Wavelength converted semiconductor light emitting devices

• US 7,250,715 B2
• Filed: 02/23/2004
• Issued: 07/31/2007
• Est. Priority Date: 02/23/2004
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Philips Lumileds Lighting Company LLC (Apollo Global Management, Inc.)
• Inventors: Mueller-Mach, Regina B., Mueller, Gerd O.
• Primary Examiner(s): Glick; Edward J.
• Assistant Examiner(s): Kiknadze; Irakli
• Application Number:
  US10/785,616
• Publication Number:
  US 20050184638A1
• Time in Patent Office: 1,254 Days
• Field of Search: 313/503, 313485-487, 313/512, 257/89, 257/98, 257/100, 362/800, 362/293, 445/50, 445/57
• US Class Current: 313/485
• CPC Class Codes: C09K 11/0883 Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/7731 with alkaline earth metals
• CPC Class Codes: C09K 11/77342 Silicates
• CPC Class Codes: C09K 11/77347 Silicon Nitrides or Silicon Oxynitrides
• CPC Class Codes: C09K 11/7774 Aluminates
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133614 using photoluminescence, e.g. phosphors illuminated by UV or blue light
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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

Abstract

In a wavelength converted semiconductor light emitting device with at least two wavelength converting materials, the wavelength converting materials in the device are arranged relative to the light emitting device and relative to each other to tailor interaction between the different wavelength converting materials in order to maximize one or more of the luminous equivalent, color rendering index, and color gamut of the combined visible light emitted by the device.

Claims

1. A system comprising:

a semiconductor light emitting device capable of emitting first light having a first peak wavelength;

a first fluorescent material layer comprising a first wavelength converting material capable of absorbing the first light and emitting second light having a second peak wavelength longer than the first peak wavelength; and

a second fluorescent material layer comprising a second wavelength converting material capable of emitting third light having a third peak wavelength longer than the second peak wavelength, wherein the second fluorescent material layer is disposed adjacent to the semiconductor light emitting device;

wherein at least one of the first fluorescent material layer and the second fluorescent material layer comprise a second material that is not a wavelength converting material; and

wherein the second fluorescent material layer is substantially free of the first wavelength converting material.

2. The system of claim 1 wherein the second fluorescent material layer overlies the semiconductor light emitting device and the first fluorescent material layer overlies the second fluorescent material layer.

3. The system of claim 1 wherein:

the first fluorescent material layer is disposed on a first portion of the semiconductor light emitting device;

the second fluorescent material layer is disposed on a second portion of the semiconductor light emitting device; and

the first portion is adjacent to the second portion.

4. The system of claim 1 wherein:

the first fluorescent material layer is disposed on a first plurality of discrete regions on the semiconductor light emitting device; and

the second fluorescent material layer is disposed on a second plurality of discrete regions on the semiconductor light emitting device.

5. The system of claim 4 wherein the first plurality of discrete regions and the second plurality of discrete regions form a checkerboard pattern.

6. The system of claim 1 wherein:

the second fluorescent material layer is disposed on a plurality of discrete regions on the semiconductor light emitting device; and

the first fluorescent material layer overlies the second fluorescent material layer.

7. The system of claim 1 wherein:

the first peak wavelength is blue;

the second peak wavelength is green; and

the third peak wavelength is red.

8. The system of claim 1 wherein:

the first peak wavelength is blue;

the second peak wavelength is yellow; and

the third peak wavelength is red.

9. The system of claim 1 wherein the first wavelength converting material is phosphor selected from the group of (Lu₁₋

x−

y−

a−

bY_xGd_y)₃(Al<sub>1−

z</sub>Ga_z)₅O₁₂;

Ce_a³⁺Pr_b³⁺to wherein 0<

x<

1, 0<

y<

1, 0<

z≦

0.1, 0<

a≦

0.2 and 0<

b≦

0.1, Lu₃Al₅O₁₂;

Ce³⁺, Y₃Al₅O₁₂;

Ce³⁺, (Sr<sub>1−

a−

b</sub>Ca_bBa_c)Si_xN_yO_z;

Eu_a²⁺ wherein a=0.002-0.2, b=0.0-0.25, c=0.0-0.25, x=1.5-2.5, y=1.5-2.5, z=1.5-2.5, SrSi₂N₂O₂;

Eu²⁺, (Sr<sub>1−

u−

v−

x</sub>Mg_uCa_vBa_x)(Ga<sub>2−

y−

z</sub>Al_yIn_zS₄);

Eu²⁺, SrGa₂S₄;

Eu²⁺, and Sr<sub>1−

x</sub>Ba_xSiO₄;

Eu²⁺.

