Yang Sangjin, Park Jaeyeong, Jeong Seonghun, Cho Yongjoon, Jeong Mingyu, Oh Jiyeon, Lee Seunglok, Park Jeewon, Yoon Seong-Jun, Yang Changduk
School of Energy and Chemical Engineering, Perovtronics Research Center, Low Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulju-gun, Ulsan 44919, South Korea.
Department of Chemistry and Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
ACS Appl Mater Interfaces. 2023 Aug 23;15(33):39636-39646. doi: 10.1021/acsami.3c06596. Epub 2023 Aug 14.
Alongside high power conversion efficiencies (PCEs), device stability, especially thermal issues, is another key factor for the successful commercialization of nonfullerene acceptor (NFA)-based organic solar cells (OSCs). Considering the significant effects of the side-chain engineering of NFAs on molecular packing and/or locking strongly associated with the thermal stability of OSCs, herein, we present two new isomeric NFAs with 4-fluoro- and 2-fluoro-substituted hexylphenyl two-dimensional (2D) outer side chains ( and , respectively). In contrast with the having a horizontal stretching conformation, exhibits a diagonal stretching conformation of the 2D outer side chains and a higher dipole moment, resulting in a huge difference in their crystalline/aggregation characteristics, i.e., possesses a higher crystallinity with a denser molecular packing than the neat film, as evidenced by thermal and morphological characterizations. Encouragingly, relative to the one based on , the OSC based on delivers a PCE as high as 16.4%, together with excellent thermal stability (88.4% PCE retention under 85 °C for 360 h), which is attributed to a more optimal and robust blend morphology induced by its better compatibility into the used donor component and stronger crystallinity. This work demonstrates that in addition to the improved photovoltaic property, the appropriate F-positioning on the 2D outer side chains can play a key role in controlling their conformations, which can promote the increase of the thermal stability of OSCs.
除了高功率转换效率（PCE）之外，器件稳定性，尤其是热稳定性问题，是基于非富勒烯受体（NFA）的有机太阳能电池（OSC）成功商业化的另一个关键因素。考虑到NFA的侧链工程对与OSC热稳定性密切相关的分子堆积和/或锁定有显著影响，在此，我们展示了两种新的异构体NFA，分别带有4-氟和2-氟取代的己基苯基二维（2D）外侧链（分别为 和 ）。与具有水平伸展构象的 相比， 表现出2D外侧链的对角伸展构象和更高的偶极矩，导致它们的结晶/聚集特性有巨大差异，即 比 纯膜具有更高的结晶度和更致密的分子堆积，热学和形态学表征证明了这一点。令人鼓舞的是，相对于基于 的OSC，基于 的OSC的PCE高达16.4%，同时具有出色的热稳定性（在85°C下360小时内PCE保留率为88.4%），这归因于其与所用供体组分更好的相容性和更强的结晶度所诱导的更优化和稳健的共混形态。这项工作表明，除了改善光伏性能外，2D外侧链上适当的氟定位在控制其构象方面可以发挥关键作用，这可以促进OSC热稳定性的提高。
