Interplay between microscopic structure and intermolecular charge transfer processes in polymer-fullerene bulk-heterojunctions

聚合物-富勒烯体异质结微观结构与分子间电荷转移过程之间的相互作用

• 批准号: 65143984
• 负责人: Professor Dr. Vladimir Dyakonov
• 金额: --
• 依托单位: Lehrstuhl für Experimentelle Physik VI
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2008
• 资助国家: 德国
• 起止时间: 2007-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/65143984?language=en
• 关键词: Interplay; between; microscopic; structure; intermolecular

In this follow-up project we plan to perform systematic studies of charge transfer (CT) processes in polymer semiconductors and their blends with electron acceptor moieties. Our investigations are aimed at clarifying the correlation between CT and film morphology on the microscopic level. In the first application period, we developed a unique set of tools to study film structure on the nanometer scale as well as excited states in organic bulk heterojunction solar cells. We implemented and applied an optically detected magnetic resonance setup, and found surprising results related to formation of triplet excitons with different spatial extent in the conjugated polymer rr-P3HT (regio-regular poly-hexylthiophene). Triplet excitons are generally considered as loss factors in organic photovoltaics. We determined spatial extents of these triplet states ranging from few Ångstroms (molecular triplet excitons) to several nanometers. The latter we identify with CT excitons, or polaron pairs, the precursor state of free charges in organic solar cells—and thus crucial for their performance. The different triplet states occur depending on the film morphology, which we studied by scanning force microscopy (SFM) based nanotomography. SFM-nanotomography was for the first time adapted to study conjugated polymers and donor-acceptor blends by development of a suitable plasma-etching recipe. So far we demonstrated 3D volume imaging with 10 nm resolution of a P3HT:PCBM blend. Although the results of the first proposal period are novel and interesting, the microscopic nature of the triplet states remains unresolved.

在此后续项目中，我们计划在聚合物半导体中对电荷转移（CT）过程进行系统研究，并与电子受体部分进行混合。我们的研究旨在阐明在微观水平上CT与膜形态之间的相关性。在第一个申请期间，我们开发了一组独特的工具，可以在纳米尺度上研究膜结构，并在有机散装异质结太阳能电池中激发态。我们实施并应用了一个光学检测到的磁共振设置，并在共轭聚合物RR-P3HT（区域性常规多甲基噻吩）中发现了与三胞胎激子形成不同空间范围的惊喜结果。三胞胎激子通常被认为是有机光伏的损失因子。我们确定了这些三胞胎状态的空间范围，范围从少数Ångstrom（分子三重态激子）到几种纳米。后者我们识别有机太阳能电池中自由电荷的前体状态的CT激子或二极管对，因此对于它们的性能至关重要。不同的三胞胎状态根据膜的形态发生，我们通过基于扫描力显微镜（SFM）纳米摄影研究了膜的形态。 SFM纳米摄影首次通过开发合适的血浆蚀刻食谱来研究共轭聚合物和供体 - 受体混合物。到目前为止，我们以10 nm的p3HT分辨率：PCBM混合物进行了3D体积成像。尽管第一个提案期的结果是新颖且有趣的，但三胞胎状态的微观性质仍未解决。