Organic solar cells (OSCs) processed with non‐halogenated solvents usually suffer from excessive self‐aggregation of small molecule acceptors (SMAs), severe phase separation and higher energy loss (Eloss), leading to reduced open‐circuit voltage (Voc) and power conversion efficiency (PCE). Here, we designed and synthesized two SMAs L8‐PhF and L8‐PhMe by introducing different substituents (fluorine for L8‐PhF and methyl for L8‐PhMe) on the phenyl end group of inner side chains of L8‐Ph, and investigated the effect of the substituents on the intermolecular interaction of SMAs, Eloss and performance of OSCs processed with non‐halogenated solvents. It is found that compared with L8‐PhF, which possesses strong intermolecular interactions but downgraded molecular packing order, L8‐PhMe exhibits more effective non‐covalent interactions, which improves the tightness and order of molecular packing. When blending the SMAs with PM6, the OSCs based on L8‐PhMe shows reduced non‐radiative energy loss, and enhanced Voc than the devices based on the other two SMAs. Consequently, the L8‐PhMe based device processed with o‐xylene and using 2PACz as the hole transport layer shows an outstanding PCE of 19.27%. This study highlights that the Eloss of OSCs processed with non‐halogenated solvents could be decreased through regulating the intermolecular interactions of SMAs by inner side chain modification.

中文翻译：

---

小分子受体的内侧链修饰可降低非卤化溶剂处理有机太阳能电池的能量损失并提高效率


使用非卤化溶剂加工的有机太阳能电池（OSC）通常会出现小分子受体（SMA）的过度自聚集、严重的相分离和较高的能量损失（Eloss），导致开路电压（Voc）和功率降低转换效率（PCE）。在这里，我们通过在L8-Ph内部侧链的苯基端基上引入不同的取代基（L8-PhF为氟，L8-PhMe为甲基）设计并合成了两种SMA L8-PhF和L8-PhMe，并研究了其影响取代基对 SMA 分子间相互作用、Eloss 和用非卤化溶剂加工的 OSC 性能的影响。研究发现，与具有较强的分子间相互作用但降低了分子堆积顺序的L8-PhF相比，L8-PhMe表现出更有效的非共价相互作用，从而提高了分子堆积的紧密性和有序性。当将 SMA 与 PM6 混合时，与基于其他两种 SMA 的器件相比，基于 L8-PhMe 的 OSC 显示出减少的非辐射能量损失和增强的 Voc。因此，用邻二甲苯处理并使用 2PACz 作为空穴传输层的 L8-PhMe 基器件显示出 19.27% 的出色 PCE。这项研究强调，通过内部侧链修饰调节 SMA 的分子间相互作用，可以降低用非卤化溶剂处理的 OSC 的 Eloss。