Xia Zihao, Gao Chuanlin, Xie Zhixiang, Wu Miaoxuan, Chen Hansheng, Li Tongzi, Zhou Jiang, Cai Ting, Hu Huawei, Shuai Jing, Xie Chen, Zhang Guangye, Chen Wenduo, Liu Shenghua
School of Materials, Shenzhen Campus of Sun Yat-sen University, No. 66, Gongchang Road, Guangming District, Shenzhen, Guangdong, 518107, China.
College of New Materials and New Energies, Shenzhen Technology University, Shenzhen, 518118, China.
Angew Chem Int Ed Engl. 2025 Mar 17;64(12):e202421953. doi: 10.1002/anie.202421953. Epub 2025 Jan 7.
Morphology control of the photoactive layer is crucial for achieving high-performance organic solar cells (OSCs), yet it remains a significant challenge in this field. One effective approach is the additive strategy, which fine-tunes the morphology of the photoactive layer. However, the underlying mechanisms governing the impact of different types of additives from liquid, solid, to volatile solid, on the bulk heterojunction morphology and device performance are not fully understood. Herein, we present an aggregation regulation strategy for acceptor molecules by incorporating three novel isomeric additives: 4-bromo-1,2-dichlorobenzene (LCB), 1-bromo-2,4-dichlorobenzene (SCB), and 2-bromo-1,4-dichlorobenzene (VCB) into the blend active layer. This approach optimizes the bulk heterojunction morphology and enhances the photovoltaic performance of OSCs. Our results reveal that these additives induce stepwise regulation of acceptor molecule aggregation during film formation. The liquid additive LCB primarily extends solvent evaporation time, effectively preventing excessive aggregation, while the solid additive SCB significantly shortens the aggregation period during the film evolution, resulting in the most compact molecular π-π stacking. Furthermore, the volatile solid additive VCB fine-tunes the intermolecular interactions and crystallization within the active layer, promoting optimal molecular self-assembly and aggregation for ideal molecular stacking. Consequently, the power conversion efficiencies of 19.33 % and 19.51 % were achieved for the VCB-processed D18 : L8-BO- and PM6 : L8-BO-based OSCs, respectively, outperforming the LCB-processed and SCB-processed devices.
光活性层的形态控制对于实现高性能有机太阳能电池（OSC）至关重要，但在该领域仍然是一项重大挑战。一种有效的方法是添加剂策略，该策略可微调光活性层的形态。然而，对于从液体、固体到挥发性固体等不同类型添加剂对本体异质结形态和器件性能影响的潜在机制尚未完全理解。在此，我们通过将三种新型异构体添加剂：4-溴-1,2-二氯苯（LCB）、1-溴-2,4-二氯苯（SCB）和2-溴-1,4-二氯苯（VCB）掺入共混活性层中，提出了一种受体分子的聚集调控策略。这种方法优化了本体异质结形态并提高了OSC的光伏性能。我们的结果表明，这些添加剂在成膜过程中诱导受体分子聚集的逐步调控。液体添加剂LCB主要延长溶剂蒸发时间，有效防止过度聚集，而固体添加剂SCB显著缩短了膜演化过程中的聚集期，导致最紧密的分子π-π堆积。此外，挥发性固体添加剂VCB微调活性层内的分子间相互作用和结晶，促进理想分子堆积的最佳分子自组装和聚集。因此，基于VCB处理的D18 : L8-BO和PM6 : L8-BO的OSC分别实现了19.33 %和19.51 %的功率转换效率，优于LCB处理和SCB处理的器件。
