Wei Yi, Liang Ningning, Jiang Wei, Zhai Tianrui, Wang Zhaohui
Key Laboratory of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing, 100084, China.
Institute of Information Photonics Technology, Faculty of Science, Beijing University of Technology, Beijing, 100124, China.
Small. 2022 Jan;18(4):e2104060. doi: 10.1002/smll.202104060. Epub 2021 Nov 25.
Molecular carbon imides, especially extended perylene diimides (PDIs) have been the best wide-band-gap nonfullerene acceptors. Despite their excellent photothermal/chemical stability, flexible reaction sites, and unique photoelectronic properties, there is still a lack of fundamental understanding of their molecular characteristics as a third component. Here, generations of PDIs with distinctive molecular architecture, are deliberately screened out as the third component to PM6:Y6. Only a rylene-fullerene hybrid, S-Fuller-PMI, surprisingly boosts the fill factor (FF) of ternary organic solar cells (OSCs) to 0.77 from 0.72 for PM6:Y6 binary ones, and therefore the power conversion efficiency (PCE) of ternary cells is enhanced from 15.3% to 16.2%. Compared with highly-flexible rylene dimer and rigid multimer, S-Fuller-PMI exhibits higher electron mobility, favorable surface tension, and, therefore tailored compatibility with Y6. These formed Y6:S-Fuller-PMI alloys play as a morphological controller to improve charge separation and transport process. Simultaneously, the suppressed photothermal-induced traps, along with inherent enlarged entropy effect, endow the ternary OSCs still with ≈70% of initial PCE even after 500 h continuous illumination, whereas only 53% is left in their binary counterparts. These results provide new insight into the molecular design principle for distinctive molecular carbon imides as the third component for efficient and durable PM6:Y6-based OSCs.
分子碳酰亚胺，尤其是扩展苝二酰亚胺（PDIs），一直是最佳的宽带隙非富勒烯受体。尽管它们具有出色的光热/化学稳定性、灵活的反应位点和独特的光电特性，但作为第三组分，人们对其分子特性仍缺乏基本了解。在此，特意筛选出几代具有独特分子结构的PDIs作为PM6:Y6的第三组分。令人惊讶的是，只有一种苝-富勒烯杂化物S-Fuller-PMI将三元有机太阳能电池（OSCs）的填充因子（FF）从PM6:Y6二元电池的0.72提高到了0.77，因此三元电池的功率转换效率（PCE）从15.3%提高到了16.2%。与高柔韧性的苝二聚体和刚性多聚体相比，S-Fuller-PMI表现出更高的电子迁移率、良好的表面张力，因此与Y6具有合适的相容性。这些形成的Y6:S-Fuller-PMI合金起到形态控制器的作用，以改善电荷分离和传输过程。同时，抑制的光热诱导陷阱以及固有的熵增效应，使三元OSCs即使在连续光照500小时后仍保持约70%的初始PCE，而其二元对应物仅剩下53%。这些结果为独特分子碳酰亚胺作为高效耐用的基于PM6:Y6的OSCs的第三组分的分子设计原则提供了新的见解。
