A-DA′D-A-Type Non-fullerene Acceptors Containing a Fused Heptacyclic Ring for Poly(3-hexylthiophene)-Based Polymer Solar Cells

A-DA'D-A-type non-fullerene acceptors (NFAs) based on a fused heptacyclic DA'D ring have shown outstanding performance upon blending with a variety of polymer donors in polymer solar cells recently. However, the application of these NFAs pairing with the cheapest photovoltaic polymer of poly(3-hexylthiophene) (P3HT) was less reported. Here, we use two reported A-DA'D-A-type NFAs, Y6 and Y5, together with a new synthesized molecule of TPBT-RCN to extend the application of these kinds of materials. The photovoltaic device of P3HT:TPBT-RCN exhibits an improved power conversion efficiency (PCE) of 5.11% in comparison with Y6 (PCE = 2.41%) and Y5 (PCE = 3.60%) devices. The better performance of P3HT:TPBT-RCN originates from the suitable energy levels and phase-separation morphology, which contribute to the higher open-circuit voltage and fill factor. Our results demonstrate that the A-DA'D-A-type NFAs are also promising candidates to combine with P3HT, but the terminal unit plays a vital role and should be fine-tuned.