Design of benzotriazole-based A₂-A₁-D-A₁-A₂-type fully non-fused non-fullerene acceptors for P3HT

Designing fitted acceptors for the homopolymer poly(3-hexylthiophene) (P3HT) has been a hot topic in research field of organic solar cells (OSCs) because of its unique advantages of low-cost, stability and simplicity of synthesis. In resent years, we have been committed to the development of fused non-fullerene acceptors (NFA) containing benzotriazole (BTA) unit in order to achieve high power conversion efficiency (PCE). The modulation of the crystallinity of P3HT in the active layer affecting exciton dissociation, charge transfer and recombination has always been a challenge. Here, two simple non-fused NFAs containing BTA with different terminal units were easily prepared. P3HT:BTA31 device delivered an initial PCE of 3.95 % due to the unbalanced charge mobility and adverse trap-assisted recombination. Due to the efficient charge separation and suppressed charge recombination, P3HT:BTA33 device showed an increased PCE of 5.68 %. Our results suggest that these non-fused NFAs are promising candidates for application of P3HT-based OSCs.