White light emitting phosphor blend for LED devices

• US 20030067008A1
• Filed: 11/18/2002
• Published: 04/10/2003
• Est. Priority Date: 05/15/2000
• Status: Active Grant

• Current Assignee: Current Lighting Solutions, LLC (f/k/a GE Lighting Solutions, LLC) (American Industrial Partners)
• Original Assignee: General Electric Company
• Inventors: Srivastava, Alok Mani, Comanzo, Holly Ann
• Granted Patent: US 7,015,510 B2
• Time in Patent Office: Days
• US Class Current: 257/79
• CPC Class Codes: C09K 11/7734 Aluminates
• CPC Class Codes: C09K 11/7738 with alkaline earth metals
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• 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
• CPC Class Codes: H10K 50/125 specially adapted for multicolour light emission, e.g. for emitting white light
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

There is provided a white light illumination system including a radiation source, a first luminescent material having a peak emission wavelength of about 570 to about 620 nm, and a second luminescent material having a peak emission wavelength of about 480 to about 500 nm, which is different from the first luminescent material. The LED may be a UV LED and the luminescent materials may be a blend of two phosphors. The first phosphor may be an orange emitting Eu²⁺, Mn²⁺ doped strontium pyrophosphate, (Sr_0.8Eu_0.1Mn_0.1)₂P₂O₇. The second phosphor may be a blue-green emitting Eu²⁺ doped SAE, (Sr_0.90-0.99 Eu_0.01-0.1)₄Al₁₄O₂₅. A human observer perceives the combination of the orange and the blue-green phosphor emissions as white light.

Claims

1. A white light illumination system comprising:

a radiation source;

a first luminescent material having a peak emission wavelength of about 570 to about 620 nm; and

a second luminescent material having a peak emission wavelength of about 480 to about 500 nm, which is different from the first luminescent material.

2. The system of claim 1, wherein the white light emitted by the system lacks any significant visible component emitted by the radiation source.

3. The system of claim 1, wherein the radiation source peak emission wavelength is 360 to 420 nm.

4. The system of claim 3, wherein the radiation source comprises a light emitting diode containing an InGaN active layer and having a peak emission wavelength between 370 and 405 nm.

5. The system of claim 1, wherein:

the radiation source comprises a gas contained in a fluorescent lamp; and

a radiation emitted by the radiation source comprises ultraviolet radiation.

6. The system of claim 1, wherein:

the radiation source comprises a gas contained in a plasma display; and

a radiation emitted by the radiation source comprises ultraviolet radiation.

7. The system of claim 1, wherein:

the first luminescent material comprises a first APO;

Eu²⁺,Mn²⁺ phosphor; and

A comprises at least one of Sr, Ca, Ba or Mg.

8. The system of claim 7, wherein the first phosphor comprises A₂P₂O₇:

Eu²⁺,Mn²⁺.

9. The system of claim 8, wherein:

the first phosphor comprises (A_1-x-yEu_xMn_y)_{2 P2} O₇;

0<

x≦

0.2; and

0<

y≦

0.2.

10. The system of claim 9, wherein the second luminescent material comprises a second phosphor selected from at least one of:

a) A₄D₁₄O₂₅;

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg, and D comprises at least one of Al or Ga;

b) (2AO*0.84P₂O₅*0.16B₂O₃);

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg;

c) AD₈O₁₃;

EU²⁺, where A comprises at least one of Sr, Ca, Ba or Mg, and D comprises at least one of Al or Ga;

d) A₁₀(PO₄)₆Cl₂;

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg;

or

e) A₂Si₃O₈*2ACl₂;

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg.

11. The system of claim 10, wherein the second luminescent material comprises a second phosphor selected from at least one of:

a) a Sr₄Al₁₄O₂₅;

Eu²⁺ phosphor;

b) a (2SrO*0.84P₂O₅* 0.16B₂O₃);

Eu²⁺ phosphor;

c) a BaAl₈O₁₃;

Eu²⁺ phosphor;

d) a (Sr,Mg,Ca)₁₀(PO₄)₆Cl₂;

Eu²⁺ phosphor;

or

e) a Sr₂Si₃O₈*2SrCl₂;

Eu²⁺ phosphor.

12. The system of claim 11, wherein the first phosphor and the second phosphor are interspersed.

13. The system of claim 12, wherein the light source comprises a light emitting diode having a peak emission wavelength of between 370 and 405 nm.

14. The system of claim 13, further comprising:

a shell containing the light emitting diode;

an encapsulating material between the shell and the light emitting diode; and

wherein;

a) the first and second phosphors are coated over a surface of the light emitting diode;

b) the first and second phosphors are interspersed in the encapsulating material;

or

c) the first and second phosphors are coated onto the shell.

15. The system of claim 14, wherein:

the first phosphor comprises (Sr_0.8Eu_0.1Mn_0.1)₂ P₂ O₇;

the second phosphor comprises (Sr_0.90-0.99 Eu_0.01-0.1)₄Al₁₄O₂₅;

the light emitting diode peak emission wavelength is about 380 nm;

a ratio by weight of the first phosphor to the second phosphor is about 77;

23; and

CIE color coordinates of a radiation emitted by the system is about x=0.39 and y=0.42.

16. The system of claim 14, wherein:

the first phosphor comprises (Sr_0.8Eu_0.1Mn_0.1)₂ P₂ O₇;

the second phosphor comprises (Sr_0.90-0.99 Eu_{0 01-0.1})₄Al₁₄O₂₅;

the light emitting diode peak emission wavelength is about 405 nm;

the ratio by weight of the first phosphor to the second phosphor is about 89;

11; and

CIE color coordinates of a radiation emitted by the system is about x=0.39 and y=0.42.

