Chen Haiyang, Sun Weiwei, Zhang Rui, Huang Yuting, Zhang Ben, Zeng Guang, Ding Junyuan, Chen Weijie, Gao Feng, Li Yaowen, Li Yongfang
Laboratory of Advanced Optoelectronic Materials, Suzhou Key Laboratory of Novel Semiconductor-optoelectronics Materials and Devices, College of Chemistry, Chemical Engineering and Materials Science Soochow University, Suzhou, 215123, China.
Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping, SE-58183, Sweden.
Adv Mater. 2024 Jul;36(27):e2402350. doi: 10.1002/adma.202402350. Epub 2024 Apr 5.
High-boiling-point nonhalogenated solvents are superior solvents to produce large-area organic solar cells (OSCs) in industry because of their wide processing window and low toxicity; while, these solvents with slow evaporation kinetics will lead excessive aggregation of state-of-the-art small molecule acceptors (e.g. L8-BO), delivering serious efficiency losses. Here, a heterogeneous nucleating agent strategy is developed by grafting oligo (ethylene glycol) side-chains on L8-BO (BTO-BO). The formation energy of the obtained BTO-BO; while, changing from liquid in a solvent to a crystalline phase, is lower than that of L8-BO irrespective of the solvent type. When BTO-BO is added as the third component into the active layer (e.g. PM6:L8-BO), it easily assembles to form numerous seed crystals, which serve as nucleation sites to trigger heterogeneous nucleation and increase nucleation density of L8-BO through strong hydrogen bonding interactions even in high-boiling-point nonhalogenated solvents. Therefore, it can effectively suppress excessive aggregation during growth, achieving ideal phase-separation active layer with small domain sizes and high crystallinity. The resultant toluene-processed OSCs exhibit a record power conversion efficiency (PCE) of 19.42% (certificated 19.12%) with excellent operational stability. The strategy also has superior advantages in large-scale devices, showing a 15.03-cm module with a record PCE of 16.35% (certificated 15.97%).
高沸点非卤代溶剂因其宽加工窗口和低毒性，是工业上生产大面积有机太阳能电池（OSC）的优质溶剂；然而，这些蒸发动力学缓慢的溶剂会导致最先进的小分子受体（如L8-BO）过度聚集，造成严重的效率损失。在此，通过在L8-BO（BTO-BO）上接枝低聚（乙二醇）侧链，开发了一种异质成核剂策略。无论溶剂类型如何，所获得的BTO-BO从溶剂中的液体转变为结晶相时的形成能都低于L8-BO。当BTO-BO作为第三组分添加到活性层（如PM6:L8-BO）中时，它很容易组装形成大量籽晶，这些籽晶作为成核位点引发异质成核，并通过强氢键相互作用增加L8-BO在高沸点非卤代溶剂中的成核密度。因此，它可以有效抑制生长过程中的过度聚集，实现具有小尺寸域和高结晶度的理想相分离活性层。所得甲苯处理的OSC表现出创纪录的19.42%的功率转换效率（认证值为19.12%），并具有出色的运行稳定性。该策略在大规模器件中也具有显著优势，展示了一个15.03平方厘米的模块，创纪录的功率转换效率为16.35%（认证值为15.97%）。
