High Performance All-Polymer Solar Cells with the Polymer Acceptor Synthesized via a Random Ternary Copolymerization Strategy.

Demonstrated in this work is a simple random ternary copolymerization strategy to synthesize a series of polymer acceptors, PTPBT-ETx, by polymerizing a small-molecule acceptor unit modified from Y6 with a thiophene connecting unit and a controlled amount of an 3-ethylesterthiophene (ET) unit. Compared to PTPBT of only Y6-like units and thiophene units, PTPBT-ETx(wherexrepresents the molar ratio of the ET unit) with an incorporated ET unit in the ternary copolymers show up-shifted LUMO energy levels, increased electron mobilities, and improved blend morphologies in the blend film with the polymer donor PBDB-T. And the all-polymer solar cell (all-PSC) based on PBDB-T:PTPBT-ET(0.3)achieved a high power conversion efficiency over 12.5 %. In addition, the PTPBT-ET0.3-based all-PSC also exhibits long-term photostability over 300 hours.