Synthetic and Mechanistic Studies of Air-Stable Organometallic Dimers as n-Dopants for Organic Electronics

本研究项目由固态与材料化学和电子与光子材料计划共同支持。 电荷传输材料的掺杂可以极大地改善有机电子器件的性能。适用于典型电子传输材料的n型掺杂剂如果通过简单的电子转移反应则不可避免地是空气敏感的。其中空气稳定的前体在膜沉积期间或之后形成掺杂剂的方法可以简化器件制造。PI最近证明，某些夹心化合物（如二茂铁）的空气稳定二聚体可以对材料进行n掺杂，形成相应的单体夹心阳离子。与其他空气稳定的前体方法相比，分子n型掺杂剂的副反应可能会最小化，并且可以掺杂具有低得多的电子亲和力（迄今为止为2.8 eV）的材料。该提案旨在详细了解这些二聚体的化学性质，并扩大其用途。合成、NMR交叉实验、动力学的可见-近红外监测以及溶液浇铸膜的XPS、UPS和电导率研究将用于确定：使用这种方法掺杂而不显著损害二聚体空气稳定性的限制;如何控制速率以允许在空气中溶液浇铸膜，随后进行掺杂剂活化;以及重金属二聚体可以被3D-金属络合物的相关二聚体或甚至全有机二聚体替代的程度。非技术概述人们对能够以低成本和低温制造的轻质柔性电子器件（显示器、照明、太阳能电池）有着广泛的兴趣。这些使用有机（含碳）分子或聚合物代替传统的半导体，其电性能可以使用掺杂剂大大改善，这增加了（n）或减少了（p）材料中的电子数量。n-掺杂剂通常是高反应性的，这使它们的使用复杂化。PI已经发现了异常稳定的n型掺杂剂，但掺杂了许多材料。该计划将能够更好地理解和控制这些掺杂剂，相关掺杂剂及其反应性，并可能导致更有效的设备。学生将接受有机电子材料的培训，更普遍的是，在调查科学问题方面，案例研究将在PI的讲座中使用。公共机构将通过以下方式教育和培训妇女和代表性不足的少数群体：接待暑期学生并鼓励他们申请研究生院，通过在HBCU和其他少数群体服务机构举办研讨会进行招聘，以及参加有大量少数群体参与的研讨会和会议。PI与NSF PREM在新墨西哥州高地大学（一所少数民族服务机构）的合作将得到支持;那里的学生将确定新掺杂剂的结构，PI将提供化学和应用方面的讲座。

TECHNICAL SUMMARYThis research project is jointly supported by the Solid State and Materials Chemistry and the Electronic and Photonic Materials Programs. Doping of charge-transport materials can greatly improve the behavior of organic electronic devices. n-Dopants suitable for typical electron-transport materials are inevitably air-sensitive if reacting by simple electron transfer. Approaches in which air-stable precursors form dopants during, or subsequent to, film deposition can simplify device fabrication. The PIs recently demonstrated that air-stable dimers of certain sandwich compounds, such as rhodocene, can n-dope materials, forming the corresponding monomeric sandwich cations. In contrast to other air-stable precursor approaches to molecular n-dopants, side reactions are likely to be minimized and materials with much lower electron affinities (2.8 eV to date) can be doped. This proposal aims to understand the chemistry of these dimers in detail and to broaden their utility. Synthesis, NMR crossover experiments, vis-NIR monitoring of kinetics, and XPS, UPS, and conductivity studies of solution-cast films will be used to establish: the limits of doping using this approach without significantly compromising the dimer air-stability; how the rate can be controlled to permit solution-casting of films in air, with subsequent dopant activation; and the extent to which heavy-metal dimers can be replaced by related dimers of 3d-metal complexes or even all-organic dimers. NON-TECHNICAL SUMMARYThere is wide interest in lightweight-flexible electronic devices (displays, lighting, solar cells), that can be made at low cost and low temperature. These use organic (carbon-containing) molecules or polymers in place of traditional semiconductors, the electrical properties of which can be greatly improved using dopants, which increase (n) or decrease (p) the number of electrons in the material. n-Dopants are generally highly reactive, which complicates their use. The PIs have discovered n-dopants that are unusually stable, yet dope many materials. This program will enable an improved understanding and control of these dopants, related dopants, and their reactivity, and may lead to more efficient devices. Students will be trained in organic electronic materials, and, more generally, in investigating scientific problems, and case-studies will be used in the PIs' lectures. The PIs will educate and train women and underrepresented minorities by: hosting summer students and encouraging their application to graduate school, recruiting via seminars at HBCUs and other minority-serving institutions, and attending workshops and conferences with significant minority participation. The PIs' work with a NSF PREM at New Mexico Highlands University, a minority-serving institution, will be supported; students there will determine the structures of new dopants, and the PIs will give lectures linking chemistry and applications.