A luminescent material represented by Formula 1, a method of preparing the same, and a light-emitting device including the same:
[A.sup.1.sub.nA.sup.2.sub.3][B.sub.2][X.sup.1.sub.mX.sup.2.sub.5]  Formula 1 A.sup.1, A.sup.2, B, X.sup.1, X.sup.2, n, and m in Formula 1 are as defined in the specification.

A potassium hexafluoromanganate is represented by General Formula: K.sub.2MnF.sub.6, and a diffuse reflectance with respect to light having a wavelength of 310 nm is 20% or more.

A potassium hexafluoromanganate is represented by General Formula: K.sub.2MnF.sub.6, and a diffuse reflectance with respect to light having a wavelength of 310 nm is 20% or more.

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.

Disclosed are quantum dots including a luminescent dopant. More particularly, each of the quantum dots according to an embodiment of the present invention includes a core and a shell surrounding the core, wherein at least one of an interior of the core and an interface between the core and the shell is doped with a luminescent group I dopant.

A method for producing a fluoride fluorescent material comprises: preparing fluoride particles having a composition containing at least one element or ion A selected from the group consisting of alkaline metal elements and NH.sub.4.sup.+, at least one element M selected from the group consisting of Group-4 elements and Group-14 elements, Mn.sup.4+, and F, in which a molar ratio of A in 1 mol of the composition is 2, a total molar ratio of M and Mn.sup.4+ is 1, a molar ratio of Mn.sup.4+ is in a range of more than 0 and less than 0.2, and a molar ratio of F is 6; subjecting the fluoride particles to a first heat treatment at a temperature of 500° C. or more in an inert gas atmosphere; washing the first heat-treated fluoride particles with a washing liquid; and bringing the washed fluoride particles into contact with a fluorine-containing substance and subjecting the resulting fluoride particles to a second heat treatment at a temperature of 400° C. or more.

To provide a semiconductor light emitting device which is capable of accomplishing a broad color reproducibility for an entire image without losing brightness of the entire image. A light source provided on a backlight for a color image display device has a semiconductor light emitting device comprising a solid light emitting device to emit light in a blue or deep blue region or in an ultraviolet region and phosphors, in combination. The phosphors comprise a green emitting phosphor and a red emitting phosphor. The green emitting phosphor and the red emitting phosphor are ones, of which the rate of change of the emission peak intensity at 100° C. to the emission intensity at 25° C., when the wavelength of the excitation light is 400 nm or 455 nm, is at most 40%.

A light emitting device comprises a light emitting element having a light emission peak wavelength in a range of 400 nm or more and 490 nm or less and a first fluorescent material having a light emission peak wavelength in a range of 570 nm or more and 680 nm or less, and emits light having a correlated color temperature being 1,950 K or less, an average color rendering index Ra being 51 or more, a full width at half maximum of a light emission peak having a maximum light emission intensity in a light emission spectrum of the light emitting device being 110 nm or less, and a first glare index Ls1/L that is a ratio of a first effective radiance Ls1 to a luminance L being 0.493 or less, wherein Ls1 and L are as defined in the disclosure.

A potassium hexafluoromanganate is represented by General Formula: K.sub.2MnF.sub.6, and a diffuse reflectance with respect to light having a wavelength of 550 nm is 60% or more.

A potassium hexafluoromanganate is represented by General Formula: K.sub.2MnF.sub.6, and a diffuse reflectance with respect to light having a wavelength of 550 nm is 60% or more.