Metal silicate-silica-based polymorphous phosphors and lighting devices

• US 7,276,183 B2
• Filed: 06/10/2005
• Issued: 10/02/2007
• Est. Priority Date: 03/25/2005
• Status: Active Grant

• Current Assignee: Lightscape Materials, Inc.
• Original Assignee: Sarnoff Corporation (SRI International, Inc.)
• Inventors: Tian, Yongchi
• Primary Examiner(s): KOSLOW, CAROL M
• Application Number:
  US11/149,648
• Publication Number:
  US 20060214175A1
• Time in Patent Office: 844 Days
• Field of Search: 252/301.4 F, 257/98, 313/503
• US Class Current: 252/301.40F
• CPC Class Codes: C09K 11/7731 with alkaline earth metals
• CPC Class Codes: C09K 11/77342 Silicates
• CPC Class Codes: H01L 2224/48091 Arched
• 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

Abstract

Provided, among other things, is a phosphor according to the formula:
[(BvSiO₃)_x(Mv₂SiO₃)_y(Tv₂(SiO₃)₃)_z]_m•(SiO₂)_n: Rε, X  (I)
wherein x, y and z are any value such that x+y+z=1; Bv is one or more divalent alkaline earth metals; Mv is one or more monovalent alkaline metals; Tv is one or more trivalent metal ions; Rε is one or more activators selected from Eu²⁺ and Mn²⁺; X is one or more halides; m is 1 or 0; and (i) n>3 if m=1 and provides an amount of silica effective to host useful luminescence or (ii) n=1 if m=0.

Claims

1. A light emitting device comprising:

a semiconductor light source that produces a light output of a wavelength of at least about 300 nm; and

a wavelength manager, which is located between the semiconductor light source and a light output produced by the light emitting device, comprising a phosphor according to formula (I);

[(BvSiO₃)_x(Mv₂SiO₃)_y(Tv₂(SiO₃)₃)_z]_m.(SiO₂)_n;

Rε

, X 

 

(I)

 

wherein;

x, y and z are each any value such that x+y+z=1;

Bv is at least one divalent metal ion;

Mv is at least one monovalent alkali metal ion;

Tv is at least one trivalent metal ion;

Rε

is at least one activator selected from Eu²⁺ and Mn²⁺ ions;

X is at least one halide ion;

m is 1 or 0, provided that;

if m is 1 and provides an amount of silica effective to host useful luminescence, then n>

3;

or

if m is 0,then n is 1.

2. The light emitting device of claim 1, wherein the wavelength manager further comprises at least one additional phosphor that adjusts the light output produced by the light emitting device.

3. The light emitting device of claim 2, wherein the wavelength manager changes the light output of the semiconductor light source such that the light output of the light emitting device is white light.

4. The light emitting device of claim 1, wherein the semiconductor light source comprises a quantum well structure having a light emitting layer sandwiched between a p-type clad layer and an n-type clad layer.

5. The light emitting device of claim 4, wherein:

the p-type clad layer is formed of Al_qGa_1-qN, wherein 0<

q<

1;

the n-type clad layer is formed of Al_rGa_1-rN, wherein 0≦

r<

1; and

optionally, the p-type clad layer has a band gap larger than a band gap of the n-type clad layer.

6. The light emitting device of claim 1, wherein the semiconductor light source comprises a light emitting layer containing indium and at least two quantum well structures.

7. The light emitting device of claim 6, wherein:

optionally, at least two quantum well structures comprise at least one well layer of InGaN and at least one barrier layer of GaN;

optionally, at least two quantum well structures comprise at least one well layer of InGaN and at least one barrier layer of AlGaN; and

optionally, at least two quantum well structures comprise at least one well layer of AlInGaN and at least one barrier layer of AlInGaN,

wherein;

at least one barrier layer has a band gap larger than a band gap of at least one well layer; and

optionally, at least one well layer has a thickness of at most about 100 angstroms.

8. The light emitting device of claim 1, wherein the semiconductor light source comprises at least two quantum well structures.

9. The light emitting device according to claim 1, wherein the semiconductor light source comprises at least one light emitting diode (LED) on a substrate.

10. The light emitting device of claim 1, wherein at least one monovalent alkali metal ion of Mv is selected from the group consisting of Li, Na and K.

11. The light emitting device of claim 1, wherein at least one divalent metal ion of Bv is selected from the group consisting of Be, Mg, Ca, Sr, Ba, Mn, Co, Ni, Cu, Zn, Cd and Hg.

12. The light emitting device of claim 11, wherein at least one divalent metal ion of Bv is selected from the group consisting of Ca and Sr.

13. The light emitting device of claim 1, wherein at least one trivalent metal ion of Tv is selected from the group consisting of Al, Ga, In, Sc, Y and La.

14. The light emitting device of claim 1, wherein Rε

comprises Eu²⁺ ions.

15. The light emitting device of claim 1, wherein Rε

comprises Mn²⁺ ions.

16. The light emitting device of claim 1, wherein Rε

comprises Eu²⁺ and Mn²⁺ ions.

17. The light emitting device of claim 1, wherein the phosphor has a formula of:

(CaSiO₃)_m.(SiO₂)_n;

Eu²⁺, Mn²⁺, I⁻

,

wherein m and n are as previously defined and the Eu²⁺ and Mn²⁺ ions have a concentration and ratio between Eu²⁺ and Mn²⁺ that provide a peak emission between about 620 nm and about 660 nm and a chromaticity of x=0.62±

0.06, y=0.30±

0.06.

18. The light emitting device of claim 1, wherein the phosphor has a formula of:

(CaSiO₃)_m.(SiO₂)_n;

Eu²⁺, I⁻

,

wherein m and n are as previously defined and the Eu²⁺ ion has a concentration that provides a peak emission between about 445 nm and about 480 nm and a chromaticity of x=0.20±

0.06, y=0.10±

0.06.