17. A white light illumination system comprising:

a light emitting diode having a peak emission wavelength between 370 and 405 nm;

a first APO;

Eu²⁺,Mn²⁺ phosphor, where A comprises at least one of Sr, Ca, Ba or Mg; and

a second phosphor selected from at least one of;

a) A₄D₁₄O₂₅;

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg, and D comprises at least one of Al or Ga;

b) (2AO*0.84P₂O₅*0.16B₂O₃);

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg;

c) AD₈O₁₃;

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg, and D comprises at least one of Al or Ga;

d) A₁₀(PO₄)₆Cl₂;

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg;

or

e) A₂Si₃O₈*2ACl₂;

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg.

18. The system of claim 17, wherein:

the first phosphor comprises (A_1-x-yEu_xMn_y)₂ P₂ O₇, where 0<

x≦

0.2; and

0<

y≦

0.2;

the second phosphor is selected from at least one of;

a) a Sr₄Al₁₄O₂₅;

Eu²⁺ phosphor;

b) a (2SrO*0.84P₂O₅*0.16B₂O₃);

Eu²⁺ phosphor;

c) a BaAl₈O₁₃;

Eu²⁺ phosphor;

d) a (Sr,Mg,Ca)₁₀(PO₄)₆Cl₂;

Eu²⁺ phosphor;

or

e) a Sr₂Si₃O₈*2SrCl₂;

Eu²⁺ phosphor; and

the first phosphor is interspersed with the second phosphor.

19. The system of claim 18, further comprising:

a shell containing the light emitting diode;

an encapsulating material between the shell and the light emitting diode; and

wherein;

a) the first and second phosphors are coated over a surface of the light emitting diode;

b) the first and second phosphors are interspersed in the encapsulating material;

or

c) the first and second phosphors are coated onto the shell.

20. The system of claim 19, wherein:

the first phosphor comprises (Sr_0.8Eu_{0 1}Mn_0.1)₂ P_{2 O7};

the second phosphor comprises (Sr_0.90-0.99 Eu_0.01-0.1)₄Al₁₄O₂₅;

CIE color coordinates of a radiation emitted by the system is about x=0.39 and y=0.42; and

the light emitting diode peak emission wavelength and a ratio by weight of the first phosphor to the second phosphor satisfy one of the following relationships;

a) the light emitting diode peak emission wavelength is about 380 nm and a ratio by weight of the first phosphor to the second phosphor is about 77;

23;

or

b) the light emitting diode peak emission wavelength is about 405 nm and a ratio by weight of the first phosphor to the second phosphor is about 89;

11.

21. A method of making a white light illumination system, comprising:

blending a first phosphor powder having a peak emission wavelength of about 570 to about 620 nm and a second phosphor powder having a peak emission wavelength of about 480 to about 500 nm to form a phosphor powder mixture; and

placing the phosphor powder mixture into the white light illumination system adjacent a radiation source.

22. The method of claim 21, wherein:

the radiation source comprises a light emitting diode having a peak emission wavelength between 370 and 405 nm;

the first phosphor powder comprises APO;

Eu²⁺,Mn²⁺, where A comprises at least one of Sr, Ca, Ba or Mg; and

the second phosphor powder is selected from at least one of;

a) A₄D₁₄O₂₅;

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg, and D comprises at least one of Al or Ga;

b) (2AO*0.84P₂O₅*0.16B₂O₃);

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg;

c) AD₈O₁₃;

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg, and D comprises at least one of Al or Ga;

d) A₁₀(PO₄)₆Cl₂;

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg;

or

e) A₂Si₃O₈*2ACl₂;

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg.

23. The method of claim 22, wherein:

the APO;

Eu²⁺,Mn²⁺ phosphor comprises (A_1-x-yEu_xMn_y)₂ P₂ O₇, where 0<

x≦

0.2 and 0<

y≦

0.2; and

the second phosphor comprises at least one of;

a) a Sr₄Al₁₄O₂₅;

Eu²⁺;

b) a (2SrO*0.84P₂O₅*0.16B₂O₃);

Eu²⁺;

c) a BaA₈O₁₃;

Eu²⁺;

d) a (Sr,Mg,Ca)₁₀(PO₄)₆Cl₂;

Eu²⁺;

or

e) a Sr₂Si₃O₈*2SrCl₂;

Eu²⁺.

24. The method of claim 23, further comprising:

mixing a SrHPO₄ powder, a Eu₂O₃ powder, a MnCO₃ powder and a (NH₄)HPO₄ powder to form a starting powder mixture;

heating the starting powder mixture in air at about 600 to 800°

C.;

firing the starting powder mixture in a reducing atmosphere at about 1000 to 1250°

C. to form a calcined body; and

converting the calcined body into the first phosphor powder.

25. The method of claim 24, further comprising blending the starting powder mixture after the step of heating and before the step of firing.

26. The method of claim 25, wherein the starting powder mixture is fired in a furnace in an atmosphere comprising nitrogen and 0.1 to 10% hydrogen for four to ten hours.

27. The method of claim 26, wherein the (NH₄)HPO₄ powder is added in an amount comprising 2% in excess of the stoichiometric ratio per mole of the first phosphor produced.

28. The method of claim 22, further comprising:

placing the light emitting diode into a shell; and

filling the shell with an encapsulating material.

29. The method of claim 28, further comprising:

a) coating a suspension of the phosphor powder mixture and a solvent over a surface of the light emitting diode and drying the suspension;

b) interspersing the phosphor powder mixture in the encapsulating material;

or

c) coating a suspension of phosphor powder mixture and a solvent onto the shell and drying the suspension.