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，德克萨斯州A M大学的Dong Hee Son教授将研究卤化铅钙钛矿纳米晶体中暗激子的作用，以产生具有受控量子特性的光和电荷。卤化铅钙钛矿材料被认为是用于各种应用如光子学和太阳能电池的有效光源和电荷源。Son教授的研究团队正在研究几纳米尺寸的卤化铅钙钛矿材料，在这种材料中，一种称为暗激子的特殊激发态变得很容易获得。暗激子的寿命可以比这些材料中的典型激发态长一千倍。此外，暗激子具有产生光的能力，其性质不同于从通常的激发态得到的那些性质。Son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，这些光和电荷具有以前不可用的新特性，受益于暗激子的独特特性。除了科学活动外，该项目还将有助于培养前沿实验物理化学的研究生;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，与K-12学生和当地社区进行外联。Son研究小组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无法从亮激子中轻易获得的可控量子特性。该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，以及暗激子和自旋极化态的相关光子对的发射。这些光子发射过程通过暗态寿命以及由卤化铅钙钛矿纳米晶体中的暗激子提供的新耦合途径来增强。这项研究将利用Son小组最近在访问和探测暗激子与亮激子分开的能量学和动力学方面的成功。暗激子的这种单独表征是通过强量子限制的钙钛矿纳米晶体中的限制增强的亮-暗能量分裂实现的。研究小组将这些纳米晶体中的可控磁性掺杂和灵活的配体钝化结合起来，再加上高Q因子微腔，以增强光和纳米晶体的相互作用，该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准。

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.