Tuning Polymer-Acceptor Backbone Coplanarity and Conformational Rigidity to Achieve High-Performance Printed All-Polymer Solar Cells with Reduced Charge Recombination

Compared with small-molecule acceptors (SMAs) based polymer solar cells, all-polymer solar cells (all-PSCs) comprising both polymer donor and polymer acceptor offer superior morphological and mechanical stability as well as a broader processing window. However, current performances of all-PSCs are still inferior to those of SMA systems, mainly because of the scarcity of high performing polymer acceptors relative to the diverse SMAs. Herein, we report a high-performance polymer acceptor incorporating intramolecular noncovalent interlocking effect that leads to a more coplanar and rigid molecular conformation compared to the polymer acceptors based on commonly used thiophene-based linkers. As a result, this new polymer shows a better backbone conjugation and tighter interchain π-stacking, leading to all-PSCs with higher charge-transport mobility and reduced energetic disorder. Furthermore, detailed morphology and photophysical investigations reveal that such blend exhibits a good balance between polymer miscibility and domain purity, thus leading to a more suppressed charge recombination and higher current density and fill factor. Overall, a significantly higher efficiency of 15.6% is achieved respect to control system (9.8%). Moreover, a remarkable efficiency of 14% is demonstrated for the solution-sheared All-PSCs under ambient conditions, which is a record-high value for devices made under conditions relevant to the real-life printing technologies. This study reveals the potential of noncovalent interlocking effect to construct polymer acceptors with more coplanar and rigid chain conformation, which are desirable properties to achieve superior All-PSCs.