Synthesis, Characterization, Charge Transport, and Photovoltaic Properties of Dithienobenzoquinoxaline- and Dithienobenzopyridopyrazine-Based Conjugated Polymers

Two donor acceptor polymers (P1 and P2) based on dithienobenzoquinoxaline (M1) and dithienobenzopyridopyrazine (M2) as acceptor and indacenodithiophene as donor were synthesized via Stile polycondensation. The fused dithienobenzene unit in M1 and M2 units can improve the intermolecular stacking of polymer and also decrease the steric hindrance. P1, with dithienobenzoquinoxaline acceptor, shows a band gap of 1.61 eV. The band gap of P2 was reduced to 1.48 eV after changing to dithienobenzopyridopyrazine as the acceptor unit. The mobilities of P1 and P2 reach 5.6 x 10(-2) and 1.5 x 10(-2) cm V(-1) s(-1), respectively. The results from photovoltaic measurements showed a very promising PCE of 6.06% for the P1/PC(71)BM blend system without any thermal or solvent treatments, showing a great offer for the roll-to-roll manufacturing of PSCs.