Zn(II)-Doped Cesium Lead Halide Perovskite Nanocrystals with High Quantum Yield and Wide Color Tunability for Color-Conversion Light-Emitting Displays
journal contributionposted on 22.07.2020 by V. Naresh, Nohyun Lee
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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.