Zn(II)-Doped Cesium Lead Halide Perovskite Nanocrystals with High Quantum Yield and Wide Color Tunability for Color-Conversion Light-Emitting Displays

Cesium lead halide (CsPbX₃; X = Cl, Br, and I) perovskite nanocrystals (PNCs) have drawn much attention toward their synthesis and optoelectronic properties, but violet-emitting CsPbCl₃ PNCs fall behind CsPbBr₃ (green) and CsPbI₃ (red) ones in terms of the photoluminescence quantum yield (PLQY) and material durability limiting their commercial use in devices. Herein, we synthesized highly stable Zn-incorporated CsPbCl₃ PNCs via a hot-injection method and demonstrated their optical performances (PLQY) and thermal-, moisture-, photostabilities. A wide range of structural characterizations were used to demonstrate the substitution of Pb²⁺ sites by Zn²⁺ ions without altering the CsPbCl₃ PNC crystal lattice. The optical measurements revealed that Zn doping had substantially improved the overall PLQY (>85%) at around 408–410 nm and had also enhanced the short-range lattice order by eliminating intrinsic defects like halide vacancies and octahedral distortions. The Zn-doped CsPbCl₃ PNCs retained 49% of their initial luminescence even after annealing at 413 K and exhibited good moisture and photostability. Blue-emitting Zn-doped CsPb­(Cl/Br)₃ PNCs with a PLQY above 90% at around 445–450 nm were synthesized and blended with PMMA to use them as a color-conversion layer in combination with CsPbBr₃(green) and CsPb­(Br/I)₃ (red) @PMMA/glasses to generate white light using a commercial ultraviolet LED chip (365 nm). The designed 20 mA driven prototype white LED device displayed a bright white light with a luminous efficiency of 67.5 lm/W, a CCT of 6285 K, and a CRI of 86.3. The designed white LED device also achieved a wide color gamut of ∼118% NTSC and 87% Rec. 2020.