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

在化学学部大分子、超分子和纳米化学项目的支持下，德州农工大学的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光子学和太阳能电池等各种应用的有效光源和电荷源。孙教授的研究小组正在研究几纳米尺度的卤化铅钙钛矿材料，在这种尺度上，一种被称为暗激子的特殊激发态很容易获得。暗激子的寿命可以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产生的光不同的特性。孙教授的团队正在探索利用暗激子产生具有以前无法获得的新性质的光和电荷的有效方法，这得益于暗激子的独特性质。除了科研活动外，该项目还将有助于培养前沿实验物理化学的研究生；这包括来自化学科学中代表性不足的群体的研究。孙教授小组还计划通过大学举办的公共活动，扩大对K-12学生和当地社区的影响。孙鹤子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从亮激子中无法轻易获得的可控量子特性。本项目重点研究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相关光子对的发射。在卤化铅钙钛矿纳米晶体中，暗态寿命和暗激子提供的新的耦合途径增强了这些光子发射过程。这项研究将利用Son小组最近在获取和探测暗激子与亮激子分开的能量学和动力学方面取得的成功。在强量子限制的钙钛矿纳米晶体中，约束增强的明暗能量分裂使暗激子的独立表征成为可能。研究团队将这些纳米晶体中的可控磁掺杂和柔性配体钝化相结合，结合高q因子微腔，提供光与纳米晶体的增强相互作用，从而探索暗激子在产生具有可控特性的光子和电荷方面的优势。该奖项反映了美国国家科学基金会的法定使命，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.