利用和频光谱技术研究有机太阳能电池中极性分子界面膜的工作机制

Organic solar cell (OSC) technology has attracted much attention as a potentially cost-effective way to harvest solar energy. An important approach to improve the performance of OSCs is to insert a proper polar-molecule interfacial layer (PMIL) between the electrode and the photoactive layer. However, there still lacks a deep understanding of the working mechanism of the PMIL. In this project, sum frequency generation (SFG) spectroscopy will be explored to study the orientation behavior of several different polar molecules during the formation of the corresponding PMIL, and the charge redistribution among the electrode/PMIL/active layer will be also surveyed. The key factors that influence the molecular orientation and charge redistribution will be elucidated in the aspects of molecular structure, substrate, and film fabrication protocols, respectively. Combined with energy band characterizations, the origin of the built-in potential in PMILs will be revealed. Furthermore, in-situ SFG measurements will be performed to study the molecular stability of PMIL during the operation of the solar cell. The obtained results will be useful for the design and fabrication of novel PMILs with improved performance.

有机太阳能电池技术作为一种潜在的廉价获取能源的手段而备受人们关注。在电极与活性层之间插入一层极性分子界面膜是改善有机太阳能电池性能的重要途径，而人们对此类界面膜的工作机制仍缺乏深入的了解。本项目拟针对几种不同的极性分子材料，利用和频光谱技术表征界面膜形成过程中极性分子的取向化行为以及电极/极性分子膜/活性层间的电荷重新分布情况，从分子结构、基底、制膜工艺等不同层面揭示影响极性分子取向性和界面电荷分布的主要因素；进而结合能带结构表征，探究极性分子膜中内建电势差的形成机制和调控途径；我们还将原位表征器件工作条件下极性界面膜分子状态的变化情况，探究极性界面膜的功能退化机制。本项目的研究成果有助于指导人们更好的设计和构筑极性分子界面膜，推动新型有机太阳能电池的研发。

极性分子界面层是新一代有机太阳能电池的重要组成部分，但其工作机制仍不清晰。本项目中，我们制备了便于进行和频光谱测试的有机太阳能电池模型器件，发展了解析提取多界面体系相干光谱信号的方法，建立了一种将和频光谱与载流子瞬态谱技术联用的新型原位测试手段；利用所发展的技术和方法，原位或非原位表征了一系列不同分子结构的极性界面膜中极性分子的取向化行为、界面电荷分布状态、工况下的动态变化，从分子角度厘清了膜内建电势差的形成机制和功能退化机制，并揭示了其关键影响因素和调控途径。以上工作将有助于推动高效有机太阳能电池的研发。