Precursor Engineering for a Large-Area Perovskite Solar Cell with >19% Efficiency

Here, we report on precursor engineering for a large-area perovskite film using an air-knife-assisted D-bar coater. Lead acetate (PbAc2) is stoichiometrically added in the mother solution consisting of methylammonium iodide (MAI) and lead iodide (PbI2) in 2-methoxyethanol (2ME), leading to MAPbI3 and byproduct methylammonium acetate (MAAc). Crystal growth can be controlled in the presence of MAAc while drying the wet film. An average power conversion efficiency (PCE) of 15.14% is achieved, whereas the quality of the perovskite film is uncontrollable in the absence of PbAc2, resulting in a PCE as low as 2.63%. Carrier lifetime is further improved by about 46% when incorporating 0.12 mol % guanidinium iodide (GAI) in the PbAc2-containing precursor solution, which demonstrates a PCE of 19.44% with a device employing a piece of the large-area perovskite film (∼46 cm2) and a PCE of 13.85% with a module with an active area of 16 cm2.