A simple multiple centrifugation method for large-area homogeneous perovskite CsPbBr₃ films with optical lasing

Large scale cesium lead-halide (CsPbX₃, X = Cl, Br, and I) perovskite films have become the basis of laser applications. Common fabrication methods such as spin-coating and thermal evaporation have a trade-off between high quality and low cost. Herein, we reported a facile method for preparing a large area homogeneous perovskite CsPbBr₃ film via a multiple centrifugal deposition and solvent annealing (MCDSA) method. This method is superior because it can control the thickness (180 nm to 880 nm) of the film, ensure the film is crack and pinhole free, has a large area (2.5 cm × 2.5 cm), and has a low surface roughness (a root mean square of 32 nm). Multiple times of centrifugation and solvent annealing in the MCDSA method are key to improving the quality of the film as well as the laser performance. With increased centrifugation cycles from one to four, the thickness of the film increases from 180 nm to 880 nm, leading to a decrease in the laser threshold from 18.1 μJ cm^-2 to 14.2 μJ cm^-2 and an increase in the gain coefficient from 78.5 cm^-1 to 112.7 cm^-1. When solvent annealing is employed, the gain coefficient is further increased to 122.7 cm^-1.