SEMICONDUCTOR LIGHT EMITTING DEVICE, BACKLIGHT, COLOR IMAGE DISPLAY DEVICE AND PHOSPHOR TO BE USED FOR THEM

• US 20100142189A1
• Filed: 02/06/2009
• Published: 06/10/2010
• Est. Priority Date: 02/07/2008
• Status: Active Grant

• Current Assignee: Citizen Electronics Company Limited, Nichia Corporation
• Original Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Inventors: Hong, Byungchul, Yoyasu, Fumiko, Horibe, Kentarou, Kijima, Naoto, Hase, Takashi, Yoshino, Masahiko, Sako, Naoki
• Granted Patent: US 8,491,816 B2
• Time in Patent Office: Days
• US Class Current: 362/97.300
• CPC Class Codes: C09K 11/0883 Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/616 with alkali or alkaline earth metals
• CPC Class Codes: C09K 11/675 with alkali or alkaline earth metals
• CPC Class Codes: C09K 11/7734 Aluminates
• CPC Class Codes: C09K 11/77342 Silicates
• CPC Class Codes: C09K 11/77347 Silicon Nitrides or Silicon Oxynitrides
• CPC Class Codes: C09K 11/77348 Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• CPC Class Codes: C09K 11/7739 with halogens
• CPC Class Codes: F21K 2/00 Non-electric light sources using luminescence using excitation by radioactivity G21H3/02, H01J65/06, H01J65/08; using excitation by an external electromagnetic field or by external corpuscular radiation H01J65/04; Light sources using electrochemiluminescence
• CPC Class Codes: F21V 3/062 the material being plastics
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02B 6/0023 provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/0043 provided on the surface of the light guide
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/1336 Illuminating devices
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133609 : including means for improving the color mixing, e.g. white
• CPC Class Codes: G02F 1/133611 : including means for improving the brightness uniformity
• CPC Class Codes: G02F 1/133614 : using photoluminescence, e.g. phosphors illuminated by UV or blue light
• CPC Class Codes: G02F 1/133615 : Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: G02F 1/133624 : characterised by their spectral emissions
• CPC Class Codes: G02F 1/1368 : in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: H01L 2224/45015 : being circular
• CPC Class Codes: H01L 2224/45124 : Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/45144 : Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 : Arched
• CPC Class Codes: H01L 2224/48247 : connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 24/45 : of an individual wire connector
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 : Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 2924/12042 : LASER
• CPC Class Codes: H01L 2924/12044 : OLED
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/20752 : larger or equal to 20 microns less than 30 microns
• CPC Class Codes: H01L 2924/20753 : larger or equal to 30 microns less than 40 microns
• CPC Class Codes: H01L 2924/3025 : Electromagnetic shielding
• CPC Class Codes: H01L 33/502 : Wavelength conversion materials
• CPC Class Codes: H01L 33/504 : Elements with two or more wavelength conversion materials
• CPC Class Codes: H05B 33/14 : characterised by the chemical or physical composition or the arrangement of the electroluminescent material , or by the simultaneous addition of the electroluminescent material in or onto the light source

Abstract

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%.

Claims

1. 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, wherein said phosphors comprise a green emitting phosphor having at least one emission peak in a wavelength region of from 515 to 550 nm and a red emitting phosphor having at least one emission peak with a half-value width of at most 10 nm in a wavelength region of from 610 to 650 nm;

said red emitting phosphor has substantially no excitation spectrum in the emission wavelength region of said green emitting phosphor and comprises Mn⁴⁺ as an activated element; and

said green emitting phosphor and said red emitting phosphor have the variation rate of the emission peak intensity at 100°

C. to the emission intensity at 25°

C. of at most 40%, when the wavelength of the excitation light is 400 nm or 455 nm.

2. The semiconductor light emitting device according to claim 1, wherein the green emitting phosphor comprises at least one compound selected from the group consisting of an aluminate phosphor, a sialon phosphor and an oxynitride phosphor.

