Identification and overcoming of loss mechanisms in nanostructured hybrid solar cells - pathways towards more efficient devices

在目前的工作中，我们想要探索纳米结构混合太阳能电池的潜力和当前的局限性，其中金属氧化物纳米线或纳米管的周期性阵列与有机半导体材料结合使用。原则上，与全有机太阳能电池相比，由于更有效的电荷分离和更高的金属氧化物稳定性，这种网络结构应该导致性能的改善和寿命稳定性的提高。然而，到目前为止，它们的效率低于全有机体异质结电池的效率。我们想探究其中的原因。根据所获得的知识，我们将制定提高绩效的策略。预计各种界面的出现将起主要作用，我们计划用先进的透射电子显微镜方法在原子尺度上对它们进行研究。我们还将研究金属氧化物纳米结构的尺寸、形状和结晶度对器件性能的影响。一个重要的部分将是器件物理的研究，特别是电荷的产生，激子的分离，重组和迁移。我们将把这些值与标准的大块异质结太阳能电池进行比较，以强调差异，这将使我们能够识别和克服纳米结构混合太阳能电池的当前局限性。

In the present work we want to explore the potential and the current limitations of nanostructured hybrid solar cells, where a periodic array of metal-oxide nanowires or nanotubes is used in combination with an organic semiconductor material. In principle, such network structures should lead to an improved performance and a better lifetime-stability compared to fully organic solar cells due to a more efficient charge separation and a higher stability of the metal oxides, respectively. However, up to now their efficiencies are lower than the ones of fully organic bulk-heterojunction cells. We want to explore the reasons for this. With the gained knowledge we will develop strategies to improve the performance. It is expected that the various interfaces which are occurring play a major role and we plan to investigate them on an atomic scale by advanced transmission electron microscopy methods. We will also study how the dimension, shape and crystallinity of the metal-oxide nanostructure effect the device performance. An important part will be the investigation of the device physics, especially charge generation, exciton separation, recombination and mobility. We will compare these values with standard bulk-heterojunction solar cells to emphasize the differences, which will enable us to identify and overcome current limitations of nanostructured hybrid solar cells.