RUI: Engineering Nanoscale Disorder in Polymer-Semiconductor Nanocrystal Composites for Minimized Optical Losses

摘要：本研究为设计和制备高性能聚合物-纳米晶体复合材料开辟了新的途径，以减少光学损耗。聚合物-纳米晶体复合材料被广泛应用于照明和显示器、闪烁探测器、发光二极管和太阳能聚光器等领域。这项研究整合了理论、合成和材料表征，使改进的聚合物-纳米晶体复合材料能够用于最苛刻的光学应用。西华盛顿大学（WWU）是一所以本科生为主的大学，本科生占科研队伍的大多数，他们参与了研究的每个阶段。每年约有五名本科生参与该项目，他们将在材料与合成化学、光学和数学方面打下坚实的基础，并有机会体验独立、创造性科学研究的乐趣。这项研究还涉及到五年级和六年级学生，以及当地高中中代表性不足的群体，以及其他外展活动。技术摘要：本研究为设计和制备致密、高性能的聚合物发光半导体纳米晶体（NC）复合材料开辟了新的途径，通过纳米到微米尺度的颗粒间距分布控制来最小化光损耗。聚合物- nc复合材料在广泛的应用中被用作光学活性元件，例如照明和显示器的降频层，闪烁探测器，混合有机/无机发光二极管和发光太阳能聚光器。这些和相关的应用通常需要比目前可实现的更高的纳米碳体积密度，以及更好的纳米颗粒分散，以最大限度地减少由光散射和粒子间能量和电荷转移引起的聚集引起的光学损失。纯随机色散不能最大限度地减少几个重要机制的光学损失，这些机制以非线性依赖于粒子间距为特征，包括弹性光散射和近场粒子间能量和电荷转移引起的猝灭，因为这些过程不是由平均粒子间分离决定的，而是由平均值周围的波动决定的。高性能聚合物- nc复合材料的开发对于最苛刻的光学应用来说，需要仔细平衡有序和无序，在纳米到微米的尺度上进行管理，需要比通常公认或追求的更仔细的设计和控制颗粒间距统计。本研究将理论、合成和材料表征结合起来，以识别、测量和控制发光NC空间分布的关键统计特性，这些特性决定了非线性距离依赖的损耗机制。总体结果是最苛刻的光学应用所需的高性能聚合物- nc复合材料的新概念和新材料。西华盛顿大学（WWU）是一所以本科生为主的大学，本科生占科研队伍的大多数，他们参与了研究的每个阶段。每年约有五名本科生参与该项目，他们将在材料与合成化学、光学和数学方面打下坚实的基础，并有机会体验独立、创造性科学研究的乐趣。pi鼓励学生通过参与区域商业计划竞赛来探索和理解他们的工作在科学之外的含义，这些竞赛的产品概念来源于这项本科研究。其他的拓展活动包括实验室之旅和通过世界大学的指南针到校园计划与五年级和六年级学生的实践活动；高中生直接参与研究；并向当地高中，特别是那些有大量西班牙裔学生的高中伸出援手。

Nontechnical Abstract:This research is developing new approaches for the design and preparation of high performance polymer- nanocrystal composites engineered to minimize optical losses. Polymer-nanocrystal composites are employed in a wide range of applications, such as for lighting and displays, as scintillation detectors, light-emitting diodes, and solar concentrators. This research is integrating theory, synthesis, and materials characterization, to enable improved polymer-nanocrystal composites for the most demanding optical applications. Western Washington University (WWU) is a primarily undergraduate institution where undergraduates comprise the majority of the scientific workforce and are involved in every phase of the research. About five undergraduates per year are participating in the project, receiving a strong foundation in materials and synthetic chemistry, optics, and mathematics, as well as the chance to experience the excitement of independent, creative scientific investigation. The research also involves outreach to 5th and 6th graders, and to underrepresented groups in local high schools, as well as other outreach activities.Technical Abstract:This research is developing new approaches for the design and preparation of densely-packed, high performance polymer-luminescent semiconductor nanocrystal (NC) composites engineered to minimize optical losses through nanometer- to micron-scale control of interparticle spacing distributions. Polymer-NC composites are employed as optically-active elements in a wide range of applications, such as downshifting layers for lighting and displays, as scintillation detectors, hybrid organic/inorganic light-emitting diodes, and luminescent solar concentrators. These and related applications often require a higher volumetric density of NCs, along with better nanoparticle dispersion, than is currently achievable, in order to minimize aggregation-induced optical losses from light scattering and interparticle energy- and charge-transfer. Purely random dispersions fail to minimize optical losses from several important mechanisms characterized by a non-linear dependence on particle spacing, including elastic light-scattering, and quenching caused by near-field interparticle energy- and charge-transfer, because these processes are dominated not by the mean interparticle separation, but instead by fluctuations around the mean. The development of high performance polymer-NC composites for the most demanding optical applications necessitates a careful balance of order and disorder, managed over nanometer- to micron-length scales, requiring more careful design and control over interparticle spacing statistics than has generally been recognized or pursued. This research is integrating theory, synthesis, and materials characterization, in order to identify, measure, and control the key statistical properties of luminescent NC spatial distributions which govern non-linear distance-dependent loss mechanisms. The overall results are new concepts and new materials for high performance polymer-NC composites needed for the most demanding optical applications. Western Washington University (WWU) is a primarily undergraduate institution where undergraduates comprise the majority of the scientific workforce and are involved in every phase of the research. About five undergraduates per year are participating in the project, receiving a strong foundation in materials and synthetic chemistry, optics, and mathematics, as well as the chance to experience the excitement of independent, creative scientific investigation. The PIs encourage students to explore and understand implications of their work beyond science by participating in regional business plan contests with product concepts derived from this undergraduate research. Additional outreach activities include laboratory tours and hands-on activities with 5th and 6th graders through WWU's Compass-to-Campus program; direct involvement of high school students in the research; and outreach to local high schools, especially those serving large populations of Hispanic students.