Ma Lijiao, Yao Huifeng, Wang Jingwen, Xu Ye, Gao Mengyuan, Zu Yunfei, Cui Yong, Zhang Shaoqing, Ye Long, Hou Jianhui
Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
Angew Chem Int Ed Engl. 2021 Jul 12;60(29):15988-15994. doi: 10.1002/anie.202102622. Epub 2021 Jun 7.
Bulk heterojunctions comprising mixed donor (D) and acceptor (A) materials have proven to be the most efficient device structures for organic photovoltaic (OPV) cells. The bulk morphology of such cells plays a key role in charge generation, recombination, and transport, thus determining the device performance. Although numerous studies have discussed the morphology-performance relationship of these cells, the method of designing OPV materials with the desired morphology remains unclear. Herein, guided by molecular electrostatic potential distributions, we have established a connection between the chemical structure and bulk morphology. We show that the molecular orientation at the D-A interface and the domain purity in the blend can be effectively modulated by modifying the functional groups. Enhancing the D-A interaction is beneficial for charge generation. However, the resulting low domain purity and increased charge transfer ratio in its hybridization with the local excitation states lead to severe charge recombination. Fine-tuning the bulk morphology can give balanced charge generation and recombination, which is crucial for further boosting the efficiency of the OPV cells.
由混合供体（D）和受体（A）材料组成的本体异质结已被证明是有机光伏（OPV）电池中最有效的器件结构。此类电池的本体形态在电荷产生、复合和传输中起关键作用，从而决定器件性能。尽管众多研究已讨论了这些电池的形态与性能关系，但设计具有所需形态的OPV材料的方法仍不明确。在此，以分子静电势分布为指导，我们建立了化学结构与本体形态之间的联系。我们表明，通过修饰官能团可以有效调节D - A界面处的分子取向以及共混物中的域纯度。增强D - A相互作用有利于电荷产生。然而，由此产生的低域纯度以及其与局部激发态杂化时增加的电荷转移率会导致严重的电荷复合。微调本体形态可实现电荷产生和复合的平衡，这对于进一步提高OPV电池的效率至关重要。
