Aluminium acetylacetonate ligand passivation for CsPbBr₃ nanocrystals with improved stability and photoluminescence

Cesium lead-halide perovskite nanocrystals (NCs) have emerged with great potential for next-generation light-emitting diode (LED) applications due to their high color purity, tunable optical bandgaps, and controllable synthesis. However, the weakly bound ligands such as oleic acid and oleylamine of perovskite NCs result in surface defects and hinder the charge carrier transport in the emitting layers. To overcome these limitations, the post-treatment strategy is adopted by using an aluminium triacetylacetone (Al(acac)(3)) ligand to exchange the insulating ligand and simultaneously passivate the lead defects of CsPbBr3 NCs with large size. Therefore, the CsPbBr3 NC films have a high photoluminescence quantum yield of 88% and the stability of the ligand-treated NC film has been significantly promoted as well. Al(acac)(3)-NC film can maintain 94% of the initial PLQY after being stored for 3 days under ambient conditions. Using the high quality Al(acac)(3)-NC films as emitting layers, the fabricated green perovskite LEDs showed high color purity with a very narrow full width at half maximum (fwhm, 16.8 nm) and effective charge injection with low turn-on voltage (<2.0 V). Our proposed passivation strategy for large-size perovskite NCs will offer a hopeful strategy for the fabrication of high-performance perovskite devices.