School of Physics, Shandong University, Jinan 250100, China.
School of Physics and Electrical Engineering, Kashgar University, Kashgar 844000, China.
Molecules. 2022 Dec 18;27(24):9037. doi: 10.3390/molecules27249037.
The fluorination strategy is one of the most efficient and popular molecular modification methods to develop new materials for organic photovoltaic (OPV) cells. For OPV materials, it is a broad agreement that fluorination can reduce the energy level and change the morphology of active layers. To explore the effect of fluorination on small molecule acceptors, we selected two non-fullerene acceptors (NFA) based bulk heterojunction (BHJ) films, involving PM6:Y6 and PM6:Y5 as model systems. The electron mobilities of the PM6:Y5 and PM6:Y6 BHJ films are 5.76 × 10 cmVs and 5.02 × 10 cmVs from the space-charge-limited current (SCLC) measurements. Through molecular dynamics (MD) simulation, it is observed that halogen bonds can be formed between Y6 dimers, which can provide external channels for electron carrier transfer. Meanwhile, the "A-to-A" type J-aggregates are more likely to be generated between Y6 molecules, and the π-π stacking can be also enhanced, thus increasing the charge transfer rate and electron mobility between Y6 molecules.
氟化策略是开发有机光伏 (OPV) 电池新材料最有效和最受欢迎的分子修饰方法之一。对于 OPV 材料，人们普遍认为氟化可以降低能级并改变活性层的形态。为了探索氟化对小分子受体的影响，我们选择了两种基于非富勒烯受体 (NFA) 的体异质结 (BHJ) 薄膜，涉及 PM6:Y6 和 PM6:Y5 作为模型系统。从空间电荷限制电流 (SCLC) 测量中得出，PM6:Y5 和 PM6:Y6 BHJ 薄膜的电子迁移率分别为 5.76×10 cmVs 和 5.02×10 cmVs。通过分子动力学 (MD) 模拟，观察到 Y6 二聚体之间可以形成卤键，这可为电子载流子的转移提供外部通道。同时，Y6 分子之间更容易产生“A-A”型 J-聚集体，并且可以增强π-π堆积，从而提高 Y6 分子之间的电荷转移速率和电子迁移率。
