中山大学深圳校区刘升华研究团队报道了光活性层中的异构化控制聚集——效率超过19.5%的有机太阳能电池的添加策略。相关研究成果于2024年12月23日发表在《德国应用化学》。

光活性层的形态控制对于实现高性能有机太阳能电池（OSCs）至关重要，但它仍然是该领域的一个重大挑战。加性策略是一种有效的方法，它可以微调光活性层的形态。然而，从液体、固体到挥发性固体的不同类型添加剂，对体异质结形态和器件性能的影响的潜在机制尚未完全清楚。

该文中，研究人员提出了一种受体分子的聚集调节策略，通过将三种新型异构添加剂：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。研究结果表明，这些添加剂在成膜过程中诱导受体分子聚集的逐步调节。

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显著缩短了薄膜演变过程中的聚集时间，从而实现了最紧凑的分子π-π堆叠。

此外，挥发性固体添加剂VCB微调了活性层内的分子间相互作用和结晶，促进了理想分子堆叠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OSCs，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。

附：英文原文

Title: Isomerization-Controlled Aggregation in Photoactive Layer: An Additive Strategy for Organic Solar Cells with Over 19.5% Efficiency

Author: Zihao Xia, Chuanlin Gao, Zhixiang Xie, Miaoxuan Wu, Hansheng Chen, Tongzi Li, Jiang Zhou, Ting Cai, Huawei Hu, Jing Shuai, Chen Xie, Guangye Zhang, Wenduo Chen, Shenghua Liu

Issue&Volume: 2024-12-23

Abstract: 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. 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.

DOI: 10.1002/anie.202421953

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202421953