Luminescent material
View Patent ↗According to one embodiment, the luminescent material shows a luminescence peak in a wavelength range of 570 to 670 nm when excited with light having an emission peak in a wavelength range of 250 to 520 nm. The luminescent material includes a host material having a crystal structure substantially same as the crystal structure of Sr 2 Si 7 Al 3 ON 13 . The host material is activated by Eu, and includes Sr and Ca to satisfy a relationship of 0.008≦M Ca /(M Sr +M Ca )≦0.114, where M Ca is a number of moles of Ca and M Sr is a number of moles of Sr.
1. A light-emitting device comprising:
a light-emitting element which emits light having an emission peak in a wavelength range of 380 to 490 nm, the element having a peak wavelength in steady-state driving shifted by 6 nm or more toward longer wavelength as compared to a peak wavelength at initial driving; and
a luminous layer comprising a red-emitting luminescent material which receives light from the light-emitting element to emit red light, the red-emitting luminescent material having a composition represented by formula 1:
[(Sr 1-p Ca p ) 1-x Eu x ] A Si B AlO C N D formula 1
wherein p, x, A, B, C and D satisfy following conditions:
0.008≦p≦0.114, 0<x≦0.4, 0.55≦A≦0.8,
2≦B≦3, 0<C≦0.6, 4≦D≦5,
the luminous layer further comprising a green-emitting luminescent material which receives light from the light-emitting element to emit green light.
2. The light-emitting device according to claim 1 , wherein the green-emitting luminescent material is 13 sialon:Eu.
3. The light emitting device of claim 1 , wherein:
p is 0.025≦p≦0.114
x is 0.031≦x≦0.036
A is 0.61≦A≦0.68
B is 2.28≦B≦2.62
C is 0.16≦C≦0.43 and
D is 4.08≦D≦4.64.
4. The light-emitting device according to claim 1 , wherein the red-emitting luminescent material has an orthorhombic crystal structure.
5. A light-emitting device comprising:
a light-emitting element which emits light having an emission peak in a wavelength range of 380 to 490 nm, the element having a peak wavelength in steady-state driving shifted by 6 nm or more toward longer wavelength as compared to a peak wavelength at initial driving; and
a luminous layer comprising a red-emitting luminescent material which receives light from the light-emitting element to emit red light, the red-emitting luminescent material having a composition represented by formula 1:
[(Sr 1-p Ca p ) 1-x Eu x ] A Si B AlO C N D formula 1
wherein p, x, A, B, C and D satisfy following conditions:
0.008≦p≦0.114, 0<x≦0.4, 0.55≦A≦0.8,
2≦B≦3, 0<C≦0.6, 4≦D≦5,
the luminous layer further comprising a yellow-emitting luminescent material which receives light from the light-emitting element to emit yellow light.
6. The light-emitting device according to claim 5 , wherein the yellow-emitting luminescent material is Y 3 Al 5 O 12 :Ce.
7. The light emitting device of claim 5 , wherein:
p is 0.025≦p≦0.114
x is 0.031≦x≦0.036
A is 0.61≦A≦0.68
B is 2.28≦B≦2.62
C is 0.16≦C≦0.43 and
D is 4.08≦D≦4.64.
8. The light-emitting device according to claim 5 , wherein the red-emitting luminescent material has an orthorhombic crystal structure.
9. A light-emitting device comprising:
a light-emitting element which emits light having an emission peak in a wavelength range of 250 to 430 nm, the element having a peak wavelength in steady-state driving shifted by 6 nm or more toward longer wavelength as compared to a peak wavelength at initial driving; and
a luminous layer comprising a red-emitting luminescent material which receives light from the light-emitting element to emit red light, the red-emitting luminescent material having a composition represented by formula 1:
[(Sr 1-p Ca p ) 1-x Eu x ] A Si B AlO C N D formula 1
wherein p, x, A, B, C and D satisfy following conditions:
0.008≦p≦0.114, 0<x≦0.4, 0.55≦A≦0.8,
2≦B≦3, 0<C≦0.6, 4≦D≦5,
the luminous layer further comprising a green-emitting luminescent material which receives light from the light-emitting element to emit green light and a blue-emitting luminescent material which receives light from the light-emitting element to emit blue light.
10. The light-emitting device according to claim 9 , wherein the green-emitting luminescent material is β sialon:Eu.
11. The light-emitting device according to claim 9 , wherein the blue-emitting luminescent material is BaMgAl 10 O 17 :Eu.
12. The light-emitting device according to claim 10 , wherein the blue-emitting luminescent material is BaMgAl 10 O 17 :Eu.
13. The light emitting device of claim 9 , wherein:
p is 0.025≦p≦0.114
x is 0.031≦x≦0.036
A is 0.61≦A≦0.68
B is 2.28≦B≦2.62
C is 0.16≦C≦0.43 and
D is 4.08≦D≦4.64.
14. The light-emitting device according to claim 9 , wherein the red-emitting luminescent material has an orthorhombic crystal structure.