Nonfullerene acceptors (NFAs) are a new focus in organic photovoltaics (OPVs), and continue to progress upon the drawbacks of many fullerene-based electron acceptors. The aim of this work is to identify some important parameters that influence the efficiency of NF-acceptors in OPVs. These results provide an enhanced understanding of the effect of the NFAs core structure (electron rich/poor group) on the photophysical and optoelectronic properties. In addition, the effect of the small ΔLUMO value (the subtle difference in energy between LUMO+1 and LUMO orbitals of NFAs; LUMO=lowest unoccupied molecular orbitals) on ultrafast charge transfer and charge separation processes in OPVs, recently identified as a key factor for all top rated high performing NFAs, is studied. So far, ΔLUMO-based theoretical studies are limited to individual NFAs; here, for the first time, the authors have extended to the respective donor/acceptor complexes as well. Finally, based on the first-principles density functional theory calculations with the seven reported NFAs, ${\mathrm{PC}}_{61}\mathrm{BM}$, P3HT, and the seven newly modeled donor–acceptor complexes, this study sheds light on important factors that will provide trends and guidelines for further rational design of more efficient NF-acceptors for OPVs.

中文翻译：

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了解核结构和能级调节对有机太阳能电池中非富勒烯受体效率影响的理论研究

非富勒烯受体 (NFA) 是有机光伏 (OPV) 中的一个新焦点，并且在许多基于富勒烯的电子受体的缺点上继续取得进展。这项工作的目的是确定一些影响 OPV 中 NF 受体效率的重要参数。这些结果提供了对 NFA 核心结构（富电子/贫电子基团）对光物理和光电特性影响的更好理解。此外，小 ΔLUMO 值（NFA 的 LUMO+1 和 LUMO 轨道之间的能量差异；LUMO=最低未占分子轨道）对 OPV 中超快电荷转移和电荷分离过程的影响，最近被确定为一个关键因素对所有顶级高性能 NFA 进行了研究。到目前为止，基于 ΔLUMO 的理论研究仅限于单个 NFA；这里，作者还首次扩展到各自的供体/受体复合物。最后，基于第一性原理密度泛函理论计算与七个报道的 NFA，${\mathrm{个人电脑}}_{61}\mathrm{BM}$、P3HT 和七个新建模的供体 - 受体复合物，这项研究揭示了重要因素，将为进一步合理设计更有效的 OPV NF 受体提供趋势和指导。