通过侧链工程提高A-D-A'-D-A型非稠环电子受体的光伏性能

Enhanced photovoltaic performance of A-D-A’-D-A type non-fused ring electron acceptors via side chain engineering

非稠环电子受体(NFREA)具有合成简单和结构修饰灵活的特点,是制备高性能低成本有机太阳电池(OSCs)的理想材料.本工作以不同侧链修饰的二氟苯并三氮唑(ffBTz)作为弱缺电子核(A’),分别设计合成了三种A-D-A’-D-A型NFREA,即ffBTz-BO、ffBTz-EH和ffBTz-C4.其中,ffBTz-EH,由于其合适的侧链长度,在分子结晶度和分子堆积优势取向之间取得了平衡,从而获得了更高的电荷迁移率.并且得益于高效的电荷传输和最合适的相分离形貌,基于ffBTz-EH的OSC获得12.96%的最高能量转换效率,这也是A-D-A’-D-A型NFREA获得的最高效率之一.本研究表明,A’核心上的烷基侧链在调节分子结晶度、活性层形貌和进一步调控器件性能方面起着至关重要的作用,这为未来设计高效低成本的A-D-A’-D-A型非稠环电子受体提供了思路.

Featuring simplified synthesis and flexible chemical alteration,non-fused ring electron acceptors(NFREAs)are the ideal candidates for constructing low-cost organic solar cells(OSCs).Herein,we report three A-D-A’-D-A type NFREAs,namely ffBTz-BO,ffBTz-EH,and ffBTz-C4,where difluorinated benzotriazole(ffBTz)with different side chain lengths were employed as the weak electron-deficient A’core.Compared with ffBTz-BO and ffBTz-C4,ffBTz-EH with appropriate side chain length strikes a balance between the enhanced molecular crystallinity and the favorable face-on orientation,resulting in high charge mobilities.Consequently,ffBTz-EH-based OSC delivered the highest power conversion efficiency(PCE)of 12.96%enabled by its efficient charge transport and most suitable phase separation,which represents one of the highest efficiencies among A-D-A’-D-A type NFREAs.This work demonstrates that alkyl side chain on the central A’core plays a critical role in tuning molecular crystallinity,active layer morphology,and further device performance,which provides a meaningful perspective for designing highly efficient A-D-A’-D-A type non-fused ring electron acceptors in the future.