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.

有机半导体是当今光电器件中常用的器件，特别是有机发光二极管（oled）。尽管它们是无定形的，但这些薄膜结构可以表现出明显的光学和（di）电性质的各向异性，这是由于分子相对于衬底法向的取向顺序造成的。通过这一更新建议，我们计划在几个方面拓宽科学重点，目标是更深入地了解有机主客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成两个互补但同样重要的实验部分来关联光学和电偶极矩，这些实验部分将在U奥格斯堡的布鲁廷小组进行。此外，KIT Wenzel小组的第三个工作包将通过分子模拟解决这些问题。从这种整体方法中，我们期望对层形态的详细见解和对机制理解的重要附加价值。此外，在发射体材料方面，我们将主要关注热激活延迟荧光（TADF）发射体，即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，人们可以预期薄膜中有很强的排列效应，另一方面，由于其CT特性，我们预计会有很强的主客相互作用，特别是与极性宿主材料。最后，我们计划对我们的实验能力进行实质性的扩展，以测量时间分辨技术的发射器方向。这对TADF发射体特别有趣，因为它们的提示和延迟荧光在时间上的作用超过几个数量级。根据时间尺度的不同，发射可以来自发射器分子上不同的电子状态，并且通常来自具有不同局部环境的染料分子。