The rise of polythiophene photovoltaics

Compared with prevailing photovoltaic polymers with complex structures and tedious synthesis, polythiophenes possess a greater commercial promise. However, their photovoltaic performances are rather poor due to mismatched energy levels and unfavorable mixing with state-of-the-art non-fullerene acceptors. In a recent Joule article, Duan and colleagues developed a new series of polythiophene-based donors (P5TCN-Fx) via just four steps and achieved a record-high efficiency that surpasses 17%. Furthermore, both polymer solubility and molecular miscibility were found to play crucial roles in achieving this unprecedented performance. The future perspectives are discussed.