LUMINOPHORE, METHOD FOR THE PRODUCTION OF A LUMINOPHORE AND RADIATION-EMITTING COMPONENT

Abstract

A luminophore has the general formula EA.sub.2xRE.sub.xSi.sub.5xyAl.sub.x+yN.sub.8yO.sub.y:A, where

0<x2 and 0y2, EA is an element or a combination of elements from the group of alkaline earth elements, RE is an element or a combination of elements from the group of rare earth elements, and A is an activator element. A method for the production of a luminophore and a radiation-emitting component are further disclosed.

Claims

1. A luminophore with the general formula
EA.sub.2xRE.sub.xSi.sub.5xyAl.sub.x+yN.sub.8yO.sub.y:A wherein $0.2<x2\mathrm{and}0y2,$ EA is an element or a combination of elements from the group Ba and Sr, RE is an element or a combination of elements from the group formed by scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium, and A is an activator element.

2. The luminophore with the general formula EA.sub.2xRE.sub.xSi.sub.5xyAl.sub.x+yN.sub.8yO.sub.y:A wherein $0<x2\mathrm{and}0y2,$ EA is an element or a combination of elements from a group of alkaline earth elements, RE is an element or a combination of elements from a group formed by scandium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium, A is an activator element, and an electromagnetic radiation emitted by the luminophore has an emission maximum of at least one emission peak between 550 nm inclusive and 620 nm inclusive.

3. The luminophore according to claim 1, wherein A is an element or a combination of elements selected from the group Ce and Eu.

4. (canceled)

5. The luminophore according to claim 1, wherein the luminophore has a formula selected from (Ba,Sr).sub.2xLa.sub.xSi.sub.5xAl.sub.xN.sub.8:Ce.sup.3+ and (Ba, Sr).sub.2xLa.sub.xSi.sub.5xAl.sub.xN.sub.8:Eu.sup.2+.

6. The luminophore according to claim 1, wherein the luminophore crystallizes in an orthorhombic space group.

7. The luminophore according to claim 1, wherein the luminophore comprises Si-centered Si(N,O).sub.4-tetrahedra and Al-centered Al(N,O).sub.4-tetrahedra, wherein the tetrahedra are corner-linked on all sides.

8. The luminophore according to claim 1, wherein the luminophore has an absorption range at least in the UV to red wavelength range of the electromagnetic spectrum.

9. The luminophore according to claim 1, wherein the luminophore emits in the cyan to orange and/or in the orange to near-infrared wavelength range of the electromagnetic spectrum.

10. The luminophore according to claim 1, wherein an electromagnetic radiation emitted by the luminophore has a centroid wavelength between 600 nm inclusive and 900 nm inclusive.

11. The luminophore according to claim 1, wherein an electromagnetic radiation emitted from the luminophore has a dominant wavelength between 450 nm inclusive and 620 nm inclusive.

12. The luminophore according to claim 1, wherein an electromagnetic radiation emitted by the luminophore has an emission maximum of at least one emission peak between 430 nm inclusive and 950 nm inclusive.

13. The luminophore according to claim 1, wherein an electromagnetic radiation emitted by the luminophore has a spectral half-width between 80 nm inclusive and 230 nm inclusive.

14. A method for the production of a luminophore having the general formula EA.sub.2xRE.sub.xSi.sub.5xyAl.sub.x+yN.sub.8yO.sub.y:A wherein $0.2<x2\mathrm{and}0y2,$ EA is an element or a combination of elements from the group Ba and Sr, RE is an element or a combination of elements from the group formed by scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium, and A is an activator element, wherein the method comprises: providing reactants, mixing the reactants to form a reactant mixture, and heating the reactant mixture.

15. The method according to the claim 14, wherein the reactant mixture is heated to a temperature from the range between 1400 C. inclusive and 2100 C. inclusive and/or wherein the reactant mixture is heated for a period of 0.5 hours inclusive up to and including 24 hours.

16. The method according to 14, wherein the reactant mixture is heated under N.sub.2 atmosphere or forming gas atmosphere.

17. The method according to claim 14, wherein the heating is carried out at normal pressure or a pressure selected from the range between 3 bar inclusive up to and including 100 bar.

18. A radiation emitting component comprising: a semiconductor chip which emits electromagnetic radiation of a first wavelength range during operation, a conversion element comprising at least a first luminophore according to claim 1, which converts electromagnetic radiation of the first wavelength range into electromagnetic radiation of a second wavelength range which is at least partially different from the first wavelength range.

