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

本研究项目由固体与材料化学和电子与光子材料项目联合支持。掺杂电荷输运材料可以极大地改善有机电子器件的性能。适用于典型电子输运材料的n掺杂剂，如果通过简单的电子转移反应，不可避免地会对空气敏感。空气稳定前体在薄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最近证明了某些夹层化合物的空气稳定二聚体，如红多茂烯，可以n-掺杂材料，形成相应的单体夹层阳离子。与其他空气稳定的分子n掺杂前驱体方法相比，副反应可能被最小化，并且可以掺杂电子亲和度低得多的材料（迄今为止为2.8 eV）。本提案旨在详细了解这些二聚体的化学性质，并扩大其应用范围。合成、核磁共振交叉实验、可见光-近红外监测动力学、XPS、UPS和电导率研究将用于确定：使用这种方法掺杂的限制，而不会显著影响二聚体的空气稳定性；如何控制速率以允许在空气中溶液铸造薄膜，随后的掺杂剂活化；以及重金属二聚体被3d金属配合物的相关二聚体甚至全有机二聚体取代的程度。人们对轻量化柔性电子器件（显示器、照明、太阳能电池）有着广泛的兴趣，这些器件可以在低成本和低温下制造。它们使用有机（含碳）分子或聚合物代替传统的半导体，其电学性能可以通过掺杂剂大大改善，掺杂剂可以增加(n)或减少(p)材料中的电子数量。n-掺杂剂通常是高活性的，这使它们的使用变得复杂。pi已经发现了n掺杂剂，它们异常稳定，但可以掺杂许多材料。该程序将能够改进对这些掺杂剂、相关掺杂剂及其反应性的理解和控制，并可能导致更有效的器件。学生将接受有机电子材料方面的培训，更一般地说，将接受调查科学问题方面的培训，并在pi的讲座中使用案例研究。私立学校将通过以下方式对妇女和未被充分代表的少数族裔进行教育和培训：接待暑期学生并鼓励他们申请研究生院，通过在HBCUs和其他少数族裔服务机构举办的研讨会进行招聘，以及参加有大量少数族裔参与的讲习班和会议。ppi与新墨西哥高地大学（一所少数族裔服务机构）的NSF PREM的合作将得到支持；那里的学生将决定新掺杂剂的结构，而pi将讲授化学和应用。

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.