Probing Ion Injection in Organic Electrochemical Transistors

可以传导电子和离子的塑料对于许多应用都很重要，例如将生物神经脉冲转换为数字电子设备可读信号的生物电子传感器，可以在短时间内提供高电流的储能设备，以及模仿大脑功能的下一代计算机。限制这些领域技术发展的因素之一是对离子如何注入这些半导体塑料并在其中传输的理解有限。该项目通过使用先进的显微镜技术在纳米尺度上分析聚合物（塑料）来解决这个问题。这些方法可以确定聚合物从离子注入中溶胀的位置，并且可以使用红外光将该响应与离子的化学特征相关联，也是在纳米级。然后将微观信息与晶体管测量进行比较，以获得对聚合物加工和结构如何影响离子运动的基本理解。该项目的科学知识可以更好地设计和加工/制造上述应用的聚合物。该项目还建立在主要研究者在教育方面的跟踪记录的基础上，使开发新的外展材料成为可能，如适合纳入现有外展计划和网络的聚合物电化学工具包。该项目还通过继续与雷尼尔学者组织的成功伙伴关系为本科生研究提供直接支持，以提供途径，帮助代表性不足的群体和第一代大学生在科学方面取得成功。该项目的科学目标是获得一个基本的理解的结构/功能关系控制离子注入π共轭聚合物作为混合离子/电子导体，同时使用混合有机电化学晶体管作为实验测试平台。这些聚合物和共混物通常表现出数十纳米尺度的特征，因此该项目使用先进的扫描探针显微镜工具来研究纳米级的离子传输过程。共轭聚合物已经成为有前途的电子和光子材料，用于在生物和数字环境之间的界面上转换信号，拟议的项目将探索这些材料的基本结构/功能特性，这些材料与这些应用程序的方式是不同的，通过独特的本地和批量方法的组合。具体来说，该项目将：1）使用一种新的方法，光诱导力显微镜（PiFM），以使纳米级地图探测如何局部化学结构和形态联合收割机结合，以影响局部离子注入; 2）应用电化学应变显微镜（ESM），以测量局部溶胀由于离子吸收的均聚物，嵌段共聚物，和共混物;以及，3）在探索新的共混物和复合材料结构的同时这样做，作为克服现有材料性能瓶颈的手段。值得注意的是，该项目使用纳米级红外显微镜来探测导电聚合物和离子导体的混合物，以测试将高电子迁移率组分和高离子迁移率组分解耦可以实现改进的电化学晶体管的假设。主要研究者在以前的工作中表明，离子注入和电子迁移率在混合导体中通常是反相关的，这是设备的瓶颈。这些实验产生一组不同的测量，使多模态分析的结构-功能关系的基础离子注入。该项目提供了重要的洞察如何流动性和体积电容在混合离子电子导体的相关，以及是否有可能通过关注离子如何从底层向上移动到聚合物中来合理地改进导电聚合物和聚合物共混物的设计。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进行评估，被认为值得支持的搜索.

Plastics that can conduct both electrons and ions are important for numerous applications such as bioelectronic sensors that convert biological nerve impulses into signals readable by digital electronics, energy storage devices that can deliver high currents for short times, and next-generation computers that mimic the function of the brain. One of the factors limiting technological developments in these fields is limited understanding of how ions inject into and transport within these semiconducting plastics. This project addresses this question by analyzing polymers (plastics) at the nanometer scale using advanced microscopy techniques. These methods can determine where polymers are swelling from ion injection and can correlate that response with the chemical signature of the ion using infrared light, also at the nanoscale. The microscopic information is then compared to transistor measurements to gain a fundamental understanding of how the polymer processing and structure influences ion motion. The scientific knowledge from this project enables better design and processing/manufacturing of polymers for the applications noted above. The project additionally builds upon the track record of the principal investigator in education by enabling development of new outreach materials such as polymer electrochemistry kits that are suitable for integration into existing outreach programs and networks. The project also provides direct support for undergraduate research through continuation of the successful partnership with the Rainier Scholars organization to provide pathways to assist under-represented groups and first-generation college students succeed in the sciences. The scientific goal of this project is to gain a fundamental understanding of the structure/function relationships controlling ion injection in pi-conjugated polymers operating as mixed ionic/electronic conductors while using blended organic electrochemical transistors as an experimental testbed. These polymers and blends typically exhibit features on the scale of tens of nanometers, and therefore this project uses advanced scanning probe microscopy tools to investigate the ion transport process at the nanoscale. Conjugated polymers have emerged as promising electronic and photonic materials for transducing signals at the interface between the biological and digital environments, and the proposed project will explore fundamental structure/function properties of these materials relevant to these applications in a way that is distinct from other efforts through a combination of unique local and bulk methods. Specifically, the project will: 1) use a new method, photoinduced force microscopy (PiFM), to make nanoscale maps probing how local chemical structure and morphology combine to affect local ion injection; 2) apply electrochemical strain microscopy (ESM) to measure local swelling due to ion uptake in homopolymers, block copolymers, and blends; and, 3) do so while exploring new blend and composite architectures as a means to overcome the bottlenecks of existing materials performance. Notably, this project uses nanoscale infrared microscopy to probe blends of conducting polymers and ionic conductors to test the hypothesis that decoupling the high electronic mobility component and high ionic mobility component can enable improved electrochemical transistors. The principal investigator has shown in previous work that ion injection and electronic mobility are often anti-correlated in mixed conductors, which serves as a device bottleneck. These experiments yield a distinct set of measurements that enable multimodal analysis of the structure-function relationships underpinning ion injection. The project provides important insight into how mobility and volumetric capacitance in mixed ionic-electronic conductors are related, and whether it is possible to rationally improve conducting polymers and polymer blends design by focusing on how ions move into the polymer from the ground up.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.