Vivid and Fully Saturated Blue Light-Emitting Diodes Based on Ligand Modified Halide Perovskite Nanocrystals

CsPbX3 (X = I, Br, Cl) perovskite nanocrystals (NCs) have recently emerged as emitting materials for optoelectronic and display applications owing to their easily tunable emissions, high photoluminescence quantum yield (PLQY), and vivid color purity (full width at half maximum (FWHM) of approximately 20 nm). However, the lagging quantum yields of blue-emitting perovskite NCs have resulted in a low efficiency compared to green or red perovskite light-emitting diodes (PeLEDs); moreover, the long insulating ligands (such as oleylamine and oleic acid) inhibit charge carrier injection. In this study, we demonstrated a facile ligand mediated post-treatment (LMPT) method for high-quality perovskite NCs with changing optical properties to allow fine-tuning to the target emission wavelength. This method involves the use of a mixed halide ion-pair ligand, di-dodecyl dimethyl ammonium bromide, and chloride, which can induce a re-construction through a self-anion exchange. Using the LMPT method, the PLQY of the surfa...