A high-conductivity thiocyanate ionic liquid (EMIMSCN) was introduced into perovskite solar cells for the first time. The high conductivity of EMIMSCN ensures an adequate supply of free SCN - anions and EMIM + cations, so as to multifunctionally passivate the I vacancy and Pb-I antisite defects and realize an optimized interfacial energy level. Consequently, the devices with EMIMSCN treatment achieve a high PCE of 22.55% with substantial enhancement in stability. This simple and efficient strategy provides new insights into the selection of passivation agents for efficient and stable PSCs.