CONVERTER SYSTEM

Abstract

The present invention relates to a light emitting device comprising a red-emitting Eu.sup.3+ material and green emitting Ce.sup.3+ material which are matched so that the resulting white light has an increased lumen equivalent of radiation for a given color rendering index than with the prior art.

Claims

1. A converter system for a light emitting device, comprising: a first material doped with Ce.sup.3+; and a second material doped with Eu.sup.3+ and emitting in the red spectral range so that the converter system shows an emission spectrum with a peak between ≥605 to ≤630 nm, wherein the ratio of the Eu.sup.3+ peak to the maximum peak in the green and/or yellow spectral range is ≥2.

2. The converter system of claim 1, wherein the first material is capable of emitting in the green and/or yellow spectral range.

3. The converter system of claim 1, wherein the converter system shows an emission spectrum with a peak between ≥610 to ≤630 nm.

4. The converter system of claim 1, wherein the converter system shows an emission spectrum with a dip between ≥520 to ≤545 nm.

5. The converter system of claim 1, wherein the converter system shows an emission spectrum with a dip between ≥530 to ≤540 nm.

6. (canceled)

7. The converter system according to claim 1, wherein the first material comprises a garnet and/or cubic material

8. The converter system according to claim 1, wherein the second material comprises a material selected from the group consisting of phosphates, sulfates, oxides, borates, molybdates, tungstates, vanadates, niobates, tantalates and mixtures or chemical combinations thereof.

