Correlation of Local Isomerization Induced Lateral and Terminal Torsions with Performance and Stability of Organic Photovoltaics

作者：Fan, Baobing; Gao, Wei; Zhang, Rui; Kaminsky, Werner; Lin, Francis R.; Xia, Xinxin; Fan, Qunping; Li, Yanxun; An, Yidan; Wu, Yue; Liu, Ming; Lu, Xinhui; Li, Wen Jung; Yip, Hin-Lap; Gao, Feng; Jen, Alex K. -Y.^*

来源：Journal of the American Chemical Society, 2023, 145(10): 5909-5919.

DOI：10.1021/jacs.2c13247

• ACCEPTORS

Organic photovoltaics (OPVs) have achieved great progress in recent years due to delicately designed non-fullerene acceptors (NFAs). Compared with tailoring of the aromatic heterocycles on the NFA backbone, the incorporation of conjugated side-groups is a cost-effective way to improve the photoelectrical properties of NFAs. However, the modifications of side-groups also need to consider their effects on device stability since the molecular planarity changes induced by side-groups are related to the NFA aggregation and the evolution of the blend morphology under stresses. Herein, a new class of NFAs with localisomerized conjugated side-groups are developed and the impact of local isomerization on their geometries and device performance/stability are systematically investigated. The device based on one of the isomers with balanced side- and terminal-group torsion angles can deliver an impressive power conversion efficiency (PCE) of 18.5%, with a low energy loss (0.528 V) and an excellent photo- and thermal stability. A similar approach can also be applied to another polymer donor to achieve an even higher PCE of 18.8%, which is among the highest efficiencies obtained for binary OPVs. This work demonstrates the effectiveness of applying local isomerization to fine-tune the side-group steric effect and non-covalent interactions between side-group and backbone, therefore improving both photovoltaic performance and stability of fused ring NFA-based OPVs.

• 单位
  西安交通大学