19. The radiation-emitting component according to claim 18, wherein the conversion element comprises a second luminophore, wherein the second lumiphore with the general formula EA.sub.2xRE.sub.xSi.sub.5xyAl.sub.x+yN.sub.8yO.sub.y:A wherein $0.2<x^{}2\mathrm{and}0y^{}2,$ EA is an element or a combination of elements from the group Ba and Sr. RE is an element or a combination of elements from the group formed by scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium, and A is an activator element, wherein the second lumiphore is configured to convert electromagnetic radiation of the first wavelength range into electromagnetic radiation of a third wavelength range which is at least partially different from the first and second wavelength range.

20. The radiation-emitting component according to claim 19, wherein x and A of the first luminophore are respectively different from x and A and of the second luminophore.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Further advantageous embodiments, configurations and further developments of the luminophore, the method for the production of a luminophore and the radiation-emitting component arise from the following exemplary embodiments in conjunction with the illustrated figures.

[0085] FIG. 1 shows a schematic sectional view of a radiation-emitting component according to an exemplary embodiment.

[0086] FIG. 2 shows a schematic sectional view of a radiation-emitting component according to an exemplary embodiment.

[0087] FIG. 3 shows emission spectra of the luminophore according to exemplary embodiments.

[0088] FIG. 4 shows emission spectra of crystals of luminophores according to exemplary embodiments.

[0089] FIG. 5 shows emission spectra of the luminophore according to exemplary embodiment.

[0090] FIG. 6 shows an emission spectrum of the luminophore according to an exemplary embodiment.

[0091] FIG. 7 shows emission spectra of the luminophore according to an exemplary embodiment and according to comparative examples in comparison to the sensitivity curve of the photoreceptor melanopsin.

[0092] FIG. 8 shows emission spectra of comparative examples.

[0093] FIG. 9 shows a simulated emission spectrum of a component according to an exemplary embodiment.

[0094] FIG. 10 shows a simulated emission spectrum of a component according to a comparative example.

[0095] FIG. 11 shows a simulated emission spectrum of a component according to a comparative example.

[0096] FIG. 12 shows emission spectra of a luminophore according to an exemplary embodiment and according to a comparative example.

[0097] FIG. 13 shows reflectance spectra of luminophores according to exemplary embodiments.

DETAILED DESCRIPTION

[0098] Elements that are identical, similar or have the same effect are marked with the same reference symbols in the figures. The figures and the proportions of the elements shown in the figures should not be considered to be to scale. Rather, individual elements, in particular layer thicknesses, may be shown in exaggerated size for better visualization and/or understanding.

[0099] FIG. 1 shows a schematic sectional view of a radiation-emitting component according to an exemplary embodiment. The radiation-emitting component 100 has a semiconductor chip 10. During operation, the semiconductor chip 10 emits electromagnetic radiation of a first wavelength range (primary radiation) from a radiation exit surface 11. The semiconductor chip 10 has an epitaxially grown semiconductor layer sequence with an active zone that is suitable for generating electromagnetic radiation. The primary radiation has, for example, wavelengths in the blue to red range, in particular in the blue and/or ultraviolet range.

[0100] Furthermore, the component has a conversion element 20. The conversion element 20 either contains a matrix in which the first luminophore 1, in particular particles of the first luminophore 1, is embedded, or the conversion element 20 has or consists of a ceramic formed from the luminophore 1. Alternatively, the conversion element 20 contains a matrix in which a luminophore mixture containing particles of the first luminophore 1 and a second luminophore 1 are embedded, or the conversion element 20 has or consists of a ceramic formed from the luminophore mixture containing the first luminophore 1 and the second luminophore 1. In addition or alternatively, a further, for example conventional, luminophore may also be present in the conversion element 20 and form a luminophore mixture with the luminophore 1 and, if appropriate, luminophore 1.

[0101] If the conversion element 20 has a matrix in which the first luminophore 1 and possibly the second luminophore 1 and/or possibly other luminophores are embedded, the matrix has a material selected from polymers such as polystyrene, polysiloxane, polysilazane, PMMA, polycarbonate, polyacrylate, polytetrafluoroethylene, polyvinyl, silicone resin, silicone, epoxy resin and transparent synthetic rubber, and glass such as silicates, water glass and quartz glass.

[0102] The conversion element 20, which is designed here as a conversion layer, can either be applied directly to the semiconductor chip 10, in particular to the radiation exit surface 11, or can be attached to it, for example by means of an adhesive layer (not explicitly shown here).

[0103] The semiconductor chip 10 with the conversion element 20 arranged thereon is arranged in the recess of a housing 30. The housing 30 has side surfaces that are beveled towards the semiconductor chip 10 and can be reflective. In this exemplary embodiment, the semiconductor chip 10 and the conversion element 20 are surrounded by a potting 40 in the housing 30. However, the presence of a potting 40 is not absolutely necessary. The potting can be formed from a silicone or epoxy resin, for example, and has a transmittance for electromagnetic radiation of the active zone 12 that is at least 85%, and in at least some instances, at least 95%.

