CAREER: The Working Mechanics of Organic Electrochemical Transistors

摘要非技术：有机电化学晶体管（OECT）是目前最成功的有机生物电子器件之一。oect的应用范围从生物分子传感器，到心电图记录，以及大脑活动的体内记录。总的来说，OECTs将为研究和监测常见疾病开辟新的途径，从而改善美国和世界各地人民的健康和生活质量。然而，尽管人们对oect有着浓厚的兴趣，但对其工作机制的了解尚不完整。用于描述oect的模型将器件分为两个独立的部分——一部分描述栅极电解质内部的离子传导，第二部分描述有机半导体内部的电子传导。离子电流和电子电流之间的这种人为分离导致了设备操作描述的不一致，为了提高oect的性能，必须解决这个问题。在其研究部分，该项目旨在加强对经合组织工作机制的了解。二维数值模拟将被实现和验证。该模型将用于量化器件内部的载流子密度和电场，了解OECTs电流不稳定的来源，并定量描述OECTs的传感机制。该项目的教育目标是提高科学导论课程学生和高中生对科学本质和科学伦理的认识和知识。将开发以著名研究人员生活中的轶事为例，解释科学本质的短篇图画小说。这些教材将在一个倒置的物理教室中使用。技术方面：有机电化学晶体管（OECTs）有望实现新的生物电子学应用，并为研究生物系统的工作机制提供新的手段。oect依赖于离子和电流之间微妙的相互作用，然而，人们对这种相互作用还没有充分了解。本提案的研究目标是缩小这一研究差距，并增强我们对经合组织工作机制的了解。为了达到这一目标，我们追求以下目标：i)制定并验证定量描述OECT行为的二维漂移扩散模型；ii)研究oect中迟滞和栅偏应力效应的来源；iii)研究和模拟oect的感知机制。为了描述OECT操作，必须求解所有涉及的载流子的连续性方程和泊松方程。漂移-扩散模拟将通过移动锋实验、金属-电解质-半导体结的阻抗谱和系统变化oect的电特性来实现和验证。一个瞬态模型将被实现来解释迟滞和门偏应力效应的起源。为了定量描述OECTs的传感机理，在模拟中加入了酶促反应。这些实验有可能推进该领域的知识：i)将澄清有机半导体内部所有载流子的稳态分布，这对于理解OECT操作的细节至关重要。ii)提出了避免当前OECTs中发现的不稳定性的方法，这对后来的商业化至关重要。iii)对oect的传感机制进行了详细的了解。该项目的教育目标是通过开发讨论科学本质和伦理的模块来加强物理入门教学。与“获得和支持成功的本科生研究经验”（ASSURE）计划合作，将为少数民族大学的学生提供暑期项目，以支持他们申请研究生院。

AbstractNontechnical:The organic electrochemical transistor (OECT) is one of the most successful organic bio-electronic devices. The list of applications of OECTs ranges from sensors for biomolecules, to electrocardiographic recordings, and in-vivo recording of brain activity. Overall, OECTs will open new ways to study and monitor common diseases, which can lead to an improvement of the health and quality of life of people in the US and around the world.However, despite the intense interest in OECTs, the understanding of their working mechanism is incomplete. Models used to describe OECTs split the device in two separate parts - one part describing ionic conduction inside the gate electrolyte, and a second part describing the electronic conduction inside the organic semiconductor. This artificial separation between ionic and electronic currents leads to inconsistencies in the description of the device operation, which have to be resolved in order to increase the performance of OECTs. In its research component, the project aims at enhancing the understanding of the working mechanisms of OECTs. A 2D numerical simulation will be implemented and validated. The model will be used to quantify carrier densities and electric fields inside the devices, to understand the origin of current instabilities of OECTs, and to quantitatively describe the sensing mechanism of OECTs.The educational goal of this project is to increase the awareness and knowledge of the nature and ethics of science for students of introductory science courses and high school students. Short graphic novels will be developed that explain the nature of science using anecdotes from the lives of famous researchers as examples. These teaching materials will be used in an inverted physics classroom.Technical:Organic Electrochemical Transistors (OECTs) hold the promise of enabling new bioelectronic applications and of providing new means to study the working mechanisms of biological systems. OECTs rely on a delicate interplay between ionic and electric currents, which, however, is not sufficiently understood. The research goal of this proposal is to close this research gap and to enhance our knowledge in the working mechanisms of OECTs. To reach this aim, the following objectives are pursued: i) To formulate and validate a two-dimensional drift-diffusion model that quantitatively describes OECT behavior; ii) to study the origin of hysteresis and gate bias stress effects in OECTs; and iii) to study and model the sensing mechanism of OECTs.To describe OECT operation, the continuity equations of all involved charge carriers must be solved along with the Poisson equation. A drift-diffusion simulation will be implemented and validated by moving front experiments, impedance spectroscopy of metal-electrolyte-semiconductor junctions, and electric characterization of systematically varied OECTs. A transient model of OECTs will be implemented to explain the origin of hysteresis and gate-bias stress effects in OECTs. Enzymatic reactions are added to the simulation in order to describe the sensing mechanism of OECTs quantitatively.These experiments have the potential to advance the knowledge in the field: i) the steady state distribution of all charge carriers inside the organic semiconductor will be clarified, which is essential to understand the details of OECT operation. ii) Approaches to avoid instabilities found in current OECTs are proposed, which is essential for a later commercialization. iii) A detailed understanding of the sensing mechanism of OECTs is developed. The educational goal of the project is to strengthen introductory physics teaching by developing modules that discuss the nature and ethics of science. In collaboration with the Access and Support for Successful Undergraduate Research Experiences (ASSURE) program, summer projects will be offered to students from minority serving universities to support them in their applications for graduate schools.