A High-Performance D-A Copolymer Based on Dithieno[3,2-b:2 ',3 '-d]Pyridin-5(4H)-One Unit Compatible with Fullerene and Nonfullerene Acceptors in Solar Cells

摘要

Development of high-performance donor-acceptor (D-A) copolymers is vital in the research of polymer solar cells (PSCs). In this work, a low-bandgap D-A copolymer based on dithieno[3,2-b:2',3'-d]pyridin-5(4H)-one unit (DTP), PDTP4TFBT, is developed and used as the donor material for PSCs with PC71BM or ITIC as the acceptor. PDTP4TFBT:PC71BM and PDTP4TFBT: ITIC solar cells give power conversion efficiencies (PCEs) up to 8.75% and 7.58%, respectively. 1,8-Diiodooctane affects film morphology and device performance for fullerene and nonfullerene solar cells. It inhibits the active materials from forming large domains and improves PCE for PDTP4TFBT:PC71BM cells, while it promotes the aggregation and deteriorates performance for PDTP4TFBT:ITIC cells. The ternary-blend cells based on PDTP4TFBT:PC71BM: ITIC (1:1.2:0.3) give a decent PCE of 9.20%.