Wang Kang, Chen Honggang, Li Shuangyuan, Zhang Jinzhong, Zou Yingping, Yang Ye
State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China.
J Phys Chem B. 2021 Jul 15;125(27):7470-7476. doi: 10.1021/acs.jpcb.1c03989. Epub 2021 Jul 5.
Recently, rapid progress in the power conversion efficiency for organic solar cells (OSCs) is achieved due to the phenomenal development of the nonfullerene electron acceptors. In addition to the pairing electron donors, conjugated donor-acceptor copolymers are another key player in the high-efficiency OSCs. Here, the temporal evolution of excited states in a typical copolymer, PM6, was traced by transient absorption spectroscopy. The spectroscopic result implies the formation of two kinetically correlated intrachain species, polaron excitons and intrachain polaron pairs. In the presence of the interchain interaction, these intrachain species quickly convert into interchain polaron pairs on a time scale of few picoseconds. Our findings reveal that the electron transfer mechanisms in PM6-based OSCs substantially depend on the PM6 environment in the bulk heterojunction blends.
近年来，由于非富勒烯电子受体的显著发展，有机太阳能电池（OSCs）的功率转换效率取得了快速进展。除了配对电子供体外，共轭供体-受体共聚物是高效OSCs中的另一个关键因素。在此，通过瞬态吸收光谱法追踪了典型共聚物PM6中激发态的时间演化。光谱结果表明形成了两种动力学相关的链内物种，极化子激子和链内极化子对。在链间相互作用存在的情况下，这些链内物种在几皮秒的时间尺度上迅速转化为链间极化子对。我们的研究结果表明，基于PM6的OSCs中的电子转移机制在很大程度上取决于本体异质结共混物中的PM6环境。
