Achieving optimal morphology and photovoltaic performance without additives remains a prominent challenge in contemporary organic solar cells (OSCs). In this work, we developed three new Y6-derived nonfullerene acceptors (NFAs), namely, BTP-H15, BTP-H13, and BTP-H17, by introducing saturated octyl chains and unsaturated octenyl or octynyl chains to the outer positions of the DA′D core. Compared with the saturated chains, the incorporation of unsaturated chains effectively reduces the spatial steric hindrance between the outer side chains and the fused skeletons, thus enhancing the planarity of the related NFAs. Although BTP-H13 exhibited stronger aggregation than the other two NFAs, the lack of an efficient co-oriented half-skeleton stacking mode resulted in a relatively loose three-dimensional (3D) network structure and poor charge transport characteristics. In contrast, BTP-H15 showcased comprehensive advantages, including optimal framework planarity, close π–π stacking distances, and a robust 3D network, leading to superior morphology and enhanced charge transport. Consequently, the additive-free OSCs based on BTP-H15 realized impressive efficiencies of 18.46% in the binary devices and 19.36% in the ternary devices.

中文翻译：

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具有不饱和烷基侧链的 Y6 衍生非富勒烯受体能够改进分子堆积，实现高效无添加剂有机太阳能电池


在没有添加剂的情况下实现最佳形态和光伏性能仍然是当代有机太阳能电池 （OSC） 面临的一个突出挑战。在这项工作中，我们通过将饱和辛基链和不饱和辛烯或辛炔链引入 DA′D 核心的外部位置，开发了三种新的 Y6 衍生的非富勒烯受体 （NFA），即 BTP-H15、BTP-H13 和 BTP-H17。与饱和链相比，不饱和链的掺入有效降低了外侧链与融合骨架之间的空间空间位阻，从而增强了相关 NFA 的平面性。尽管 BTP-H13 表现出比其他两种 NFA 更强的聚集性，但缺乏高效的共向半骨架堆叠模式导致三维 （3D） 网络结构相对松散，电荷传输特性较差。相比之下，BTP-H15 展示了综合优势，包括最佳框架平面度、近距离π-π堆叠距离和强大的 3D 网络，从而实现了卓越的形态和增强的电荷传输。因此，基于 BTP-H15 的无添加剂 OSC 在二进制器件中实现了 18.46% 的令人印象深刻的效率，在三元器件中实现了 19.36% 的令人印象深刻的效率。