Metal silicate halide phosphors and LED lighting devices using the same

• US 7,713,442 B2
• Filed: 09/28/2007
• Issued: 05/11/2010
• Est. Priority Date: 10/03/2006
• Status: Expired due to Fees

• Current Assignee: Lightscape Materials, Inc. (DuPont de Nemours, Inc.)
• Original Assignee: Lightscape Materials, Inc. (DuPont de Nemours, Inc.)
• Inventors: Zakharov, Olga, Sides, Alison, Tian, Yongchi
• Primary Examiner(s): Gurley; Lynne A
• Assistant Examiner(s): YUSHINA, GALINA G
• Application Number:
  US11/863,445
• Publication Number:
  US 20080128679A1
• Time in Patent Office: 956 Days
• Field of Search: 250/484.4, 428/403, 428/404, 428/405, 428/406, 257/98, 257/89, 313/487, 252/301, 252/301.4 R, 252/301.6 R, 252/301.4 F
• US Class Current: 252/301.40R
• CPC Class Codes: C09K 11/77342 Silicates
• 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

Abstract

The present invention relates to metal silicate halide (halosilicate) phosphors, the phosphors with an oxide coating, methods of making the phosphors, and light emitting diode- (LED-) based lighting devices modified with the phosphors.

Claims

1. A phosphor having a formula of (M1_x,M2₁₋

x)₆(SiO₄)₂X₄;

A,

wherein;

M1 and M2 are each independently at least one metal ion selected from the group consisting of Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Zn²⁺ and Cd²⁺;

x is a value from about 0.001 to about 1;

X is at least one halide ion in ionic form; and

A is at least one activator ion selected from the group consisting of Eu²⁺, Yb²⁺, Mn²⁺, Bi³⁺, Pb²⁺, Ce³⁺, Nd³⁺, Pr³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺, Tm³⁺ and Yb³⁺.

2. The phosphor of claim 1, wherein:

M1 and M2 are each independently Ca²⁺, Sr²⁺, Ba²⁺ or a combination thereof;

X is fluoride, chloride, bromide or a combination thereof; and

A is Eu²⁺, Mn²⁺, Ce³⁺ or combination thereof.

3. The phosphor of claim 1, wherein:

M1 is Sr²⁺;

M2 is Ca²⁺, Ba²⁺ or a combination thereof;

X is fluoride, chloride or a combination thereof; and

A is Eu²⁺, Mn²⁺, Ce³⁺ or a combination thereof.

4. The phosphor of claim 1, wherein the phosphor has the formula:

(Sr_x,Ca<sub>1−

x</sub>)₆(SiO₄)₂Cl₄;

Eu²⁺.

5. The phosphor of claim 4, wherein:

x is a value from about 0.01 to about 1; and

Eu²⁺ is of an amount from about 0.0001 mole to about 0.1 mole of the phosphor.

6. A coated phosphor comprising:

a) a phosphor according to claim 1;

b) at least one layer of a coating on the phosphor, wherein the layer comprises at least one oxide.

7. The coated phosphor of claim 6, wherein the coating comprises at least two layers.

8. A lighting device comprising:

a) a light source that emits light at wavelengths of at least 300 nm; and

b) at least one phosphor according to claim 1, wherein;

(1) the phosphor is capable of absorbing at least a portion of the light emitted from the light source;

(2) the phosphor modifies a chromaticity of the portion of the light absorbed from the light source;

(3) the phosphor emits light of a longer wavelength than that of the light absorbed from the light source.

9. The lighting device of claim 8, wherein the lighting device produces white light.

10. The lighting device of claim 8, wherein the light source is a light emitting diode (LED).

11. The lighting device of claim 10, wherein:

the LED comprises a quantum well structure having a light emitting layer sandwiched between a p-type clad layer and an n-type clad layer.

12. The lighting device of claim 11, wherein:

the p-type clad layer is formed of Al_qGa<sub>1−

q</sub>N, wherein 0<

q<

1; and

the n-type clad layer is formed of Al_rGa<sub>1−

r</sub>N, wherein 0≦

r<

1.

13. The lighting device of claim 12, wherein the p-type clad layer has a band gap that is larger than the band gap of the n-type clad layer.

14. The lighting device of claim 12, wherein the LED comprises a light emitting layer containing indium and at least one quantum well structure.

