Effects of Oxygen Atoms Introduced at Different Positions of Non-Fullerene Acceptors in the Performance of Organic Solar Cells with Poly(3-hexylthiophene)

With the development of large-area fabrication technologies for organic solar cells (OSCs), poly­(3-hexylthiophene) (P3HT) is the best choice as a photovoltaic donor polymer because it can be easily synthesized in the scale of kilograms at low cost. However, non-fullerene acceptors (NFAs) matching with P3HT for high performance OSCs are very rare. Herein, by introducing oxygen atoms into the side chains or the fused-ring core of indaceno­[1,2-b:5,6-b′]­dithiophene, we synthesized two new A₂–A₁–D–A₁–A₂ type NFAs, where benzotriazole (BTA) and 2-(1,1-dicyanomethylene)­rhodanine were used as the bridged A₁ and terminal A₂, respectively. The final NFAs, named BTA43 and BTA53, show wider absorption spectra and enhanced intermolecular/intramolecular interaction in comparison with their analogue BTA3 without oxygen atoms. The photovoltaic devices based on P3HT:BTA43 and P3HT:BTA53 can achieve a high power conversion efficiency of 6.56 and 6.31%, respectively, which are obviously higher than that of BTA3 (5.64%). Our results provide a simple and effective strategy to design promising NFAs to pair with the classic photovoltaic polymer P3HT.