9. The converter system according to claim 1, wherein the second, Eu.sup.3+ doped red emitting material comprises a material of the group comprising (Ba.sub.1−xSr.sub.x).sub.2+nSiO.sub.4+n:Eu, (Sr.sub.1−xCa.sub.x).sub.2+nSiO.sub.4+n:Eu, (Sr.sub.1−xCa.sub.x)Ga.sub.2S.sub.4:Eu with x≥0% to ≤1 and n=0 or 1 (Sr.sub.1−xCa.sub.x)Ga.sub.2S.sub.4:Eu with x≥0% to ≤1 ALn.sub.1−x−yEu.sub.xM.sub.2O.sub.8:RE.sub.y (Ln.sub.1−x−yEu.sub.x).sub.2MO.sub.6:RE.sub.2y (Ln.sub.1−x−yEu.sub.x).sub.2M.sub.2O.sub.9:RE.sub.2y (Ln.sub.1−x−yEu.sub.x).sub.2M.sub.3O.sub.12:RE.sub.2y (Ln.sub.1−x−yEu.sub.x).sub.2M.sub.4O.sub.15:RE.sub.2y (Ln.sub.1−x−yEu.sub.x).sub.6MO.sub.12:RE.sub.6y (AE.sub.1−2x−yEu.sub.xA.sub.x+y).sub.3MO.sub.6:RE.sub.3y A.sub.3AE.sub.2(Ln.sub.1−x−yEu.sub.x).sub.3(MO.sub.4).sub.8:RE.sub.y wherein—for each structure independently—A is an alkaline metal, i.e. selected from the group consisting of lithium, sodium, potassium, rubidium, cesium and mixtures or chemical combinations thereof, AE is an alkaline earth metal, i.e. selected from the group consisting of beryllium, magnesium, calcium, strontium, barium and mixtures or chemical combinations thereof, Ln is a rare earth metal selected from the group consisting of scandium, yttrium, lanthanum, gadolinium, lutetium and mixtures or chemical combinations thereof, M is molybdenum, tungsten or mixtures or chemical combinations thereof, RE is a rare earth metal selected from the group consisting of terbium, dysprosium, praseodymium, neodymium and mixtures or chemical combinations thereof, wherein 0<x≤1 and 0≤y is ≤0.05; and/or Li.sub.3Ba.sub.2(Tb.sub.1−x−yEu.sub.xLn.sub.y).sub.3(Mo.sub.1−zW.sub.z).sub.8O.sub.32, A.sub.3AE.sub.2(Tb.sub.1−x−yEu.sub.xLn.sub.y).sub.3(Mo.sub.1−zW.sub.z).sub.8O.sub.32, A(Tb.sub.1−x−yEu.sub.xLn.sub.y)(Mo.sub.1−zW.sub.z).sub.2O.sub.8, (Tb.sub.1−x−yEu.sub.xLn.sub.y).sub.2(Mo.sub.1−zW.sub.z)O.sub.6, (Tb.sub.1−x−yEu.sub.xLn.sub.y).sub.2(Mo.sub.1−zW.sub.z).sub.2O.sub.9, (Tb.sub.1−x−yEu.sub.xLn.sub.y).sub.2(Mo.sub.1−zW.sub.z).sub.4O.sub.15, (Tb.sub.1−x−yEu.sub.xLn.sub.y).sub.2SiO.sub.5, (Tb.sub.1−x−yEu.sub.xLn.sub.y).sub.2Si.sub.2O.sub.7, A(Tb.sub.1−x−yEu.sub.xLn.sub.y)SiO.sub.4, Ba.sub.2(Tb.sub.1−x−yEu.sub.xLn.sub.y).sub.2Si.sub.4O.sub.13, AE.sub.2(Tb.sub.1−x−yEu.sub.xLn.sub.y).sub.2Si.sub.4O.sub.13, Sr.sub.3(Tb.sub.1−x−yEu.sub.xLn.sub.y).sub.2Si.sub.6O.sub.18, AE.sub.3(Tb.sub.