LIGHT EMITTING DEVICE

Abstract

A high-energy LED is provided, in particular based on the n-polar technique, comprising a Eu.sup.3+ activated converter material based on tungsten/molybdenum oxide. Surprisingly, these materials do not show any saturation.

Claims

1. A light emitting device comprising: a semiconductor component which emits UV-A or blue primary radiation having a radiation power of ≧4 Wopt/mm.sup.2 and a converter material which predominantly includes a material selected from the following list:
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.4O.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 and mixtures thereof, wherein—for each structure independently—A is an alkaline earth metal selected from the group consisting of lithium, sodium, potassium, rubidium, cesium and mixtures thereof, AE is an alkaline earth metal selected from the group consisting of magnesium, calcium, strontium, barium or mixtures thereof, Ln is a rare earth metal selected from the group consisting of scandium, yttrium, lanthanum, gadolinium and lutetium and mixtures thereof, M is molybdenum, tungsten or mixtures thereof, and RE is a rare earth metal selected from the group consisting of terbium, dysprosium, praseodymium, neodymium and mixtures thereof, wherein 0<x≦1 and 0≦y≦0.05.

2. The light-emitting device according to claim 1, wherein the energization of the UV-A or blue primary radiation emitting semiconductor component is 2 A/mm.sup.2.

3. The light-emitting device according to claim 1, wherein the radiation power of the UV-A or blue primary radiation emitting semiconductor component is ≧6 W/mm.sup.2.

4. The light-emitting device according to claim 1, wherein the UV-A or blue primary radiation emitting semiconductor component is based or designed on the n-Pola technology.

5. The light-emitting device according to claim 1, wherein the converter material is provided as a ceramic material.

6. The light-emitting device according to claim 1, further comprising a green emitting material.

7. The light-emitting device according to claim 1, further comprising a material selected from the group consisting of BaMgAl.sub.10O.sub.17:Eu.sup.2+,Mn.sup.2+, (Sr.sub.1-xBa.sub.x)Si.sub.2N.sub.2O.sub.2:Eu.sup.2+, (Sr.sub.1-xBa.sub.x).sub.2SiO.sub.4:Eu.sup.2+, (Sr.sub.1-xBa.sub.x).sub.3SiO.sub.5:Eu.sup.2+, (Sr.sub.1-xBa.sub.x)Ga.sub.2S.sub.4:Eu.sup.2+, (Lu.sub.1-xY.sub.x).sub.3(Al.sub.1-yGa.sub.y).sub.5O.sub.12:Ce.sup.3+, (Lu.sub.1-xY.sub.x).sub.3(Al.sub.1-ySc.sub.y).sub.5O.sub.12:Ce.sup.3+ and mixtures of these materials.

8. The light-emitting device according to claim 1, further comprising a yellow emitting material.

9. The light-emitting device according to claim 1, further comprising a material selected from the group consisting of Ba.sub.2Si.sub.5N.sub.8:Eu.sup.2+, (Ca.sub.1-xSr.sub.x)Si.sub.2N.sub.2O.sub.2:Eu.sup.2+, (Y.sub.1-xGd.sub.x).sub.3(Al.sub.1-yGa.sub.y).sub.5O.sub.12:Ce.sup.3+, (Y.sub.1-xTb.sub.x).sub.3(Al.sub.1-yGa.sub.y).sub.5O.sub.12:Ce.sup.3+, SrLi.sub.2SiO.sub.4:Eu.sup.2+, (Ca.sub.1-xSr.sub.x).sub.2SiO.sub.4:Eu.sup.2+, (Ca.sub.1-xSr.sub.x).sub.3SiO.sub.5:Eu.sup.2+ and mixtures of these materials.

10. The light-emitting device according to claim 1, further comprising a blue emitting material.

Description

BRIEF DESCRIPTION

[0051] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

[0052] FIG. 1 is a very schematic cross-section through a first embodiment of a device according to embodiments of the invention;

[0053] FIG. 2 is a very schematic experimental view for measuring the saturation of materials;

[0054] FIG. 3 is a diagram showing the integrated emission versus the excitation density of a corresponding material; and

[0055] FIG. 4 is the emission spectrum of the material from FIG. 3.

DETAILED DESCRIPTION

[0056] FIG. 1 shows a first embodiment of the device according to embodiments of the invention in the sense of a “remote phosphor” application. However, this is not restrictive and it is self-evident to a person skilled in the art that other embodiments are also conceivable. According to FIG. 1 the device 1 comprises a UV-A or blue emitting semiconductor component 10 which is e.g. based on the n-Pola technology (GaN-on-GaN technology). Alternatively, the semiconductor component may be a laser or be implemented according to other LED technologies which achieve a higher radiation power per mm.sup.2 by enabling a higher energization of the light-emitting surface.

[0057] The semiconductor component 10 is arranged in a reflective housing 30 above which the luminescence conversion element is located which includes the red emitting converter 20 and is configured as a ceramic.

[0058] The following is further presented with reference to the following example, which is purely illustrative and not restrictive.

Example I

[0059] FIGS. 2 to 4 refer to Li.sub.3Ba.sub.2La.sub.1.8Eu.sub.1.2(MoO).sub.4, which was prepared as follows:

[0060] Synthesis of Li.sub.3Ba.sub.2La.sub.1.8Eu.sub.1.2(MoO.sub.4).sub.8

[0061] 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, 0.4223 g (1.200 mmol) Eu.sub.2O.sub.3 and 0.5865 g (1.800 mmol) La.sub.2O.sub.3 were ground in a mortar with acetone as a grinding aid. The resulting powder was dried, transferred to a porcelain crucible and calcined at 800° C. for 12 h in the air. The cake thus obtained was ground and sieved through a 36 μm sieve.

[0062] FIG. 2 shows a very schematic experimental view for measuring the saturation of materials used to create the diagram of FIG. 3.

[0063] In the experimental view a sample 101 is irradiated with a laser diode 102 (OBIS Laser 375 nm LX 50 mW), the light of which is focused by a lens 103. In this case the sample 101 is cooled by the cooler 105 either passively (silver substrate) or actively (He cryostat).

[0064] Subsequently, the light after having passed through a monochromator 105 is directed onto the detector 106.

[0065] FIG. 3 shows a diagram in which the relative emission integrals are plotted versus the excitation density upon irradiation of the material according to Example I. Here, both a powder (dashed line) and a ceramic (dotted line) were measured.

[0066] It can clearly be seen in FIG. 3 that the curve extends linearly, that is, saturation does not occur or is not significant.

[0067] FIG. 4 shows the emission spectrum of the material of FIG. 1, wherein it is clearly seen that the material is red emitting.

[0068] Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

[0069] For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements. The mention of a “unit” or a “module” does not preclude the use of more than one unit or module.