Efficient MAPbI 3 solar cells made via drop-coating at room temperature

Here we demonstrate a room-temperature drop-coating method for MAPbI3 films. By using low-boiling-point solvent, high-quality MAPbI3 films were made by simply casting a drop of solution onto the substrate at room temperature. This approach took advantage of the synergistic effect of good wettability and volatility of the solvent, enabling high nuclei density and compact film at room temperature. The crystal growth in different solvents was in-situ observed by using optical microscope, which helped us to understand the mechanism for the formation of different film morphology. Perovskite solar cells gave a PCE of 18.21%.