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, CH2CCH, or CH2CN groups are applied as dopants in the synthesis of CH3NH3PbI3‐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 CH2CCH and CH2CN groups result in perovskite layers that lead to solar cell devices with similar or lower power conversion efficiencies than the dopant‐free cell. Perovskite films, grown from PbI2:MAI in DMSO in the presence of functionalized ionic‐liquid (imidazolium iodide) dopants and incorporated into perovskite solar cells, are reported. One cell has a power conversion efficiency exceeding 19%. Difference in power conversion efficiency can be traced to the physical properties of imidazolium‐PbI3 salts that form during the preparation of the film.