1−x−yEu.sub.xLn.sub.y).sub.2Si.sub.6O.sub.18, (Tb.sub.1−x−yEu.sub.xLn.sub.y).sub.2GeO.sub.5, (Tb.sub.1−x−yEu.sub.xLn.sub.y).sub.2Ge.sub.2O.sub.7, A(Tb.sub.1−x−yEu.sub.xLn.sub.y)GeO.sub.4, Ba.sub.2(Tb.sub.1−x−yEu.sub.xLn.sub.y).sub.2Ge.sub.4O.sub.13, AE.sub.2(Tb.sub.1−x−yEu.sub.xLn.sub.y).sub.2Ge.sub.4O.sub.13, Sr.sub.3(Tb.sub.1−x−yEu.sub.xLn.sub.y).sub.2Ge.sub.6O.sub.18 AE.sub.3(Tb.sub.1−x−yEu.sub.xLn.sub.y).sub.2Ge.sub.6O.sub.18 (Tb.sub.1−x−yEu.sub.xLn.sub.y).sub.2(Ge.sub.1−a−bZr.sub.aHf.sub.b)O.sub.5, (Tb.sub.1−x−yEu.sub.xLn.sub.y).sub.2(Ge.sub.1−a−bZr.sub.aHf.sub.b).sub.2O.sub.7, A(Tb.sub.1−x−yEu.sub.xLn.sub.y)(Ge.sub.1−a−bZr.sub.aHf.sub.b)O.sub.4, Ba.sub.2(Tb.sub.1−x−yEu.sub.xLn.sub.y).sub.2(Ge.sub.1−a−bZr.sub.aHf.sub.b).sub.4O.sub.13, Sr.sub.3(Tb.sub.1−x−yEu.sub.xLn.sub.y).sub.2(Ge.sub.1−a−bZr.sub.aHf.sub.b).sub.6O.sub.18 with (for each material independently) Ln=La, Gd, Lu, Y or mixtures or chemical combinations thereof, A=Li, Na, K, Rb, Cs or mixtures or chemical combinations thereof, preferably Li, AE=Sr, Ca, Ba, or mixtures or chemical combinations thereof, preferably Ba and/or Sr, x>0 and <1 and y≥0 and <1, wherein 1−x−y>0 and a, b≥0 and <0.2 and z≥0 and ≤1, or mixtures or chemical combinations thereof; and/or: (Ca,Sr)Ga.sub.2O.sub.6:Eu, (Ca,Sr,Ba)La.sub.2Bi.sub.2(SiO.sub.4).sub.3O:Eu, (Ca,Sr,Ba)SnO.sub.3:Eu, (Ca,Y,Gd)MoO.sub.4:Eu, (Y,Gd)BO.sub.3 (pseudo-vaterite):Eu, (Y,Tb)SiO.sub.5:Eu, A-La.sub.2O.sub.3:Eu, Ba.sub.2(SiO.sub.4):O.sub.2—:Eu, Ba.sub.2MgSi.sub.2O.sub.7:Eu, Ba.sub.2Y(BO.sub.3).sub.2Cl:Eu, Ba.sub.3(PO.sub.4).sub.2:Eu, Ba.sub.3Ca.sub.3(PO.sub.4).sub.4:Eu, Ba.sub.3Gd(BO.sub.3).sub.3:Eu, Ba.sub.3Gd.sub.2(BO.sub.3).sub.4:Eu, Ba.sub.3La.sub.2(BO.sub.3).sub.4:Eu, Ba.sub.3V.sub.2O.sub.8:Eu, Ba.sub.3Y.sub.2(BO.sub.3).sub.4:Eu, BaBsO1.sub.3:Eu, BaBPO.sub.5:Eu, BaFCl:Eu, BaGd.sub.2 O.sub.4:Eu, BaGd.sub.4 Si.sub.5O1.sub.7:Sm:Eu, BaGdB.sub.9O1.sub.6:Eu, BaLaB.sub.9O1.sub.6:Eu, BaSO.sub.4:Eu, BaY.sub.2F.sub.8:Yb:Eu, BaY.sub.2Si.sub.3O1O:Eu, BaYB.sub.9O1.sub.6:Eu, BaZr(BO.sub.3).sub.2:Eu, BaZrO.sub.3:Eu, BaZrO.sub.3:Eu, b-BaB.sub.2O.sub.4:Eu, B—Gd.sub.2O.sub.3:Eu, Ca.sub.2Al(AlSiO.sub.7):Eu, Ca.sub.2Gd.sub.2(GeO.sub.4).sub.2O:Eu, Ca.sub.2Gd.sub.8(SiO.sub.4).sub.6O.sub.2:Eu, Ca.sub.2Gd.sub.8Si.sub.6O.sub.26:Eu, Ca.sub.2La.sub.8(SiO.sub.4).sub.6O.sub.2:Eu, Ca.sub.3(BO.sub.3).sub.2:Eu, Ca.sub.3Al.sub.2O.sub.6:Eu, Ca.sub.3Gd