[0104] Alternatively, the housing 30 can also have no side walls and thus no recess and be designed as a carrier (not shown here). FIG. 2 shows another exemplary embodiment of a radiation-emitting component. The explanations made with reference to FIG. 1 apply to the elements with the same reference signs. In this exemplary embodiment, the conversion element 20 is not arranged directly on the semiconductor chip 10, but spaced from it on the side of the potting 40 facing away from the semiconductor chip 10. Here too, the conversion element 20 is again formed as a conversion layer.

[0105] The components shown in FIGS. 1 and 2 are LEDs, for example. For the sake of clarity, additional elements, such as electrical contacts, are not shown in FIGS. 1 and 2.

[0106] The exemplary embodiment mentioned below apply equally to the first luminophore 1 and the second luminophore 1. For the sake of simplicity, only the luminophore 1 is referred to below.

[0107] During operation of the radiation-emitting component 100, the luminophore 1 converts electromagnetic radiation of the first wavelength range into electromagnetic radiation of the second wavelength range (secondary radiation). If several different luminophores are present, the total secondary radiation is composed of the respective wavelength ranges emitted by the luminophores.

[0108] In the following, the preparation of exemplary embodiments of the luminophore 1 of the general formula EA.sub.2xRE.sub.xSi.sub.5xyAl.sub.x+yN.sub.8yO.sub.y:A where EA=Ba, RE=La and A is either Eu or Ce is explained.

[0109] The reactants LaN, BaN.sub.y with y approximately equal to 0.7 to 1, Si.sub.3N.sub.4, AlN and, depending on the selected activator element A, CeO.sub.2 or Eu.sub.2O.sub.3 are provided, intimately mixed in a glovebox under an inert gas atmosphere and then transferred to a tungsten crucible. The synthesis of the luminophore 1 takes place during heating at temperatures between 1400 C. and 2100 C., including, for example, between 1500 C. and 2000 C., or between 1600 C. and 1950 C., for a period of 0.5 h to 24 h under N.sub.2 or forming gas. In addition, an overpressure of 3 bar to 100 bar, for example, 5 bar to 50 bar, or for example, 10 bar to 30 bar can be used. It is also possible to carry out the process without overpressure.

[0110] Tables 1 and 2 show the weights for exemplary embodiments 1 to 11. Exemplary embodiments 1 to 7 have the formula Ba.sub.2xLa.sub.xSi.sub.5xAl.sub.xN.sub.8:Ce.sup.3+ with variable x (Table 1), exemplary embodiments 8 to 11 have the formula Ba.sub.2xLa.sub.xSi.sub.5xAl.sub.xN.sub.8:Eu.sup.2+ with variable x (Table 2). The x was calculated in each case from the weighed ratio of La and Ba. The x-values given in Tables 1 and 2 therefore correspond to the nominal weights.

TABLE-US-00001 TABLE 1 x LaN AlN BaN.sub.y Si.sub.3N.sub.4 CeO.sub.2 Exemplary 0.16 0.426 g 0.112 g 5.025 g 4.402 g 0.035 g embodiment 1 Exemplary 0.36 0.957 g 0.251 g 4.236 g 4.517 g 0.040 g embodiment 2 Exemplary 0.66 1.638 g 0.430 g 3.223 g 4.664 g 0.045 g embodiment 3 Exemplary 1.14 2.543 g 0.668 g 1.877 g 4.860 g 0.053 g embodiment 4 Exemplary 1 0.5833 g 0.4691 g 0.5709 g 0.3568 g 0.02 g embodiment 5 Exemplary 1 0.8187 g 0.1097 g 0.8012 g 0.2504 g 0.02 g embodiment 6 Exemplary 1 0.5704 g 0.1530 g 0.5585 g 0.6980 g 0.02 g embodiment 7

