Ionic liquid gel microspheres as multifunctional bi-component additives for the crystallinity manipulation and defect passivation in all-air-processed perovskite solar cells

Additives have played a critical role in enhancing the efficiency and stability of perovskite solar cells (PSCs). At present, most of the effective additives are composed of one component, with little attention being given to the potential of bi-component. Herein, we report a novel synergistic strategy to construct ionic liquid gel microspheres (ILG-microspheres) as multifunctional bi-component additives by emulsion polymerization. The synergistic effect of polymeric methyl methacrylate and 1-butyl-3-methylimidazole hexafluorophosphate (BMIMPF6) can effectively improve perovskite crystallization quality and passivated GBs. As a result, an all-air-processed champion device with ILG-microsphere exhibits a power conversion efficiency of 22.31 % with a Voc of 1.206 V. Moreover, the long-term stability of optimized PSC remains 86.5 % of initial efficiency after being stored in the air atmosphere for 1500 h, and its thermal stability is also enhanced. This exploitation of ILG-microsphere as multifunctional bi-component additives provides a promising strategy for the development of all-air-processed high-performance PSCs.