15. The lighting device of claim 14, wherein:

at least one quantum well structure comprises at least one well layer of InGaN and at least one barrier layer of GaN;

at least one quantum well structure comprises at least one well layer of InGaN and at least one barrier layer of AlGaN;

or

at least one quantum well structure comprises 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 energy larger than a band gap energy of at least one well layer.

16. The lighting device of claim 15, wherein the well layer has a thickness of at most 100 angstroms.

17. The lighting device of claim 8, wherein for the at least one phosphor:

M1 and M2 are each independently Ca²⁺, Sr²⁺, Ba²⁺ or a combination thereof;

X is fluoride, chloride, bromide or a combination thereof; and

A is Eu²⁺, Mn²⁺, Ce³⁺ or a combination thereof.

18. The light device of claim 8, wherein for the at least one phosphor:

M1 is Sr²⁺;

M2 is Ca²⁺, Ba²⁺ or a combination thereof;

X is fluoride, chloride or a combination thereof; and

A is Eu²⁺, Mn²⁺, Ce³⁺ or a combination thereof.

19. The lighting device of claim 8, wherein the at least one phosphor has the formula (Sr_x, Ca₁₋

x)₆(SiO₄)₂Cl₄;

Eu²⁺.

20. The lighting device of claim 19, wherein:

x is a value from about 0.01 to about 1; and

Eu²⁺ is of an amount from about 0.0001 mole to about 0.1 mole of the phosphor.

21. The lighting device of claim 8, further comprising at least one additional phosphor having formula (I):

CaSiO₃.(SiO₂)_n;

Rε

, Y 

 

(I)

wherein;

Rε

is at least one activator ion selected from the group consisting of Eu²⁺ and Mn²⁺; and

Y is at least one halide ion in ionic or atomic form or is absent.

22. The lighting device of claim 21, wherein the at least one additional phosphor comprises formula (II):

CaSiO₃.(SiO₂)_n;

Eu²⁺,I⁻

 

 

(II)

and the additional phosphor emits blue light.

23. The lighting device of claim 22, wherein the at least one additional phosphor comprises formula (III):

CaSiO₃.(SiO₂)_n;

Eu²⁺,Mn²⁺,I⁻

 

 

(III)

and the additional phosphor emits red light.

24. The lighting device of claim 23, further comprising at least two additional phosphors, wherein:

one phosphor comprises formula (II);

CaSiO₃.(SiO₂)_n;

Eu²⁺,I<sup>−

; and</sup>

 

 

(II)

second phosphor comprises formula (III);

CaSiO₃.(SiO₂)_n;

Eu²⁺,Mn²⁺,I⁻

 

 

(III).

25. The lighting device of claim 8, further comprising at least one additional phosphor having further comprises at least one additional phosphor having a formula selected from:

(a) (M1_xM2<sub>1−

x</sub>)₂LiSiO₄X;

A;

(b) (M1_xM2<sub>1−

x</sub>)₅SiO₄X₆;

A;

(c) (M1_xM2<sub>1−

x</sub>)₃SiO₄X₂;

A;

(d) (M1_xM2<sub>1−

x</sub>)₅(SiO₄)₂X₂;

A;

(e) (M1_xM2<sub>1−

x</sub>)₅Si₂O₇X₄;

A;

(f) (M1_xM2<sub>1−

x</sub>)₁₀(Si₂O₇)₃X₂;

A;

(g) (M1_xM2<sub>1−

x</sub>)₄Si₂O₇X₂;

A;

(h) M1₆M2₄(Si₂O₇)₃X₂;

A;

(i) (M1_xM2<sub>1−

x</sub>)₇Si₂O₇X₈;

A;

(j) (M1_xM2<sub>1−

x</sub>)₄Si₃O₈X₂;

A;

(k) (M1_xM2<sub>1−

x</sub>)₄Si₃O₈X₄;

A;

(l) (M1_xM2<sub>1−

x</sub>)₈Si₄O₁₂X₈;

A;

(m) (M1_xM2<sub>1−

x</sub>)₅Si₂O₆X₆;

A;

(n) (M1_xM2<sub>1−

x</sub>)₁₅Si₆O₁₈X₈;

A;

(o) (M1_xM2<sub>1−

x</sub>)₅Si₄O₁₀X₅;

A;

(p) (M1_xM2<sub>1−

x</sub>)₁₀(SiO₄)₃(SO₄)₃X₂;

A;

(q) (M1_xM2<sub>1−

x</sub>)₄(SiO₄)(SO₄)X₂;

