Phosphor based on a combination of quantum dot and conventional phosphors

1. A phosphor composition comprising:

first phosphor particles of a first size, said first phosphor particles of a first size converting light of an excitation wavelength to light having a first spectrum characterized by an intensity of light that varies as a function of wavelength, said first spectrum being independent of said size of said first phosphor particles; and

particles of a QD phosphor of a second size that convert light of said excitation wavelength to light having a QD phosphor spectrum characterized by an intensity of light that varies as a function of wavelength;

wherein each of said first phosphor particles of a first size are coated with one or more of said particles of a QD phosphor of a second size.

2. The phosphor composition of claim 1 wherein said first phosphor particles of a first size comprise particles of a first chemical composition and said particles of a QD phosphor of a second size comprise phosphors of a second chemical composition.

3. The phosphor composition of claim 2 wherein said first chemical composition is different from said second chemical composition.

4. The phosphor composition of claim 1 wherein said first phosphor particles of a first size and said particles of a QD phosphor of a second size are present in a ratio of concentrations and wherein said ratio, said first phosphor particles of a first size, and said particles of a QD phosphor of a second size are chosen such that a combined spectrum comprising said QD phosphor spectrum and said first spectrum has an intensity that is more uniform as a function of wavelength than either said QD phosphor spectrum or said first spectrum.

5. The phosphor composition of claim 4 wherein said combined spectrum is perceived to be white light.

6. The phosphor composition of claim 1 wherein said first phosphor particles of a first size comprise particles chosen from the group consisting of garnet, sulphide, thiometallate, silicate, oxides, oxynitrides, nitrides, and selenide based phosphor.

7. The phosphor composition of claim 6 wherein said first phosphor particles of a first size are doped with a rare earth element.

8. The phosphor composition of claim 1 wherein said particles of a QD phosphor of a second size comprise CdS, CdSe, CdTe, CdPo, ZnS, ZnSe, ZnTe, ZnPo, Mgs, MgSe, MgTe, PbSe, PbS, PbTe, HgS, HgSe, HgTe, Cd(S 1-x ,Se x ), BaTiO 3 , PbZrO 3 , PbZr z Ti 1-z O 3 , SrTiO 3 , SrTiO 3 , LaMnO 3 , CaMnO 3 , and La 1-x Ca x MnO 3 .

9. The phosphor composition of claim 1 wherein said first phosphor particles of a first size are coated with a layer of material that provides protection from moisture.

10. The phosphor composition of claim 1 wherein said particles of a QD phosphor of a second size are coated with a layer of material that inhibits said particles of a QD phosphor of a second size from sticking to one another.

11. A light source comprising:

an excitation light source that emits excitation light of an excitation wavelength;

a layer of phosphor comprising:

first phosphor particles of a first size, said first phosphor particles of a first size converting light of an excitation wavelength to light having a first spectrum characterized by an intensity of light that varies as a function of wavelength, said first spectrum being independent of said size of said first phosphor particles; and

particles of a QD phosphor of a second size that convert light of said excitation wavelength to light having a QD phosphor spectrum characterized by an intensity of light that varies as a function of wavelength;

wherein each of said first phosphor particles of a first size are coated with one or more of said particles of a QD phosphor of a second size.

12. The light source of claim 11 wherein said first phosphor particles of a first size comprise particles of a first chemical composition and said particles of a QD phosphor of a second size comprise phosphors of a second chemical composition.

13. The light source of claim 12 wherein said first chemical composition is different from said second chemical composition.

14. The light source of claim 11 wherein said first phosphor particles of a first size and said particles of a QD phosphor of a second size are present in a ratio of concentrations and wherein said ratio, said first phosphor particles of a first size, and said particles of a QD phosphor of a second size are chosen such that a combined spectrum comprising said QD phosphor spectrum and said first spectrum has an intensity that is more uniform as a function of wavelength than either said QD phosphor spectrum or said first spectrum.

15. The light source of claim 14 wherein said combined spectrum is perceived to be white light.

16. The light source of claim 15 wherein said combined spectrum further comprises a portion of said excitation light.

17. The light source of claim 11 wherein said first phosphor particles of a first size comprise particles chosen from the group consisting of garnet, sulphide, thiometallate, silicate, oxides, oxynitrides, nitrides, and selenide based phosphor.

18. The light source of claim 17 wherein said first phosphor particles of a first size are doped with a rare earth element.

19. The light source of claim 11 wherein said particles of a QD phosphor of a second size comprise CdS, CdSe, CdTe, CdPo, ZnS, ZnSe, ZnTe, ZnPo, Mgs, MgSe, MgTe, PbSe, PbS, PbTe, HgS, HgSe, HgTe, Cd(S 1-x ,Se x ), BaTiO 3 , PbZrO 3 , PbZr z Ti 1-z O 3 , Ba x Sr 1-x TiO 3 , LaMnO 3 , CaMnO 3 , and La 1-x Ca x MnO 3 .

20. The light source of claim 11 wherein said first phosphor particles of a first size are coated with a layer of material that provides protection from moisture.

21. The light source of claim 11 wherein said particles of a QD phosphor of a second size are coated with a layer of material that inhibits said particles of a QD phosphor of a second size from sticking to one another.