Effective Purification of CsPbBr<sub>3</sub> Nanocrystals with High Quantum Yield and High Colloidal Stability via Gel Permeation Chromatography
Sakiru L. Abiodun, Perry J. Pellechia, Andrew B. Greytak
Abstract
Inorganic halide perovskites such as CsPbX3 (X = Cl, Br, I) have emerged as an intriguing alternative to chalcogenide and pnictide nanocrystals due to their ease of preparation, narrow emission peak widths, and remarkably high photoluminescence (PL) quantum yield (QY) in colloidal solution. However, progress has been hindered by several factors centered on stability. The ionic character of these nanocrystals makes them very sensitive to polar solvents typically used in precipitation-based purification steps. Here, we report the use of gel permeation chromatography (GPC) as a route for effective purification of CsPbBr3 perovskite quantum dots that does not require exposure to a polar solvent. We also report that ligand exchange with didodecyldimethylammonium bromide (DDAB) afforded CsPbBr3 QDs that, when effectively purified by GPC, exhibit near-unity QY with improved colloidal stability. We have used this precise and repeatable purification process to investigate the ligand population and PL lifetimes of native and ligand-exchanged samples.