All-polymer solar cells (all-PSCs) are thought to be the most promising candidate for the practical application of organic solar cells (OSCs). However, the efficiencies of all-PSCs remains lower than those of small molecule acceptor (SMA)-based OSCs due to their unfavorable active-layer morphology. The complicated molecular interaction and aggregation behavior involved in all-polymer blends make it highly challenging to achieve optimal morphology. Herein, two volatile solid additives named dibenzothiophene (DBTP) and 4-bromodibenzothiophene (4-BDBTP) were developed to finely modulate the morphology of all-PSCs. We clarify that the subtle bromine substitution enables 4-BDBTP to form enhanced intermolecular interactions with the host material, which is beneficial to controlling the molecular aggregation and crystallization, thus facilitating the formation of more ordered molecular stacking and well-defined fibril networks in the all-polymer blend. As a result, the 4-BDBTP-treated-PM6:PY-DT all-PSC achieved a high efficiency of 19.30% (certified as 18.82%). Moreover, two other all-polymer systems validate the broad applicability of 4-BDBTP, and these devices all showed enhanced efficiencies. Our work demonstrates the promising role of solid additive on regulating molecular aggregation and packing in all-polymer blends, offering valuable insight into fabricating high-performance all-PSCs.

中文翻译：

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基于溴二苯并噻吩的固体添加剂可实现效率为 19.30% 的二元全聚合物太阳能电池


全聚合物太阳能电池 （all-PSC） 被认为是有机太阳能电池 （OSC） 实际应用最有前途的候选者。然而，由于活性层形态不佳，全 PSC 的效率仍然低于基于小分子受体 （SMA） 的 OSC。全聚合物共混物中涉及复杂的分子相互作用和聚集行为，使得实现最佳形态极具挑战性。在此，开发了两种名为二苯并噻吩 （DBTP） 和 4-溴二苯并噻吩 （4-BDBTP） 的挥发性固体添加剂，以精细调节全 PSC 的形态。我们阐明，微妙的溴取代使 4-BDBTP 能够与主体材料形成增强的分子间相互作用，这有利于控制分子聚集和结晶，从而促进在全聚合物混合物中形成更有序的分子堆叠和明确的原纤维网络。结果，4-BDBTP 处理的 PM6：PY-DT 全 PSC 实现了 19.30% 的高效率（认证为 18.82%）。此外，另外两种全聚合物系统验证了 4-BDBTP 的广泛适用性，这些装置都显示出更高的效率。我们的工作证明了固体添加剂在调节全聚合物共混物中的分子聚集和堆积方面有前途的作用，为制备高性能全 PSC 提供了有价值的见解。