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制作光能在被称为量子点的微小半导体纳米粒子之间传播的“电影”。这些量子点是高效的光吸收材料，有可能用于太阳能电池或发光二极管等设备。在设备中，量子点必须紧密堆积在一起，才能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。通过成像不同填充物的量子点固体中的能量运动，这项研究旨在为通过控制能量迁移率来设计高效光能收集结构提供指导。为了实现这些目标，人们开发了合成策略来控制量子点的大小和用于连接它们的化学连接物。然后，这些量子点被用作“人造原子”，组装成被称为超晶格的有序结构。研究小组还开发了显微镜技术，以10飞秒(一飞秒是千分之一秒)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)的分辨率成像能量迁移距离。研究和教育活动相结合，通过K-12、本科和研究生科学教育培养下一代太阳能研究人员。PIS与普渡大学的科学快报和AP星期五合作，让K-12学生参与尖端实验室环境。这个项目的成果被用来通过播客和视频媒体教育普通公众关于新的太阳能技术。胶体量子点固体中的长程激子传输和相干性对于它们的光电子和量子信息应用是非常理想的。然而，到目前为止，胶体量子点固体中的激子输运几乎完全是在非相干区实现的，激子定域在单个量子点中，这是因为与这些系统中的电子耦合强度相比，这些系统中的能量无序相对较大。局域激子的非相干输运是获得长程相干和输运的主要限制。在这个项目中，钙钛矿量子点之间的强偶极-偶极相互作用被用来通过促进离域激子的相干运动来增强输运。该团队利用时间分辨率约为10飞秒、空间分辨率优于50纳米的超快相干显微镜阐明了传输机制。测量了激子传播距离、离域长度和相干输运贡献随温度的变化。激子离域的程度是通过改变粒子间的距离、电子耦合和维度来系统地利用配基化学来控制的。该项目提供了使用钙钛矿量子点作为积木设计激子材料的指导方针。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。

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