OPTOELECTRONIC SEMICONDUCTOR ELEMENT WITH DEFINED COLOR POINT SHIFT AND METHOD FOR FABRICING AN OPTOELECTRONIC SEMICONDUCTOR ELEMENT WITH DEFINED COLOR POINT SHIFT

Abstract

Conversion element including: n different phosphors, where n≥3 and where each phosphor has an absorption spectrum and a normalized emission spectrum, wherein two of the at least three phosphors each have a different absorption spectrum and areas under the normalized emission spectra of the at least two phosphors overlap by at least x%, where x = 75, and wherein the two or at least three phosphors each exhibit wavelength-dependent absorption in the range of the changing excitation wavelength for optoelectronic semiconductor devices, and wherein two of the at least three phosphors have absorption maxima that are located at approximately the same distance from the present excitation wavelength of the semiconductor device at shorter or longer wavelengths, and wherein two of the at least three phosphors, each exhibiting a different absorption spectrum and with areas overlapping at least x% under the normalized emission spectra, are selected from the group consisting of the garnet phosphors (Y,Tb,Lu)3(Al,Ga)5O 12 :Ce 3+ ; and The third phosphor selected is from the group consisting of aluminonitridosilicates.

Description

[0001] A conversion element, an optoelectronic semiconductor device, a method for manufacturing a conversion element, a method for manufacturing an optoelectronic semiconductor device, and the use of a conversion element are described.

[0002] A conversion element typically consists of phosphor particles embedded in a matrix material, such as silicon, and is introduced into the beam path of a radiation-emitting semiconductor chip with a typical primary radiation in the wavelength range between 300 nm and 570 nm.

[0003] Such conversion elements are known, for example, from US 2018 / 0006197A1 and JP 2011-171590A. DE 102012219460A1 also shows such elements.

[0004] A common problem with LEDs (light-emitting diodes) that incorporate phosphor conversion elements is the undesirable color shift at different operating temperatures and currents. This is because the emission of the light-emitting layer of the radiation source changes with temperature and / or operating current, and the light absorption of the phosphor depends on the excitation wavelength. For example, the emission of the light-emitting layer of the radiation source shifts to a longer wavelength with increasing temperature, resulting in an initial color shift. Furthermore, the ratio of the light from the radiation source to the converted light in the LED's emission spectrum changes, depending on whether the excitation wavelength shifts towards wavelength ranges of higher or lower absorption by the phosphor.shifts into or out of an excitation maximum of the phosphor. For LEDs with multiple phosphors, the ratios of the colors within the converted part of the LED spectrum can even change depending on the relative positions of the absorption maxima of the phosphors used.

[0005] Generally, a color point shift is understood to be a change in the spectrum of the lighting device that leads to a change in the color coordinates in the selected color space.

[0006] The color shift caused by the wavelength-dependent absorption (e.g., of blue light) of the phosphor material depends on the phosphor material system. Typical phosphor materials used in the prior art for lighting devices are, for example, garnet phosphors of the general formula (Y,Lu,Tb)3(Al,Ga)5O 12 :Ce 3+and so-called (S)CASN phosphors of the general formula (Sr,Ca)SiAIN3:Eu 2+ , which each exhibit different absorption properties. (S)CASN phosphor materials have a more or less stable absorption in the wavelength range of common primary radiation sources, whereas the absorption of typical garnet phosphors is very narrowly and therefore strongly wavelength-dependent. Thus, even small changes in the excitation wavelength of the primary radiation source can lead to a dramatic increase or decrease in the absorption of the primary radiation by the garnet phosphor.

[0007] The object of the present invention was therefore to overcome some disadvantages of the prior art and to provide a new conversion element, a new method for manufacturing a conversion element, a new optoelectronic semiconductor device, a new method for manufacturing an optoelectronic semiconductor device, and the use of a new conversion element.

[0008] The object of the present invention is achieved by a conversion element according to claim 1, an optoelectronic semiconductor device according to claim 5, a method for manufacturing a conversion element according to claim 6, a method for manufacturing an optoelectronic semiconductor device according to claim 7, and the use of a conversion element according to claim 9. Advantageous further developments and embodiments are the subject of the dependent patent claims.

