Polythiophene Derivatives for Efficient All-Polymer Solar Cells

Polymerized small molecule acceptors have recently greatly facilitated the development of all-polymer solar cells (All-PSCs) with respect to the power conversion efficiencies (PCEs). However, high-performance and low-cost polymer donors for All-PSCs are still lacking, limiting further large-scale manufacturing of All-PSCs. Herein, this work designs and synthesizes a new thiophene derivative, FETVT, featuring vinyl-bridged fluorine and ester-substituted monothiophene. Incorporation of FETVT into a polymer yields a high-performance polythiophene derivative PFETVT-T, which exhibits deep-lying HOMO level, suitable solution pre-aggregation ability, finely-tuned polymer crystallinity, and appropriate thermodynamic miscibility with the polymer acceptor L15. As a result, binary based on PFETVT-T achieves a record PCE of 11.81% with agood stability, representing a breakthrough for polythiophenes and their derivatives-based All-PSCs, which is also significantly higher than that (1.92%) of All-PSCs based on its isomerized analog. Remarkably, PFETVT-T achieves an impressive PCE exceeding 16% via the implementation of a ternary blend design. These findings offer a hopeful pathway toward attaining high-performance, stable, and cost-effective PSCs.