Development and application of relativistic propagator methods for accurate theoretical descriptions of organic triplet emitters

有机电子学因其广泛的适用性和低能耗而成为未来的关键技术之一。与用固态物理方法描述的半导体器件不同，有机电子学是基于分子结构的，需要不同的量子化学方法。在这两种情况下，数值要求都非常高，要求发展有效的理论方法，以便获得深入的见解并跟上技术进步。在这个项目中，我们专注于含有重金属过渡金属的有机三重态发射器，它们表现出非常高的量子产率。这种高效率可以通过提供导致每个注入的电子/空穴对几乎完全重组到材料中的机制来实现。该激子定位于发射中心，具有25%单线态和75%三重态的统计混合特征。三重态激子不能直接适应复合，如果引入重过渡金属，则会发生剧烈的变化。因此，由于存在强自旋轨道耦合（SOC），三重态重组非常有效。因此，准确描述由引入重原子、包含电子相关和环境引起的所有效应，是设计新的高效三重态发射器的必要条件。我们小组开发了一种理想的方法来实现这一目标，该方法基于完全相对论性偏振传播子。迄今为止应用的方法通常是引入近似的SOC处理方法，或者在处理过程中相当复杂。在我们的新生产套件中应该避免这种情况。已经可用的数值算法和实现将被扩展，以处理溶剂或特定分子环境中的大型有机金属配合物。通过这种方式，它旨在支持材料科学开发高效的有机发光二极管。此外，还计划与实验工作组进行意义深远的科学合作，以使该项目最富有成果。

Organic electronics is one of the future key technologies due to its broad applicability and low energy consumption. In contrast to semiconductor devices, that are to be described by methods of solid state physics, organic electronics is based on molecular structures necessitating different quantum chemical approaches. In both cases numerical requirements are very high asking for the development of efficient theoretical methods in order to gain deep insight and to keep up with technological progress. In this project we focus on organic triplet emitters containing heavy transition metals that are exhibiting very high quantum yields. This high efficiency can be achieved by providing mechanisms that lead to a nearly complete recombination of each injected electron/hole pair into the material. This exciton is localized at the emitting center and shows a statistical mixture of 25% singlet and 75% triplet character. The triplet excitons are not directly amenable to recombination which changes drastically if heavy transition metals are introduced to the complex. Hereby also the triplet states recombine very efficiently by presence of strong spin-orbit coupling (SOC). Therefore, an accurate description of all effects caused by the introduction of heavy atoms, the inclusion of electron correlation and of the environment is therefore mandatory for the design of new efficient triplet emitters. An ideally suited method to achieve this was developed in our group and is based on the fully relativistic polarization propagator. Methods applied so far often introduce approximative treatments of SOC or are quite complex in their handling. This should be avoided in our new production suite. The already available numerical algorithms and implementations will be extended in order to tackle large organic metal complexes in a solvent or specific molecular environment. By this it is intended to support material science in the development of efficient OLEDs. Additionally, far-reaching opportunities for scientific cooperations with experimentally working groups are planned to make the project most fruitful.