[0009] The subject of the present invention is a conversion element comprising: n different phosphors, where n≥3 and where each phosphor has an absorption spectrum and a normalized emission spectrum, wherein at least two of the phosphors each have a different absorption spectrum and areas under the normalized emission spectra of the at least two phosphors overlap by at least x%, where x = 75, wherein the two or at least three phosphors each exhibit wavelength-dependent absorption in the range of the changing excitation wavelength for optoelectronic semiconductor devices, and wherein the two of the at least three phosphors have absorption maxima that are located at approximately the same distance to shorter or longer wavelengths from the present excitation wavelength of the semiconductor device, and wherein one of the at least two of the at least three phosphors, each exhibiting a different absorption spectrum and whose areas under the normalized emission spectra overlap by at least x%, is selected from the group consisting of the garnet phosphors (Y,Tb,Lu)3(Al,Ga)5O12:Ce3+; and the third phosphor is selected from the group consisting of the aluminonitridisosilicates.

[0010] In the context of the present invention, a conversion element is an optoelectronic component by means of which light of a certain first wavelength (primary radiation) can be converted wholly or partially into light of at least a second wavelength (secondary radiation).

[0011] A conversion element according to the present invention comprises n different phosphors, where n ≥ 3. In general, a phosphor is understood to be a substance that converts electromagnetic radiation of a first wavelength range into electromagnetic radiation of a second wavelength range.

[0012] According to the present invention, the phosphors are different, i.e., they can have different physical and / or chemical properties or structures. Physical properties can include, among others, the absorption and emission properties of the phosphors.

[0013] In one embodiment, n is 3.

[0014] In one embodiment, n is 4.

[0015] In one embodiment, n is 5.

[0016] In one embodiment, n is in the range between 3 and 15.

[0017] In one embodiment, n is in the range between 3 and 10.

[0018] In another embodiment, primary radiation of a specific wavelength is converted into secondary radiation of a specific wavelength.

[0019] In one embodiment, light from a primary radiation source is at least partially converted into yellow and / or green light.

[0020] In one embodiment, light from a primary radiation source is completely converted into yellow and / or green light.

[0021] In another embodiment, light from a primary radiation source is at least partially converted into red light.

[0022] In another embodiment, light from a primary radiation source is completely converted into red light.

[0023] Within the scope of the present invention, the primary radiation can be excitation wavelengths in the range of 300 nm to 570 nm, preferably in the range of 350 nm to 500 nm, more preferably in the range of 420 nm to 480 nm.

[0024] In one embodiment, the primary radiation is UV radiation.

[0025] In one embodiment, the primary radiation is blue light.

[0026] In one embodiment, the primary radiation is green light.

[0027] In one embodiment, the primary radiation is yellow light.

[0028] In one embodiment, the primary radiation is green-yellow light.

[0029] In one embodiment, the secondary radiation can be white light.

[0030] Within the scope of the present invention, at least two of the phosphors present in the conversion element each have a different absorption spectrum.

[0031] An absorption spectrum is a color or electromagnetic spectrum that contains dark spectral lines. It is produced when broadband light passes through matter and light quanta (photons) of specific wavelengths or wavelength ranges are absorbed. An absorption spectrum shows the absorption of electromagnetic radiation by matter as a function of the wavelength of the incident electromagnetic radiation.

[0032] Preferably, the at least two phosphors of the conversion element have an identical or similar emission spectrum.

[0033] According to the present invention, the areas under the normalized emission spectra of the at least two phosphors overlap by at least 75%.

[0034] In the context of the present invention, the areas in question are the area bounded by the x-axis of the spectrum and the emission curve.

[0035] An emission spectrum is the electromagnetic spectrum emitted by atoms, molecules, or materials without the input of electromagnetic radiation of the same frequency. The emission spectrum is the spectrum of electromagnetic radiation emitted when an atom or molecule transitions from a higher energy state to a lower energy state. An emission spectrum is the counterpart to an absorption spectrum.

[0036] A normalized emission spectrum is an emission spectrum scaled to the maximum value of the spectral power distribution.

[0037] In one embodiment, the conversion element has two phosphors, wherein the two phosphors each have a different absorption spectrum and the areas under the normalized emission spectra of the two phosphors overlap by at least x%, where x = 75.

[0038] In one embodiment, x = 80.

[0039] In one embodiment, x = 85.

[0040] In one embodiment, x = 90.

[0041] In one embodiment, x = 95.

[0042] In one embodiment, x = 98.

[0043] In one embodiment, x = 99.

[0044] In one embodiment, x = 100.

[0045] In one embodiment, the conversion element comprises n phosphors, where n > 3, wherein at least two of the n phosphors each have a different absorption spectrum and the areas under the normalized emission spectra of the at least two phosphors overlap by at least 75%. In this embodiment, x can assume other values ​​mentioned herein.

