Conjugated Polymers Doped via Covalent Dopant-Molecule Adducts

在化学系大分子、超分子和纳米化学项目的支持下，霍华德教授E。约翰霍普金斯大学的Katz和Paulette Clancy正在开发用于掺杂共轭聚合物的小有机分子。 共轭聚合物是碳基大分子，含有由交替的双键和单键组成的长链。 当双键排列通过去除或添加电子而改变时，聚合物中会产生正电荷和负电荷，使它们能够像铜等金属一样导电。 目前，共轭聚合物是用于光电器件如移动的设备和计算机中的LED（发光二极管）屏幕的最重要的一类材料;也用于保护此类电子元件免受外部电干扰。 在这项研究中，使用实验和计算方法相结合的系统研究将仔细研究这些聚合物体系中的电子转移机制，这种机制的许多细节仍然未知。 对这种系统的进一步了解有可能导致具有与柔性电子和功率器件相关的可调电子特性的新型共轭材料。 该项目的教育和推广活动将侧重于约翰霍普金斯大学针对低收入巴尔的摩市参与者的工程创新计划。 一个关于编程的靴子训练营将提供给中学生，目的是提高未来STEM（科学、技术、工程和数学）科学家的编程技能，特别是针对女性和代表性不足的群体。这项研究的目标是一系列噻吩基分子和低聚物，用于共轭聚合物的掺杂。 提出的理论和实验研究的目的是测试的假设，自由能的变化从（a）在空穴/电子亲和性的差异，（B）的工作，电荷分离，和（c）离域/分布熵之间的中性共轭聚合物和共价离子加合物将导致电荷转移和导电性。 用于加合物形成研究的基于噻吩的共轭分子和低聚物将被选择为具有一定范围的硬度/柔软度，并且有利于在非质子溶剂中形成成对电子共价键（与电子转移相互作用相反），以能够测试共价加合物是否最终用作共轭聚合物的电子转移剂。 广泛的光谱和电化学表征方法被用来获得更深入的了解掺杂机制，以及结构变化如何影响掺杂水平，固态结构，导电性和塞贝克系数。 与这项研究相关的结果有可能导致共轭聚合物中更可靠的掺杂策略-这是进一步开发有机生物电子和柔性导体的关键挑战。该奖项反映了NSF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。

With the support of the Macromolecular, Supramolecular and Nanochemistry program in the Division of Chemistry, Professors Howard E. Katz and Paulette Clancy of the Johns Hopkins University are developing small organic molecules for use in doping of conjugated polymers. Conjugated polymers are carbon-based macromolecules that contain long chains consisting of alternating double and single bonds. When the double bond arrangements are changed by removing or adding electrons, positive and negative charges are created in the polymers that enable them to conduct electricity similarly to metals such as copper. Currently, conjugated polymers are the most important class of materials used for optoelectronic devices such as LED (light-emitting diode) screens in mobile devices and computers; also being used to protect such electronic components from outside electrical interference. In this research, systematic studies using a combination of experimental and computational approaches will closely examine the mechanism of electron transfer in these polymeric systems, a mechanism for which many details are still not known. Increased understanding of such systems has the potential to lead to novel conjugated materials with tunable electronic properties of relevance to flexible electronics and power devices. The education and outreach activities of this project will focus on the engineering innovation program at Johns Hopkins University targeting low-income Baltimore City participants. A boot camp on coding will be offered to middle schoolers with the goal of improving the programming skills of future STEM (Science, Technology, Engineering and Math) scientists, with the particular goal of reaching women and members of underrepresented groups.This research is targeting a series of thiophene-based molecules and oligomers for use in doping of conjugated polymers. The proposed theoretical and experimental studies are designed to test the hypothesis that the free energy change from (a) difference in hole/electron affinities, (b) work of charge separation, and (c) delocalization/distribution entropy between neutral conjugated polymers and covalent ion-adducts will lead to charge transfer and electrical conductivity. Thiophene-based conjugated molecules and oligomers for adduct formation studies will be selected with a range of hardness/softness and to favor paired-electron, covalent bond formation (as opposed to electron transfer interactions) in aprotic solvents to enable testing of whether the covalent adducts ultimately serve as electron transfer agents of conjugated polymers. Extensive spectroscopic and electrochemical characterization methods are to be used to gain a deeper understanding of the doping mechanism and how structural changes affect doping levels, solid-state structures, conductivity, and the Seebeck coefficient. The results associated with this research have the potential to lead to more reliable doping strategies in conjugated polymer- a key challenge for further development of organic bioelectronics and flexible conductors.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.