A; and

(r) (M1_xM2<sub>1−

x</sub>)₈Mg(SiO₄)₄X₂;

A,

where;

M1 and M2 are each independently at least one metal ion selected from the group consisting of Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Zn²⁺ and Cd²⁺;

x is a value from about 0.001 to about 1;

X is at least one halide ion in ionic form;

A is at least one activator ion selected from the group consisting of Eu²⁺, Yb²⁺, Mn²⁺, Bi³⁺, Pb²⁺, Ce³⁺, Nd³⁺, Pr³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺, Tm³⁺ and Yb³⁺;

if the phosphor has the formula (M1_xM2<sub>1−

x</sub>)₂LiSiO₄X;

A, and M1 is Sr²⁺, x is 1 and X is fluoride or M2 is Sr²⁺, x is 0 and X is fluoride, then A is not Eu²⁺; and

if the phosphor has the formula (M1_xM2<sub>1−

x</sub>)₃SiO₄X₂;

A, and M1 is Ca²⁺, x is 1 and X is chloride or M2 is Ca²⁺, x is 0 and X is chloride, then A is not Eu²⁺; and

if the phosphor has the formula (M1_xM2<sub>1−

x</sub>)₈Mg(SiO₄)₄X₂;

A, and M1 is Ca²⁺, x is 1 and X is chloride or M2 is Ca²⁺, x is 0 and X is chloride, then A is not Eu²⁺.

26. The lighting device of claim 8, wherein the phosphor further comprises at least one layer of a coating tat comprises at least one oxide.

27. A lighting device comprising:

a) a light source that emits light at wavelengths of at least 300 nm, wherein the light source is a light emitting diode (LED); and

b) at least one phosphor according to claim 1, wherein;

(1) the phosphor is capable of absorbing at least a portion of the light emitted from the light source;

(2) the phosphor modifies a chromaticity of the portion of the light absorbed from the light source; and

(3) the phosphor emits light of a longer wavelength than that of the light absorbed from the light source,

wherein the lighting device produces white light.

28. The lighting device of claim 27, wherein in the phosphor further comprises at least one layer of a coating that comprises at least one oxide.

34. A method of preparing a metal silicate halide phosphor of claim 1, comprising a first heating step conducted at a temperature of between about 600°

C. to about 1000°

C. and a second heating step conducted at a temperature of between about 800°

C. to about 1200°

C.

35. The method of claim 34, wherein the phosphor has the formula (Sr_x,Ca₁₋

x)₆(SiO₄)₂Cl₄;

Eu²⁺, wherein x is a value from about 0.001 to about 1.

36. The method of claim 34, wherein the phosphor has the formula Ca_5.72Sr_0.28(SiO₄)₂Cl₄:

Eu²⁺.

29. A phosphor having the formula of Ca_5.72Sr_0.28(SiO₄)₂Cl₄:

Eu²⁺.

30. The phosphor of claim 29, wherein the phosphor is crystallized in a monoclinic lattice.

31. The phosphor of claim 30, wherein the phosphor is crystallized in a monoclinic lattice having a space symmetry of P2₁/n with a=10.959 Å

, b=10.1920 Å

, c=11.8305 Å

, β

=90.263°

, and α

=γ

=90.0°

, and wherein the unit cell volume is 1321.41 Å

³.

32. The phosphor of claim 29, having the fluorescence excitation and emission spectra shown in FIG. 5.

33. The phosphor of claim 29, wherein the phosphor emits light having an emission peak wavelength of about 590 nm and having a FWHH value of about 120 nm, upon such phosphor being excited by light having a wavelength ranging from about 300 nm to about 500 nm.

37. A light emitting device comprising:

a) a light source that emits light at wavelengths of at least 300 nm; and

b) the phosphor according to claim 29.

38. The light emitting device of claim 37, further comprising a phosphor having the formula CaSiO₃.(SiO₂:

Eu²⁺, I⁻

.

39. The light emitting device of claim 38, wherein the lighting device produces white light.

40. The light emitting device of claim 38, wherein the light emitting device is characterized by chromaticity coordinates x=0.3835, y=0.3074, correlated color temperature (CCT)=3192 K and color rendition index (Ra)=74.12.

41. The light emitting device of claim 38, wherein the light emitting device is characterized by chromaticity coordinates x=0.3419, y=0.2678, correlated color temperature (CCT)=4647 K and color rendition index (Ra)=67.72.