One Hundred-Nanometer-Sized CsPbBr3/m-SiO2 Composites Prepared via Molten-Salts Synthesis are Optimal Green Phosphors for LCD Display Devices

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Abstract The exploitation of the optimal optical properties of lead halide perovskite nanocrystals in optoelectronic devices is mainly hindered by the low stability of such materials. Here, a molten-salts approach is developed to encapsulate CsPbBr3 nanocrystals (together with KNO3, NaNO3, and KBr inorganic salts) inside different nanoscale mesoporous SiO2 host matrices, having sizes between 100 and 300 nm. The comparison between optical properties and stability of the products, including the previously reported ≥600-nm-sized CsPbBr3/m-SiO2 composite, indicates that 100-nm-sized CsPbBr3/m-SiO2 particles feature the best stability against humidity, light irradiation and heat, and exhibit a green (peaked at 517 nm) narrow photoluminescence (full width at half maximum of 18 nm) with high quantum yield (77\%). Such properties make these composite particles optimal green phosphors for down conversion liquid crystal displays (LCDs). Indeed, the authors demonstrate that a proof-of-concept 7-in. LCD in which the green color conversion layer is a polymer film loaded with 100-nm-sized CsPbBr3/m-SiO2 particles, features an optimal white emission (with correlated color temperature of 6861 K), that is close to the reference white point of NTSC, and covers 92\% of NTSC standard color gamut area of CIE1931, higher than that of a reference commercial LCD (Dell XPS 15 7590 laptop).

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