Enhance the performance of polymer solar cells via extension of the flanking end groups of fused ring acceptors

• 来源期刊: 中国科学:化学（英文版）
• 年，卷（期）: 2018,（10）
• 页码范围: 1320-1327
• 页数: 8页
• 语种: 英文

摘要

Two new fused ring electron acceptors (FREAs) IDT-IC-T and IDT-IC-B with thienyl or phenyl substituents at the terminal INCN unit are synthesized.Theoretical calculations indicate that the two acceptors dominantly favor an intermolecular π-π stacking between the flanking terminal groups.The twist angle between the aryl substituent and INCN unit has a significant influence on the π-π stacking distance of terminal unit.IDT-IC-T with a smaller twist angle has a shorter π-π stacking distance than that of IDT-IC-B with a larger twist angle.In addition,extending the conjugation also affects the blend film morphology.IDT-IC-T and IDT-IC-B based photoactive films show appropriate nanoscale phase separations;whereas,blend films based on the parent compound IDT-IC show large-size acceptor domains.As expected,PBDB-T:IDT-IC-T blend films show higher and more balanced electron and hole mobilities.Moreover,these two acceptors present a good charge-transport connectivity arising from the extended conjugation and the increased intermolecular overlapping.Ultimately,IDT-IC-T demonstrates the highest electron mobility (1.47× 10-4 cm2 V-1s-1) and the best power conversion efficiency (PCE) of 9.43％.As for IDT-IC,which only shows an electron mobility of 7.33×10-5 cm2 V-1 s-1 and a PCE of 5.82％.These findings provide a facile and effective way to improve the photovoltaic performance.