Various substituents have been incorporated into nonfullerene acceptors (NFAs) to modulate absorption scopes and energy levels for boosting efficiencies of organic solar cells (OSCs). The manipulation of the NFAs' molecular order and crystallinity via those substitutions is equally crucial to OSC performances, which yet remains interesting and challenging. The hydroxyl group, which can potentially form strong intermolecular hydrogen bonds (H‐bonds) for improving molecular arrangements, has, however, never been considered. Herein, two hydroxyl‐functionalized NFAs, IT‐OH with one hydroxyl and IT‐DOH with two hydroxyls, are synthesized to tune the molecular packing and crystallinity. The ordered molecular arrangement and higher crystallinity are observed for the IT‐OH and IT‐DOH than the parent ITIC. This is assigned to the formation of intermolecular H‐bonds induced by the hydroxyls, which elongates molecular conjugated planes leading to long‐range‐ordered structures via π–π stacking. By the appropriate crystallinity and miscibility with donor polymer, an IT‐DOH‐based nonannealed OSC affords an efficiency of 12.5% with good device stability. This work provides a promising strategy to tune the molecular packing and crystallinity to design NFAs by introducing hydroxyl groups.

中文翻译：

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H-Bonds辅助的非富勒烯受体的分子顺序操纵，用于高效的非退火有机太阳能电池

各种取代基已掺入非富勒烯受体（NFA）中，以调节吸收范围和能级，从而提高有机太阳能电池（OSC）的效率。通过这些取代操作来控制NFA的分子顺序和结晶度对于OSC性能同样至关重要，但这仍然很有趣且具有挑战性。然而，从未考虑过可为形成分子排列而形成强分子间氢键（H键）的羟基。本文中，合成了两个羟基官能化的NFA，即一个羟基的IT-OH和两个羟基的IT-DOH，以调节分子堆积和结晶度。与母体ITIC相比，IT-OH和IT-DOH观察到有序的分子排列和更高的结晶度。这被认为是由羟基诱导的分子间氢键的形成，它延长了分子共轭平面，通过π-π堆积导致了长程有序结构。通过适当的结晶度和与供体聚合物的混溶性，基于IT-DOH的非退火OSC可以提供12.5％的效率，并具有良好的器件稳定性。这项工作为通过引入羟基调整分子堆积和结晶度以设计NFA提供了一种有前途的策略。