Zhu Can, Meng Lei, Zhang Jinyuan, Qin Shucheng, Lai Wenbin, Qiu Beibei, Yuan Jun, Wan Yan, Huang Wenchao, Li Yongfang
Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
School of Chemical Science, University of Chinese Academy of Sciences, Beijing, 100049, China.
Adv Mater. 2021 Jun;33(23):e2100474. doi: 10.1002/adma.202100474. Epub 2021 Apr 29.
Side-chain engineering has been an effective strategy in tuning electronic energy levels, intermolecular interaction, and aggregation morphology of organic photovoltaic materials, which is very important for improving the power conversion efficiency (PCE) of organic solar cells (OSCs). In this work, two D-A copolymers, PBQ5 and PBQ6, are designed and synthesized based on bithienyl-benzodithiophene (BDTT) as the donor (D) unit, difluoroquinoxaline (DFQ) with different side chains as the acceptor (A) unit, and thiophene as the π-bridges. PBQ6 with two alkyl-substituted fluorothiophene side chains on the DFQ units possesses redshifted absorption, stronger intermolecular interaction, and higher hole mobility than PBQ5 with two alkyl side chains on the DFQ units. The blend film of the PBQ6 donor with the Y6 acceptor shows higher and balanced hole/electron mobilities, less charge carrier recombination, and more favorable aggregation morphology. Therefore, the OSC based on PBQ6:Y6 achieves a PCE as high as 17.62% with a high fill factor of 77.91%, which is significantly higher than the PCE (15.55%) of the PBQ5:Y6-based OSC. The PCE of 17.62% is by far one of the highest efficiencies for the binary OSCs with polymer donor and Y6 acceptor.
侧链工程一直是调节有机光伏材料的电子能级、分子间相互作用和聚集形态的有效策略，这对于提高有机太阳能电池（OSC）的功率转换效率（PCE）非常重要。在这项工作中，基于联噻吩-苯并二噻吩（BDTT）作为给体（D）单元、带有不同侧链的二氟喹喔啉（DFQ）作为受体（A）单元以及噻吩作为π桥，设计并合成了两种D-A共聚物PBQ5和PBQ6。在DFQ单元上带有两个烷基取代氟噻吩侧链的PBQ6，与在DFQ单元上带有两个烷基侧链的PBQ5相比，具有红移吸收、更强的分子间相互作用和更高的空穴迁移率。PBQ6给体与Y6受体的共混膜表现出更高且平衡的空穴/电子迁移率、更少的电荷载流子复合以及更有利的聚集形态。因此，基于PBQ6:Y6的OSC实现了高达17.62%的PCE以及77.91%的高填充因子，这显著高于基于PBQ5:Y6的OSC的PCE（15.55%）。17.62%的PCE是目前聚合物给体和Y6受体二元OSC的最高效率之一。
