The electron acceptor materials in organic solar cells (OSCs) play an essential role in enhancing power conversion efficiency (PCE). Although Y6-based nonfullerene acceptors (NFAs) have shown fascinating experimental progress, molecular engineering is an effective strategy for further improvement of PCE. Herein, a series of Y6-based symmetric and asymmetric NFAs are designed using the Y6-based core with various end-group units. The impact of end group units on geometric, electronic, and excited state properties of NFAs is studied using state-of-the-art density functional theory methods. Various selection criteria are used to screen potential NFAs among 18 newly designed NFAs. The interfacial electronic properties between conjugated polymer and NFAs are thoroughly studied in the excited state to analyze the potentiality of screened NFAs. More importantly, the screened asymmetric NFAs have shown improved charge mobilities with a lower charge recombination rate than prototype FRY6. It is noticed that screened NFAs have multiple charge transfer pathways through direct excitation, hot excitons, and intermolecular electric field mechanisms. Overall, the results obtained from this computational study give useful guidance for developing NFAs for high-performance OSCs.

中文翻译：

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新设计的Y系列非富勒烯受体在高效有机太阳能电池中的应用

有机太阳能电池（OSC）中的电子受体材料在提高功率转换效率（PCE）方面发挥着重要作用。尽管基于Y6的非富勒烯受体（NFA）已经显示出令人着迷的实验进展，但分子工程是进一步提高PCE的有效策略。在此，使用具有各种端基单元的基于Y6的核设计了一系列基于Y6的对称和不对称NFA。使用最先进的密度泛函理论方法研究了端基单元对 NFA 的几何、电子和激发态性质的影响。使用各种选择标准在 18 个新设计的 NFA 中筛选潜在的 NFA。在激发态下深入研究了共轭聚合物和 NFA 之间的界面电子特性，以分析筛选的 NFA 的潜力。更重要的是，筛选的不对称 NFA 表现出比原型 FRY6 更高的电荷迁移率和更低的电荷复合率。值得注意的是，筛选的 NFA 通过直接激发、热激子和分子间电场机制具有多种电荷转移途径。总的来说，从这项计算研究中获得的结果为开发高性能 OSC 的 NFA 提供了有用的指导。