[0046] In one embodiment, the areas under the normalized emission spectra of the at least two phosphors, each having a different absorption spectrum, overlap by at least 80%.

[0047] In another embodiment, the areas under the normalized emission spectra of the at least two phosphors, each having a different absorption spectrum, overlap to at least 85%.

[0048] In another embodiment, the areas under the normalized emission spectra of the at least two phosphors, each having a different absorption spectrum, overlap to at least 90%.

[0049] In another embodiment, the areas under the normalized emission spectra of the at least two phosphors, each having a different absorption spectrum, overlap to at least 95%.

[0050] In another embodiment, the areas under the normalized emission spectra of the at least two phosphors, each having a different absorption spectrum, overlap to at least 97%.

[0051] In another embodiment, the areas under the normalized emission spectra of the at least two phosphors, each having a different absorption spectrum, overlap to at least 98%.

[0052] In another embodiment, the areas under the normalized emission spectra of the at least two phosphors, each having a different absorption spectrum, overlap to at least 99%.

[0053] In another embodiment, the areas under the normalized emission spectra of the at least two phosphors, each having a different absorption spectrum, overlap by 100%.

[0054] In general, the at least two phosphors can be selected to have essentially the same emission spectrum but different absorption spectra. The absorption spectra can be selected to preferably cover the entire range of emission shifts from the primary radiation source or the light-emitting layer of the primary radiation source that occur due to changes in operating temperature and / or current. Even if the emission from the light-emitting layer of the primary radiation source or the primary radiation source shifts to longer and / or shorter wavelengths due to changing temperature and / or current during operation, it is advantageous that the same or nearly the same amount of light is absorbed by the at least two phosphors and the same or nearly the same amount of converted light is emitted by the at least two phosphors.

[0055] In one embodiment, the at least two phosphors, each exhibiting a different absorption spectrum and with areas overlapping under the normalized emission spectra by at least x%, are selected from the group consisting of garnets (basic structure of AlO4 or (AlGa)O4 units), nitride silicates (basic structure of SiN n -units), oxynitridosilicates (basic structure of Si(N,O) n -units), aluminonitridosilicates (basic framework of (Al,Si)N n -units), Alumooxynitridosilicates (base structure of (Al,Si)(O,N) n -units) and oxysilicates (basic structure of SiO₂) n -units).

[0056] In one embodiment, the n phosphors are selected from two garnet phosphors and at least one SCASN phosphor ((Ca,Sr)AlSiN3:Eu 2+ ).

[0057] In one embodiment, the n phosphors are selected from two garnet phosphors and at least one phosphor of the general formula M2Si5N8:Eu, where M = Ca, Sr, Ba (alone or in combination).

[0058] In one embodiment, the n phosphors are selected from two garnet phosphors and at least one quantum dot.

[0059] In one embodiment, the n phosphors are selected from two garnet phosphors and at least one KSF phosphor (K2SiF6:Mn). 4+ ).

[0060] In one embodiment, the n phosphors are selected from two phosphors, each exhibiting a different absorption spectrum, and the areas under the normalized emission spectra of the two phosphors overlap by at least x%, where x = 75, and at least one phosphor originating from a different material class than the two phosphors. In this embodiment, x can assume other values ​​mentioned herein.

[0061] The influence of the narrow band absorption of garnet phosphor materials is advantageously overcome by using different phosphor materials with varying absorption characteristics. Alternative phosphor materials, which exhibit more or less uniform absorption across the wavelength range of the primary radiation source and emit light in the green to yellow range, often have disadvantages in a variety of applications compared to the conventionally used garnet phosphor materials.

[0062] Alternative phosphor materials often do not exhibit the desired emission colors, show poorer absorption and / or quantum efficiency compared to garnet phosphors, and / or are less stable under thermal and / or radiation stress under typical operating conditions. Therefore, alternative phosphor materials are often unsuitable for a wide range of applications, as they lead to lower efficiency and / or shorter lifetimes of optoelectronic semiconductor devices manufactured with alternative phosphor materials.

[0063] Garnet phosphors can generally be produced in a wide variety of colors, especially in the green to yellow spectral range, by modifying the general composition A3B5O. 12 (with A = Y, Lu, Tb alone or in combinations thereof; B = Al alone or in combination with Ga).

