Nonfullerene acceptors (NFAs) have emerged as tremendous materials, efficiently advancing bulk-heterojunction organic solar cells (OSCs) technology. Unlike their fullerene counterparts, NFAs offer the unique advantage of finely tunable electronic energy levels and optical characteristics, which correspond to substantial enhancement in power conversion efficiency of OSCs. Herein, we have introduced a new series of near-infrared NFAs (AY1–AY8) to advance this technology further. Our research deeply investigates the structure–property relationship and thoroughly explores the optical, optoelectronics, photophysical, and photovoltaic characteristics of a synthetic reference molecule (R) and the modeled AY1–AY8 NFAs series. We performed advanced quantum chemical simulations using density functional theory (DFT) and time-dependent DFT methods. Additionally, we also estimated key geometric characteristics such as frontier molecular orbitals, hole–electron overlap, density of states, molecular electrostatic potential, molecular excitation and binding energies, transition density matrix, and reorganizational energy of electrons and holes and compared them with those of a synthetic reference molecule (R). Our findings show that all designed materials (AY1–AY8) exhibit red-shift absorption, improved electronic charge mobility, and low binding and excitation energies compared to R. Notably, these designed materials (AY1–AY8) display significantly narrower electronic energy gaps (E_g 1.89–1.71 eV), indicating enhanced charge shifting from the highest occupied molecular orbital to lowest unoccupied molecular orbital and broadening of the absorption spectrum. Moreover, we also revealed a comprehensive study of the donor/acceptor complex of PTB7-Th/AY8 to understand charge shifting between donor and acceptor molecules. Therefore, we strongly recommend this designed (AY1–AY8) series to the experimentalists for the future development of highly efficient OSC devices.

中文翻译：

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基于4H-环戊基[1,2-b:5,4-b']二噻吩受体的有机太阳能电池近红外小分子系统工程


非富勒烯受体（NFA）已成为一种巨大的材料，有效地推进了本体异质结有机太阳能电池（OSC）技术。与富勒烯同类产品不同，NFA 具有可精细调节电子能级和光学特性的独特优势，这与 OSC 功率转换效率的大幅提高相对应。在此，我们推出了一系列新的近红外 NFA (AY1–AY8)，以进一步推进这项技术。我们的研究深入研究了合成参考分子 (R) 和建模的 AY1-AY8 NFA 系列的结构-性能关系，并彻底探索了光学、光电子学、光物理和光伏特性。我们使用密度泛函理论 (DFT) 和瞬态 DFT 方法进行了高级量子化学模拟。此外，我们还估计了关键的几何特征，如前沿分子轨道、空穴电子重叠、态密度、分子静电势、分子激发和结合能、跃迁密度矩阵以及电子和空穴的重组能，并将它们与合成参考分子 (R)。我们的研究结果表明，与 R 相比，所有设计的材料 (AY1–AY8) 均表现出红移吸收、改进的电子电荷迁移率以及较低的结合能和激发能。值得注意的是，这些设计的材料 (AY1–AY8) 显示出明显更窄的电子能隙（ E _g 1.89–1.71 eV)，表明电荷从最高占据分子轨道向最低未占据分子轨道的转移增强，吸收光谱变宽。 此外，我们还对 PTB7-Th/AY8 供体/受体复合物进行了全面研究，以了解供体和受体分子之间的电荷转移。因此，我们强烈推荐这个设计的（AY1-AY8）系列给实验人员，用于未来高效OSC器件的开发。