| 초록 |
Effect of backbone extension with thiophene-based pi-bridges on intrinsic and photovoltaic properties of electron D-A copolymers were studied systematically. A series of D-A copolymers, PBT (without pi-bridge), PBT-OT (with 3-octylthiophene), and PBT-OTT (with 3-octylthieno[3,2-b]thiophene), based on EHSeBDT as donor moiety and BOTPD as acceptor moiety were synthesized. Incorporation of OTT pi-bridges into PBT, extended the delocalization length along the backbone of the PBT-OTT and strengthened the pi-pi intermolecular interaction between neighboring PBT-OTTs. As a result, absorption coefficient and charge transport properties were significantly enhanced. The PBT-OTT had the best miscibility with PC71BM and the photo-active layers showed interpenetrating bicontinuous networks for better charge separation, and yielded OSCs with high PCE of 7.21 %. These results showed importance of incorporation of OTT pi-bridges into D-A copolymers in developing highly-efficient OSCs. |
