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.

该项目使用超快速激光器制作“电影”的“电影”，在小的半导体纳米颗粒之间传播的轻能，称为量子点。这些量子点是有效的光吸收器，可能对诸如太阳能电池或发光二极管等设备有用。在设备中，必须将量子点紧密堆积在一起，以促进能量从一个量子点转移到另一个量子点。结果，量子点与能量迁移的速度之间的距离对设备效率具有很强的影响。通过对能量如何在具有不同包装的量子点固体中移动，该研究旨在为设计结构提供指南，以通过控制能量迁移速率来有效地收获光能。为了实现这些目标，制定了合成策略来控制量子点的大小以及用于连接它们的化学连接器。然后，这些量子点被用作“人造原子”，并组装成被井井有条的结构，称为超晶格。研究团队还开发了显微镜技术，以10秒的分辨率记录快速能量转移事件（飞秒是四分之一的四分之一），并以50纳米计的分辨率（纳米分辨率为十亿分之一）来对能量迁移距离进行成像。研究和教育活动旨在通过K-12，本科和研究生科学教育来教育下一代太阳能研究人员。 PIS与普渡大学的科学快车和AP Fridays合作，将K-12学生参与到尖端的实验室环境中。该项目的结果被用来使用播客和视频媒体对新的太阳能技术进行教育。胶体量子点固体中的长距离激动人心的运输和连贯性对于其光电和量子信息应用是非常需要的。然而，迄今为止，与这些系统中的电子耦合强度相比，由于相对较大的能量障​​碍，由于相对较大的能量障​​碍，在胶体量子点固体中的刺激转运几乎仅在不连贯的方向上实现。局部激子的不一致运输在获得远距离连贯和运输方面提出了一个主要限制。在这个项目中，钙钛矿量子点之间的强偶极 - 偶极相互作用通过促进分离式激子的相干运动来增强运输。该团队通过使用〜10 fs时间分辨率的超快相干显微镜且高于50 nm的空间分辨率来阐明运输机制。激子的传播距离，离域长度和相干传输贡献是根据温度的函数测量的。使用配体化学的颗粒间距离，电子耦合和尺寸性，激子离域的程度是系统地控制的。该项目提供了使用Perovskite量子点设计令人兴奋的材料的指南，该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子优点和更广泛的影响评估标准来评估的珍贵支持。

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