19. The light emitting device of claim 1, wherein the phosphor has a formula of:

(CaSiO₃)_m.(SiO₂)_n;

Eu²⁺, Mn²⁺, Cl⁻

,

wherein m and n are as previously defined and the Eu²⁺ and Mn²⁺ ions have a concentration and ratio that provide a chromaticity of x=0.40±

0.06, y=0.20±

0.06.

20. The light emitting device of claim 1, wherein the silica comprises a cristobalite form.

21. The light emitting device of claim 20, wherein Bv, Mv, Tv or a combination thereof comprises metal silicate in calcite form.

22. The light emitting device of claim 20, wherein Bv, Mv, Tv or a combination thereof comprises metal silicate in Wollastonite form.

23. The light emitting device of claim 20, wherein Bv, Mv, Tv or a combination thereof comprises metal silicate in enstalite form.

24. A phosphor according to formula (I):

[(BvSiO₃)_x(Mv₂SiO₃)_y(Tv₂(SiO₃)₃)_z]_m.(SiO₂)_n;

Rε

, X 

 

(I)

wherein;

x, y and z are each any value such that x+y+z=1;

Bv is at least one divalent metal ion;

Mv is at least one monovalent alkali metal ion;

Tv is at least one trivalent metal ion;

Rε

is at least one activator selected from Eu²⁺ and Mn²⁺ ions;

X is at least one halide ion;

m is 1 or 0, provided that;

if m is 1 and provides an amount of silica effective to host useful luminescence, then n>

3;

or

if m is 0, then n is 1.

25. The phosphor of claim 24, wherein at least one monovalent alkali metal ion of Mv is selected from Li, Na and K.

26. The phosphor of claim 25, wherein at least one divalent metal ion of Bv is selected from Ca and Sr.

27. The phosphor of claim 24, wherein at least one divalent metal ion of Bv is selected from the group consisting of Be, Mg, Ca, Sr, Ba, Mn, Co, Ni, Cu, Zn, Cd and Hg.

28. The phosphor of claim 24, wherein at least one trivalent metal ion of Tv is selected from the group consisting of Al, Ga, In, Sc, Y and La.

29. The phosphor of claim 24, wherein Rε

comprises Eu²⁺ ions.

30. The phosphor of claim 24, wherein Rε

comprises Mn²⁺ ions.

31. The phosphor of claim 24, wherein Rε

comprises Eu²⁺ and Mn²⁺ ions.

32. The phosphor of claim 24, wherein the phosphor has a formula of:

(CaSiO₃)_m.(SiO₂)_n;

Eu²⁺, Mn²⁺, I⁻

,

wherein m and n are as previously defined and the Eu²⁺ and Mn²⁺ ions have a concentration and ratio between Eu²⁺ and Mn²⁺ that provide a peak emission between about 620 nm and about 660 nm and a chromaticity of x=0.62±

0.06, y=0.30±

0.06.

33. The phosphor of claim 24, wherein the phosphor has a formula of:

(CaSiO₃)_m.(SiO₂)_n;

Eu²⁺, I⁻

,

wherein m and n are as previously defined and the Eu²⁺ ion has a concentration that provides a peak emission between about 445 nm and about 480 nm and a chromaticity of x=0.20±

0.06, y=0.10±

0.06.

34. The phosphor of claim 24, wherein the phosphor has a formula of:

(CaSiO₃)_m.(SiO₂)_n;

Eu²⁺, Mn²⁺, Cl⁻

,

wherein m and n are as previously defined and the Eu²⁺ and Mn²⁺ ions have a concentration and ratio between Eu²⁺ and Mn²⁺ provide a chromaticity of x=0.40±

0.06, y=0.20±

0.06.

35. The phosphor of claim 24, wherein Bv, Mv, Tv or a combination thereof comprises metal silicate in Wollastonite form and the silica comprises a cristobalite form.

36. The phosphor of claim 24, wherein Bv, Mv, Tv or a combination thereof comprises metal silicate in calcite form and the silica comprises a cristobalite form.

37. The phosphor of claim 24, wherein Bv, Mv, Tv or a combination thereof comprises metal silicate in enstalite form and the silica comprises a cristobalite form.

38. The phosphor of claim 24, wherein X has a mole percentage of about 0.002% to about 5% of SiO₂.

39. A method of producing a phosphor according to formula (I):

[(BvSiO₃)_x(Mv₂SiO₃)_y(Tv₂(SiO₃)₃)_z]_m.(SiO₂)_n;

Rε

, X 

 

(I)

wherein;

x, y and z are each any value such that x+y+z=1;

Bv is at least one divalent metal ion;

Mv is at least one monovalent alkali metal ion;

Tv is at least one trivalent metal ion;

Rε

is at least one activator selected from Eu²⁺ and Mn²⁺ ions;

X is at least one halide ion;

m is 1 or 0, provided that;

if m is 1 and provides an amount of silica effective to host useful luminescence, then n>

3;

or

if m is 0, then n is 1,

the method comprising the steps of;

providing an appropriate mixture of precursors; and

firing the appropriate mixture at a temperature from about 900°

C. to about 1300°

C. under a reducing atmosphere and in presence of a halide source to produce the phosphor,

wherein X of the phosphor has a mole percentage of about 0.002% to about 5% SiO₂.

40. The method of claim 39, further comprising the step, prior to the firing step, of heating the appropriate mixtureat a temperature from about 700°

C. to about 1100°

C. under a reducing atmosphere, wherein the heating is at a temperature lower than the temperature of the firing step.

41. The method of claim 40, wherein a halide source is present in during the heating step.