Acta Phys. -Chim. Sin. ›› 2025, Vol. 41 ›› Issue (3): 100027.doi: 10.3866/PKU.WHXB202406007

• ARTICLE • Previous Articles     Next Articles

Thickness-Insensitive, Cyano-Modified Perylene Diimide Derivative as a Cathode Interlayer Material for High-Efficiency Organic Solar Cells

Yikai Wang1, Xiaolin Jiang2, Haoming Song1, Nan Wei1, Yifan Wang2, Xinjun Xu1, Cuihong Li1,*(), Hao Lu2,*(), Yahui Liu2,*, Zhishan Bo1,*()   

  1. 1 Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875, China
    2 College of Textiles & Clothing, State Key Laboratory of Bio-fibers and Eco-textiles, Qingdao University, Qingdao 266071, Shandong Province, China
  • Received:2024-06-06 Revised:2024-07-10 Accepted:2024-07-11 Published:2024-12-14
  • Contact: Email: licuihong@bnu.edu.cn (Cuihong Li)luhao@qdu.edu.cn (Hao Lu)liuyh@qdu.edu.cn (Yahui Liu)zsbo@bnu.edu.cn (Zhishan Bo)
  • Supported by:
    the National Natural Science Foundation of China(22375024); the National Natural Science Foundation of China(21975031); the National Natural Science Foundation of China(51933001); the National Natural Science Foundation of China(21734009)

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Abstract:

Interlayer materials play a crucial role in achieving high efficiency in organic solar cells (OSCs). However, slight increases in film thickness often lead to significant charge accumulation and recombination, presenting a challenge for large-scale OSC device fabrication. Therefore, there is a pressing need for interlayer materials that are insensitive to variations in thickness. In this study, we synthesized a cost-effective cyano-modified perylene diimide (PDI) derivative, PDINBrCN, as an interlayer material. Compared to the analogous PDINBr, the introduction of cyano groups lowers the lowest unoccupied molecular orbital (LUMO) energy level of the molecule, enhancing electron injection and charge transport efficiency. Additionally, PDINBrCN demonstrates excellent solubility in 2, 2, 2-trifluoroethanol (TFE) and effectively modifies the electrode work function, facilitating device fabrication through orthogonal solvent processing. When utilized as the cathode interlayer in D18:L8-BO devices, PDINBrCN achieved a high power conversion efficiency (PCE) of 18.83% with a film thickness of 10 nm. Importantly, PDINBrCN maintained a PCE of 17.90% even when the film thickness was increased to 50 nm. In contrast, the analogous PDI derivatives PDINBr and the star cathode interlayer material anthra[2, 1, 9-def: 6, 5, 10-d'e'f']diisoquinoline-1, 3, 8, 10(2H, 9H)-tetrone (PDINN) achieved PCEs of 17.17% and 17.06%, respectively, at the same film thickness. Notably, PDINBrCN maintained a PCE of over 16% even with an interlayer thickness of 80 nm, marking one of the best results for small molecule PDI derivatives as cathode interlayer materials at this thickness. Our findings demonstrate that PDINBrCN exhibits excellent processability, electrode work function adjustment capability, and crucially, thickness-insensitive properties. Therefore, PDINBrCN holds promise as an efficient and cost-effective cathode interlayer material, with potential for future commercial applications in OSCs.

Key words: Cathode interlayer material, Organic solar cell, Power conversion efficiency, Thickness-insensitive property, Cyano group