Preparation of high quality perovskite thin film in ambient air using ethylacetate as anti-solvent

Methylamine lead iodide (CH3NH3PbI3) perovskite thin film solar cell has attracted much attention due to its low cost and high photoelectric conversion efficiency. Preparation of high quality perovskite thin film is the key to obtain high conversion efficiency of solar cells. Here, the pinhole-free CH3NH3PbI3 layer with high coverage and smooth surface is prepared by the one-step solution method in air with ethylacetate as anti-solvent on an electron transport hybrid layer of TiO2 nanoparticles coated porous carbon. The effect of ethylacetate as anti-solvent on the quality of perovskite thin film is studied in detail by comparing with chlorobenzene and ethylether. The high saturation and humidity resistance of ethylacetate in air control the nucleation and growing kinetics of perovskite crystals during the spin coating process, which facilitates the formation of uniform pinhole-free perovskite thin films. The perovskite solar cell based on the prepared high quality thin film achieves the highest conversion efficiency of 17.41% in ambient air with a relative humidity of 35%, which is superior to the perovskite thin films prepared with chlorobenzene and ethylether (conversion efficiency of 10.80% and 10.20%). The higher light-to-electric conversion efficiency is due to high coverage of the pinhole-free perovskite thin film and good contact with the electron transport layer and the hole transport layer.