Ligand-Mediated Intergrain Isolation Strategy for Narrow-Emission Deep-Blue Perovskite Quantum Dot Light-Emitting Diodes

Deep-blue perovskite quantum dot (QD) emitters with narrow emission line widths are critical for next-generation wide-color-gamut QD displays. However, achieving narrow primary deep-blue emission perovskite QDs compliant with Rec. 2100 remains challenging. This difficulty mainly arises from the intrinsic phase segregation of mixed-halide perovskite QDs, the presence of defects, and the inhomogeneous distribution of halide ions among the particles. Herein, we develop a ligand-mediated strategy for the phase separation inhibition and surface reconstruction of CsPb(Br x Cl 1– x ) 3 QDs. Specifically, we implement a sequential ligand treatment protocol comprising ion exchange with methyltrioctylammonium chloride, surface cleaning using octylphosphonic acid, and defect passivation via CF 3 –PEABr. This approach effectively promotes a distinct intergrain isolation and facilitates the homogenized halide distribution throughout the QDs ensemble. The resulting deep-blue quantum dot light-emitting diode (QLED) exhibits stable electroluminescence emission with an ultranarrow full width at half-maximum (fwhm) of 13.4 nm. This achievement marks the narrowest fwhm record of primary deep-blue perovskite QLEDs to date, featuring a 99.1% gamut coverage of Rec. 2100 standard. This work proposes a feasible strategy for ultrahigh color purity deep-blue QLEDs tailored for Rec. 2100 wide-color-gamut displays.