Designing Intermolecular Interactions for High-Performance Small-Molecule Bulk Heterojunctions

技术说明：本项目对小分子给体-受体材料的光电性能进行了系统的研究，最终目标是开发用于高效小分子体异质结太阳能电池的可溶性给体-受体分子，以及用于光折变器件的新型敏化剂（受体）。该项目旨在实现以下三个目标：建立电荷光生、输运和复合对供体-受体分子和分子堆积的相对能量的依赖性（宏观层面）;为了量化供体-受体域和供体-受体界面面积对电荷光生，传输，和复合取决于供体和受体分子及其包装（微观层面）;并确定分子物理学、三维排列和结构域形成趋势，晶体供体宿主中客体受体分子的数量取决于供体和受体分子的分子结构和无序（单分子水平）。样品的制作和处理的影响进行了研究。为了实现这些目标，时间分辨光电流的测量（包括扫描光电流显微镜）和时间分辨荧光（包括近场扫描光学显微镜和单分子荧光光谱）结合数值模拟进行。非技术描述：该项目最重要的方面之一是其对太阳能和光折射三维显示技术的潜在影响，以及基于可溶液加工的有机膜的其它光电应用。该项目将基础物理和化学与材料设计和设备技术相结合，从而为博士后研究人员和研究生和本科生提供跨学科的教育资源和基础设施。PI积极努力让包括女生和少数民族学生在内的大学生参与该项目。根据研究结果，研究团队开发了教育材料，演示和网络教程，引入研究生和高级本科物理和工程课程，以加深学生对材料的理解，并将其纳入大学新生和高中生的活动中。

Technical Description: In this project, optoelectronic properties of small-molecule donor-acceptor materials are systematically explored, with the ultimate goal of developing soluble donor-and-acceptor molecules for efficient small-molecule bulk heterojunction solar cells and novel sensitizers (acceptors) for photorefractive devices with improved properties. The project aims to fulfill the following three objectives: to establish dependence of charge photogeneration, transport, and recombination on the relative energies of the donor-and-acceptor molecules and molecular packing (macroscopic level); to quantify contributions of the donor-and-acceptor domains and donor-acceptor interfacial areas to charge photogeneration, transport, and recombination depending on the donor-and-acceptor molecules and their packing (microscopic level); and to determine molecular photophysics, three-dimensional alignment and domain formation tendencies, of guest acceptor molecules in crystalline donor hosts depending on the molecular structures of the donor-and-acceptor molecules and disorder (single-molecule level). Effects of sample fabrication and processing are also studied. In order to fulfill these objectives, measurements of time-resolved photocurrent (including scanning photocurrent microscopy) and time-resolved fluorescence (including near-field scanning optical microscopy and single-molecule fluorescence spectroscopy) combined with numerical modeling are carried out.Non-technical Description: One of the most important aspects of the project is its potential impact on solar and photorefractive three-dimensional display technology, as well as on other optoelectronic applications based on solution-processable organic films. The project integrates fundamental physics and chemistry with materials design and device technologies and thus provides interdisciplinary educational resources and infrastructure for postdoctoral researchers and graduate and undergraduate students contributing to research. The PI makes active efforts to involve undergraduates, including female and minority students, in the project. Based on research results, the research team develops educational materials, demonstrations, and web tutorials that are introduced into graduate and upper-level undergraduate physics and engineering courses to deepen students' understanding of the material as well as incorporated into events for college freshmen and high-school students.