TABLE-US-00002 TABLE 2 x LaN AlN BaN.sub.y Si.sub.3N.sub.4 Eu.sub.2O.sub.3 Exemplary 0.16 1.067 g 0.281 g 12.431 g 11.040 g 0.181 g embodiment 8 Exemplary 0.36 2.396 g 0.629 g 10.461 g 11.311 g 0.203 g embodiment 9 Exemplary 0.66 4.093 g 1.076 g 7.944 g 11.657 g 0.231 g embodiment 10 Exemplary 1.14 6.339 g 1.666 g 4.614 g 12.114 g 0.268 g embodiment 11
The phases Ba.sub.2xLa.sub.xSi.sub.5xAl.sub.xN.sub.8:Ce.sup.3+ and Ba.sub.2xLa.sub.xSi.sub.5xAl.sub.xN.sub.8:Eu.sup.2+ were found mixed with other phases in the specified exemplary embodiments. The exact composition of the crystals results from the ratio of Ba to La, which was determined by means of energy dispersive X-ray spectroscopy (EDX) analysis, and the charge neutrality, which is achieved by an adjusted ratio of Si to Al. This results, for example, in a composition of Ba.sub.1,86La.sub.0,14Si.sub.4,86Al.sub.0,14N.sub.8 for the crystal from exemplary embodiment 2 and a composition of Ba.sub.1,13La.sub.0,87Si.sub.4,13Al.sub.0,87N.sub.8 for the crystal from exemplary embodiment 7. For two crystals of exemplary embodiment 5, x=0.37 and 0.56 could be determined.

[0111] In the following, the preparation of the luminophore 1 according to exemplary embodiment 12 with the general formula EA.sub.2xRE.sub.xSi.sub.5xyAl.sub.x+yN.sub.8yO.sub.y:A where EA=Sr, RE=La and A=Ce is explained.

[0112] The reactants LaN, Sr.sub.3N.sub.2, Si.sub.3N.sub.4, AlN and CeO.sub.2 are provided, intimately mixed in a glovebox under an inert gas atmosphere and then transferred to a tungsten crucible. The synthesis of the luminophore according to exemplary embodiment 12 takes place during heating at temperatures between 1400 C. and 2100 C., for example, between 1500 C. and 2000 C., or for example, between 1600 C. and 1950 C., for a period of 0.5 h to 24 h under N.sub.2 or forming gas. In addition, an overpressure of 3 bar to 100 bar, for example, 5 bar to 50 bar, or for example, 10 bar to 30 bar can be used.

[0113] For example, crystals with the composition according to exemplary embodiment 12 were formed from a reactant mixture of 4.171 g Sr.sub.3N.sub.2, 10.161 g Si.sub.3N.sub.4, 0.594 g AlN and 0.075 g CeO.sub.2, the lanthanum content found in EDX measurements originates from contaminants of the crucible used with LaN from previous syntheses.

[0114] The phase Sr.sub.2xLa.sub.xSi.sub.5xAl.sub.xN.sub.8:Ce.sup.3+ was found mixed with other phases in the given exemplary embodiment. The exact composition of the crystals results from the ratio Sr to La, which was determined by means of energy dispersive X-ray spectroscopy (EDX) analysis, as well as the charge neutrality, which is achieved by an adapted ratio Si to Al. This results, for example, in a composition of Sr.sub.1,7La.sub.0,3Si.sub.4,7Al.sub.0,3N.sub.8 for the crystal from exemplary embodiment 12.

[0115] For all exemplary embodiments, the phase Ba.sub.2-xLa.sub.xSi.sub.5-xAl.sub.xN.sub.8 or Sr.sub.2-xLa.sub.xSi.sub.5-xAl.sub.xN.sub.8 was clearly detected in the corresponding samples by single crystal diffractometry. Table 3 shows the lattice parameters, the crystallographic data and the basic quality parameters of Ba.sub.2xLa.sub.xSi.sub.5xAl.sub.xN.sub.8:Ce.sup.3+, which were determined by X-ray diffraction on crystals of exemplary embodiment 2 and exemplary embodiment 7.

TABLE-US-00003 TABLE 3 Single crystal Single crystal from exemplary from exemplary embodiment 2 embodiment 7 Molecular formula (Ba,La).sub.2(Si,Al).sub.5N.sub.8 (Ba,La).sub.2(Si,Al).sub.5N.sub.8 Crystal system Orthorhombic Orthorhombic Room group Pmn2.sub.1 (No. 31) Pmn2.sub.1 (No. 31) a/ 5.7854 (4) 5.8064 (3) b/ 6.9432 (5) 6.8550 (4) c/ 9.4016 (7) 9.4932 (5) Cell volume/.sup.3 377.65 (5) 377.86 (4) T/K 296 (2) 296 (2) Radiation CuK ( = 1.542 CuK ( = 1.542 ) ) Measuring range 6.4 < < 71.7 6.5 < < 66.7 7 h 6 6 h 6 8 k 8 8 k 7 9 l 11 10 l 9 Number of all reflexes 6422 2007 Independent reflexes 786 642 Number of parameters 83 46 .sub.max, .sub.min/e.sup.3 2.355/1.766 1.882/2.387 R.sub.1 (obs/all) 0.0709/0.1076 0.0683/0.1015 wR.sub.2 (obs/all) 0.1725/0.1974 0.1415/0.1627 GooF 0.991 1.120

[0116] The crystallographic position parameters of exemplary embodiment 7 are summarized in Table 4. The Wyckoff position describes the symmetry of the point positions according to R. W. G. Wyckoff. x, y and z indicate the atomic positions. U.sub.ani is the radius of the anisotropic deflection parameters of the respective atom. U.sub.iso is the radius of the isotropic deflection parameters of the respective atom.