10. The system of claim 1 wherein the second wavelength converting material is a phosphor selected from the group of (Ca₁₋

xSr_x)S;

Eu²⁺ wherein 0<

x≦

1, CaS;

Eu²−

, SrS;

Eu²⁺, (Sr<sub>1−

x−

y</sub>Ba_xCa_y)<sub>2−

z</sub>Si<sub>5−

a</sub>Al_aN<sub>8−

a</sub>O_a;

Eu_z²⁺ wherein 0≦

a<

5, 0<

x≦

1, 0≦

y≦

1, and 0<

z≦

1, and Sr₂Si₅N₈;

Eu²⁻

,

11. The system of claim 1 wherein the second material is selected from the group of resin, silicone, and silica.

12. The system of claim 1 wherein the first fluorescent material layer and second fluorescent material layer are arranged to maximize a luminous equivalent of a combination of the first, second, and third light.

13. The system of claim 1 wherein the first fluorescent material layer and second fluorescent material layer are arranged to maximize color rendering index of a combination of the first, second, and third light.

14. The system of claim 1 further comprising a third fluorescent material layer comprising a third wavelength converting material capable of emitting fourth light having a fourth peak wavelength.

15. The system of claim 14 wherein:

the first peak wavelength is UV;

the second peak wavelength is blue;

the third peak wavelength is red; and

the fourth peak wavelength is green.

16. The system of claim 15 wherein:

the second fluorescent material layer is adjacent to the semiconductor light emitting device;

the third fluorescent material layer overlies the second fluorescent material layer; and

the first fluorescent material layer overlies the third fluorescent material layer.

17. The system of claim 1 wherein the first fluorescent material layer comprises an amount of second wavelength converting material.

18. A device comprising:

at least one semiconductor light emitting device capable of emitting first light having a first peak wavelength;

a first fluorescent material layer comprising a first wavelength converting material, the first wavelength converting material capable of absorbing the first light and emitting second light having a second peak wavelength, the second peak wavelength being longer than the first peak wavelength; and

a second fluorescent material layer comprising a second wavelength converting material, the second wavelength converting material capable of emitting third light having a third peak wavelength longer than the second peak wavelength;

wherein the first fluorescent material layer and the second fluorescent material layer are disposed in a path of light emitted by the light emitting device and are spaced apart from the light emitting device.

19. The device of claim 18 wherein the third light combines with the first light and the second light to form mixed light that appears white.

20. The device of claim 18 wherein the first fluorescent material layer and second fluorescent material layer are arranged to maximize a luminous equivalent of a combination of the first, second, and third light.

21. The device of claim 18 further comprising one or more filters.

22. The device of claim 21 wherein the first fluorescent material layer and second fluorescent material layer are arranged to maximize a gamut of color after the first, second, and third light are filtered by the one or more filters.

23. The device of claim 18 wherein the first wavelength converting material and second wavelength converting material are formed as discrete layers.

24. The device of claim 23 wherein the second fluorescent material layer is closer to the at least one semiconductor light emitting device than the first fluorescent material layer.

25. The device of claim 18 wherein the first wavelength converting material is selected from the group of (Lu₁₋

x−

y−

a−

bY_xGd_y)₃(Al<sub>1−

z</sub>Ga_z)₅O₁₂;

Ce_a³⁺Pr_b³⁺wherein 0<

x<

1, 0<

y<

1, 0<

z≦

0.1, 0<

a≦

0.2 and 0<

b≦

0.1, Lu₃Al₅O₁₂;

Ce, Y₃Al₅O₁₂;

Ce³⁺, (Sr_1-a-bCa_bBa_c)Si_xN_yO_z;

Eu_a²⁺ wherein a=0.002-0.2, b=0.0-0.25, c=0.0-0.25, x=1.5-2.5, y=1.5-2.5, z=1.5-2.5, SrSi₂N₂O₂;

Eu²⁺, (Sr<sub>1−

u−

v−

x</sub>Mg_uCa_vBa_x)(Ga<sub>2−

y−

z</sub>Al_yIn_zS₄);

Eu²⁺, SrGa₂S₄;

Eu²⁺, and Sr<sub>1−

x</sub>Ba_xSiO₄;

Eu²⁺.

26. The device of claim 18 wherein the second wavelength converting material is selected from the group of(Ca₁₋

xSr_x)S;

Eu²⁺ wherein 0<

x≦

1, CaS;

Eu²⁺, SrS;

Eu²⁺, (Sr<sub>1−

x−

y</sub>Ba_xCa_y)<sub>2−

z</sub>Si<sub>5−

a</sub>Al_aN<sub>8−

a</sub>O_a;

Eu_z²⁺ wherein 0≦

a<

5, 0<

x≦

1, 0≦

y≦

1, and 0<

z≦

1, and Sr₂Si₅N₈;

Eu²⁺.

27. The device of claim 18 further comprising an LCD.

28. The device of claim 18 further comprising a cover plate spaced apart from the at least one semiconductor light emitting device.

29. The device of claim 28 wherein the first fluorescent material layer and the second fluorescent material layer are disposed on the cover plate.

30. The device of claim 18 wherein the second fluorescent material layer is substantially free of the first wavelength converting material.

31. The device of claim 18 further comprising a sidewall disposed adjacent to at least one of the first and second fluorescent material layers.

32. The device of claim 31 wherein the sidewall is reflective.

33. The device of claim 31 wherein the sidewall is substantially perpendicular to a plane on which the light emitting device is disposed.