[0064] In general, a garnet within the scope of the present invention is a compound of the general formula A3B5O 12 :Ce 3+ understood, where A is at least one of Y, Lu, and Tb, and B is Al and / or Ga. In an alternative notation, a garnet can be a compound of the formula (Y,Lu,Tb)3(Al,Ga)5O 12 :Ce 3+ Examples of garnet compounds are Y3Al5O. 12 :Ce 3+ , Lu3Al5O 12 :Ce 3+ , Tb3Al5O 12 :Ce 3+ , (Y,Lu)3Al5O 12 :Ce 3+ , Y3(Al,Ga)5O 12 :Ce 3+ , Lu3(Al,Ga)5O 12 :Ce 3+ , (Tb,Y)3Al5O 12 :Ce 3+ and (Tb,Y)3(Al, Ga)5O 12 : Ce 3+ .

[0065] In general, a nitridosilicate within the scope of the present invention is defined as a compound with a framework based on SiN n -units understood. Examples of these would be: - M2Si5N8:Eu 2+, where M is at least one of Ca, Sr and Ba, and - M2(Si,Al)5(N,O):Eu 2+ , where M is at least one of Ca, Sr and Ba.

[0066] Examples of nitridosilicates are (Ca,Ba,Sr)2Si5N8:Eu 2+ and (Ca,Ba,Sr)2(Si,Al)5(N,O)8:Eu 2+ .

[0067] In general, an oxynitridosilicate within the scope of the present invention is a compound with a framework based on Si(O,N) n -units understood. Examples of these would be: - EASi2N2O2:Eu 2+ with EA = Sr, Ba, Ca and / or Mg, - Nitridodoorthosilicates M 2-x Lu x SiO 4-x N x :Eu 2+ with M=Ba, Sr, Ca, Mg (alone or in combination).

[0068] Examples of oxynitride silicates are CaSi2O2N2:Eu 2+ , SrSi2O2N2:Eu 2+ , BaSi2O2N2:Eu 2+ , (Sr,Ba)Si2O2N2;Eu 2+ , Sr 1.5 Lu 0.5 SiO 3.5 N 0.5 :Eu2+ and Ba 1.75 Lu 0.25 SiO 3.75 N 0.25 :Eu 2+ .

[0069] In general, an aluminonitridisolicate within the scope of the present invention is a compound with a framework based on (Si,Al)N n -units understood. Examples of these would be: - Compounds of the general formula MAISiN3:Eu 2+ , where M is at least one of Ca and Sr, where optionally the Al:Si ratio can deviate from 1:1, where the compensation for charge balance can be achieved, for example, by a simultaneous exchange of N for O or of Ca, Sr for Li; - (Sr,Ca)AlSiN3*Si2N2O:Eu 2+ - Sr(Ca,Sr)Si2Al2N6:Eu 2+ .

[0070] Examples of aluminonitrile silicates are CaAlSiN3:Eu 2+ (CASN), (Ca,Sr)AlSiN3:Eu 2+ (SCASN) and (Sr,Ca)AlSiN3*Si2N2O:Eu 2+ .

[0071] In general, an aluminoxynitridosilicate within the scope of the present invention is a compound with a framework based on (Si,Al)(N,O) n -units understood. Examples of these would be: - β-SiAlONe EU x Si 6-z Al z O z N 8-z , - α-SiAlONe M x Si 12-m-n Al m+n O n N 16-n :Eu (x=m / v, v=valence of the metal M).

[0072] In addition to garnets, nitridosilicates, oxynitridosilicates, aluminonitridosilicates, and / or aluminooxynitridosilicates, other phosphors may also be present in the conversion element. Examples of other phosphors are (Sr,Ca)[LiAl3N4]:Eu 2+ , Orthosilicates M2SiO4:Eu 2+ with M=Ba, Sr, Ca, Mg (alone or in combination), K2SiF6:Mn 4+ , (K, Na)2(Si, Ti)F6:Mn 4+ , AE4Al 14 O 25 :Eu 2+with AE = Sr, Ba, Ca, Mg (alone or in combination) and quantum dots.

[0073] In another embodiment, the n phosphors are not grenades.

[0074] In a further embodiment, the at least two phosphors, each having a different absorption spectrum and with areas overlapping under the normalized emission spectra of the at least two phosphors by at least x%, where x = 75, are selected from the group consisting of garnet phosphors (Y,Tb,Lu)3(Al,Ga)5O 12 :Ce 3+ Examples of garnet phosphors are Y3Al5O 12 :Ce 3+ , Lu3Al5O 12 :Ce 3+ , Tb3Al5O 12 :Ce 3+ , (Y,Lu)3Al5O 12 :Ce 3+ , Y3(Al,Ga)5O 12 :Ce 3+ , Lu3(Al,Ga)5O 12 :Ce 3+ , (Tb,Y)3Al5O 12 :Ce 3+ and (Tb,Y)3(Al,Ga)5O 12 :Ce 3+In this embodiment, x can take on other values ​​mentioned herein.