TABLE-US-00004 TABLE 4 Atom Wyckoff U.sub.iso Name type location x y z Occupation *U.sub.ani Ba01 Ba 2a 0 0.8821(5) 0.0000(4) 0.5 0.0308(13)* La01 La 2a 0 0.8821(5) 0.0000(4) 0.5 0.0308(13)* Ba02 Ba 2a 0 0.8544(5) 0.6303(3) 0.5 0.0269(12)* La02 La 2a 0 0.8544(5) 0.6303(3) 0.5 0.0269(12)* Si01 Si 4b 0.2507(14) 0.6637(11) 0.3078(14) 1 0.0092(19) Si02 Si 2a 0 0.0550(15) 0.304(2) 1 0.008(3) Si03 Si 2a 0 0.403(2) 0.5288(16) 1 0.011(3) Si04 Si 2a 0 0.424(2) 0.0857(16) 1 0.010(3) N001 N 2a 0 0.175(6) 0.464(5) 1 0.018(12) N002 N 4b 0.237(5) 0.914(4) 0.295(4) 1 0.020(7) N003 N 4b 0.247(5) 0.445(4) 0.635(3) 1 0.017(7) N004 N 2a 0 0.578(5) 0.399(4) 1 0.008(9) N005 N 2a 0 0.186(7) 0.151(6) 1 0.023(11) N006 N 2a 0 0.426(5) 0.907(4) 1 0.008(9)

[0117] It can thus be shown that the luminophore 1 crystallizes in the structure of the rare earth-free, known Ba.sub.2Si.sub.5N.sub.8.

[0118] Both Ba and La as well as Si and Al occupy the same crystallographic positions. Due to the comparable electron density, these elements cannot be differentiated using X-ray methods; in the refinement, the occupation was either fixed or only Ba or Si was refined.

[0119] The luminophore 1 with the formula Ba.sub.2xLa.sub.xSi.sub.5xAl.sub.xN.sub.8:Ce.sup.3+ crystallizes in the orthorhombic space group Pmn2.sub.1 (No. 31). Its structure is a three-dimensionally linked network of on all sides corner-linked SiN.sub.4-tetrahedra. These SiN.sub.4- and AlN.sub.4-tetrahedra form six-membered rings and four-membered rings; the Ba and La atoms occupy gaps within the six-membered rings.

[0120] The spectral properties of exemplary embodiments 1 to 7 are given in Tables 5 and 6:

TABLE-US-00005 TABLE 5 Exemplary Exemplary Exemplary Exemplary embodiment 1 embodiment 2 embodiment 3 embodiment 4 Dominant wavelength 488 nm Not calculable 578 nm 581 nm .sub.dom (center color triangle) Peak wavelength .sub.max 471 nm 490 nm 588 nm 597 nm FWHM 106 nm 161 nm 178 nm 172 nm CIE-x 0.215 0.290 0.434 0.485 CIE-y 0.296 0.371 0.435 0.451

[0121] The data shown in Table 5 were obtained with an excitation at 408 nm. For exemplary embodiment 2, the dominant wavelength cannot be calculated because the chromaticity coordinate of the luminophore is too central in the CIE color triangle, so that it is not possible to extrapolate clearly to the edge.

TABLE-US-00006 TABLE 6 Exemplary Exemplary Exemplary Exemplary embodiment 2, embodiment 5, embodiment 5, embodiment 7, crystal 1 crystal 1 crystal 2 crystal 1 x (determined by EDX) 0.14 0.37 0.56 0.87 Excitation 408 nm 408 nm 448 nm 448 nm wavelength .sub.ex Dominance 486 nm Not calculable 577 nm 583 nm wavelength .sub.dom (center color triangle) Peak 465 nm 493 nm 585 nm 602 nm wavelength .sub.max FWHM 103 nm 176 nm 158 nm 162 nm CIE-x 0.203 0.304 0.475 0.525 CIE-y 0.277 0.384 0.484 0.462

[0122] Table 6 shows the spectral data of four crystals of exemplary embodiments 2, 5 and 7. For exemplary embodiment 5, crystal 1, the dominant wavelength cannot be calculated because the chromaticity coordinate of the luminophore is too central in the CIE color triangle, so that it is not possible to extrapolate clearly to the edge.

