Ultra-small CsPbBr3 quantum dots achieved by imidazolium chloride for highly efficient deep-blue emission

The development of deep-blue emitting perovskite quantum dots (PeQDs) has been significantly hindered by the surface defects and halide migration. To overcome these problems, a synergistic strategy combining strong quantum confinement and mixed-halide engineering was proposed to achieve highly efficient deep-blue emission. An excellent multidentate ligand 1-carboxymethyl-3-methylim-idazolium chloride (HOOCMIMCl) was introduced into CsPbBr 3 QDs, resulting in ultra-small monodisperse particles with an average diameter of 4.2 nm. The ultra-small CsPbBr 3 QDs exhibited deep-blue emission at 457 nm with a high photoluminescence quantum yield (PLQY) of 77%. Based on density functional theory (DFT) calculations and experimental results, HOOCMIMCl ligand also passivated uncoordinated Pb 2+ by C = O and reduced bromine vacancies (V Br ) through C = N in imidazole ring, improving the PLQY and stability of CsPbBr₃ QDs. It opens a new pathway for realizing highly efficient deep-blue emitting PeQDs with a tunable emission wavelength and offers a research basis for advancing high-performance PeLEDs in the deep-blue region.