Red light emitting phosphor, its production and light emitting device

• US 20040145307A1
• Filed: 01/28/2003
• Published: 07/29/2004
• Est. Priority Date: 01/28/2003
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Fine Rubber Kenkyuusho
• Original Assignee: Kabushiki Kaisha Fine Rubber Kenkyuusho
• Inventors: Odaki, Tsutomu
• Granted Patent: US 6,982,523 B2
• Time in Patent Office: Days
• US Class Current: 313/512
• CPC Class Codes: C01G 39/006 Compounds containing, besides molybdenum, two or more other elements, with the exception of oxygen or hydrogen
• CPC Class Codes: C01G 41/006 Compounds containing, besides tungsten, two or more other elements, with the exception of oxygen or hydrogen
• CPC Class Codes: C01P 2002/77 by unit-cell parameters, atom positions or structure diagrams
• CPC Class Codes: C01P 2002/84 by UV- or VIS- data
• CPC Class Codes: C09K 11/7734 Aluminates
• CPC Class Codes: C09K 11/7736 Vanadates; Chromates; Molybdates; Tungstates
• CPC Class Codes: C09K 11/7739 with halogens
• CPC Class Codes: C09K 11/7789 Oxysulfides
• CPC Class Codes: C09K 11/7794 Vanadates; Chromates; Molybdates; Tungstates
• 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 2224/8592 Applying permanent coating, e.g. protective coating
• 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 33/502 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

As a red light emitting phosphor capable of efficiently emitting red light at a high luminance in response to exciting light having a wavelength of 350-420 nm, and practically used in a light emitting device for red display or a light emitting device for white or intermediate color display in combination with green and blue light emitting phosphors, the invention provides a red light emitting phosphor capable of emitting red light upon excitation with light having a wavelength of 350-420 nm and having compositional formula (1):

AEu_xLn_(1−x)M₂O₈  (1)

wherein A is at least one element selected from among Li, Na, K, Rb and Cs, Ln is at least one element selected from among Y and rare earth elements exclusive of Eu, M is at least one element selected from among W and Mo, and x is a positive number satisfying 0<x≦1; and a red light emitting phosphor having compositional formula (2):

D_0.5Eu_yLn_(1−y)M₂O₈  (2)

wherein D is at least one element selected from among Mg, Ca, Sr and Ba, Ln is at least one element selected from among Y and rare earth elements exclusive of Eu, M is at least one element selected from among W and Mo, and y is a positive number satisfying 0<y≦1. Methods for preparing the red light emitting phosphors, and light emitting devices using the red light emitting phosphors are also provided.

Claims

1. A red light emitting phosphor capable of emitting red light upon excitation with light having a wavelength of 350 to 420 nm, characterized by having a composition of compositional formula (1):

AEu_xLn<sub>(1−

x)</sub>M₂O₈ 

 

(1)

wherein A is at least one element selected from the group consisting of Li, Na, K, Rb and Cs,

Ln is at least one element selected from the group consisting of Y and rare earth elements exclusive of Eu,

M is at least one element selected from the group consisting of W and Mo, and

x is a positive number satisfying 0<

x≦

1.

2. The red light emitting phosphor of claim 1, characterized in that A in the compositional formula (1) is partially substituted with at least one element selected from the group consisting of Mg, Ca, Sr and Ba to be added as a co-activator.

4. The red light emitting phosphor of claim 1 or 3, characterized in that Ln in the formula is at least one element selected from the group consisting of Y, La, Gd and Lu.

5. The red light emitting phosphor of claim 1 or 3, characterized in that Eu constituting the red light emitting phosphor is in the form of trivalent europium ions (Eu³⁺) which are arranged in a two- or one-dimensional array.

6. A method for preparing the red light emitting phosphor of claim 1, characterized by comprising the steps of mixing raw materials containing elements constituting the red light emitting phosphor, firing the resulting mixture, and washing the fired product with an aqueous alkali solution.

8. A light emitting device comprising a semiconductor light emitter capable of emitting light having a wavelength of 350 to 420 nm, enclosed in an encapsulant, characterized in that the red light emitting phosphor of claim 1 or 3 is dispersed in the encapsulant.

9. A light emitting device comprising a semiconductor light emitter capable of emitting light having a wavelength of 350 to 420 nm, enclosed in an encapsulant, characterized in that

a fluorescent layer containing the red light emitting phosphor of claim 1 or 3 is disposed in an optical path of the light from the semiconductor light emitter.

10. A light emitting device comprising a semiconductor light emitter capable of emitting light having a wavelength of 350 to 420 nm, enclosed in an encapsulant, characterized in that

a fluorescent layer containing the red light emitting phosphor of claim 1 or 3 is disposed on the semiconductor light emitter or the encapsulant.

11. A light emitting device comprising a semiconductor light emitter capable of emitting light having a wavelength of 350 to 420 nm, enclosed in an encapsulant, characterized in that

a fluorescent layer comprising the red light emitting phosphor of claim 1 or 3 dispersed in a resin, rubber, elastomer or glass is disposed on the semiconductor light emitter or the encapsulant.

3. A red light emitting phosphor capable of emitting red light upon excitation with light having a wavelength of 350 to 420 nm, characterized by having a composition of compositional formula (2):

D_0.5Eu_yLn<sub>(1−

y)</sub>M₂O₈ 

 

(2)

wherein D is at least one element selected from the group consisting of Mg, Ca, Sr and Ba,

Ln is at least one element selected from the group consisting of Y and rare earth elements exclusive of Eu,

M is at least one element selected from the group consisting of W and Mo, and

y is a positive number satisfying 0<

y≦

1.

7. A method for preparing the red light emitting phosphor of claim 3, characterized by comprising the steps of mixing raw materials containing elements constituting the red light emitting phosphor, firing the resulting mixture, and washing the fired product with an aqueous acid solution.