The present invention aims to provide an image display device including an optical film having a thickness suitable for practical use without including any special inorganic material, wherein the image display device has high color rendering properties and is capable of minimizing the occurrence of blackout and interference colors (rainbow unevenness) even when the image display device includes light sources that emit light having a narrow emission spectrum. The present invention provides an image display device including an optical film having an in-plane birefringence and a polarizer in this order, wherein the optical film and the polarizer are disposed to form an angle of about 45 between a slow axis of the optical film and an absorption axis of the polarizer, the optical film has a retardation of 3000 nm or more, and light incident on the optical film provides at least 50% coverage of ITU-R BT.2020.

A red-light emitting phosphor is provided, having a basic composition represented by K.sub.a(Si.sub.1-x,Mn.sub.x)F.sub.b and also having a particular Raman spectrum, wherein the intensity ratio I.sub.1/I.sub.0, which is a ratio of (I.sub.1) the peak in a Raman shift of 60010 cm.sup.1 assigned to MnF bonds in the crystal to that (I.sub.0) in a Raman shift of 65010 cm.sup.1 assigned to SiF bonds in the crystal, is 0.09 to 0.22. This phosphor is produced by bringing a silicon source in contact with an aqueous reaction solution containing potassium permanganate and hydrogen fluoride, wherein a molar ratio of hydrogen fluoride to potassium permanganate is 87 to 127.

The present invention relates to a method for producing core-shell nanocrystals consisting of a metal-containing nanocrystal core and a shell layer comprising at least one metal oxide material having variable shell thicknesses, and use of the core-shell nanocrystals for different applications.

A light-emitting diode package includes a light-emitting diode chip disposed in a housing, a first phosphor configured to emit green light, and a second and a third phosphor configured to emit red light. White light is configured to be formed by a synthesis of light emitted from the light-emitting diode chip, the first phosphor, the second phosphor, and the third phosphor. At least one of the second and third phosphor is a nitride based phosphor that includes at least one of MSiN.sub.2, MSiON.sub.2, and M.sub.2Si.sub.5N.sub.8, where M is one of Ca, Sr, Ba, Zn, Mg, and Eu.

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 luminescent material, including a first compound represented by Formula 1 and a second compound represented by Formula 2:
[A][Cu][X].sub.3Formula 1
R.sub.21R.sub.22R.sub.23NFormula 2 wherein, in Formulae 1 and 2, A, X, and R.sub.21 to R.sub.23 are understood by referring to the definitions thereof provided in the detailed description of the specification.

A method of forming a perovskite thin film and a light-emitting device including a layer manufactured by the method.

A exemplary light emitting device includes an excitation source operable to generate excitation light with a dominant wavelength in a range 450 nm to 470 nm; a red photoluminescence material which generates light with a peak emission wavelength in a range 600 nm to 620 nm with a full width at half maximum emission intensity greater than 70 nm and less than 80 nm; a yellow to green photoluminescence material which generates light with a peak emission wavelength in a range 530 nm to 550 nm; and a narrow-band red photoluminescence material which generates light with a peak emission wavelength in a range 625 nm to 635 nm with a full width at half maximum emission intensity greater than about 5 nm and less than about 25 nm.

A stabilized fluoride phosphor for light emitting diode (LED) applications includes a particle comprising manganese-activated potassium fluorosilicate and an inorganic coating on each of the particles. The inorganic coating comprises a silicate. A method of making a stabilized fluoride phosphor comprises forming a reaction mixture that includes particles comprising a manganese-activated potassium fluorosilicate; a reactive silicate precursor; a catalyst; a solvent; and water in an amount no greater than about 10 vol. %. The reaction mixture is agitated to suspend the particles therein. As the reactive silicate precursor undergoes hydrolysis and condensation in the reaction mixture, an inorganic coating comprising a silicate is formed on the particles. Thus, a stabilized fluoride phosphor is formed.

A light-emitting diode package includes a light-emitting diode chip disposed in a housing, a first phosphor configured to emit green light, and a second and a third phosphor configured to emit red light. White light is configured to be formed by a synthesis of light emitted from the light-emitting diode chip, the first phosphor, the second phosphor, and the third phosphor. At least one of the second and third phosphor is a nitride based phosphor that includes at least one of MSiN.sub.2, MSiON.sub.2, and M.sub.2Si.sub.5N.sub.8, where M is one of Ca, Sr, Ba, Zn, Mg, and Eu.