Understanding and Controlling Molecular Orientation in Organic Guest-Host Systems

了解和控制有机客主系统中的分子取向

• 批准号: 341263954
• 负责人: Professor Dr. Wolfgang Brütting
• 金额: --
• 依托单位: Lehrstuhl für Experimentalphysik IV
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/341263954?language=en
• 关键词: Understanding; Controlling; Molecular; Orientation; Organic

Organic semiconductors are nowadays frequently used in optoelectronic devices, particularly in organic light emitting diodes (OLEDs). In spite of their amorphous nature, these thin film structures can exhibit a pronounced anisotropy of their optical and (di)electric properties, resulting from orientational order of the molecules with respect to the substrate normal. With this renewal proposal we plan to broaden the scientific focus in several aspects with the goal to achieve a deeper understanding of the driving forces for molecular orientation in organic guest-host systems. Most importantly, we will correlate optical and electrical dipole moments by structuring our work program into two complementary, but equally important experimental parts to be conducted in the Bruetting group at U Augsburg. Additionally, a third work package by the Wenzel group at KIT will address these topics by molecular simulation. From this holistic approach, we expect detailed insights into the layer morphology and significant added value into the mechanistic understanding. Moreover, regarding the class of emitter materials, we will mainly focus on thermally acitvated delayed fluorescence (TADF) emitters, i.e. donor-acceptor systems with charge-transfer (CT) character in the excited state. On the one hand, owing to their extended molecular structures, one can expect strong alignment effects in thin films, and on the other hand, due to their CT character we anticipate strong guest-host interactions, specifically with polar host materials. Finally, we plan a substantial extension of our experimental capabilities for measuring emitter orientation towards time-resolved techniques. This is particularly interesting for TADF emitters with their prompt and delayed fluorescence acting over several orders of magnitude in time. Depending on the time scale, the emission can originate from different electronic states on the emitter molecule and often stems from dye molecules with different local environments.

有机半导体如今频繁地用于光电子器件，特别是用于有机发光二极管（OLED）。尽管它们的无定形性质，这些薄膜结构可以表现出其光学和（介电）电性能的显著各向异性，这是由分子相对于衬底法线的取向顺序引起的。通过这一更新建议，我们计划在几个方面扩大科学重点，目标是更深入地了解有机客体-主体系统中分子取向的驱动力。最重要的是，我们将通过将我们的工作计划结构化为两个互补但同样重要的实验部分来关联光学和电偶极矩，这两个部分将在U Augsburg的Bruetting小组进行。此外，KIT的Wenzel小组的第三个工作包将通过分子模拟来解决这些问题。通过这种整体方法，我们期望对层形态的详细了解和对机械理解的显著附加值。此外，关于发射体材料的类别，我们将主要关注热激活延迟荧光（TADF）发射体，即在激发态具有电荷转移（CT）特征的供体-受体系统。一方面，由于其扩展的分子结构，人们可以预期在薄膜中的强对准效应，另一方面，由于其CT特性，我们预期强的客体-主体相互作用，特别是与极性主体材料。最后，我们计划对我们的实验能力进行大幅扩展，以测量发射器朝向时间分辨技术。这对于TADF发射体特别有趣，其即时和延迟荧光在时间上作用于几个数量级。根据时间尺度，发射可以源自发射体分子上的不同电子状态，并且通常源自具有不同局部环境的染料分子。