3. The semiconductor light emitting device according to claim 1, wherein the red emitting phosphor has the variation rate of the emission peak intensity at 100°

C. to the emission peak intensity at 25°

C. of at most 18%, when the wavelength of the excitation light is 455 nm.

4. The semiconductor light emitting device according to claim 1, wherein the red emitting phosphor has a main emission peak with a half-value width of at most 10 nm in a wavelength region of from 610 to 650 nm.

5. The semiconductor light emitting device according to claim 1, wherein the red emitting phosphor is a fluoride complex phosphor, and said solid light emitting device is formed on an electrically conductive substrate.

6. The semiconductor light emitting device according to claim 5, wherein the red emitting phosphor has at least 0.01 μ

g/min of thermally decomposed fluorine amount per 1 g of the phosphor at 200°

C.

7. The semiconductor light emitting device according to claim 6, wherein the red emitting phosphor has at 20°

C. is at least 0.005 g and at most 7 g of solubility in 100 g of water at 20°

C.

8. The semiconductor light emitting device according to claim 1, wherein the red emitting phosphor is a fluoride complex phosphor, and the semiconductor light emitting device comprises a layer comprising said red emitting phosphor and has at least one of the following structures (a) to (c):

(a) a layer of a material not containing said red emitting phosphor between the solid light emitting device and the layer containing said red emitting phosphor,

(b) part or whole of the surface of the light emitting device covered by a layer of a material not containing said red emitting phosphor, and

(c) the layer comprising said red emitting phosphor, covered by a layer of a material not containing said red emitting phosphor.

9. The semiconductor light emitting device according to claim 8, wherein the red emitting phosphor has at least 0.01 μ

g/min of thermally decomposed fluorine amount per 1 g of the phosphor at 200°

C.

10. The semiconductor light emitting device according to claim 9, wherein the red emitting phosphor has at least 0.005 g and at most 7 g of solubility in 100 g of water at 20°

C.

11. The semiconductor light emitting device according to claim 1, wherein the red emitting phosphor comprises a crystal phase having a chemical composition represented by any one of the following formulae (1) to (8):

M^I₂[M^IV_1-xR_xF₆] 

 

(1)

M^I₃[M^III_1-xR_xF₆] 

 

(2)

M^II[M^IV_1-xR_xF₆] 

 

(3)

M^I₃[M^IV_1-xR_xF₇] 

 

(4)

M^I₂[M^III_1-xR_xF₅] 

 

(5)

Zn₂[M^III_1-xR_xF₇] 

 

(6)

M^I[M^III_2-2xR_2xF₇] 

 

(7)

Ba_0.65Zr_0.35F_2.70;

Mn⁴⁺ 

 

(8)

In the formulae (1) to (8), M^I is at least one monovalent group selected from the group consisting of Li, Na, K, Rb, Cs and NH₄, 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.

12. The semiconductor light emitting device according to claim 11, wherein the red emitting phosphor comprises a crystal phase having a chemical composition represented by the following formula (1′

), wherein the proportion of Mn based on the total mols of M^IV′

and Mn is at least 0.1 mol % and at most 40 mol %, and the specific surface area is at most 1.3 m²/g;

M^I′

₂M^IV′

F₆;

R 

 

(1′

)

In the formula (1′

), 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.

