Disclosed are a method for preparing a fluorescent nanomaterial-polymer composite and a wavelength converting element, and a light emitting device. The method for preparing the fluorescent nanomaterial-polymer composite includes: at least one precursor provided, the precursor includes a fluorescent nanomaterial and a polymer; and in a first temperature at or higher than a melting point of the polymer, the precursor is mixed, and then cooled.

There is provided a method of preparing formamidinium lead halide perovskite quantum dots having a photoluminescence quantum yield higher than before. The disclosed method comprises steps of: preparing a lead halide solution by dissolving lead halide (II), oleic acid and oleylamine in a nonpolar solvent; preparing a formamidinium solution by dissolving formamidine acetate salt and oleic acid in a nonpolar solvent; mixing the formamidinium solution and the lead halide solution to form quantum dots; and centrifuging the mixed solution to obtain sediment; dispersing the sediment in a nonpolar solvent to prepare a crude quantum dot solution; mixing the crude quantum dot solution with methyl acetate; and centrifuging the crude quantum dot solution mixed with the methyl acetate to obtain sediment as purified quantum dots. The durable quantum dots are stably formed by injecting the lead halide solution into the formamidinium solution heated at 60° C.-90° C.

A quantum dot having a perovskite crystal structure and including a compound represented by Chemical Formula 1:

ABX.sub.3+α  Chemical Formula 1

wherein, A is a Group IA metal selected from Rb, Cs, Fr, and a combination thereof, B is a Group IVA metal selected from Si, Ge, Sn, Pb, and a combination thereof, X is a halogen selected from F, Cl, Br, and I, BF.sub.4, or a combination thereof, and α is greater than 0 and less than or equal to about 3; and wherein the quantum dot has a size of about 1 nanometer to about 50 nanometers

Disclosed is a light-emitting composition with a perovskite compound and a halogen-containing compound.

The present invention provides a fluorescent diamond containing an MV center emitting fluorescence at a concentration of 1×10.sup.14/cm.sup.3 or higher, where M represents a metal or metalloid, and V represents a vacancy.

Provided are a core-shell structured perovskite particle light-emitter, a method of preparing the same, and a light emitting device using the same. The core-shell structured perovskite particle light-emitter or metal halide perovskite particle light-emitter has a perovskite nanocrystal structure and a core-shell structured particle structure. Therefore, in the perovskite particle light-emitter of the present invention, as a shell is formed of a substance having a wider band gap than that of a core, excitons may be more dominantly confined in the core, and durability of the nanocrystal may be improved to prevent exposure of the core perovskite to the air using a perovskite or inorganic semiconductor, which is stable in the air, or a polymer.

Disclosed is a particle with a component (1) and a component (2), in which the component (2) covers at least a portion of the surface of the component (1), and the component (2) includes an organic silicon compound layer including a siloxane bond and an inorganic silicon compound layer including a siloxane bond.

Disclosed is a particle with a component (1) and a component (2), in which the component (2) covers at least a portion of the surface of the component (1), and the component (2) includes an organic silicon compound layer including a siloxane bond and an inorganic silicon compound layer including a siloxane bond.

In one aspect, composite nanoparticles are provided. In some embodiments, a composite nanoparticle comprises a host matrix comprising A.sub.4BX.sub.6-ZY.sub.Z and ABX.sub.3-PY.sub.P inclusions dispersed within the host matrix of the composite nanoparticle, wherein A is an alkali metal, B is an element selected from the group consisting of transition metals, Group IVA elements and rare earth elements and X and Y are independently selected from Group VIIA elements, 0≤z≤6, and 0≤p<3.

An object of the present invention is to provide a luminescent particle having an emission maximum wavelength in a long wavelength range of 680 nm or longer and exhibiting a high quantum yield; and a compound having an emission maximum wavelength in a long wavelength range of 680 nm or longer and exhibiting a high quantum yield in the particles. According to the present invention, provided is a luminescent particle containing at least one kind of compound represented by Formula (1) (definitions of substituents in the formula are as set forth in the description) and a particle.

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