Completely Non‐Fused Low‐Cost Acceptor Enables Organic Photovoltaic Cells with 17 % Efficiency

Abstract To meet the industrial requirements of organic photovoltaic (OPV) cells, it is imperative to accelerate the development of cost‐effective materials. Thiophene‐benzene‐thiophene central unit‐based acceptors possess the advantage of low synthetic cost, while their power conversion efficiency (PCE) is relatively low. Here, by incorporating a para ‐substituted benzene unit and 1 st ‐position branched alkoxy chains with large steric hindrance, a completely non‐fused non‐fullerene acceptor, TBT‐26, was designed and synthesized. The narrow band gap of 1.38 eV ensures the effective utilization of sunlight. The favorable phase separation morphology of TBT‐26‐based blend film facilitates the efficient exciton dissociation and charge transport in corresponding OPV cell. Therefore, the TBT‐26‐based small‐area cell achieves an impressive PCE of 17.0 %, which is the highest value of completely non‐fused OPV cells. Additionally, we successfully demonstrated the scalability of this design by fabricating a 28.8 cm 2 module with a high PCE of 14.3 %. Overall, our work provides a practical molecular design strategy for developing high‐performance and low‐cost acceptors, paving the way for industrial applications of OPV technology.