Alighting apparatus can include a light emitting element that can irradiate light, and an optical conversion layer disposed on the light emitting element for converting the irradiated light. The optical conversion layer can include crystal grains of a first phosphor and crystal grains of a second phosphor, and the crystal grains of the first phosphor and the crystal grains of the second phosphor can be in mixed form in the optical conversion layer.

A method of producing a nitride fluorescent material having relatively high light emission intensity is provided. The method of producing a nitride fluorescent material includes preparing a calcined product having a composition containing at least one first element selected from the group consisting of Ba, Sr, Ca, and Mg, at least one second element selected from the group consisting of Eu, Ce, Tb, and Mn, and Si and N, and bringing the calcined product into contact with a fluorine-containing substance at a temperature in a range of −20° C. or higher and lower than 150° C.

A nitride phosphor having a composition containing Eu, Si, Al, N, and a group 2 element including at least one selected from the group consisting of Mg, Ca, Sr, and Ba. In the composition, a ratio of a total molar content of the group 2 element and Eu to a molar content of Al is 0.8 or more and 1.1 or less, a molar ratio of Eu is 0.002 or more and 0.08 or less, a molar ratio of Si is 0.8 or more and 1.2 or less, and a total molar ratio of Si and Al is 1.8 or more and 2.2 or less. The nitride phosphor has a first peak in a range of 17° 2θ or more and 19° 2θ or less and a second peak in a range of 34° 2θ or more and 35.5° 2θ or less in a CuKα powder X-ray diffraction pattern.

A nitride phosphor having a composition containing Eu, Si, Al, N, and a group 2 element including at least one selected from the group consisting of Mg, Ca, Sr, and Ba. In the composition, a ratio of a total molar content of the group 2 element and Eu to a molar content of Al is 0.8 or more and 1.1 or less, a molar ratio of Eu is 0.002 or more and 0.08 or less, a molar ratio of Si is 0.8 or more and 1.2 or less, and a total molar ratio of Si and Al is 1.8 or more and 2.2 or less. The nitride phosphor has a first peak in a range of 17° 2θ or more and 19° 2θ or less and a second peak in a range of 34° 2θ or more and 35.5° 2θ or less in a CuKα powder X-ray diffraction pattern.

A radiation-emitting optoelectronic component may include a semiconductor chip or a semiconductor laser which, in operation of the component, emits a primary radiation in the UV region or in the blue region of the electromagnetic spectrum. The optoelectronic component may further include a conversion element comprising a first phosphor configured to convert the primary radiation at least partly to a first secondary radiation having a peak wavelength in the green region of the electromagnetic spectrum between 475 nm and 500 nm inclusive. The first phosphor may be or include BaSi.sub.4Al.sub.3N.sub.9, SrSiAl.sub.2O.sub.3N.sub.2, BaSi.sub.2N.sub.2O.sub.2, ALi.sub.3XO.sub.4, M*.sub.(1−x*−y*−z*) Z*.sub.z*[A*.sub.a*B*.sub.b*C*.sub.c*D*.sub.d*E*.sub.e*N.sub.4-n*O.sub.n*], and combinations thereof.

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.

The present disclosure relates to the technical field of luminescent materials, and more particularly, to a nitride luminescent material and a light emitting device comprising the luminescent material. The nitride luminescent material recited in the present disclosure includes an inorganic compound with the structural composition R.sub.wQ.sub.xSi.sub.yN.sub.z, the excitation wavelength of the luminescent material is between 300-650 nm, and the emission main peak of the NIR light region is broadband emission between 900-1100 nm; the excitation wavelength of the luminescent material is relatively broad and capable of excellent absorption of ultraviolet visible light, and has more intensive NIR emission as compared with NIR organic luminescent materials and inorganic luminescent materials of other systems, so it is an ideal application material for NIR devices.

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 wavelength converter may include a phosphor layer and a filter layer where the filter layer may be directly attached to the phosphor layer. The wavelength converter may have an overall thickness ranging from 20 μm to 80 μm.

A light emitting device assembly and methods for preparing a wavelength converter and methods for preparing a light emitting device assembly are also disclosed.