CAREER: Structure-Function-Property Relationships in Charged Conjugated Polymers

本职业项目旨在了解用于塑料电子产品的带电共轭聚合物的结构-功能-性质关系。共轭聚合物（CPs）是一种既具有半导体的光学和电学性能又具有塑料的机械性能的材料。该项目的重点是对阳离子和阴离子共轭聚合物（共轭聚电解质）的光学和电子特性的基本理解，这些特性是分子结构、电荷密度（每个重复单元的电荷数）、反离子类型和材料加工条件的函数。含有带电官能团的共轭聚合物的优点是，它们可以很好地控制溶液中的聚合物构象，从而控制薄膜中聚合物链的电子相互作用程度（链间相互作用）。在生物传感器、发光二极管（led）、太阳能电池和场效应晶体管（fet）等基于cp的器件中，这些链间相互作用强烈地影响光学和电子特性和降解率，如光致发光量子产率和寿命、能量迁移和电荷迁移率，以及器件效率和使用寿命。该方法是通过改变溶剂、浓度、盐、官能团、电荷密度以及共轭聚合物的主链和膜形态，通过聚合物构象、退火工艺和各种成膜方法来控制溶液中的聚合物构象。光散射、稳态和时间分辨光谱、扫描探针技术（原子力显微镜、静电力显微镜和导电原子力显微镜），以及原型设备评估将用于全面了解聚合物构象、薄膜形态、光学和电子性质，以及纳米尺度上的电荷传输，以及分子结构和加工条件的功能。具体目标包括：1)通过分子结构和加工条件了解和控制溶液中带电共轭聚合物的构象，以及聚合物构象的变化如何影响其光物理性质。2)理解和控制聚合物薄膜的光物理和电荷输运特性作为分子结构、电荷密度（每个重复单元的电荷数）、反离子类型和加工条件的函数。该项目更广泛的影响将是在加州大学圣巴巴拉分校和圣巴巴拉社区的研究和教育之间建立联系。研究生和本科生将是开展研究的关键。该研究计划促进有机半导体领域研究生和本科生的教学、培训和学习。这项研究是高度跨学科的；学生将接触到材料设计和合成、材料表征、器件制造和评估方面的广泛研究经验，为他们未来的职业生涯提供广度和灵活性。他们将发展化学、物理和材料科学方面的知识。PI将开发一些研究生和本科课程，以加强和更新UCSB科学课程中的新科学。通过UCSB的几个外展项目，PI将邀请暑期本科生、大学生和高中教师到她的实验室参加研究活动。为了增加多样性并促进孩子们上大学并主修科学，PI将参加科学和技术日，这是一年一度的活动，将初中和高中的学生和教师聚集到UCSB参加科学研讨会和竞赛。

TechnicalThis CAREER project aims to understand the structure-function-property relationships in charged conjugated polymers for applications in plastic electronics. Conjugated polymers (CPs) are materials that have the optical and electrical properties of semiconductors with the mechanical properties of plastics. The project focus is on fundamental understanding of the optical and electronic properties of cationic and anionic conjugated polymers (conjugated polyelectrolytes) as a function of molecular structure, charge density (number of charge per repeat unit), type of counter ions, and material processing conditions. The advantage of conjugated polymers containing electrically charged functional groups is that they offer fine control of the polymer conformation in solution, and hence, the degree of electronic interaction of polymer chains in films (interchain interactions). These interchain interactions strongly influence optical and electronic properties and degradation rate such as photoluminescence quantum yield and lifetime, energy migration, and charge mobility in CP-based devices such as biosensors, light-emitting diodes (LEDs), solar cells, and field effect transistors (FETs), and so, the device efficiencies and operational lifetime. The approach is to control polymer conformation in solution by changing solvent, concentration, salt, functional group, charge density, and conjugated polymer backbone and film morphology by polymer conformation, annealing process, and various film fabrication methods. Light-scattering, steady-state and time-resolved spectroscopies, scanning probe techniques (Atomic Force Microscopy, Electrostatic Force Microscopy, and Conducting Atomic Force Microscopy), along with prototype device evaluation will be used to obtain a comprehensive understanding of polymer conformation, film morphology, optical and electronic properties, and charge transport at the nanoscale, and in bulk as a function of molecular structure and processing conditions. Specific goals include: 1) To understand and control charged conjugated polymer conformation in solution via molecular structure and processing conditions and how change in polymer conformation affects its photophysics. 2) To understand and control polymer photophysics and charge transport properties of polymer films as a function of molecular structure, charge density (number of charge per repeat unit), type of counter ions, and processing conditions. Non-TechnicalThe broader impact of the project will be the link established between research and education at UCSB and the Santa Barbara community. Graduate and undergraduate students will be essential to carrying out the research. The research plan promotes teaching, training, and learning of graduate and undergraduate students in the field of organic semiconductors. The research is highly interdisciplinary; students will be exposed to a wide range of research experience in material design and synthesis, materials characterization, and device fabrication and evaluation that will provide breadth and flexibility for their future careers. They will develop knowledge in chemistry, physics, and materials science. Several graduate and undergraduate courses will be developed by the PI to strengthen and update new science in the science curriculum at UCSB. Through several outreach programs at UCSB, the PI will bring summer undergraduate students, college students, and high school teachers to her laboratory to participate in research activities. To increase the diversity and to promote children to go to college and major in science, the PI will participate in Science and Technology Day, an annual event that brings students and teachers from middle and high schools to UCSB to participate in science workshops and competitions.