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

Functionalized imidazolium iodide salts (ionic liquids) modified with CH₂CHCH₂, CH₂CCH, or CH₂CN 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 CH₂CHCH₂ 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 CH₂CCH and CH₂CN 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.

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