[0123] FIGS. 3 and 4 show the corresponding emission spectra. In each case, the wavelength in nm is plotted against the relative intensity I/I.sub.max. In these and the following figures, the spectra of the respective exemplary embodiments are labeled with the number of the exemplary embodiment preceded by A. FIG. 3 shows the emission spectra of exemplary embodiments 1 to 4 when excited at 408 nm (Al: solid line, nominal x=0.16, A2: dashed line, nominal x=0.36, A3: dotted line, nominal x=0.66, A4: dash-dot line, nominal x=1.14). FIG. 4 shows emission spectra of one crystal of exemplary embodiment 2 (excitation 408 nm, A2, dotted line, x =0.14 confirmed by EDX), two crystals of exemplary embodiment 5 (A5-1: Crystal 1, excitation 408 nm, solid line, X=0.37 confirmed by EDX, A5-2: Crystal 2, excitation 448 nm, dashed line, x=0.56 confirmed by EDX) and one crystal of exemplary embodiment 7 (A7, excitation 448 nm, dash-dot line, x=0.87 confirmed by EDX).

[0124] The luminophore 1 with A=Ce according to exemplary embodiments 1 to 7 thus converts, depending on x, UV to blue primary radiation into secondary radiation in the cyan to orange spectral range. Depending on x, the dominant wavelength is between 486 nm (crystal from exemplary embodiment 2) and 583 nm (crystal from exemplary embodiment 7). The emission band has a spectral half-width FWHM of 103 nm to 178 nm. This makes Ba.sub.2xLa.sub.xSi.sub.5xAl.sub.xN.sub.8:Ce.sup.3+ suitable for use in LEDs as a cyan-green or orange conversion luminophore, depending on x.

[0125] Table 7 shows the spectral data of exemplary embodiments 8 to 11, which were obtained with excitation at 448 nm.

TABLE-US-00007 TABLE 7 Exemplary Exemplary Exemplary Exemplary embodiment 8 embodiment 9 embodiment 10 embodiment 11 Centroid wavelength.sub.centroid 679 nm 789 nm 822 nm 828 nm Peak wavelength .sub.max 584 nm 805 nm 801 nm 804 nm FWHM 90 nm 210 nm 206 nm 208 nm

[0126] The corresponding emission spectra are shown in FIG. 5. Exemplary embodiment 8 is shown with the solid line (A8, nominal x=0.16), exemplary embodiment 9 with the dashed line (A9, nominal x=0.36), exemplary embodiment 10 with the dotted line (A10, nominal x=0.66) and exemplary embodiment 11 with the dash-dot line (A11, nominal x=1.14).

[0127] The luminophore 1 with A=Eu according to exemplary embodiments 8 to 11 converts UV to blue primary radiation into secondary radiation in the red to NIR spectral range. It emits with a centroid wavelength of .sub.centroid from 679 nm to 828 nm. The emission band has a spectral half-width FWHM of 90 nm to 210 nm. This makes Ba.sub.2xLa.sub.xSi.sub.5xAl.sub.xN.sub.8:Eu.sup.2+ suitable, depending on x, as a deep red conversion luminophore with NIR content for use in LEDs, e.g. in IR-enhanced LEDs, or as an NIR luminophore for use in NIR LEDs, e.g. for spectrometric applications.

[0128] Table 8 shows the spectral data of exemplary embodiment 12, which were obtained with excitation at 408 nm.

TABLE-US-00008 TABLE 8 Exemplary embodiment 12, crystal 1 x (determined by EDX) 0.3 Excitation wavelength .sub.ex 408 nm Dominant wavelength .sub.dom 573 nm Peak wavelength .sub.max 574 nm FWHM 173 nm CIE-x 0.439 CIE-y 0.494

[0129] The corresponding emission spectrum is shown in FIG. 6.

[0130] The luminophore 1 with A=Ce and EA=Sr according to the exemplary embodiment 12 converts UV to blue primary radiation into secondary radiation in the orange spectral range. It emits with a dominant wavelength of .sub.dom Of 573 nm. The emission band has a spectral half-width FWHM of 173 nm. This makes Sr.sub.2-xLa.sub.xSi.sub.5-xAl.sub.xN.sub.8:Eu.sup.2+ suitable as an orange conversion luminophore for use in LEDs.

[0131] In the following, various properties and applications of the luminophore 1 are described with reference to the exemplary embodiments in comparison to the comparative examples 1(Ba.sub.2Si.sub.5N.sub.8:Ce.sup.3+), 2 (Y.sub.3(Al, Ga).sub.5O.sub.12: Ce.sup.3+, YAGaG), 3 (Lu.sub.3Al.sub.5O.sub.12:Ce.sup.3+, LuAG), 4 (Y.sub.3Al.sub.5O.sub.12:Ce.sup.3+, YAG:Ce.sup.3+) and 5 (Ba.sub.2Si.sub.5N.sub.8:Eu.sup.2+). The spectra of the comparative examples shown in the figures are preceded by a V.