.sub.2(BO.sub.3).sub.4:Eu, Ca.sub.3La.sub.2(BO.sub.3).sub.4:Eu, Ca.sub.3Y.sub.2(BO.sub.3).sub.4:Eu, Ca.sub.4GdO(BO.sub.3).sub.3:Eu, Ca.sub.5(PO11).sub.3F:Eu, Ca.sub.5(PO.sub.4).sub.3Br:Eu, Ca.sub.5(PO.sub.4).sub.3F:(.sub.4f-site):Eu, Ca.sub.5(PO.sub.4).sub.3F:(.sub.6h-site):Eu, Ca.sub.5(PO.sub.4).sub.3OH:Eu, CaBPO.sub.5:Eu, CaF.sub.2:Eu, CaLaB.sub.7O1.sub.3:Eu, calcite-CaCO.sub.3:Eu, CaO:Eu, CaSO.sub.4:Eu, CaYO(BO.sub.3):Eu, C—Gd.sub.2O.sub.3:Eu, C—Lu.sub.2O.sub.3:(C.sub.2):Eu, C—Lu.sub.2O.sub.3:(C.sub.3i):Eu, Cs.sub.2NaYF.sub.6:Tm:Eu, C—Sc.sub.2O.sub.3:Yb:Eu, C—Y.sub.2O.sub.3:Eu, Eu[(ttfa).sub.3(phen)]0:Eu, Gd1.sub.7.33(BO.sub.3).sub.4(B.sub.2O.sub.5).sub.2O.sub.16:Eu, GdBO.sub.3:Eu, Gd.sub.2BaZnO.sub.5:Eu, Gd.sub.2O.sub.2(SO.sub.4):Eu, Gd.sub.2O.sub.2S:Eu, Gd.sub.2P.sub.4O1.sub.3:Eu, Gd.sub.3O.sub.4Br:Eu, Gd.sub.3PO.sub.7:Eu, Gd.sub.3Te.sub.2Li.sub.3O1.sub.2:Eu, Gd.sub.8P.sub.2O1.sub.7:Eu, GdAl.sub.3 (BO.sub.3).sub.4:Eu, GdAlO.sub.3:Eu, GdAlO.sub.3:Eu, GdB.sub.3O.sub.6:Eu, GdBO.sub.3:Eu, GdGaO.sub.3:Eu, GdOBr:Eu, GdOCl:Eu, GdP.sub.3O.sub.9:Eu, GdPO.sub.4:Eu, I—CaB.sub.2O.sub.4:Eu, InBO.sub.3:Eu, I—SrB.sub.2O.sub.4:Eu, KCaGd(PO.sub.4).sub.2:Eu, La.sub.26O.sub.27(BO.sub.3).sub.8:Eu, La.sub.2BaZnO.sub.5:Eu, La.sub.2Hf.sub.2O.sub.7:Eu, La.sub.2O.sub.2(SO.sub.4):Eu, La.sub.2O.sub.2S:Eu, La.sub.2O.sub.2S:Eu, La.sub.2W.sub.3O.sub.12:Eu, La.sub.2Zr.sub.3(MoO.sub.4).sub.9:Eu, La.sub.3TaO.sub.4Cl.sub.6:Eu, La.sub.3TaO.sub.4Cl.sub.6:Eu, La.sub.3WO.sub.6Cl.sub.3:Eu, La.sub.3WO.sub.6Cl.sub.3:Eu, LaAlO.sub.3:Eu, LaAlO.sub.3:Eu, LaB.sub.3O.sub.6:Eu, LaBO.sub.3:Eu, LaF.sub.3:Eu, LaF.sub.3:Eu, LaGaO.sub.3:Eu, LaMgB.sub.5O10:Eu, LaOBr:Eu, LaOCl:Eu, LaOF:Eu, LaOI:Eu, LaP.sub.3O.sub.9:Eu, LaPO.sub.4:Eu, LaYO.sub.3:Eu, Li.sub.2Lu.sub.5O.sub.4(BO.sub.3).sub.3:Eu, Li.sub.3Ba.sub.2La.sub.3(MoO.sub.4).sub.8:Eu, Li.sub.3La.sub.2(BO.sub.3).sub.3:Eu, Li.sub.6Gd(BO.sub.3).sub.3:Eu, Li.sub.6Y(BO.sub.3).sub.3:Eu, LiCaAlF.sub.6:Eu, LiEuMo.sub.2O.sub.8:Eu, LiGd.sub.6O.sub.5(BO.sub.3).sub.3:Eu, LiGdF.sub.4:Eu, LiGdGeO.sub.4:Eu, LiGdO.sub.2:Eu, LiGdSiO.sub.4:Eu, LiLa.sub.2O.sub.2BO.sub.3:Eu, LiLaGeO.sub.4:Eu, LiLaO.sub.2:Eu, LiLaP.sub.4O1.sub.2:Eu, LiLaSiO.sub.4:Eu, LiLuGeO.sub.4:Eu, LiLuO.sub.2:Eu, LiLuSiO.sub.4:Eu, LiScO.sub.2:Eu, LiSr.sub.2YO.sub.4:Eu, LiSrAlF.sub.6:Eu, LiSrAlF.sub.6:Eu, LiY.sub.6O.sub.5(BO.sub.3).sub.3:Eu, LiYF.sub.4:Eu, LiYGeO.sub.4:Eu, LiYO.sub.2:Eu, LiYSiO.sub.4:Eu, Lu.sub.2O.sub.2(SO.sub.4):Eu, Lu.sub.2Si.sub.2O.sub.7:Eu, Lu.sub.3Al.sub.5O1.sub.2:Eu, Lu.sub.3Al.sub.5O1.sub.2:Yb:Eu, LuBO.sub.3:Eu, LuBO.sub.3 (calcite):Eu, LuOCl:Eu, LuPO.sub.4:Eu, Mg.sub.2Gd.sub.8(SiO.sub.4).sub.6O.sub.2:Eu, Mg.sub.2La.sub.8(SiO.sub.4).sub.6O.sub.2:Eu, MgO:Eu, MgSiO.sub.3:Eu, Na.sub.3YSi.sub.3O.sub.9:Eu, Na.sub.6Gd(BO.sub.3).sub.3:Eu, NaGdGeO.sub.4:Eu, NaGdO.sub.2:Eu, NaGdSiO.sub.4:Eu, NaGdSiO.sub.4:Eu, NaLaGeO.sub.4:Eu, NaLaO.sub.2:Eu, NaLaSiO.sub.4:Eu, NaLuGeO.sub.4:Eu, NaLuSiO.sub.4:Eu, NaScO.sub.2:Eu, NaSrLa(VO.sub.4).sub.2:Eu, NaYGeO.sub.4:Eu, NaYSiO.sub.4:Eu, ScBO.sub.3:Eu, ScOCl:Eu, ScPO.sub.4:Eu, Sr.sub.2B.sub.2O.sub.5:Eu, Sr.sub.2Gd.sub.8(SiO.sub.4).sub.6O.sub.2:Eu, Sr.sub.2La.sub.2Zn.sub.2O.sub.7:Eu, Sr.sub.2La.sub.2Zn.sub.2O.sub.7:Eu, Sr.sub.2LaAlO.sub.5:Eu, Sr.sub.3(BO.sub.3).sub.2:Eu, Sr.sub.3(PO.sub.4).sub.2:Eu, Sr.sub.3(PO.sub.4).sub.2:Sm:Eu, Sr.sub.3Gd.sub.2(BO.sub.3).sub.4:Eu, Sr.sub.3La.sub.2(BO.sub.3).sub.4:Eu, Sr.sub.3La.sub.6(SiO.sub.4).sub.6:Eu, Sr.sub.3Y.sub.2(BO.sub.3).sub.4:Eu, Sr.sub.5(PO.sub.4).sub.3F:Eu, Sr.sub.9Ln(VO.sub.4).sub.7:Eu, SrAl.sub.2 B.sub.2O.sub.7:Eu, SrB.sub.4O.sub.7:Eu, SrB.sub.6O10:Eu, SrCO.sub.3:Eu, SrGdAlO.sub.4:Eu, SrHfO.sub.3:Tm:Eu, SrLa.sub.2BeO.sub.5:(.sub.4c):Eu, SrLa.sub.2BeO.sub.5:(.sub.8d):Eu, SrLaAlO.sub.4:Eu, SrLaGa.sub.3O.sub.7:Eu, SrLaO(BO.sub.3):Eu, SrO:Eu, SrY.sub.2O.sub.4:(Sr-site):Eu, SrY.sub.2O.sub.4:(Y-site1):Eu, SrY.sub.2O.sub.4:(Y-site.sub.2):Eu, Tb.sub.2Mo.sub.3O1.sub.2:Eu, Tb.sub.2W.sub.3O1.sub.2:Eu, TbBO.sub.3:Eu, ThO.sub.2:Eu, X1-Gd.sub.2SiO.sub.5:Eu, X1-Y.sub.2SiO.sub.5:Eu, X.sub.2—Y.sub.2SiO.sub.5:Eu, Y1.sub.7.33(BO.sub.3).sub.4(B.sub.2O.sub.5).sub.2O.sub.16:Eu, YBO.sub.3:Eu, Y.sub.2Ge.sub.2O.sub.7:Eu, Y.sub.2GeO.sub.5:Eu, Y.sub.2O.sub.2(SO.sub.4):Eu, Y.sub.2O.sub.2S:Eu, Y.sub.2O.sub.2S:Eu, Y.sub.2O.sub.3:Eu, Y.sub.2P.sub.4O.sub.13:Eu, Y.sub.2Si.sub.2O.sub.7:Eu, Y.sub.2SiO.sub.5:Eu, Y.sub.3Al.sub.5O.sub.12:Eu, Y.sub.3Ga.sub.5O.sub.12:Eu, Y.sub.3O.sub.4Br:Eu, Y.sub.3O.sub.4Cl:Eu, Y.sub.3PO.sub.7:Eu, Y.sub.4GeOs:Eu, Y.sub.8P.sub.2O.sub.17:Eu, YAl.sub.3(BO.sub.3).sub.4:Eu, YAlO.sub.3:Eu, YAlO.sub.3:Eu, YBO.sub.3:Eu, YbOBr:Yb:Eu, YF.sub.3:Eu, YOBr:Eu, YOCl:Eu, YOCl:Eu, YOF:Eu, YOF:Eu, YP.sub.3O.sub.9:Eu, YPO.sub.4:Eu, YTaO.sub.4:Eu, YVO.sub.4:Eu, ZrP.sub.2O.sub.7:Eu, or mixtures or chemical combinations thereof.

