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.

A light emitting device includes a first light emitting element including a rectangular first light extraction surface, a second light emitting element including a rectangular second light extraction surface and emitting light having an emission peak wavelength different from an emission peak wavelength of the first light emitting element, and a light-transmissive member covering the first light extraction surface and the second light extraction surface. The light-transmissive member includes a first light-transmissive layer facing the first light extraction surface and the second light extraction surface, a wavelength conversion layer located on the first light-transmissive layer, and a second light-transmissive layer located on the wavelength conversion layer. The first light-transmissive layer contains a first matrix and first diffusive particles. The wavelength conversion layer contains a second matrix and wavelength conversion particles. The second light-transmissive layer contains a third matrix and second diffusive particles.

Light emitting devices and LED-filaments comprise an excitation source (e.g. LED) and a photoluminescence material comprising a combination of a first narrow-band red photoluminescence material which generates light with a peak emission wavelength in a range 580 nm to 628 nm and a full width at half maximum emission intensity in a range 45 nm to 60 nm and a second narrow-band red photoluminescence material generates light with a peak emission wavelength in a range 628 nm to 640 nm and a full width at half maximum emission intensity in a range 5 nm to 20 nm. At least one of the first and second narrow-band red photoluminescence materials can comprise a narrow-band red phosphor or a quantum dot (QD) material.

There is provided a display backlight (604), including an excitation source (644) for generating blue light (650); and a wavelength converter (654) being a unitary construction including a combination of a wavelength selective filter layer (658) bonded to a photoluminescence layer (660), where the photoluminescence layer (658) includes a green photoluminescence material and a red photoluminescence material; and where the wavelength selective filter layer (658) is transmissive to blue light and reflective to green and red light.

A phosphor composition of an embodiment and a light emitting device package including the same includes: a green phosphor excited by blue light to emit green light; a first red phosphor of a nitride series which is excited by the blue light and emits first red light; and a second red phosphor of a fluorine series which is excited by the blue light and emits second red light, and is capable of emitting white light without deterioration of optical characteristics at a high temperature while improving luminous flux and color reproduction rate as compared with a light emitting device package including a conventional phosphor composition.

Briefly, in one aspect, the present invention relates to processes for producing a stabilized Mn.sup.4+ doped phosphor in solid form and a composition containing such doped phosphor. Such process may include combining a) a solution comprising at least one substance selected from the group consisting of: K.sub.2HPO.sub.4, an aluminum phosphate, oxalic acid, phosphoric acid, a surfactant, a chelating agent, or a combination thereof, with b) a Mn.sup.4+ doped phosphor of formula I in solid form, where formula I may be: A.sub.x [MF.sub.y]:Mn.sup.4+. The process can further include isolating the stabilized Mn.sup.4+ doped phosphor in solid form. In formula I, A may be Li, Na, K, Rb, Cs, or a combination thereof. In formula I, M may be Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof. In formula I, x is the absolute value of the charge of the [MF.sub.y] ion and y is 5, 6 or 7.

There is provided a fluoride phosphor composite including: fluoride phosphor core particles that may be expressed by the empirical formula A.sub.xMF.sub.y:Mn.sup.4+, wherein A may be at least one selected from the group consisting of Li, Na, K, Rb, and Cs, M may be at least one selected from the group consisting of Si, Ti, Zr, Hf, Ge, and Sn, the composition ratio (x) of A may satisfy 2≦x≦3, the composition ratio (y) of F may satisfy 4≦y≦7, each fluoride phosphor composite particle may be coated with a Mn-free fluoride coating. The Mn-free fluoride coating may have a thickness less than or equal to 35% of the size of each fluoride phosphor composite particle.

There is provided a fluoride phosphor composite including: fluoride phosphor core particles that may be expressed by the empirical formula A.sub.xMF.sub.y:Mn.sup.4+, wherein A may be at least one selected from the group consisting of Li, Na, K, Rb, and Cs, M may be at least one selected from the group consisting of Si, Ti, Zr, Hf, Ge, and Sn, the composition ratio (x) of A may satisfy 2≦x≦3, the composition ratio (y) of F may satisfy 4≦y≦7, each fluoride phosphor composite particle may be coated with a Mn-free fluoride coating. The Mn-free fluoride coating may have a thickness less than or equal to 35% of the size of each fluoride phosphor composite particle.

A process for preparing a Mn.sup.+4 doped phosphor of formula I

A.sub.x[MF.sub.y]:Mn.sup.+4   I

includes combining a first solution comprising a source of A and a second solution comprising H.sub.2MF.sub.6 in the presence of a source of Mn, to form the Mn.sup.+4 doped phosphor; wherein A is Li, Na, K, Rb, Cs, or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; y is 5, 6 or 7; and
wherein a value of a Hammett acidity function of the first solution is at least −0.9.

Particles produced by the process may have a particle size distribution with a D.sub.50 particle size of less than 10 μm.

A method includes obtaining a potassium hexafluorosilicate (PFS)-based powder, obtaining a fluidization material, and mixing the PFS-based powder with the fluidization material to form a PFS-based mixture. The PFS-based mixture is configured to be mixed with a resinous material to form a flowing phosphor blend configured to be placed onto a light source to form a phosphor on the light source.