CAREER: Controlling the Deformability of Quantum Dots Solids for Wearable NIR Optoelectronics

发射和检测近红外(IR)光的非技术性可穿戴电子设备有望实现负担得起的非侵入性医疗保健，包括疾病的早期检测和光线治疗。为了适应皮肤的自然运动，材料必须在变形或受力的同时保持其结构完整性和电子性质。许多在近红外中活跃的材料是刚性和脆性的，因此不能用于可穿戴设备。由于缺乏对其在应力或应变下的行为的基本了解，近红外电子产品的新材料的发现受到阻碍。这个项目直接应对了这一挑战。PI将合成并系统地研究将量子点的强近红外光学响应与有机半导体的诱人的电子和物理性质相结合的复合材料。通过这些材料的无缝集成，PI将控制它们的相互作用，并研究它们的机械、光学和电子行为。通过该项目开发的对分子相互作用的基本了解将使医疗保健、软机器人和其他领域的柔性电子产品取得突破。该协会致力于通过加强从高中到研究生学习的途径，扩大对STEM的参与。教育努力将使高中生学习纳米材料和纳米技术。这个项目旨在更好地了解胶体量子点(CQD)固体如何响应应变，通过发展关键的结构-性质关系来揭示CQD和共轭聚合物(CP)之间的分子水平的化学和结构相互作用如何影响所产生的异质结构的机械、光学和电子性质，以及重要的是这些关键性质如何对机械变形做出反应。然而，目前还不清楚这两个组分之间的分子水平的化学和结构相互作用如何影响载流子的传输和复合过程，它们的变形能力，以及更关键的是，在应变下化学、结构和光电性质如何变化。本项目通过(1)研究CQD和CP之间的化学和结构相互作用及其对具有不同界面化学的CQD-CP异质结的载流子输运和复合特性的影响；(2)了解CQD-CP异质结在应变下关键的化学、结构和光电性质的变化，从而加深对CQD-CP异质结机械-光电性质的基本理解。为了实现这一目标，研究小组将首先利用一种独特的配体交换策略在分子水平上构建界面可控的CQD-CP异质结构。然后，研究小组将在施加和不施加应变的情况下，使用X射线光电子和X射线衍射光谱、透射电子光谱、稳定和时间分辨光学光谱以及电学表征，以深入了解界面化学如何影响结构、电荷传输和复合，以及它们在应变下的变化。这些研究活动提供了基础知识，为基于CQD的可穿戴光电子产品的合理设计奠定了基础，并释放了它们在个人保健和软机器人方面的潜力。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。

NontechnicalWearable electronics that emit and detect near-infrared (IR) light hold promise for affordable and non-invasive healthcare, including early detection of disease and light therapy. In order to adapt to the natural movements of the skin, materials must maintain their structural integrity and electronic properties while being deformed or stressed. Many materials active in the near-IR are rigid and brittle, and thus cannot be used for wearable devices. The discovery of new materials for near-IR electronics is hindered due to a lack of fundamental understanding of how they behave under stress or strain. This project directly addresses that challenge. The PI will synthesize and systematically investigate composites that combine the strong near-IR optical response of quantum dots with the attractive electronic and physical properties of organic semiconductors. Through seamless integration of these materials, the PI will control their interactions and investigate their mechanical, optical, and electronic behavior. The fundamental understanding of molecular interactions developed through this project will enable breakthroughs in flexible electronics for healthcare, soft robotics, and in other fields. The PI is committed to broadening participation in STEM through strengthening pathway for students from high school through postgraduate studies. Education efforts will engage high school students in learning about nanomaterials and nanotechnology. The PI will create a new undergraduate course with interactive STEM outreach, and host a summer undergraduate research intern, thereby fostering diversity, equity, and inclusion in STEM.TechnicalThis project aims to better understand how colloidal quantum dot (CQD) solids respond to strain, by developing crucial structure-property relationships to reveal how the molecular-level chemical and structural interactions between CQD and conjugated polymers (CP) impact the mechanical, optical, and electronic properties of the resulting heterostructures, and importantly how these key properties respond to mechanical deformation. However, it is currently unclear how the molecular-level chemical and structural interactions between these two components impact the carrier transport and recombination process, their ability to deform, and, more critically, how the chemical, structural, and optoelectronic properties change under strain. This project develops critical fundamental understandings of the mechano-optoelectronic properties of the CQD-CP heterostructures by (1) investigating the chemical and structural interaction between CQD and CP and their impact on the charge carrier transport and recombination characteristics of the CQD-CP heterostructures with different interfacial chemistry; (2) understanding the changes of the key chemical, structural and optoelectronic properties under strain and elucidate the underlying mechanism. To achieve this, the research team will first utilize a unique ligands exchange strategy to construct CQD - CP heterostructures with controllable interfaces at the molecular level. The research team will then employ X-ray photoelectron and X-ray diffraction spectroscopy, transmission electron spectroscopy, steady and time-resolved optical spectroscopy, and electrical characterization, with and without applied strain, to provide insights into how structure, charge transport, and recombination are impacted by the interfacial chemistry, and how they change under strain. The research activities provide fundamental knowledge that is foundational toward the rational design of CQD-based wearable optoelectronics and unlock their potential in personal healthcare, and soft robotics.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.