Understanding Thermal Transport Properties in Electrically Conductive Polymers

导电聚合物使现代设备发生了革命性的变化，使塑料太阳能电池、电子学和热电设备取得了进步。这些设备的性能与热如何通过传导散失或热如何通过绝缘被捕获有关。本项目旨在研究导电聚合物中的热传输特性如何受载流子和聚合物主链结构的影响。通过加强我们对聚合物中热输运的基本了解，该项目将为设计高效的基于聚合物的器件提供有价值的新知识和新的实用策略。通过为少数族裔社区提供研究机会，促进可再生能源领域的多样性，该项目还将教育K-12和本科生实践可再生热能收集项目，培养下一代能源技术工程师和科学家。了解聚合物中的热传输物理一直是一个长期的挑战。现有的理论和模拟不能定量描述聚合物的导热系数增强(或降低)。该项目的主要目标是阐明载流子(极化子和双极化子)和结构参数(短程位置顺序、取向顺序和链构象)如何定量影响沿(和跨)链方向的导热系数，这是提供导电聚合物热传导微观图像的缺失部分。该项目将通过包括瞬时频域热反射在内的最先进技术来研究随温度变化的热导率、热容、电导率和塞贝克系数。通过电化学掺杂工程，设计和合成了具有精确控制掺杂水平、可调谐载流子密度和可定制链结构的噻吩基共轭聚合物，以预测其热导率。该项目不仅将深入了解导电聚合物的热传输过程，还将为开发基于微观能量载体相互作用的新型电子器件提供变革性的机会。聚(3-烷基噻吩基)共轭聚合物作为一种模型聚合物，广泛应用于有机电子器件，包括场效应晶体管和太阳能电池，具有可控的热导率，将为提高效率提供独特的机会。这项工作的更广泛的技术影响包括更好的热管理应用的新战略，例如没有过热问题的有机发光二极管(OLED)。该教育计划将促进工程劳动力中所有群体的多样性和包容性，包括女性和来自代表性不足的种族和民族群体的个人。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。

Electrically conductive polymers have revolutionized modern devices, enabling advancements in plastic solar cells, electronics, and thermoelectric devices. The performance of these devices is linked to how heat is dissipated through conduction or how heat is trapped through insulation. This project aims to investigate how thermal transport properties in electrically conductive polymers are affected by charge carriers and polymer backbone structures. By enhancing our fundamental understanding of thermal transport in polymers, this project will provide valuable new knowledge and new practical strategies to design high-efficiency polymer-based devices. By providing research opportunities to underrepresented minority communities and promoting the diversity of the renewable energy field, this project will also educate K-12 and undergraduate students with hands-on renewable thermal energy harvesting projects, creating the next generation of engineers and scientists in energy technologies.Understanding thermal transport physics in polymers has been a long-standing challenge. Existing theories and simulations do not quantitatively describe thermal conductivity enhancement (or reduction) in polymers. The overarching goal of this project is to elucidate how charge carriers (polarons and bipolarons) and structural parameters (short-range positional orders, orientational orders, and chain conformations) quantitively affect thermal conductivities along (and across) chain directions, which are the missing pieces in providing a microscopic picture of heat conduction in electrically conductive polymers. This project will study temperature-dependent thermal conductivities, heat capacities, electrical conductivities, and Seebeck coefficients through state-of-the-art techniques including a transient frequency-domain thermoreflectance. To tune the thermal conductivities predictively, thiophene-based conjugated polymers with precisely controlled doping levels, tuned charge carrier densities, and tailored chain structures will be designed and synthesized by electrochemical doping engineering. This project will not only create insights into thermal transport processes in electrically conductive polymers, but also provide transformative opportunities to develop novel electronic devices based on the interaction of microscopic energy carriers. As a model polymer, poly(3-alkylthiophene) conjugated polymer that is widely used for organic electronics, including field-effect transistors and solar cells, with controllable thermal conductivity will offer unique opportunities for improved efficiency. The broader technical impacts of this work include new strategies for better thermal management applications such as organic light-emitting diodes (OLEDs) without overheating issues. The education plan will promote diversity and inclusion of all groups in engineering workforce, including women and individuals from underrepresented racial and ethnic groups.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.