Using halogenated additive to optimize the active layer morphology has been proven effective in boosting the power conversion efficiency (PCE) of organic solar cells (OSCs). However, the halogenated isomerism of solid additives, which finely tunes blend morphology, has been understudied, with the associated mechanisms requiring further investigation. Herein, a brominated isomerization engineering using 1-chloronaphthalene (CN)-derived solid additives (2-bromo-1-chloronaphthalene/o-BrCN, 3-bromo-1-chloronaphthalene/m-BrCN, and 4-bromo-1-chloronaphthalene/p-BrCN, respectively) is firstly developed. Among these, p-BrCN, with symmetrically halogenated positions, exhibits a small dipole moment, facilitating an extraordinary non-covalent interaction with both donor and acceptor components. Consequently, the p-BrCN-treated active layer obtains better molecular crystallinity, π-π stacking, and phase separation, helping to improve the exciton dissociation and charge transport of OSCs. Ultimately, the p-BrCN-treated OSC based on PM6:L8-BO offers a higher PCE (18.18%) compared to those treated with o-BrCN (17.89%) and m-BrCN (17.39%). Remarkably, the p-BrCN-treated OSCs based on D18:L8-BO and D18:L8-BO:BTP-eC9 further improve PCEs to 19.14% and 19.68%, placing them among the highest values for binary and ternary OSCs, respectively. This work highlights that brominated isomerization engineering in CN-derived additives is a promising strategy to optimize morphology for obtaining efficient OSCs, and elucidates the underlying mechanism.

中文翻译：

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1-氯萘衍生固体添加剂的溴化异构化工程可实现 19.68% 效率的有机太阳能电池


使用卤化添加剂优化活性层形态已被证明可有效提高有机太阳能电池 （OSC） 的功率转换效率 （PCE）。然而，固体添加剂的卤代异构性（微调共混形态）尚未得到充分研究，相关机制需要进一步研究。在此，首先开发了一种使用 1-氯萘 （CN） 衍生的固体添加剂（分别为 2-溴-1-氯萘/o-BrCN、3-溴-1-氯萘/m-BrCN 和 4-溴-1-氯萘/对-BrCN）的溴化异构化工程。其中，具有对称卤化位置的 p-BrCN 表现出较小的偶极矩，促进了与供体和受体组分的非共价相互作用。因此，p-BrCN 处理的活性层获得了更好的分子结晶度、π-π 堆叠和相分离，有助于改善 OSC 的激子解离和电荷传输。最终，与用 o-BrCN （17.89%） 和 m-BrCN （17.39%） 处理的 OSC 相比，基于 PM6：L8-BO 的 p-BrCN 处理的 OSC 提供了更高的 PCE （18.18%）。值得注意的是，基于 D18：L8-BO 和 D18：L8-BO：BTP-eC9 的 p-BrCN 处理的 OSC 进一步将 PCE 提高到 19.14% 和 19.68%，分别是二元和三元 OSC 的最高值之一。这项工作强调，CN 衍生添加剂中的溴化异构化工程是一种很有前途的策略，可以优化形态以获得有效的 OSC，并阐明了潜在的机制。