Materials World Network: Understanding the Design and Characterization of Air-Stable N-Type Charge Transfer Dopants for Organic Electronics

技术总结充电转移掺杂是实现高效有机发光二极管和有机太阳能电池的关键，也是控制有机场效应晶体管的电特性所必需的。虽然p型掺杂剂的发展已经取得了很大进展，但由于对n型掺杂剂的详细掺杂机理了解有限，目前还缺乏有效的空气稳定溶液可加工的n型掺杂剂。为了弥补这一空白，材料世界网络项目得到了固体与材料化学计划和材料研究部特殊计划办公室的支持，旨在a)了解基于一类有希望的以(1，3-dimethyl-2，3-dihydro-1H-benzoimidazol-2-yl)phenyl为模型系统的掺杂剂的空气稳定n掺杂的设计规则，以及b)了解n型掺杂的详细掺杂机制。参与该项目的三个小组拥有互补专业知识的独特组合。BaO小组将合成具有系统不同能级和取代基的DMBI掺杂剂，以改善与基质的相容性，以帮助理解掺杂机理。用UV-VIS-NIR和电子顺磁共振对掺杂的化学过程进行了研究。掺杂层的形貌将通过原子力显微镜、各种X射线技术和纳米SIMS进行研究。德国的LEO小组将通过阻抗光谱、紫外光电子光谱、Seebeck测量以及通过主方程模型模拟电荷传输特性来研究掺杂的物理机制。空气稳定性将进行测试，掺杂剂将用于最先进的有机器件，如发光二极管、太阳能电池或晶体管。最后，德国库尼伯蒂小组将利用高分辨率扫描隧道显微镜在单分子水平上研究掺杂效应，并将基于密度泛函理论的从头计算对掺杂过程进行模拟。非技术概述：电荷转移掺杂对于实现高效显示器、固态照明、有机太阳能电池至关重要，并且是控制有机场效应晶体管的电特性所必需的。虽然p型掺杂剂的发展已经取得了很大进展，但由于对n型掺杂剂的详细掺杂机理了解有限，目前还缺乏有效的空气稳定溶液可加工的n型掺杂剂。材料世界网络项目将通过跨化学/化学工程、基础物理和理论学科的国际合作，促进对兴奋剂的化学和物理的理解。这些发现将有助于更好地理解稳定高效的n掺杂和更高效的器件的设计规则。该项目将培养具有扎实的基础知识和全球经验的学生和博士后。该项目将通过促进有机电子和相关产业领域的发展，帮助促进经济增长。这个项目将培养学生接触跨学科的研究和不同的文化。鲍康如将与斯坦福NSF中心和科学外展办公室密切合作，接触从K-12到社区大学、本科生和研究生的广泛人群，并为未来的教师培养新的科学和技术领域。

TECHNICAL SUMMARYCharge transfer doping is crucial in enabling highly efficient organic light emitting diodes and organic solar cells, and is needed for controlling the electrical characteristics of organic field effect transistors. Whereas the development of p-type dopants is well advanced, there is still a lack of effective air-stable solution processabile n-type dopants, due to limited knowledge on the detailed doping mechanisms. To address this gap, this Materials World Network project, supported by the Solid State and Materials Chemistry program and the Office of Special Programs, Division of Materials Research, aims at a) understanding the design rules for air-stable n-dopants based on a promising class of dopants with (1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl (DMBI) as the model system and b) understanding the detailed doping mechanisms of n-type doping. The three groups involved in the project have a unique combination of complementary expertise. The Bao group will synthesize DMBI dopants with systematically varied energy levels and substituents for better miscibility with the matrix to aid the understanding of doping mechanisms. The chemical process of doping will be investigated with UV-vis-NIR and electron paramagnetic resonance. The morphology of doped layers will be studied by atomic force microscopy, various X-ray techniques and nanoSIMS. The Leo group in Germany will study the physical mechanisms of doping by impedance spectroscopy, ultraviolet photoelectron spectroscopy, the Seebeck measurement, and modeling of the charge transport characteristic by a master equation model. The air-stability will be tested and the dopants will be used in state-of-the art organic devices such as light emitting diodes, solar cells, or transistors. Finally, the Cuniberti group in Germany will study the doping effect on a single molecular level by high resolution scanning tunneling microscopy and will model the doping process by ab initio calculations based on density functional theory. NON-TECHNICAL SUMMARY: Charge transfer doping is crucial in enabling highly efficient displays, solid-state lighting, organic solar cells, and is needed for controlling the electrical characteristics of organic field effect transistors. Whereas the development of p-type dopants is well advanced, there is still a lack of effective air-stable solution processabile n-type dopants, due to limited knowledge on the detailed doping mechanisms. This Materials World Network project will advance the understanding of the chemistry and physics of doping through an international co-operation across the disciplines of chemistry/ chemical engineering, fundamental physics and theory. These findings will lead to better understanding of design rules for stable and efficient n-dopants and more efficient devices. This project will train students and postdocs with a solid fundamental understanding as well as a global experience. This project will help to foster economic growth by furthering the field of organic electronics and the associated industry. This project will train students with exposure to interdisciplinary research and diverse cultures. Bao will work closely with Stanford NSF centers and Office of Science Outreach to reach out to a broad population ranging from K-12, community college, undergraduate, and graduate students, as well as prepare the teachers of tomorrow for new areas of science and technology.