Highly Efficient Blue Perovskite Quantum Dots Light-Emitting Diodes Based on Ligand-Assisted Anion Exchange Method

High-performance blue perovskite quantum dots (PQDs)are of keyimportance for electroluminescent light-emitting diodes (LEDs) towardfull color display in the future. Here, mixed halogen PQDs CsPb(Br- x /Cl1-x )(3) with a tunable emission wavelength was obtained througha strategy of ligand-assisted anion exchange assisted by didodecydimethyammoniumchloride (DDAC) ligand. Surface Br- vacancies ofthe PQD are passivated by the halogen atoms in the anchored DDAC ligand,enabling a high efficiency emission of blue light from the PQD. Stableanchoring of the ligand also improves the robustness of the PQD duringits purification in weak polar solvents. Well-controlled chlorinestoichiometry of the PQD also allows fine-tuning of its photoluminescenceand electroluminescence spectra in the range of 424-514 nmand 453-500 nm. The external quantum efficiency of the fabricatedPQDs LED device reaches 10.1% at 495 nm, 6.5% at 484 nm, and 5.1%at 470 nm (NTSC pure blue) under a constant current test. Our workprovides a facile method without additional purification or ligandseparation to achieve highly efficient blue PQDs with a tunable emissionwavelength, promoting the advance of blue PQDs LED.