Revealing the Influence of Electrolyte Solvents and Ions on Electronic and Ionic Transport in Electrochemically Doped Conjugated Polymers

电力无处不在。离子，带电的原子和分子，是电流流经生物体的方式。带负电荷的电子和带正电荷的空穴在电脑和手机等电子产品的半导体中流动。传导离子和电子的材料在这两个世界之间架起了桥梁。这给了它们许多潜在的应用，将电子学和生物学结合在一起。半导体聚合物和电荷平衡电解质的混合物是一类很有前途的混合离子和电子导体。特别是，它们具有生物相容性和柔韧性。这使得它们成为可穿戴和植入式生物电子学的有吸引力的材料，甚至可能是受人脑启发的神经形态计算机。理想情况下，混合导体可以根据给定的需要按需设计。然而，聚合物和离子电解质之间的化学反应是复杂的，许多方面还不清楚。为了使这些材料充分发挥其潜力，必须解决理解关系的这些基本限制。该项目汇集了一个跨学科团队，将材料表征、建模和设备测试相结合，为这些关系提供基础知识。该项目的成果将用于推进这些材料系统的使用技术。在这个项目中工作的学生将发展所需的技术、沟通和批判性思维技能。所有这些都是为未来的STEM劳动力做好准备的必要条件。与社区的接触是这个项目的一个组成部分。每年的面对面研讨会将为高中科学教师提供制作和表征电致变色和晶体管等设备的实践经验。后续课程包括教师制作工作装置和电路的材料，以及与这些材料和实验相配套的学习模块。这些学习活动将通过将化学和物理的基本概念与学生的日常生活联系起来，加强STEM教育。技术描述共轭聚合物中的电子和离子传输取决于复杂的变量网络，范围从聚合物结构到溶剂诱导聚合物膨胀的程度。本项目研究了影响电子和离子传输的三个主要变量，包括电解质溶剂化学、电解质离子化学和聚合物侧链化学。光谱和器件级测量将与量子化学计算和分子动力学模拟相结合，以建立从分子级化学相互作用到器件级离子和电子输运性质的基本理解。在电解质溶剂方面，该项目确定了溶剂的介电常数和溶剂膨胀聚合物的能力如何影响电子和离子输运。在电解质离子化学方面，该项目确定了离子形状和疏水性如何影响电子结构以及离子和电子输运作为聚合物侧链化学的函数。该项目的结果对于建立一个全面的预测模型至关重要，该模型可用于指导各种电化学掺杂共轭聚合物的材料设计和电解质选择。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical DescriptionElectricity is everywhere. Ions, charged atoms and molecules, are the way in which electricity flows through living organisms. Negatively-charged electrons and positively-charged holes flow through semiconductors in electronics such as computers and mobile phones. Materials that conduct both ions and electrons bridge these worlds. This gives them many potential applications that bring together electronics and biology. Blends of semiconducting polymers and charge-balancing electrolytes are a promising class of mixed ionic and electronic conductors. In particular, they can be biocompatible and flexible. This makes them attractive materials for wearable and implantable bioelectronics and possibly even neuromorphic computers inspired by the human brain. Ideally, a mixed conductor could be designed on-demand for a given need. However, the chemistry between polymers and ionic electrolytes is complex and many aspects are poorly understood. These fundamental limits in understanding relationships must be addressed for these materials to reach their full potential. This project brings together an interdisciplinary team that combines material characterization, modeling, and device testing to provide fundamental knowledge into these relationships. The results of this project will be used to advance the technologies in which these material systems are used. Students working in this project will develop in-demand technical, communications and critical thinking skills. All of these are essential for preparing the future STEM workforce. Outreach to the community is an integral component of the project. Annual in-person workshops will provide high school science teachers hands-on experience in making and characterizing devices such as electrochromics and transistors. Follow-through includes materials for teachers to make working devices and circuits and learning modules to accompany these materials and experiments. These learning activities will enhance STEM education by connecting fundamental concepts of chemistry and physics with the everyday lives of the students.Technical DescriptionElectronic and ionic transport in conjugated polymers depends on a complicated web of variables, ranging from polymer structure through the extent of solvent-induced polymer swelling. This project investigates three primary variables that influence electronic and ionic transport, including electrolyte solvent chemistry, electrolyte ion chemistry, and polymer sidechain chemistry. Spectroscopic and device level measurements will be combined with quantum-chemical calculations and molecular dynamics simulations to establish a fundamental understanding that spans from molecular level chemical interactions to device level ionic and electronic transport properties. In terms of electrolyte solvent, the project determines how the dielectric constant of the solvent and the solvent’s ability to swell the polymer impact electronic and ionic transport. In terms of electrolyte ion chemistry, the project determines how ion shape and hydrophobicity impact electronic structure and ionic and electronic transport as a function of polymer sidechain chemistry. The results of this project are essential for building a comprehensive predictive model that can be used to guide materials design and electrolyte selection for various applications of electrochemically doped conjugated polymers.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.