Phosphor composition and method for producing the same, and light-emitting device using the same
View Patent ↗A light-emitting device is produced using a phosphor composition containing a phosphor host having as a main component a composition represented by a composition formula: aM 3 N 2 .bAlN.cSi 3 N 4 , where “M” is at least one element selected from the group consisting of Mg, Ca, Sr, Ba, and Zn, and “a”, “b”, and “c” are numerical values satisfying 0.2≦a/(a+b)≦0.95, 0.05≦b/(b+c)≦0.8, and 0.4≦c/(c+a)≦0.95. This enables a light-emitting device emitting white light and satisfying both a high color rendering property and a high luminous flux to be provided.
1. A light-emitting device comprising a light-emitting element and a phosphor layer,
the light-emitting element being a blue light-emitting element that emits light having an emission peak in a wavelength range of 440 nm to less than 500 nm,
the phosphor layer containing a yellow phosphor having an emission peak in a wavelength range of 560 nm to less than 600 nm and a red phosphor having an emission peak in a wavelength range of 600 nm to less than 660 nm, the red phosphor being a nitride or oxynitride containing Eu 2+ as a luminescent center ion,
the yellow phosphor and the red phosphor being excited with light emitted by the blue light-emitting element to emit light, and
output light of the light-emitting device containing light-emitting components emitted by the yellow phosphor, the red phosphor, and the blue light-emitting element,
wherein the phosphor layer substantially contains no phosphor other than those activated with Eu 2+ or Ce 3+ , and
the yellow phosphor has an excitation peak on a shorter wavelength side than an excitation wavelength as a peak of the light emitted by the blue light-emitting element.
2. The light-emitting device according to claim 1 , wherein the red phosphor is a nitridoaluminosilicate-based red phosphor.
3. The light-emitting device according to claim 1 , wherein the red phosphor is a phosphor represented by the composition formula (M 1-x Eu x )AlSiN 3 , where M is at least one element selected from Mg, Ca, Sr, Ba, and Zn, and x is a numerical value satisfying 0.005≦x≦0.3.
4. The light-emitting device according to claim 1 , wherein the red phosphor is a phosphor represented by the composition formula (M 1-x Eu x ) 2 Si 4 AlON 7 , where M is at least one element selected from Mg, Ca, Sr, Ba, and Zn, and x is a numerical value satisfying 0.005≦x≦0.3.
5. The light-emitting device according to claim 1 , wherein an excitation peak of an excitation spectrum of the yellow phosphor on a longest wavelength side is in a wavelength range of less than 420 nm.
6. The light-emitting device according to claim 1 , wherein the phosphor layer substantially contains no nitride or oxynitride phosphor other than the red phosphor.
7. The light-emitting device according to claim 1 , wherein the yellow phosphor is at least one yellow phosphor selected from the group consisting of a nitride phosphor or oxynitride phosphor activated with Eu 2+ , an alkaline-earth metal orthosilicate phosphor activated with Eu 2+ , a thiogallate phosphor activated with Eu 2+ , and a phosphor having a garnet structure activated with Ce 3+ .
8. The light-emitting device according to claim 1 , wherein the yellow phosphor is one selected from the group consisting of 0.75(Ca 0.9 Eu 0.1 )O.2.25AlN.3.25 Si 3 N 4 :Eu 2+ , Ca 1.5 Al 3 Si 9 N 16 :Eu 2+ , CaSiAl 2 O 3 N 2 :Eu 2+ , Ca Si 6 AlON 9 :Eu 2+ , (Sr, Ba) 2 SiO 4 :Eu 2+ , (Sr, Ca) 2 SiO 4 :Eu 2+ , CaGa 2 S 4 :Eu 2+ , and (Y, Gd) 3 Al 5 O 12 :Ce 3+ .
9. The light-emitting device according to claim 1 , wherein the blue light-emitting element has an emission peak wavelength in a range of 450 nm to 480 nm.
10. The light-emitting device according to claim 1 , wherein an excitation peak of an excitation spectrum of the yellow phosphor on a longest wavelength side is outside a wavelength range of the emission peak of the blue light-emitting element.