Organic-inorganic metal-halide perovskite solar cells (PSCs) have achieved a certified power-conversion efficiency (PCE) of 25.5%. However, long-term stability and air stability of the PSCs are still major concerns and hamper commercialization. Herein, we employ a multi-functional ionic liquid (IL), 1,3-bis(cyanomethyl)imidazolium bis(trifluoromethylsulfonyl)imide ([Bcim][TFSI]), which contains an imidazolium cation functionalized with nitrile (CN) groups and the TFSI anion and is, additionally, able to form an extensive network of low-barrier H bonds, as an additive in perovskite-precursor solutions. Because of a combination of the Lewis-basic CN groups and the hydrophobic TFSI anion in the IL, highly crystalline perovskite films with large grain sizes are obtained. The IL-modified perovskite films afford PSCs with long-term stability and PCEs > 21%. The stability of unencapsulated devices retain >95% of their original efficiency after 1,000 h of aging. This study demonstrates the considerable potential of TFSI-based ILs to improve the performance of PSCs.

有机-无机金属卤化物钙钛矿太阳能电池 (PSC) 的认证功率转换效率 (PCE) 为 25.5%。然而，PSC 的长期稳定性和空气稳定性仍然是主要问题并阻碍其商业化。在此，我们采用多功能离子液体 (IL)、1,3-双（氰甲基）咪唑鎓双（三氟甲基磺酰基）亚胺（[Bcim][TFSI]），其中含有用腈 (CN) 基团官能化的咪唑鎓阳离子和TFSI 阴离子，此外，能够形成广泛的低势垒 H 键网络，作为钙钛矿前体溶液中的添加剂。由于路易斯碱性 CN 基团和 IL 中的疏水性 TFSI 阴离子的组合，获得了具有大晶粒尺寸的高结晶钙钛矿薄膜。IL 改性的钙钛矿薄膜提供具有长期稳定性和 PCE > 21% 的 PSC。未封装器件的稳定性在老化 1,000 小时后仍保持其原始效率的 95% 以上。这项研究证明了基于 TFSI 的 IL 在提高 PSC 性能方面的巨大潜力。