Semiconductor light emitting device, backlight, color image display device and phosphor to be used for them
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%.
1. A phosphor comprising a crystal phase having a chemical composition represented by the formula (1′):
M I′ 2 M IV′ F 6 :R (1′)
wherein
M I′ is at least one element selected from the group consisting of K and Na,
M IV′ is at least one metal element selected from the group consisting of Groups 4 and 14 of the Periodic Table comprising at least Si, and
R is an activated element comprising at least Mn 4+ ,
wherein the proportion of Mn based on the total cools of M IV′ and Mn is at least 0.1 mol % and at most 6 mol %, and the specific surface area is at most 1.3 m 2 /g, and
wherein thermally decomposed F amount per 1 g of the phosphor is at most 2 μg/min.
2. The phosphor of claim 1 , wherein the particle size distribution of the phosphor has one peak value.
3. The phosphor of claim 1 , wherein the quantile deviation of the particle size distribution is at most 0.6.
4. The phosphor of claim 1 , which has a weight-average median diameter D 50 of at least 10 μm and at most 30 μm.
5. The phosphor of claim 1 , wherein the specific surface area is at most 1.0 m 2 /g.
6. The phosphor of claim 1 , wherein e quantile deviation of the particle size distribution is at most 0.25.
7. The phosphor of claim 1 , which is a red emitting phosphor.
8. The phosphor of claim 1 , which is a red emitting phosphor having at least one emission peak with a half-value width of at most 10 urn in a wavelength region of from 610 to 650 nm.
9. The phosphor of claim 1 , which is a red emitting phosphor having a main emission peak with a half-value width of at most 10 nm in a wavelength region of from 610 to 650 nm.
10. The phosphor of claim 1 , which is a red emitting phosphor and a fluoride complex phosphor.
11. The phosphor of claim 1 , which has at least 0.01 μg/min thermally decomposed fluorine amount per 1 g of the phosphor at 200° C.
12. The phosphor of claim 1 , which is a red emitting phosphor and comprises a crystal phase having a chemical composition represented by any one of the following formulae (1) to (8):
M I 2 [M IV 1-x R x F 6 ] (1)
M I 3 [M III 1-x R x F 6 ] (2)
M II [M IV 1-x R x F 6 ] (3)
M I 3 [M IV 1-x R x F 7 ] (4)
M I 2 [M III 1-x R x F 5 ] (5)
Zn 2 [M III 1-x R x F 7 ] (6)
M I [M III 2-2x R 2x F 7 ] (7)
Ba 0.65 Zr 0.35 F 2.70 :Mn 4+ (8)
wherein
M I is at least one monovalent group selected from the group consisting of Li, Na, K, Rb, Cs and NH 4 ,
M II is an alkaline earth metal element,
M III is at least one metal element selected from the group consisting of Groups 3 and 13 of the Periodic Table,
M IV is at least one metal element selected from the group consisting of Groups 4 and 14 of the Periodic Table,
R is an activated element comprising at least Mn, and
x is a numerical value of 0<x<1.
13. A semiconductor light emitting device comprising the phosphor of claim 1 .