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Achieving good stability while maintaining excellent properties is one of the main challenges for enhancing the competitiveness of luminescent perovskite CsPbX 3 (X=Cl, Br, I) nanocrystals (NCs). Here, we propose a facile strategy to synthesize ceramic-like stable and highly luminescent CsPbBr 3 NCs by encapsulating them into silica derived from molecular sieve templates at high temperature (600-900 o C). The obtained CsPbBr 3 -SiO 2 powders not only show high photoluminescence quantum yield (~71%), but also show an exceptional stability comparable to the ceramic Sr 2 SiO 4 :Eu 2+ green phosphor. They can maintain 100% of their photoluminescence value under illumination on blue light-emitting diodes (LEDs) chips (20 mA, 2.7 V) for 1000 h, and can also survive in a harsh hydrochloric acid aqueous solution (1 M) for 50 days. We believe that the above robust stabilities will significantly enhance the potential of perovskite CsPbX 3 NCs to be practically applied in LEDs and backlight displays.

Recently, two-dimensional colloidal perovskite nanoplatelets (NPLs) have attracted great attention as one of the most promising candidate blue emitters due to their large exciton binding energy and precisely tunable thickness. However, the lack of techniques to simultaneously obtain highly emissive and stable perovskite NPLs has limited the successful exploitation of highly efficient perovskite NPL-based optoelectronic devices. Herein, we report the surface ligand-engineering strategy to enhance the photoluminescence quantum yields and stability of perovskite NPLs using a short-chain halide ion-pair ligand. Benefits from the shorter-chain ligand treatment, the electronic conductivity, and carrier injection of perovskite NPL films have also been improved significantly, enabling us to realize highly efficient blue (469 nm) electroluminescence devices with a peak external quantum efficiency of 1.42%, which is among the highest efficiencies of colloidal pure-bromide perovskite NPL-based light-emitting diodes.

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Perovskite nanocrystals (NCs) as promising narrow green emitters are widely studied, and many colloidal synthetic methods have been developed. However, large amounts of expensive and toxic organic solvents are consumed in synthesis. Herein, a high temperature solid-state confined growth strategy was developed to prepare highly emissive CsPbBr 3 NCs using the in situ formed mesoporous Al 2 O 3 as the template. The obtained CsPbBr 3 −Al 2 O 3 powders possessed high quantum yield up to 70%, narrow emission line width of 25 nm, and outstanding thermal stability even better than the KSF phosphor. In addition, 500 g CsPbBr 3 − Al 2 O 3 powders in one batch have been achieved, which demonstrated the potential capability of mass production with this method. Finally, this method can be expanded to other CsPbX 3 (X = Cl, I) NCs through changing the halide salts. We believe that this versatile method opens up a new avenue for the large scale synthesis of high quality perovskite NCs with low cost.

CsPbCl3 nanocrystals are potential ultrapure emitters. But it is challenging to synthesize CsPbCl3 nanocrystals with sufficient stability, which impedes their application in light-emitting devices. In this work, we report a facile phosphoryl-chemistry-mediated synthesis approach to synthesizing stable CsPbCl3 nanocrystals, in which the phenylphosphonic dichloride (PhPOCl2) precursor is employed. In addition to the high reactivity of the P–Cl bond of PhPOCl2 for providing adequate Cl, the derived P=O with good proton affinity facilitates the formation of a distinct nanocrystal surface with the nonprotonated oleylamine (OLA) ligand. Accordingly, the L-type-ligand-capped CsPbCl3 nanocrystals exhibited not only bright luminance but also good stability that endured repeated purification up to 10 cycles. Based on the stable CsPbCl3 nanocrystals, we achieved violet LEDs with extremely narrow electroluminescence spectra (full width at half-maximum ≈ 10.6 nm).

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