13. A backlight having the semiconductor light emitting device according to claim 1 as a light source.

14. A color image display device comprising light shutters, a color filter having at least trichromatic color elements of red, green and blue corresponding to the light shutters and the backlight as defined in claim 13, in combination, wherein the relationship between the light use efficiency Y and the NTSC ratio W representing the color reproduction range of the color image display device is represented by the following formula:

$\begin{array}{cc}Y\geqq <br><br>-0.4<br><br>W+64<br><br><br><br>W<br><br>\left(\mathrm{where}<br><br><br><br>W\geqq <br><br>85\right)& \\ X=\frac{{\int <br><br>}_{380}^{780}<br><br>\stackrel{\_}{x}<br><br>\left(\mathrm{\lambda <br><br>}\right)<br><br>S<br><br>\left(\mathrm{\lambda <br><br>}\right)<br><br>T<br><br>\left(\mathrm{\lambda <br><br>}\right)<br><br><br><br><br><br>\mathrm{\lambda <br><br>}}{{\int <br><br>}_{380}^{780}<br><br>\stackrel{\_}{y}<br><br>\left(\mathrm{\lambda <br><br>}\right)<br><br>S<br><br>\left(\mathrm{\lambda <br><br>}\right)<br><br><br><br>\mathrm{\lambda <br><br>}}& x=\frac{X}{X+Y+Z}\\ Y=\frac{{\int <br><br>}_{380}^{780}<br><br>\stackrel{\_}{y}<br><br>\left(\mathrm{\lambda <br><br>}\right)<br><br>S<br><br>\left(\mathrm{\lambda <br><br>}\right)<br><br>T<br><br>\left(\mathrm{\lambda <br><br>}\right)<br><br><br><br><br><br>\mathrm{\lambda <br><br>}}{{\int <br><br>}_{380}^{780}<br><br>\stackrel{\_}{y}<br><br>\left(\mathrm{\lambda <br><br>}\right)<br><br>S<br><br>\left(\mathrm{\lambda <br><br>}\right)<br><br><br><br>\mathrm{\lambda <br><br>}}& y=\frac{Y}{X+Y+Z}\\ Z=\frac{{\int <br><br>}_{380}^{780}<br><br>\stackrel{\_}{z}<br><br>\left(\mathrm{\lambda <br><br>}\right)<br><br>S<br><br>\left(\mathrm{\lambda <br><br>}\right)<br><br>T<br><br>\left(\mathrm{\lambda <br><br>}\right)<br><br><br><br><br><br>\mathrm{\lambda <br><br>}}{{\int <br><br>}_{380}^{780}<br><br>\stackrel{\_}{y}<br><br>\left(\mathrm{\lambda <br><br>}\right)<br><br>S<br><br>\left(\mathrm{\lambda <br><br>}\right)<br><br><br><br>\mathrm{\lambda <br><br>}}& \end{array}$

wherein the definitions of the respective symbols are as follows;

x(λ

), y(λ

), z(λ

);

color matching functions of XYZ color system

S(λ

);

relative emission spectrum of the backlight

T(λ

);

transmittance of the color filter

15. The color image display device according to claim 14, wherein the green pixel of the color filter comprises a zinc phthalocyanine bromide pigment.

16. The color image display device according to claim 14, wherein each pixel of the color filter has a film thickness of at least 0.5 μ

m and at most 3.5 μ

m.

17. A phosphor comprising a crystal phase having a chemical composition represented by the following formula (1′

), wherein the proportion of Mn based on the total mols of M^IV′

and Mn is at least 0.1 mol % and at most 40 mol %, and the specific surface area is at most 1.3 m²/g;

M^I′

₂M^IV′

F₆;

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.

18. The phosphor according to claim 17, wherein the particle size distribution of said red emitting phosphor has one peak value.

19. The phosphor according to claim 17, wherein the quantile deviation of the particle size distribution is at most 0.6.

20. A process for producing the phosphor according to claim 17, comprising reacting a solution comprising at least Si and F with a solution comprising at least K, Mn and F to obtain a compound represented by the formula (1′

).

22. A phosphor-containing composition comprising the phosphor according to claim 17 and a liquid medium.

21. A process for producing a phosphor comprising a crystal phase having a chemical composition represented by the following formula (1′

), comprising mixing at least two types of solutions each comprising at least one element selected from the group consisting of K, Na, Si, Mn and F;

M^I′

₂M^IV′

F₆;

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.