[0075] In one embodiment, the at least two phosphors, each having a different absorption spectrum and with areas overlapping under the normalized emission spectra of the at least two phosphors to at least x%, where x = 75, can be selected from the group consisting of Y3Al5O 12 :Ce 3+ and Y3(Al,Ga)5O 12 :Ce 3+ , Y3Al5O 12 :Ce 3+ and (Y,Tb)3(Al,Ga)5O 12 :Ce 3+ , Y3Al5O 12 :Ce 3+ and (Lu,Y)3Al5O 12 :Ce 3+ or Y3Al5O 12 :Ce 3+ and (Lu,Y)3(Al,Ga)5O 12 :Ce 3+ In this embodiment, x can take on other values ​​mentioned herein.

[0076] In a further embodiment, the at least two phosphors, which have different absorption spectra and whose areas under the normalized emission spectra overlap by at least x%, are present in a specific ratio (e.g., of approx. 50 wt.%: approx. 50 wt.%, of approx. 60 wt.%: approx. 40 wt.%, of approx. 70 wt.%: approx. 30 wt.%, of approx. 80 wt.%: approx. 20 wt.%, or of approx. 90 wt.%: approx. 10 wt.%), where x = 75.

[0077] In a further embodiment, the at least two phosphors, which have different absorption spectra and whose areas under the normalized emission spectra overlap by at least x%, are present in a specific ratio (e.g., approximately 50 wt.%: approximately 50 wt.%, approximately 60 wt.%: approximately 40 wt.%, approximately 70 wt.%: approximately 30 wt.%, approximately 80 wt.%: approximately 20 wt.%, or approximately 90 wt.%: approximately 10 wt.%), where x = 80.

[0078] In a further embodiment, the at least two phosphors, which have different absorption spectra and whose areas under the normalized emission spectra overlap by at least x%, are present in a specific ratio (e.g., of approx. 50 wt.%: approx. 50 wt.%, of approx. 60 wt.%: approx. 40 wt.%, of approx. 70 wt.%: approx. 30 wt.%, of approx. 80 wt.%: approx. 20 wt.%, or of approx. 90 wt.%: approx. 10 wt.%), where x = 85.

[0079] In a further embodiment, the at least two phosphors, which have different absorption spectra and whose areas under the normalized emission spectra overlap by at least x%, are present in a specific ratio (e.g., of approx. 50 wt.%: approx. 50 wt.%, of approx. 60 wt.%: approx. 40 wt.%, of approx. 70 wt.%: approx. 30 wt.%, of approx. 80 wt.%: approx. 20 wt.%, or of approx. 90 wt.%: approx. 10 wt.%), where x = 90.

[0080] In a further embodiment, the at least two phosphors, which have different absorption spectra and whose areas under the normalized emission spectra overlap by at least x%, are present in a specific ratio (e.g., approximately 50 wt.%: approximately 50 wt.%, approximately 60 wt.%: approximately 40 wt.%, approximately 70 wt.%: approximately 30 wt.%, approximately 80 wt.%: approximately 20 wt.%, or approximately 90 wt.%: approximately 10 wt.%), where x = 98.

[0081] In a further embodiment, the at least two phosphors, which have different absorption spectra and whose areas under the normalized emission spectra overlap by at least x%, are present in a specific ratio (e.g., of approx. 50 wt.%: approx. 50 wt.%, of approx. 60 wt.%: approx. 40 wt.%, of approx. 70 wt.%: approx. 30 wt.%, of approx. 80 wt.%: approx. 20 wt.%, or of approx. 90 wt.%: approx. 10 wt.%), where x = 99.

[0082] In a further embodiment, the at least two phosphors, which have different absorption spectra and whose areas under the normalized emission spectra overlap by at least x%, are present in a specific ratio (e.g., approximately 50 wt.%: approximately 50 wt.%, approximately 60 wt.%: approximately 40 wt.%, approximately 70 wt.%: approximately 30 wt.%, approximately 80 wt.%: approximately 20 wt.%, or approximately 90 wt.%: approximately 10 wt.%), where x = 100.