10. A light emitting device comprising a converter system according to claim 1 and a blue light emitting material.

11. The light emitting device according to claim 10, wherein the blue light emitting material emits light towards the converter system with a wavelength of <465 nm.

12. The light emitting device according to claim 10, wherein the light emitting device emits white light.

13. The light emitting device according to claim 12, wherein the white light is characterized by a lumen equivalent of radiation greater than 330 lm/W.

14. The light emitting device according to claim 12, wherein the white light is characterized by a color rendering index greater than 85.

15. A lighting system comprising a light emitting device according to claim 10.

16. The lighting system according to claim 15, wherein the lighting system is a lamp or luminaire.

Description

[0078] Further details, features and advantages of the object of the present invention can be obtained from the claims and from the following description of the accompanying drawings, in which—by way of example—several embodiments of the device according to the invention are shown, as well as with respect to the examples, which are to be considered as purely illustrative and not limiting. In the drawings:

[0079] FIG. 1 shows an emission spectrum of a converter system of Example I

[0080] FIG. 2 shows several emission spectra of a converter system of Example II

[0081] FIG. 3 shows a diagram illustrating the change of x-chromaticity against the LED excitation wavelength for the converter system of Example II

[0082] FIG. 4 shows a diagram illustrating the change of y-chromaticity against the LED excitation wavelength for the converter system of Example II

[0083] FIG. 5 shows a diagram illustrating the change of LER against the excitation wavelength for the converter system of Example II;

[0084] FIG. 6 shows a diagram illustrating the change of CRI against the excitation wavelength for the converter system of Example II

[0085] FIG. 7 shows a diagram of LER vs color rendering properties for white LED emission spectra based on converter systems of the prior art vs. several of those for the present invention.

[0086] FIG. 8 show a diagram of LER vs color rendering properties for white LED emission spectra based on converter systems of the prior art vs. several of those for the present invention.

[0087] Hereinafter the invention is explained by way of examples, which are to be considered purely as illustrative and not as limiting.

