Novel Pyrrolo [3,4-b] Dithieno [3, 2-f:2″,3″-h] Quinoxaline-8,10 (9H)-Dione Based Wide Bandgap Conjugated Copolymers for Bulk Heterojunction Polymer Solar Cells

Two D-A copolymers consisted of fused ring pyrrolo-dithieno-quinoxaline acceptor are synthesized with different donor units, i.e., benzodithiophene (BDT) with alkylthienyl (P134) and 2-ethylhexyloxy (P117) side chains. These copolymers are used as donor and a narrow bandgap acceptor Y6 to fabricate bulk heterojunction polymer solar cell devices. Owing to the strong electron-deficient fused ring pyrrolo-bithieno-quinoxaline and weak alkyl thienyl side chains in BDT, the polymer solar cells based on P134:Y6 attained the power conversion efficiency of 15.42%, which is higher than P117:Y6 counterpart (12.14%). The superior value of PCE for P134:Y6 could be associated with more well-adjusted charge transport, weak charge recombination, proficient exciton generation and dissociation into free charge carriers and their subsequent charge collection owing to the dense π-π stacking distance and more considerable crystal coherence length for the P134:Y6 thin films. This investigation confirms the great potential of a strong acceptor-weak donor tactic for developing efficient D-A copolymers consists of quinoxaline acceptor for polymer solar cells. This article is protected by copyright. All rights reserved.