Green-emitting, garnet-based phosphors in general and backlighting applications
View Patent ↗Disclosed herein are green-emitting, garnet-based phosphors having the formula (Lu 1-a-b-c Y a Tb b A c ) 3 (Al 1-d B d ) 5 (O 1-e C e ) 12 :Ce,Eu, where A is selected from the group consisting of Mg, Sr, Ca, and Ba; B is selected from the group consisting of Ga and In; C is selected from the group consisting of F, Cl, and Br; and 0≦a≦1; 0≦b≦1; 0<c≦0.5; 0≦d≦1; and 0<e≦0.2. These phosphors are distinguished from anything in the art by nature of their inclusion of both an alkaline earth and a halogen. Their peak emission wavelength may lie between about 500 nm and 540 nm; in one embodiment, the phosphor (Lu,Y,A) 3 Al 5 (O,F,Cl) 12 :Eu 2+ has an emission at 540 nm. The FWHM of the emission peak lies between 80 nm and 150 nm. The present green garnet phosphors may be combined with a red-emitting, nitride-based phosphor such as CaAlSiN 3 to produce white light.
1. A green-emitting, garnet-based phosphor having the formula:
(Lu 1-a-b-c Y a Tb b A c ) 3 (Al 1-d B d ) 5 (O 1-e C e ) 12 :Ce,Eu, where
A is selected from the group consisting of Mg, Sr, Ca, and Ba;
B is selected from the group consisting of Ga and In;
C is selected from the group consisting of F, Cl, and Br; and
0≦a≦1;
0≦b≦1;
0<c≦0.5;
0≦d≦1; and
0<e≦0.2.
2. The green-emitting, garnet-based phosphor of claim 1 , wherein A is a single element selected from the group consisting of Mg, Sr, Ca, and Ba.
3. The green-emitting, garnet-based phosphor of claim 1 , wherein A is a combination of elements selected from the group consisting of Mg, Sr, Ca, and Ba.
4. The green-emitting, garnet-based phosphor of claim 1 , wherein said green-emitting, garnet-based phosphor is configured to absorb blue light and emit light having a peak emission wavelength within the range of 500 nm to 540 nm.
5. The green-emitting, garnet-based phosphor of claim 4 , wherein the full width at half maximum of the emission peak is in the range of 80 nm to 150 nm.
6. A green-emitting, garnet-based phosphor having the formula:
(Y,A) 3 (Al,B) 5 (O,C) 12 :Ce, where
A is at least one of Tb, Gd, Sm, La, Lu, Sr, Ca, and Mg, including combinations of those elements, and wherein the amount of substitution of those elements for Y ranges from about 0.1 to about 100 percent stoichiometrically;
B is at least one of Si, Ge, B, P, and Ga, including combinations, wherein B substitutes for Al in amounts ranging from about 0.1 to about 100 percent stoichiometrically; and
C is at least one of F, Cl, N, and S, including combinations, wherein C substitutes for oxygen in amounts ranging from about 0.1 to about 100 percent stoichiometrically.
7. A green-emitting, garnet-based phosphor having the formula:
(A 1-x 3+ B x 2+ ) m Al 5 (O 1-y 2− C y 1− ) n :Ce,Eu, where
A is selected from the group consisting of Y, Sc, Gd, Tb, and Lu;
B is selected from the group consisting of Mg, Sr, Ca, and Ba;
C is selected from the group consisting of F, Cl, and Br;
0≦x≦0.5;
0<y≦0.5;
2≦m≦4; and
10≦n≦14.
8. A green-emitting, garnet-based phosphor having the formula:
(A 1-x 3+ B x 2+ ) m Al 5 (O 1-y 2− C y 1− n:Ce,Eu, where
A is selected from the group consisting of Y, Sc, Gd, Tb, and Lu;
B is selected from the group consisting of Mg, Sr, Ca, and Ba;
C is selected from the group consisting of F, Cl, and Br;
0≦x≦0.5;
0≦y≦0.5;
2≦m≦4; and
10≦n≦14;
subject to the proviso that m is not equal to 3.
9. A green-emitting, garnet-based phosphor having the formula:
(A 1-x 3+ B x 2+ ) m Al 5 (O 1-y 2− Cy 1− ) n :Ce,Eu, where
A is selected from the group consisting of Y, Sc, Gd, Tb, and Lu;
B is selected from the group consisting of Mg, Sr, Ca, and Ba;
C is selected from the group consisting of F, Cl, and Br;
0≦x≦0.5;
0≦y≦0.5;
2≦m≦4; and
10≦n≦14;
subject to the proviso that n is not equal to 12.
10. A white LED comprising:
a radiation source configured to provide radiation having a wavelength greater than about 280 nm;
a green-emitting, garnet-based phosphor having the formula:
(Lu 1-a-b-c Y a Tb b A c ) 3 (Al 1-d B d ) 5 (O 1-e C e ) 12 :Ce,Eu, where
A is selected from the group consisting of Mg, Sr, Ca, and Ba;
B is selected from the group consisting of Ga and In;
C is selected from the group consisting of F, Cl, and Br; and
0≦a≦1;
0≦b≦1;
0<c≦0.5;
0≦d≦1; and
0<e≦0.2; and
at least one of a red-emitting phosphor or a yellow-emitting phosphor.
11. The white LED of claim 10 , wherein the red-emitting phosphor is a nitride.
12. The white LED of claim 10 , wherein the nitride has the formula (Ca,Sr)AlSiN 3 :Eu 2+ .
13. The white LED of claim 10 , wherein the yellow-emitting phosphor is a silicate.
14. The white LED of claim 10 , wherein the silicate has the formula (Sr,Ba) 2 SiO 4 :Eu 2+ .
15. A white LED comprising:
a radiation source configured to provide radiation having a wavelength greater than about 280 nm;
a green-emitting, garnet-based phosphor having the formula:
(Y,A) 3 (Al,B) 5 (O,C) 12 :Ce, where
A is at least one of Tb, Gd, Sm, La, Lu, Sr, Ca, and Mg, including combinations of those elements, and wherein the amount of substitution of those elements for Y ranges from about 0.1 to about 100 percent stoichiometrically;
B is at least one of Si, Ge, B, P, and Ga, including combinations, wherein B substitutes for Al in amounts ranging from about 0.1 to about 100 percent stoichiometrically; and
C is at least one of F, Cl, N, and S, including combinations, wherein C substitutes for oxygen in amounts ranging from about 0.1 to about 100 percent stoichiometrically; and
at least one of a red-emitting phosphor or a yellow-emitting phosphor.
16. The white LED of claim 15 , wherein the red-emitting phosphor is a nitride.
17. The white LED of claim 15 , wherein the nitride has the formula (Ca,Sr)AlSiN 3 :Eu 2+ .
18. The white LED of claim 15 , wherein the yellow-emitting phosphor is a silicate.
19. The white LED of claim 15 , wherein the silicate has the formula (Sr,Ba) 2 SiO 4 :Eu 2+ .