A Strategy to Produce High Efficiency, High Stability Perovskite Solar Cells Using Functionalized Ionic Liquid‐Dopants

Functionalized imidazolium iodide salts (ionic liquids) modified with CH2 CHCH2 , CH2 CCH, or CH2 CN groups are applied as dopants in the synthesis of CH3 NH3 PbI3 -type perovskites together with a fumigation step. Notably, a solar cell device prepared from the perovskite film doped with the salt containing the CH2 CHCH2 side-chain has a power conversion efficiency of 19.21%, which is the highest efficiency reported for perovskite solar cells involving a fumigation step. However, doping with the imidazolium salts with the CH2 CCH and CH2 CN groups result in perovskite layers that lead to solar cell devices with similar or lower power conversion efficiencies than the dopant-free cell.