[0132] Comparative examples 2 and 4 are luminophores that crystallize in the garnet structure in the cubic space group Ia3d. YAG absorbs radiation in the blue spectral range and emits in the yellow spectral range. The exact emission position can be influenced somewhat by replacing Al with Ga. The exact spectral values for YAG and YAGaG depend on the degree of doping, grain size and the exact composition (Ga content). Typical spectral values for YAG are between 565 nm and 574 nm for the dominant wavelength and between 110 nm and 125 nm for the spectral half-width. LuAG absorbs radiation in the blue spectral range and emits in the green spectral range. Typical spectral values for LuAG are between 558 nm to 562 nm for the dominant wavelength and between 106 nm to 120 nm for the spectral half-width.

[0133] FIG. 7 shows the overlap of the emission spectra of exemplary embodiment 1 (A1, solid, thin line), comparative example 1 (V1, dashed line), comparative example 2 (V2, dot-dash line) and comparative example 3 (V3, dotted line) with the sensitivity curve of the photoreceptor melanopsin (M, solid, thick line). FIG. 8 again shows the emission spectra of comparative examples 2 (V2, dashed line) and 3 (V3, solid line) at an excitation of 460 nm.

[0134] Exemplary embodiment 1, Ba.sub.2xLa.sub.xSi.sub.5xAl.sub.xN.sub.8:Ce.sup.3+ with x<0.5, emits in a narrow band in the cyan spectral range. The emission is significantly narrower than that of comparative example 1, resulting in a greater overlap with the sensitivity curve of the photoreceptor melanopsin and thus a higher melanopic efficacy of luminous radiation (melanopic ELR). The overlap is even smaller for the comparative examples 2 and 3.

[0135] Table 9 shows the achieved values of the melanopic ELR (relative to daylight) for exemplary embodiment 1 and the comparative examples 1 to 3:

TABLE-US-00009 TABLE 9 Comparative Comparative Comparative Exemplary example 1 example 2 example 3 embodiment 1 Luminophore (Ba.sub.2Si.sub.5N.sub.8:Ce.sup.3+) (YAGaG:Ce.sup.3+) (LuAG:Ce.sup.3+) (Ba.sub.2xLa.sub.xSi.sub.5xAl.sub.xN.sub.8:Ce.sup.3+) melanopic ELR 0.7914 0.6236 0.7325 1.6625 relative 100% 79% 93% 210% melanopic ELR

[0136] Comparative example 1 is surpassed by exemplary embodiment 1 by 110%, the difference compared to comparative examples 2 and 3 is even greater. In addition, the luminophores of comparative examples 2 and 3 cannot be excited in the NUV and deep blue spectral range, in contrast to luminophore 1, such as here, for example, in exemplary embodiment 1, which makes them less flexible for use in human-centric lighting applications.

[0137] Exemplary embodiment 4, Ba.sub.2xLa.sub.xSi.sub.5xAl.sub.xN.sub.8:Ce.sup.3+ with x>0.5, emits broadband in the orange spectral range. This makes it an efficient Ce.sup.3+-based luminophore that emits in the orange spectral range (.sub.dom>575 nm). Luminophore 1 can therefore be advantageous for all applications in which a slight red component is required in addition to brightness (e.g. lighting solutions for general lighting, automotive headlights or flashing lights).

[0138] As an example of such an application, FIGS. 9 to 11 show simulated spectra and Table 10 shows the associated spectral data for white light LEDs consisting of a blue LED and the luminophore 1 according to exemplary embodiment 4 (FIG. 9), the La-free Ba.sub.2Si.sub.5N.sub.8:Ce.sup.3+ (comparative example 1, FIG. 10) or a commercially available luminophore (comparative example 4, YAG:Ce, FIG. 11):

TABLE-US-00010 TABLE 10 Comparative Comparative Exemplary example 1 example 4 embodiment 4 Luminophore (Ba.sub.2Si.sub.5N.sub.8:Ce.sup.3+) (YAG:Ce.sup.3+) (Ba.sub.2xLa.sub.xSi.sub.5xAl.sub.xN.sub.8:Ce.sup.3+) Color temperature CCT 10888 K 4369 K 2788 K Color rendering CRI 89 63 77

[0139] The solution with the luminophore 1 according to exemplary embodiment 4 achieves a higher color rendering index CRI=77 compared to CRI=63 for the solution with comparative example 4. Comparative example 4 is one of the longest wavelength Ce.sup.3+-activated luminophores in use today. As the achievable color temperature depends directly on the emission position, the color temperature of 4369 K simulated here is one of the lowest color temperatures that can be achieved with conventional Ce.sup.3+-activated luminophores. Color temperatures below 4000 K (CCT<4000 K) are usually not achievable with these luminophores. The simulated solution with luminophore 1 (exemplary embodiment 4), on the other hand, achieves a color temperature of 2788 K. This means that luminophore 1 considerably extends the range in which Ce.sup.3+-activated luminophores can be used compared to the solutions available today.

