantages of Dark Exciton in Perovskite Nanostructures as the Quantum Emitter and the Source of Charge Carriers

在化学系大分子、超分子和纳米化学项目的支持下，德克萨斯农工大学的孙栋熙教授将研究暗激子在卤化铅钙钛矿纳米晶体中产生光和电荷的作用，并控制量子性质。卤化铅钙钛矿材料被认为是光子学和太阳能电池等各种应用的有效光源和电荷来源。孙教授的研究团队正在研究几纳米尺度的卤化铅钙钛矿材料，在这种材料中，一种名为暗激子的特殊激发态变得容易获得。暗激子的寿命可能比这些材料中典型的激发态长一千倍。此外，暗激子有能力产生与通常激发态不同的性质的光。孙教授的团队正在探索利用暗激子产生光和电荷的有效方法，得益于暗激子的独特特性，这些新特性是以前无法获得的。除了科学活动外，该项目还将有助于对研究生进行尖端实验物理化学方面的培训；这包括化学科学中代表性不足的群体的研究。孙教授的团队还计划通过大学举办的公共活动，接触到K-12学生和当地社区。Son研究团队正在研究暗激子的作用及其在产生光子和电荷方面的优势，这些光子和电荷具有可控的量子属性，而这些量子属性是无法从亮激子中轻易获得的。这个项目特别关注暗激子形成的单激子和双激子态的能量和弛豫动力学，以及暗激子和自旋偏振态的关联光子对的发射。这些光子发射过程被暗态寿命以及卤化铅钙钛矿纳米晶中暗激子提供的新的耦合途径所增强。这项研究将利用Son小组最近的成功，将暗激子的能量学和动力学与明亮的激子分开访问和探测。这种对暗激子的单独表征是通过在强量子受限的钙钛矿纳米晶体中的限制增强的明暗能量分裂来实现的。该研究团队将这些纳米晶体中可控的磁性掺杂和灵活的配体钝化与高Q因子微腔相结合，以提供增强的光和纳米晶体的相互作用，从而探索暗激子在创造具有可控特征的光子和电荷方面的优势。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

With support from the Macromolecular, Supramolecular, and Nanochemistry Program in the Chemistry Division, Professor Dong Hee Son at Texas A&M University will investigate the role of dark excitons in lead halide perovskite nanocrystals for generating light and charges with controlled quantum properties. Lead halide perovskite materials are recognized as efficient sources of light and charges for various applications such as photonics and solar cells. Professor Son's research team is studying lead halide perovskite materials at the few-nanometer size scale where a special excited state called the dark exciton becomes readily accessible. Dark excitons can have lifetimes a thousand-fold longer than the typical excited state in these materials. Additionally, dark excitons have the ability to generate light with properties that differ from those derived from the usual excited states. Professor Son's team is exploring effective ways of utilizing the dark excitons to produce light and charges with new properties that were previously unavailable, benefiting from the unique properties of the dark exciton. In addition to the scientific activities, this project will contribute to the training of graduate students in cutting edge experimental physical chemistry; this includes studies from groups underrepresented in the chemical sciences. Professor Son's team also plans to engage in outreach to K-12 students and to the local community through University-run public events. The Son research team is investigating the role of the dark exciton and its advantages in generating photons and charges with controllable quantum properties that cannot be readily obtained from the bright exciton. This project is focusing specifically on the energy and relaxation dynamics of single- and bi-exciton states formed from dark excitons, as well as the emissions of correlated photon pairs from dark excitons and spin-polarized states. These photon emission processes are enhanced by dark state longevity as well as new coupling pathways afforded by the dark excitons in lead halide perovskite nanocrystals. This research will leverage recent success by the Son group in accessing and probing the energetics and dynamics of the dark excitons separately from the bright excitons. This separate characterization of dark excitons is enabled by the confinement-enhanced bright-dark energy splitting in strongly quantum-confined perovskite nanocrystals. The research team combines the controllable magnetic doping and flexible ligand passivation in these nanocrystals, in conjunction with the high Q-factor microcavity, to provide enhanced interaction of light and nanocrystals, thereby exploring the advantages of the dark exciton in creating photons and charges with controllable characteristics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.