A series of narrow bandgap electron acceptors is designed and synthesized for efficient near‐infrared (NIR) organic solar cells. Extending π‐conjugation of donor frameworks leads to an intense intramolecular charge transfer, resulting in broad absorption profiles with band edge reaching 950 nm. When blended with an electron donor polymer PTB7‐Th, IOTIC‐2F exhibits efficient charge transfer even with a small energetic offset, so as to achieve a large photogenerated current over 22 mA cm⁻² with small energy losses (≈0.49 eV) in solar cell devices. With an intense NIR absorbance, PTB7‐Th:IOTIC‐2F‐based cells achieve a power conversion efficiency of 12.1% with good visible transparency (52% transmittance from 370 to 740 nm). Analysis of film morphology reveals that processing with solvent additives enhances crystalline features of acceptor components, while keeping an appropriate level of donor:acceptor intermixing in the binary blends. The incorporation of the third component, ITIC‐2F, into the PTB7‐Th:IOTIC‐2F blends increases the device efficiency up to 12.9%. The improvement is assigned to the cascaded energy‐level structure and desirable nanoscale phase separation of the ternary blends, which is beneficial to the photocurrent generation. This work provides an efficient molecular design strategy to optimize nonfullerene acceptor properties for efficient NIR organic photovoltaics.

中文翻译：

---

具有近红外光吸收能力的非富勒烯受体的设计

设计和合成了一系列窄带隙电子受体，用于高效的近红外（NIR）有机太阳能电池。扩展供体骨架的π共轭会导致强烈的分子内电荷转移，从而导致宽吸收谱，带边缘达到950 nm。与电子给体聚合物PTB7-Th混合时，即使在能量偏移较小的情况下，IOTIC-2F仍能显示出有效的电荷转移，从而可在22 mA cm ^{-2的范围内}获得较大的光生电流在太阳能电池设备中的能量损失很小（≈0.49eV）。基于PTB7-Th：IOTIC-2F的电池具有很强的近红外吸收率，实现了12.1％的功率转换效率，并具有良好的可见透明性（从370到740 nm的透射率为52％）。对膜形态的分析表明，使用溶剂添加剂进行处理可增强受体组分的晶体特征，同时在二元共混物中保持适当水平的供体：受体混合。将第三种成分ITIC-2F掺入PTB7-Th：IOTIC-2F混合物中可使设备效率提高高达12.9％。改进归因于三元共混物的级联能级结构和理想的纳米级相分离，这有利于光电流的产生。