Ma Shanshan, Wu Shihao, Zhang Jie, Song Yu, Tang Haoran, Zhang Kai, Huang Fei, Cao Yong
Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, People's Republic of China.
ACS Appl Mater Interfaces. 2020 Nov 18;12(46):51776-51784. doi: 10.1021/acsami.0c19033. Epub 2020 Nov 6.
The reduction of energy offsets between donors and acceptors is a direct way to improve the open-circuit voltage () and overall performance of organic solar cells (OSCs). In this work, two nonfullerene acceptors (NFAs) (BDTBO-4F and BDTBO-4Cl) were synthesized, which were composed of a heptacyclic ,-heteroacene core and terminal units with halogen atoms, where the latter modulates the energy level of the frontier molecular orbital. Consequently, BDTBO-4Cl exhibited a deeper highest occupied molecular orbital level () and lowest unoccupied molecular orbital level () than BDTBO-4F. Moreover, these two NFAs exhibited high electron mobility and strong absorption at 700-900 nm. The polymer donor PM6 was combined with BDTBO-4F and BDTBO-4Cl, and the resulting OSCs exhibited outstanding power conversion efficiencies of 14.83% for the PM6:BDTBO-4F device and 13.87% for the PM6:BDTBO-4Cl device. More encouragingly, these OSCs exhibited efficient hole transfer from NFAs to PM6, despite small Δ values (<0.10 eV). These results prove that modulation of of acceptors to decrease Δ is an efficient strategy for high-performance OSCs.
减小供体和受体之间的能量差是提高有机太阳能电池（OSC）开路电压（）和整体性能的直接方法。在这项工作中，合成了两种非富勒烯受体（NFA）（BDTBO-4F和BDTBO-4Cl），它们由七环、-杂并苯核心和带有卤素原子的末端单元组成，后者调节前沿分子轨道的能级。因此，BDTBO-4Cl比BDTBO-4F表现出更深的最高占据分子轨道能级（）和最低未占据分子轨道能级（）。此外，这两种NFA在700-900nm处表现出高电子迁移率和强吸收。聚合物供体PM6与BDTBO-4F和BDTBO-4Cl相结合，所得的OSC对于PM6:BDTBO-4F器件表现出14.83%的出色功率转换效率，对于PM6:BDTBO-4Cl器件表现出13.87%的出色功率转换效率。更令人鼓舞的是，尽管Δ值较小（<0.10eV），这些OSC仍表现出从NFA到PM6的有效空穴转移。这些结果证明，调节受体的以减小Δ是用于高性能OSC的有效策略。
