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相反，有机电子学基于需要不同量子化学方法的分子结构。在这两种情况下，数值要求非常高，要求发展有效的理论方法，以获得深刻的见解，并跟上技术进步。在这个项目中，我们专注于有机三重态发光体含有重过渡金属，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/空穴对几乎完全复合到材料中的机制来实现。该激子位于发射中心，并显示出25%的单重态和75%的三重态特征的统计混合物。三重态激子不直接服从重组，如果将重过渡金属引入络合物，重组会发生急剧变化。由此，三重态也通过强自旋轨道耦合（SOC）的存在而非常有效地重组。因此，准确描述由引入重原子引起的所有效应，包括电子相关性和环境，因此对于设计新的有效三重态发射体是强制性的。一个理想的方法来实现这一点，在我们的小组开发，是基于完全相对论偏振传播。到目前为止，应用的方法经常引入SOC的近似处理，或者在处理中相当复杂。在我们的新生产套件中应避免这种情况。已经可用的数值算法和实现将被扩展，以解决在溶剂或特定的分子环境中的大型有机金属络合物。通过这一点，它旨在支持材料科学在高效OLED的发展。此外，还计划与实验工作组进行意义深远的科学合作，以使该项目取得最大成果。

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.