Nondestructive purification process for inorganic perovskite quantum dot solar cells

Lead halide perovskites have attracted much attention following their successful use in photovoltaic devices with impressive power-conversion efficiencies. Owing to perovskite quantum dots' ionic nature, the surface ligands are easy to be overdamaged in polar solvents. Thus, there have been some difficulties in protecting the surface ligands of the quantum dots during purification processes, especially in solvent reprecipitation techniques. Here, we used mixtures of ethyl acetate and methyl acetate during the purification process to precipitate perovskite quantum dots that showed scarcely any damage to their surface ligands; furthermore, these purified CsPbBr3 quantum dots displayed high performances in devices. Quantum dot films were prepared via spin-coating from solution for use in solar cells with a simple structure (indium tin oxide/ZnO/quantum dots/Au), which displayed power-conversion efficiencies of up to 2.43%. Multiple purification cycles of this purification process allowed us to obtain near-perfectly modified perovskite colloidal quantum dots, ideal for application in optoelectronic devices.