Phosphors for warm white emitters

1. A method for fabricating light-emitting devices, the method comprising:

obtaining a plurality of light-emitting diode (LED) chips fabricated to emit blue light;

preparing a phosphor-containing material comprising a matrix material having dispersed therein a mixture of a red phosphor and a green phosphor, wherein the phosphor-containing material has about 60-80 units of red phosphor and 390-430 units of green phosphor; and

disposing different thicknesses of the phosphor-containing material on different ones of the LED chips, wherein the LED chips having different thicknesses of the phosphor-containing material emit light characterized by different points along the Planckian locus in a CIE chromaticity diagram;

combining two or more of the LED chips covered with different thicknesses of the phosphor-containing material to form an LED emitter, which emits light characterized by a point along the Planckian locus in the CIE chromaticity diagram.

2. The method of claim 1 , wherein the green phosphor has a peak emitting wavelength that is less than 550 nm.

3. The method of claim 1 , wherein the green phosphor has a peak emitting wavelength that is less than 525 nm.

4. The method of claim 1 , wherein the green phosphor has a peak emitting wavelength in a range from about 515 nm to about 518 nm.

5. The method of claim 1 , wherein the fixed ratio is a ratio of about one part of red phosphor to 5-7 parts of green phosphor by weight.

6. A method for fabricating light-emitting devices, the method comprising:

obtaining a plurality of light-emitting diode (LED) chips fabricated to emit blue light;

preparing a phosphor-containing material comprising a matrix material having dispersed therein a mixture of a red phosphor and a green phosphor, wherein the phosphor-containing material has about 60-80 units of red phosphor and 390-430 units of green phosphor, wherein LED chips having different thicknesses of the phosphor-containing material emit light characterized by an ellipse having a long axis substantially parallel to the Planckian locus in a CIE chromaticity diagram; and

disposing different thicknesses of the phosphor-containing material on different ones of the LED chips, and

combining two or more of the LED chips covered with different thicknesses of the phosphor-containing material to form an LED emitter.

7. The method of claim 1 , wherein the phosphor-containing material has about 60-80 units of red phosphor and 390-430 units of green phosphor.

8. The method of claim 1 , wherein the fixed ratio is a ratio of about one part of red phosphor to 5-7 parts of green phosphor by weight.

9. An LED (light-emitting-diode) emitter, comprising:

a plurality of light-emitting-diode (LED) chips configured to emit blue light, wherein different ones of the LED chips have different thicknesses of a phosphor-containing material formed thereon, the phosphor-containing material comprising a matrix material having dispersed therein a mixture of a red phosphor and a green phosphor, wherein the phosphor-containing material has about 60-80 units of red phosphor and 390-430 units of green phosphor, wherein a distribution of light emitted from the plurality of LED chips having different thicknesses of the phosphor-containing material is characterized by an ellipse having a long axis substantially parallel to the Planckian locus in a CIE chromaticity diagram.

10. The plurality of light emitting devices of claim 9 , wherein the green phosphor has a peak emitting wavelength that is 525 nm or less.

11. The plurality of light emitting devices of claim 9 , wherein the green phosphor has a peak emitting wavelength in a range from about 515 nm to about 518 nm.

12. The plurality of light emitting devices of claim 9 , wherein the fixed ratio is a ratio of about one unit of red phosphor to 5-7 units of green phosphor.

13. An LED (light-emitting-diode) emitter, comprising:

a first light-emitting device including a wavelength-conversion material having a first thickness overlying a first light-emitting-diode (LED) chip configured to emit light of a first color; and

a second light-emitting device including the wavelength-conversion material having a second thickness overlying a second light-emitting-diode (LED) chip configured to emit light of the first color, the second thickness being different from the first thickness;

wherein the wavelength-conversion material comprises a matrix material having dispersed therein a mixture of a first phosphor and a second phosphor, wherein the phosphor-containing material has about 60-80 units of red phosphor and 390-430 units of green phosphor; and

wherein the first light-emitting device and the first light-emitting device emit light characterized by different points along the Planckian locus in a CIE chromaticity diagram.

14. The plurality of light emitting devices of claim 13 , further comprising a third light-emitting device including the phosphor-containing material having a third thickness overlying a third light-emitting-diode (LED) chip configured to emit light of the first color, the third thickness being different from the first thickness and the second thickness,

wherein light from the third light-emitting device is characterized by a third point along the Planckian locus in the CIE chromaticity diagram.

15. The plurality of light emitting devices of claim 13 , wherein the first color is blue, the first phosphor is a red phosphor, and the second phosphor is a green phosphor.

16. The plurality of light emitting devices of claim 15 , wherein the green phosphor has a peak emitting wavelength that is less than 525 nm.

17. The plurality of light emitting devices of claim 15 , wherein the fixed ratio is a ratio of about one unit of red phosphor to 5-7 units of green phosphor.