Oligomer‐Assisted Photoactive Layers Enable >18?% Efficiency of Organic Solar Cells

作者：Cheng Yujun; Huang Bin; Huang Xuexiang; Zhang Lifu; Kim Seoyoung; Xie Qian; Liu Chao; Heumüller Thomas; Liu Zuoji; Zhang Youhui; Wu Feiyan; Yang Changduk; Brabec Christoph J.; Chen Yiwang; Chen Lie

来源：Angewandte Chemie, 2022, 134(21).

DOI：10.1002/ANGE.202200329

• Organic Solar Cells
• Performance
• Stability

Although ternary organic solar cells (OSCs) have unique advantages in improving device performance, the morphology assembly in the ternary‐phase would be more uncertain or complex than that in the binary‐phase. Here, we propose a new concept of oligomer‐assisted photoactive layers for high‐performance OSCs. The formed alloy‐like phase of the oligomer?:?host polymer blend enabled the oligomer‐assisted OSCs to fuse the advantages of both binary and ternary devices, exhibiting substantially enhanced performance and stability compared to the control devices. With the addition of oligomers, outstanding efficiencies of 17.33?% for a PM6?:?Y6 device, 18.32?% for a PM6?:?BTP‐eC9 device, and 17.13?% for a PM6/Y6 pseudo‐bilayer device were achieved, all of which are one of the highest values in their corresponding fields. The improved performance originated from the downshift energy levels, enhanced light absorption, optimized blend morphology, favorable charge dynamics, and reduced non‐radiative energy loss.(#br)A new concept of oligomer‐assisted high‐performance organic solar cells (OSCs) was proposed. Developing the oligomer‐assisted OSCs is a facile and general strategy with the combination of the advantages of both binary and ternary devices, which enables >18?% device efficiency together with improved stability.