EXAMPLE I

[0088] Example I refers to a light emitting device targeting a white light emission and comprising a ceramic made of 90 vol.-% Li.sub.3Ba.sub.2Eu.sub.2.4Tb.sub.0.6(MoO.sub.4).sub.8 and 10 Vol.-% Lu.sub.3Al.sub.5O.sub.12:Ce(0.065%). This was prepared as follows:

[0089] Synthesis of Li.sub.3Ba.sub.2Eu.sub.2.4Tb.sub.0.6(MoO.sub.4).sub.8

[0090] 0.7894 g (4.000 mmol) BaCO.sub.3, 2.3030 g (16.000 mmol) MoO.sub.3, 0.2217 g (3.000 mmol) Li.sub.2CO.sub.3, 0.8446 g (2.400 mmol) Eu.sub.2O.sub.3 and 0.2243 g (0.300 mmol) Tb.sub.4O.sub.7 were pounded in a mortar with acetone as grinding aid. The obtained powder was dried, transferred to a porcelain crucible and calcinated in air at 800° C. for 12 h. The cake thus obtained was ground and sieved through a 36 μm sieve.

[0091] Synthesis of Lu.sub.2.9805Ce.sub.0.00195Al.sub.5O.sub.12

[0092] 2.9825 g (7.495 mmol) Lu.sub.2O.sub.3, 0.00168 g (0.0098 mmol) CeO.sub.2 and 1.2745 g (12.500 mmol) Al.sub.2O.sub.3 were thoroughly pounded in a mortar with acetone as grinding aid. The obtained powder was dried, transferred to a porcelain crucible and heated at 1750° C. for 12 h under a CO atmosphere.

[0093] Manufacture of the Ceramic

[0094] A mixture of 90 vol.-% Li.sub.3Ba.sub.2Eu.sub.2.4Tb.sub.0.6(MoO.sub.4).sub.8 and 10 Vol.-% Lu.sub.3Al.sub.5O.sub.12:Ce(0.065%) was thoroughly ground in a mill. The crude phosphor powder thus obtained was mixed with a polyvinylpyrrolidone binder, pressed into pellets and compacted by axial pressing at approximately 225 MPa. The thus obtained ceramic green bodies were placed on a corundum firing shelve and heated at 850° C. in air. After cooling to room temperature, the ceramics were sawed into wafers. The quantum yield is 67% and the color point is located at x=0.510 and y=0.458.

[0095] FIG. 1 shows the emission spectrum of a converter system based on Example I upon excitation with a 450 nm LED. As can be seen from FIG. 1, the spectrum shows a dip at 535 nm and a peak at 615 nm. This results in a CCT of 2891, a CRI of 90, a R9 of 1 and a LER of 351.

[0096] As will be shown also in FIG. 7 later on, this results in a light emitting device with a much better LER for a given CRI than with the prior art.

EXAMPLE II

[0097] Example I refers to a converter system comprising Lu.sub.3Al.sub.5O.sub.12:Ce.sup.3+ and Li.sub.3Ba.sub.2La.sub.2(MoO.sub.4).sub.8:Eu.sup.3+ which was made mutatis mutandis as in Example II.

[0098] FIG. 2 shows several emission spectra of a converter system of Example II FIGS. 3 to 6 show the change in x-chromaticity, y-chromaticity, LER and CRI, re-spectively, for the converter system of Example II against the excitation wavelength.

[0099] Surprisingly it was found that the ideal excitation wavelength is <465, for this particular example around 445 to 460 nm.

[0100] A surprising result for these examples which target white light emission is that the preferred wavelength of excitation is not at 465 nm, which is the maximum in excitation for Eu.sup.3+ phosphor materials. Instead, the inventors' experimental data show that it is preferable to excite the system at shorter wavelengths than 465 nm in order to optimize spectral properties.

