Direct Arylation Polycondensation-Derived Polythiophene Achieves Over 16% Efficiency in Binary Organic Solar Cells via Tuning Aggregation and Miscibility

Polythiophenes are the most appealing donor materials in organic solar cells (OSCs) due to their simple chemical structures. However, the top-performance polythiophenes are typically synthesized via Stille polycondensation, which is problematic due to significant toxicity and poor atom economy. By contrast, direct arylation polycondensation (DArP) is an eco-friendly, and atom-efficient alternative for synthesizing conjugated polymers, while the best efficiency for DArP-derived polythiophenes is below 12%. This study reports a series of polythiophene-based donors synthesized via DArP. Among these, PT4F-Th reaches a power conversion efficiency (PCE) of 16.4%, which not only matches the current record for polythiophene-based donor materials, but also marks the highest PCE achieved by DArP-derived donors to date. The superior performance of PT4F-Th is largely attributed to its optimal temperature-dependent aggregation behavior and moderate miscibility with acceptors, along with the highest crystallinity among the candidates, resulting in the most favorable blend film morphology. This study underscores the significant potential of DArP-derived polythiophenes in developing high-performance and eco-friendly OSCs. A series of polythiophene-based donors are synthesized using direct arylation polycondensation (DArP), highlighting PT4F-Th, which achieves an outstanding power conversion efficiency (PCE) of 16.4% in binary organic solar cells (OSCs). This efficiency sets a new record for DArP-derived donors. Blend film morphology is characterized by X-ray scattering and microscopy, emphasizing the synergistic effects of temperature-dependent aggregation behavior and miscibility. image