Carrier dynamics and fast switching by dipole engineering in solution processed thin film transistors

摘要：非技术：低成本、大面积、溶液处理的薄膜聚合物晶体管正在成为下一代技术，允许电子元件集成到柔性基板中。然而，聚合物薄膜晶体管具有低开关时间的缺点，使得它们在分析和数字逻辑电路中的使用存在问题。聚合物晶体管中的快速开关时间可以通过使器件尺寸更小来实现，但这需要纳米光刻，这对于低成本印刷方法是不切实际的。该项目利用材料工程的低成本策略，与目前最先进的薄膜聚合物晶体管相比，将开关时间提高了几个数量级，这将为许多新的应用开辟印刷聚合物电路技术。此外，基于非线性光学的新的实验方法将被开发用于探测和可视化聚合物晶体管中的电荷运动。这种技术允许准确确定载流子迁移率，这是控制开关时间的关键参数。技术和教育之间的联系将通过设计项目来加强，本科生将打印聚合物逻辑电路作为其高级物理实验室课程的一部分。国际范围将为美国学生提供在工业和学术界就业所必需的可转移技能。研究生和本科生将获得多学科技术技能的专业知识，从而接受培训，为美国柔性电子领域的劳动力做出贡献。高中生的实践研讨会和代表性不足的研究生的指导计划也将是该项目的一部分。技术：该计划的目标是提高全聚合物薄膜晶体管的开关时间，并开发一种非线性光学方法用于载流子输运的可视化。电介质层的偶极工程，使用低成本的溶剂处理和极化聚合物铁电介质，可能会对在长沟道可印刷薄膜有机场效应晶体管和逻辑电路中实现快速开关时间的技术产生变革性影响。一系列新的侧链取代的给体-受体共聚物将被用作有源半导体层。场效应晶体管中有机半导体的载流子迁移率受到器件几何形状、有机半导体的物理/化学属性以及各种界面（金属-半导体和半导体-绝缘体）的强烈影响。将建立基于三阶极化率的瞬态电场诱导二次谐波产生方法，从而可以直接和选择性地探测场效应晶体管中的动态载流子运动。这种技术将是一种强大的方法，用于可视化新一代施主-受主双极晶体管中的输运，并为预测准确的载流子迁移率铺平道路，不受接触电阻问题和器件几何因素的影响。晶体管结构中聚合物薄膜的掠角X射线散射研究不仅可以揭示聚合物的结构，还可以揭示偏置应力下结构的变化。

Abstract: Non-Technical: Low-cost, large area, solution processed, thin film polymer transistors are emerging as a next-generation technology, allowing electronic components to be integrated into flexible substrates. However, polymer thin film transistors suffer from low switching times, rendering their use in analytical and digital logic circuits problematic. Fast switching times in polymer transistors may be achieved by miniaturizing the device size, but this requires nanolithography, which is impractical for low-cost printing methods. This project utilizes low-cost strategies for materials engineering to improve switching times by orders of magnitude compared to the present state-of-the-art thin film polymer transistors, which will open up the printed polymer circuit technology for many new applications. Furthermore, a new experimental method based on non-linear optics will be developed for probing and visualizing the motion of charges in polymer transistors. This technique allows an accurate determination of the carrier mobility, which is a crucial parameter that controls switching times. The connection between technology and education will be reinforced by designing projects where undergraduate students will print polymer logic circuits as part of their Advanced Physics Laboratory course. The international scope will provide US students transferable skills that are essential for employment in industry and academia. Graduate and undergraduate students will gain expertise in a multidisciplinary range of technical skills, and thus be trained to contribute to the US workforce in the area of flexible electronics. Hands-on workshops for high school students and mentoring programs for underrepresented graduate students will also be part of the project.Technical: The objective of this program is to improve switching times in all-polymer thin film transistors and to develop a non-linear optical method for visualization of carrier transport. Dipole engineering of the dielectric layer, using low-cost solvent processing and poling polymer ferroelectric dielectrics, is likely to have a transformative impact on technology where fast switching times may be realized in long-channel printable thin film organic field-effect transistors and logic circuits. A new series of side-chain substituted donor-acceptor copolymers will be used as the active semiconductor layer. Carrier mobilities of organic semiconductors in field-effect transistors are strongly impacted by device geometry, physical/chemical attributes of the organic semiconductor, and the various interfaces: metal-semiconductor and semiconductor-insulator. Transient electric field-induced second-harmonic generation methods, based on the third-order susceptibility, will be established, allowing direct and selective probing of dynamic carrier motion in field-effect transistors. This technique will be a powerful methodology for visualizing transport in a new generation of donor-acceptor ambipolar transistors and pave the way for predicting accurate carrier mobilities, free from contact resistance issues and device geometrical factors. Grazing angle X-ray scattering studies from polymer films in transistor architectures will reveal not just the structure of the polymer, but also the changes in structure upon bias stress.