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.

有机半导体如今经常用于光电器件，特别是有机发光二极管（OLED）。尽管它们具有无定形性质，但这些薄膜结构可以表现出明显的光学和（介）电特性各向异性，这是由于分子相对于基板法线的取向顺序造成的。通过这一更新提案，我们计划在多个方面扩大科学焦点，目标是更深入地了解有机客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构建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，这两个部分将在奥格斯堡大学的 Bruetting 小组中进行。此外，卡尔斯鲁厄理工学院 Wenzel 小组的第三个工作包将通过分子模拟来解决这些主题。通过这种整体方法，我们期望对层形态有详细的了解，并为机械理解带来显着的附加值。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，即在激发态下具有电荷转移（CT）特征的供体-受体系统。一方面，由于它们扩展的分子结构，人们可以预期在薄膜中具有强烈的排列效应，另一方面，由于它们的 CT 特性，我们预计会有强烈的客主相互作用，特别是与极性主体材料的相互作用。最后，我们计划大幅扩展我们测量发射器方向的实验能力，以实现时间分辨技术。这对于 TADF 发射器来说特别有趣，因为它们的即时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，发射可能源自发射体分子上的不同电子态，并且通常源自具有不同局部环境的染料分子。