[0140] Comparative example 1, on the other hand, achieves a very high CRI of 89 however with a very high color temperature of 10888 K and is therefore not suitable for use as a single luminophore for a white light solution.

[0141] The luminophore 1 with the formula Ba.sub.2xLa.sub.xSi.sub.5xAl.sub.xN.sub.8:Eu.sup.2+ emits broadband in the deep red to NIR (IR-A) spectral range, in which not many known luminophores emit. The broadband emission of luminophore 1 in the near infrared range is well suited to provide radiation in the near-infrared window for biological tissue. This lies in the wavelength range from approx. 650 nm to 1350 nm and refers to the wavelength range in which light can propagate as far as possible through biological tissue. Light sources that provide broadband light in this spectral range are therefore advantageous for spectroscopic investigations in biological samples. The luminophore 1 is well suited for this purpose, as it provides a lot of broadband radiation between approx. 640 nm and 1040 nm (see FIG. 5), especially at high x (for example, exemplary embodiment 11).

[0142] Furthermore, NIR radiation in illuminating devices can have a health-promoting effect. For example, NIR luminophores in the 600 nm to 1000 nm range can be used advantageously in the treatment of eye diseases. The luminophore 1 is therefore also suitable for these new IR-enhanced human centric lighting applications, as this range can be covered with the luminophore 1. The version with low x, in particular x<0.5, (for example exemplary embodiment 8), which provides both a red component for generating white light and an NIR component, is particularly suitable for this purpose. In contrast, comparative example 5, Ba.sub.2Si.sub.5N.sub.8:Eu.sup.2+ without La, only provides emission in the orange spectral range. For an IR-enhanced human centric lighting application, using this comparative example would therefore require an additional NIR luminophore, which would increase the complexity of the overall system. The comparison of the emission spectra of exemplary embodiment 8 (A8) and comparative example 5 (V5) is shown in FIG. 12.

[0143] FIG. 13 shows the reflectance spectra of exemplary embodiments 1 (A1) and 8 (A8). The wavelength in nm is plotted against the reflectance R in %. It can be seen that the luminophore 1 according to exemplary embodiment 1 can be excited up to a wavelength of about 450 nm, according to exemplary embodiment 8 up to a wavelength of about 550 nm.

[0144] The features and exemplary embodiments described in connection with the figures can be combined with one another according to further exemplary embodiments, even if not all combinations are explicitly described. Furthermore, the exemplary embodiments described in connection with the figures may alternatively or additionally have further features as described in the general part.

[0145] The present disclosure is not limited to the description based on the exemplary embodiments. Rather, the present disclosure includes any new feature as well as any combination of features, which includes in particular any combination of features in the patent claims, even if this feature or combination itself is not explicitly stated in the patent claims or exemplary embodiments.

List of Reference Symbols

[0146] 1 Luminophore [0147] 1 Second luminophore [0148] 10 Semiconductor chip [0149] 11 Radiation exit surface [0150] 20 Conversion element [0151] 30 Housing [0152] 40 Potting [0153] 100 Radiation-emitting component [0154] Wavelength [0155] I/I.sub.max Relative intensity [0156] R Reflectance [0157] A1 Spectrum of exemplary embodiment 1 [0158] A2 Spectrum of exemplary embodiment 2 [0159] A3 Spectrum of exemplary embodiment 3 [0160] A4 Spectrum of exemplary embodiment 4 [0161] A5-1 Spectrum of exemplary embodiment 5, crystal 1 [0162] A5-2 Spectrum of exemplary embodiment 5, crystal 2 [0163] A7 Spectrum of exemplary embodiment 7 [0164] A8 Spectrum of exemplary embodiment 8 [0165] A9 Spectrum of exemplary embodiment 9 [0166] A10 Spectrum of exemplary embodiment 10 [0167] A11 Spectrum of exemplary embodiment 11 [0168] V1 Spectrum of the comparative example 1 [0169] V2 Spectrum of the comparative example 2 [0170] V3 Spectrum of the comparative example 3 [0171] V4 Spectrum of the comparative example 4 [0172] V5 Spectrum of the comparative example 5