A2-A1-DA1D-A1-A2-Type Non-Fullerene Acceptors for Poly(3-hexylthiophene)-Based Organic Photovoltaic Application

In virtue of unique advantages of low cost, stability, and simple synthesis, the homopolymer poly(3-hexylthiophene) (P3HT) shows great potential in the field of organic photovoltaics (OPV) for large-area fabrication. Designing non-fullerene acceptors (NFAs) for P3HT has always been a hot topic of P3HT research, which has not yet met the power conversion efficiency (PCE) required for commercialization. Our group is the first to focus on A2-A1-D-A1-A2-type NFAs with benzotriazole (BTA) as the A1 unit used in the P3HT system and has contributed to the development of P3HT-based OPVs. Herein, we first introduce a DAD ladder-type fused core into the A2-A1-D-A1-A2-type NFAs and synthesize two A2-A1-DA1D-A1-A2-type NFAs (BTA91 and BTA93) with different end-capping A2 groups. With a red-shifted absorption spectrum and appropriate blend morphology, the P3HT:BTA93 device achieved an improved PCE of 5.46% compared to that of P3HT:BTA91 (2.03%). In summary, the fused central core in the A2-A1-DA1D-A1-A2-type NFAs would be a great promise for P3HT devices, and fine-tuning the structure remains key to improve the device performance since the crystallization behavior of P3HT blends is difficult to control completely.