HEFOS – High Electric Fields at Organic Semiconductor Heterojunction Interfaces

II型异质结载流子的转移在有机半导体领域引起了极大的关注。界面上的相关电荷转移状态不仅负责有机太阳能电池中的重组过程，它们定义了开路电压和电荷产生，而且它们也被用于所谓的“激复”发光二极管，以合理的效率产生光。此外，穿过异质结界面的电荷可以吸收光。虽然该过程的横截面相对较低，但最近的出版物表明，通过与微腔结合，大部分入射光被吸收，从而导致新一代近红外光电探测器。与分子内的重组和吸收过程相比，外部电场对分子间系统的潜在影响要大得多。这样，接口转换的属性很可能可以在外部进行调优。本课题的目标是设计出在施主和受主材料界面施加高电场的器件结构，以调整发射和吸收的光谱范围。此外，详细阐述在这种界面处强电荷积累的操作将是有趣的，这对于潜在的高激发实验和应用（如电驱动激光器）是重要的。我设想通过与几个外部合作伙伴合作来澄清潜在的物理原理，他们将带来他们的专业知识和知识。

The transfer of charge carriers at heterojunctions of type II has gained an enormous attraction in the field of organic semiconductors. Related charge-transfer states at the interface are not only responsible for recombination processes in organic solar cells where they define the open circuit voltage and the charge generation but they have also been employed in so-called "exciplex" light-emiting diodes to create light with reasonable efficiency. Further, charges traversing the hetorojunction interface can absorb light. Although the cross-section for this process is relatively low, recent publications reveal that by combination with a micro-cavity, a major part of the incident light is absorbed, leading to a new generation of NIR photodetectors.Intermolecular systems can potentially be affected much stronger by an external electrical field, e.g. in contrast to intramolecular recombination and absorption processes. By that, it is likely that the properties of the interface transitions can be tuned externally. It is the aim of this project to work out device structures to apply high electric fields to the interfaces of donor and acceptor materials in order to tune the spectral range of emission and absorption. Further, it will be of interest to elaborate the operation at strong charge accumulation at such interfaces which is important for potential high excitation experiments and applications, such as an electrically driven laser. I envision to clarify the underlying physics by cooperating with several external partners who will bring in their expertise and knowledge.