Study on interactions among ortho-biphenyl groups in oligothiophene for structural control of bulk heterojunction films

Herein, we synthesized oligothiophene with sterically bulky o-biphenyl groups possessing molecular flexibility. We achieved balance between the morphological control of BHJ films and improvement of the fill factor. In this study, we suggest that improvement of fill factor is attributed to increasing hole mobility and crystallinity by ortho-biphenyl group.