[0101] More detailed results are given in Table 1 below, which shows the characteristics of several converter systems in relation to the excitation wavelength:

TABLE-US-00004 TABLE 1 445 nm 448 nm 450 nm 454 nm 463 nm 465 nm 474 nm 479 nm CCT 3338 3167 3065 2904 2628 2794 3306 3718 (K) x 0.4217 0.4305 0.4362 0.4447 0.4621 0.4543 0.4303 0.4125 y 0.4125 0.4112 0.4107 0.4080 0.4055 0.4127 0.4292 0.4420 u′ 0.2374 0.2435 0.2472 0.2539 0.2663 0.2580 0.2361 0.2206 v′ 0.5224 0.5230 0.5239 0.5241 0.5257 0.5273 0.5299 0.5319 X 0.00075405 0.001175 0.00086238 0.0014532 0.00107060 0.00155780 0.00158680 0.00088151 Y 0.00073758 0.00112220 0.00081207 0.0013334 0.00093948 0.00141490 0.00158280 0.00094458 Z 0.00029644 0.00043193 0.00030276 0.0004813 0.00030679 0.00045600 0.00051813 0.00031087 CRI 84 87 88 90 79 77 67 61 R9 −6 1 3 10 21 30 60 74 LER 353 347 345 335 320 319 315 314 (lm/W) Rf 83 86 87 87 74 68 50 41 Rg 97 97 97 96 89 84 69 61

[0102] FIG. 7 shows a diagram of LER vs CRI for several converter systems of the prior art (taken from databases) and several converter systems of the present invention. It can be seen that the converter systems of the present invention allow for much higher LER for a given CRI than with the prior art.

[0103] The data for FIG. 7 is shown in Table 2 below:

TABLE-US-00005 TABLE 2 CRI 90 90 90 88 89 89 CCT (K) 3028 2891 2928 3111 3000 2931 x 0.4361 0.4481 0.4398 0.4276 0.4389 0.4400 y 0.4060 0.4130 0.4014 0.3979 0.4082 0.4019 u′ 0.2492 0.2539 0.2536 0.2472 0.2501 0.2535 v′ 0.5220 0.5265 0.5208 0.5175 0.5233 0.5210 X 0.00097040 0.00480050 0.00992900 0.00589890 0.00103000 0.00089858 Y 0.00090335 0.00442500 0.00906060 0.00548860 0.00095791 0.00082082 Z 0.00035126 0.00148820 0.00358460 0.00240710 0.00035899 0.00032301 R9 9 1 5 14 8 10 LER (lm/W) 339 351 344 330 340 334 Rf 87 87 88 86 87 87 Rg 96 95 98 95 96 97 CRI 89 88 88 90 CCT (K) 2932 3031 2993 3000 x 0.4424 0.4343 0.4354 0.4370 y 0.4068 0.4026 0.4002 0.4043 u′ 0.2529 0.2495 0.2512 0.2505 v′ 0.5233 0.5204 0.5196 0.5215 X 0.00094669 0.00029190 0.00642040 0.00106460 Y 0.00087067 0.00027058 0.00590150 0.00098502 Z 0.00032273 0.00010957 0.00242530 0.00038667 R9 8 2 7 10 LER (lm/W) 337 340 332 336 Rf 87 86 87 88 Rg 96 98 96 97

[0104] In addition to the standard measure color rendering index (CRI), color properties based on the Illuminating Engineering Society of North America (IESNA) Technical Memorandum (TM) No. 30 are included in the experimental data of Tables 1 and 2, and designated by the fidelity metric Rf and gamut metric Rg. FIG. 8 shows a diagram of LER vs Rf for the experimental data in Table 2. It can be seen that the converter systems of the present invention allow for much higher LER for a given Rf than with the prior art.

[0105] The individual combinations of the ingredients and the characteristics of the embodiments mentioned above are exemplary, the exchange and substitution of the teachings included in this publication with other teachings included in the cited doc-uments are also explicitly contemplated. A person skilled in the art will recognize that variations and modifications of the embodiments described herein and other embodiments may be realized without departing from the spirit and scope of the invention. Accordingly, the above description is to be considered exemplary and not as limiting. The word “comprises” used in the claims does not exclude other ele-ments or steps. The indefinite article “a” does not exclude the importance of a plural. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage. The scope of the invention is defined in the following claims and the associated equivalents.