Enhance Exciton Transport in Perovskite Quantum Dot Solids through Coherent Interactions

通过相干相互作用增强钙钛矿量子点固体中的激子传输

• 批准号: 2004339
• 负责人: Libai Huang
• 金额: $ 54.15万
• 依托单位: Purdue University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-01 至 2023-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2004339&HistoricalAwards=false
• 关键词: Enhance; Exciton; Transport; Perovskite; Quantum

This project uses ultrafast lasers to make “movies” of light energy traveling between tiny semiconductor nanoparticles known as quantum dots. These quantum dots are efficient light absorbers and potentially useful for devices such as solar cells or light emitting diodes. In a device, quantum dots must be closely packed together in order to facilitate energy transfer from one quantum dot to the next. As a result, the distance between quantum dots and the speed at which energy migrates has a strong effect on device efficiency. By imaging how energy moves in quantum dot solids with different packings, this research aims to provide guidelines for designing structures for efficient light energy harvesting through control of energy migration rates. To achieve these goals, synthetic strategies are developed to control the size of the quantum dots and the chemical linkers used to connect them. Then, these quantum dots are used as “artificial atoms” and assembled into well-ordered structures known as superlattices. The research team also develops microscopy techniques to record fast energy transfer events with a resolution of 10 femtoseconds (a femtosecond is one quadrillionth of a second) and to image energy migration distances with a resolution of 50 nanometers (a nanometer is one billionth of a meter). The research and educational activities are integrated to educate the next generation of solar energy researchers through K-12, undergraduate, and graduate science education. The PIs partner with Science Express and AP Fridays at Purdue to involve K-12 students in a cutting-edge laboratory environment. Results from this project are utilized to educate the general public on new solar energy technologies using podcast and video media.Long-range exciton transport and coherence in colloidal quantum dot solids are highly desirable for their optoelectronic and quantum information applications. However, exciton transport in colloidal quantum dot solids thus far has been almost exclusively realized in the incoherent regime with excitons localized in individual quantum dots due to the relatively large energetic disorder compared to the electronic coupling strength in these systems. Incoherent transport of localized excitons presents a major limitation in obtaining long-range coherence and transport. In this project, strong dipole-dipole interactions between perovskite quantum dots are leveraged to enhance transport by promoting coherent motion of delocalized excitons. The team elucidates transport mechanisms by employing ultrafast coherent microscopy with ~10 fs time resolution and better than 50 nm spatial resolution. Exciton propagation distance, delocalization length, and coherent transport contributions are measured as a function of temperature. The extent of exciton delocalization is systematically controlled by varying inter-particle distance, electronic coupling, and dimensionality using ligand chemistry. The project provides guidelines for designing excitonic materials using perovskite quantum dots as building blocks.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.

该项目使用超快激光器制作光能在称为量子点的微小半导体纳米颗粒之间传播的“电影”。这些量子点是有效的光吸收剂，可能可用于太阳能电池或发光二极管等设备。在器件中，量子点必须紧密堆积在一起，以促进能量从一个量子点转移到下一个量子点。因此，量子点之间的距离和能量迁移的速度对器件效率有很大影响。通过对能量如何在具有不同填料的量子点固体中移动进行成像，本研究旨在为通过控制能量迁移速率来设计高效光能收集的结构提供指导。为了实现这些目标，开发了合成策略来控制量子点和用于连接它们的化学连接体的尺寸。然后，这些量子点被用作“人造原子”并组装成有序的结构，称为超晶格。研究团队还开发了显微镜技术，以 10 飞秒（一飞秒是十亿分之一秒）的分辨率记录快速能量转移事件，并以 50 纳米（一纳米是十亿分之一米）的分辨率对能量迁移距离进行成像。 研究和教育活动相结合，通过 K-12、本科生和研究生科学教育来培养下一代太阳能研究人员。 PI 与普渡大学的 Science Express 和 AP Fridays 合作，让 K-12 学生参与尖端的实验室环境。该项目的结果用于通过播客和视频媒体向公众宣传新的太阳能技术。胶体量子点固体中的长程激子传输和相干性对于其光电和量子信息应用来说是非常理想的。然而，迄今为止，胶体量子点固体中的激子传输几乎完全在非相干状态下实现，激子集中在各个量子点中，因为与这些系统中的电子耦合强度相比，能量无序相对较大。局域激子的非相干传输是获得长程相干和传输的主要限制。在该项目中，利用钙钛矿量子点之间的强偶极-偶极相互作用，通过促进离域激子的相干运动来增强传输。该团队通过采用具有约 10 fs 时间分辨率和优于 50 nm 空间分辨率的超快相干显微镜来阐明传输机制。激子传播距离、离域长度和相干传输贡献被测量为温度的函数。激子离域的程度是通过改变粒子间距离、电子耦合和使用配体化学的维度来系统地控制的。该项目为使用钙钛矿量子点作为构建块设计激子材料提供了指南。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Superradiance and Exciton Delocalization in Perovskite Quantum Dot Superlattices

• DOI: 10.1021/acs.nanolett.2c02427
• 发表时间: 2022-09-21
• 期刊: NANO LETTERS
• 影响因子: 10.8
• 作者: Blach, Daria D.;Lumsargis, Victoria A.;Huang, Libai
• 通讯作者: Huang, Libai