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High‐quality backlit display puts forward urgent demand for color‐converting materials. Recently, metal halide perovskites (MHPs) with full spectral tunability, high photoluminescence quantum yields (PLQYs), and high color purity have found potential application in wide‐color‐gamut display. Regrettably, naked MHPs suffer from long‐term instable issue and cannot pass harsh stability tests. Herein, amorphous‐glass‐protected green/red CsPbX3 quantum dots (QDs) are prepared by elaborately optimizing glass structure, perovskite concentration, and in situ crystallization. PLQYs of green CsPbBr3@glass and red CsPbBr1.5I1.5@glass reach 94% and 78%, respectively, which are the highest ones of CsPbX3@glass composites reported so far and comparable to colloidal counterparts. Benefited from complete isolation of QDs from external environment by glass network, CsPbX3@glass can endure harsh commercial standard aging tests of 85 °C/85%RH and blue‐light‐irradiation, which are applied to construct white light‐emitting diodes (wLEDs) with high external quantum efficiency of 13.8% and ultra‐high luminance of 500 000 cd m−2. Accordingly, the perovskite wLED arrays‐based backlit unit and a prototype display device are designed for the first time, showing more vivid and wide‐color‐gamut feature benefited from narrowband emissions of CsPbX3 QDs. This work highlights practical application of CsPbX3@glass composite as an efficient and stable light color converter in backlit display. [ABSTRACT FROM AUTHOR]

• NIR laser triggered UC emissions in glass-stabilized CsPbX 3 perovskites are realized. • The UC mechanism is radiative energy transfer from Tm: KYb 2 F 7 to CsPbX 3. • Tunable DS/UC combined luminescence is demonstrated via tailoring halogens in glass and selecting diverse excitation modes. • Visualized anti-counterfeits using screen-printable CsPbX 3 inks are practically applicable. • The luminescence of anti-counterfeiting patterns is well retained after storing in water for 30 days. Photon upconversion (UC) of perovskite nanocrystals (PeNCs) is an attractive topic and has been recently realized in colloidal solution. However, this scheme suffers from system instability owing to the easy decomposition of PeNCs, which will greatly limit their applications. This work reports the achievement of radiative energy transfer UC of glass-stabilized CsPbX 3 (X = Cl, Br, I) PeNCs triggered by Tm: KYb 2 F 7 NCs upon 980 nm near-infrared (NIR) laser excitation, which shows the advantages of superior long-term stability and enables them to find practical application. Both CsPbX 3 @glass and Tm: KYb 2 F 7 @glass nanocomposites are fabricated by an in-situ glass crystallization method, and their mixtures yield tunable downshifting/upconverting combined luminescence via tailoring halogen components in glass and selecting diverse excitation modes (UV, NIR or concurrent UV and NIR). Consequently, screen-printing multiple anti-counterfeiting patterns containing ultra-stable CsPbX 3 PeNCs with convenient encryption/decryption and excellent water resistance are experimentally demonstrated, providing a very high level of security. [ABSTRACT FROM AUTHOR]

CsPbX 3 (X = Cl, Br, I) perovskite quantum dots (QDs) have attracted extensive attention due to their great application prospects in the photoelectronic field. However, the poor long-term stability still limits their practical use. In this work, a whole series of CsPbX 3 QDs were precipitated in a germanate glass matrix by a melt quenching method. The emission wavelength can be tunable in the entire visible spectral region by adjusting of the halide ions and the thermal treatment process. The photoluminescence quantum yield of CsPbBr x I 3-x QDs glass can reach up to 38.24%. The exciton binding energies of CsPbBr x Cl 3-x , CsPbBr 3 and CsPbI 3 QDs glass are about 67 meV, 160 meV and 290 meV, respectively. Additionally, the influence of the thermal treatment temperature on photoluminescence properties of CsPbBr x I 3-x QDs glass was investigated in detail. These results will be of benefitting to their practical applications, such as display devices and WLEDs. • A whole series of CsPbX 3 (X = Cl, Br, I) QDs were precipitated in germanate glass matrix. • Emission wavelength can be tunable in the whole visible spectral region by adjusting the halide ions. • Exciton binding energy of CsPbX 3 QDs glass increases as the halide ions change from Cl to I. • The obtained QDs glass can be potential applications in WLEDs, display devices, etc. [ABSTRACT FROM AUTHOR]

[Display omitted] • Effective Ni2+ doping in CsPbI 3 nanocrystals is achieved. • Ni2+ doping enables to stabilize cubic CsPbI 3 up to 7 months in atmosphere. • Ni2+ doping leads to significantly improve PLQY approaching near-unity. • Ni2+-doped perovskite LED outperforms the device using pristine CsPbI 3 nanocrystals. • The device exhibits a peak EQE of ~7% and a maximal luminance of 830 cd/m2. Room temperature phase instability of cubic CsPbI 3 perovskite nanocrystals is one of the notorious limitations for practical applications in optoelectronic fields. Herein, the incorporation of Ni2+ ions into CsPbI 3 lattice was successfully achieved by a modified hot-injection method using nickel acetate as doping precursor. The as-prepared Ni2+ (3.3 mol%): CsPbI 3 nanocrystals exhibited an improved, near-unity (95%~100%) photoluminescence quantum yield owing to the enhanced radiative decay rate and the decreased non-radiative decay rate. Additionally, Ni-doping was demonstrated to stabilize CsPbI 3 lattice and the Ni2+: CsPbI 3 film and colloidal solution can retain their red luminescence up to 15 days and 7 months in atmosphere, respectively. First-principle calculations verified that the significantly improved optical performance and stability of Ni2+: CsPbI 3 nanocrystals arose primarily from the increased formation energy due to the successful doping of Ni2+ in CsPbI 3. Benefiting from such an effective doping strategy, the as-prepared Ni2+-doped CsPbI 3 perovskite nanocrystals can function well as efficient red-light emitter toward the fabrication of high-performance perovskite LED with a peak external quantum efficiency of ~7%. [ABSTRACT FROM AUTHOR]