[0083] The ratio of the at least two phosphors is adjusted in particular so that the absorption properties and the emission properties result in the lowest possible color point shift.

[0084] Table 1 shows selected phosphor pairs with matched emission and absorption properties suitable for conversion elements according to the invention. The phosphor pairs listed here can be used alone or in combination with other phosphors. The percentages refer to the doping level of the base structure. Table 1 Nr. Leuchtstoff 1 Leuchtstoff 2 1 Y3Al5O 12 Ce(1.8%) Y3(Al 0.9 Gao 0.1 )5O 12 Ce(3.4%) 2 Y3Al5O 12 :Ce(3%) (Y 0.9 Tb 0.1 3)Al 0.9 Ga 0.1 5O 12 Ce(4.5%) 3 Y3Al5O 12 Ce(2.2%) (Lu 0.35 Y 0.65 3Al5O 12 Ce(4.3%) 4 SrSi2O2N2:Eu(10%) (Y 0.15 Read 0.95 )Al5O 12 :This(3%)

[0085] Furthermore, the present invention relates to an optoelectronic semiconductor device comprising at least one conversion element as described herein.

[0086] In one embodiment, an optoelectronic semiconductor device comprises a radiation-emitting semiconductor chip as a primary radiation source. The radiation-emitting semiconductor chip emits electromagnetic radiation of a first wavelength range (primary radiation) from a radiation-emitting surface. Preferably, the radiation-emitting semiconductor chip emits primary radiation in the wavelength range between 300 nm and 570 nm, more preferably in the range of 350 nm to 500 nm, and more preferably in the range of 420 nm to 480 nm.

[0087] According to a further embodiment, the optoelectronic semiconductor device comprises a conversion element of the present invention, which converts electromagnetic radiation of the first wavelength range (primary radiation) into electromagnetic radiation of the second wavelength range (secondary radiation). For example, the conversion element is applied in direct contact to the radiation-emitting surface of the light-emitting semiconductor chip.

[0088] Preferably, the conversion element of the present invention converts blue radiation from the semiconductor chip into green to red radiation. The optoelectronic semiconductor device preferably emits mixed-color radiation, which is composed of unconverted radiation from the first wavelength range and converted radiation from the second wavelength range. Preferably, the mixed-color light consists of blue radiation from the semiconductor chip and green to red converted radiation from the second wavelength range. Particularly preferably, the mixed-color light has a color point in the white range.

[0089] Furthermore, the present invention relates to a method for producing a conversion element according to the invention.

[0090] A method according to the invention for producing a conversion element according to the present invention comprises the steps: - Introducing n phosphors, where n≥3, into a matrix material, or - Mixing n phosphors, where n≥3, and sintering a ceramic from the mixture of the n phosphors, wherein at least two of the phosphors each have a different absorption spectrum and the areas under the normalized emission spectra of the at least two phosphors overlap by at least x%, where x = 75.

[0091] The n different phosphors, where n≥3, can be mixed before being incorporated into a matrix material.

[0092] In one embodiment, the n different phosphors, where n≥3, are mixed with the matrix material.

[0093] The phosphors can be in solid form or dispersed in a solvent.

[0094] In one embodiment, the phosphors are incorporated into a matrix material. The matrix material can be, for example, silicone, epoxy resin, polysiloxane, polysilazane, glass, polycarbonate, polymethacrylate, water glass, Al2O3, or the undoped base material of the phosphor (i.e., phosphor without activator), as well as combinations thereof.

[0095] In a further step of the inventive process, the mixture of the phosphors and the matrix material can be cured or sintered.

[0096] In an alternative embodiment of the method according to the invention, the n phosphors, where n≥3, are sintered to form a ceramic.

[0097] In a further embodiment, the method according to the invention comprises the step of introducing the conversion element into the beam path of a radiation-emitting semiconductor chip, in particular into the beam path of a blue-light-emitting semiconductor chip.

[0098] Another aspect of the present invention is the use of a conversion element in a lighting device. A lighting device is a component comprising a radiation source that emits primary radiation in the wavelength range between 300 nm and 570 nm, preferably in the range of 350 nm to 500 nm, and more preferably in the range of 420 nm to 480 nm.

[0099] Examples of lighting devices include streetlights, interior lights, projectors, light panels, screens, automotive headlights, video walls, etc.

[0100] Further advantageous embodiments and developments of the invention will become apparent from the exemplary embodiments described below in conjunction with the figures. Figures Fig. Figure 1 shows 1- R(λ) for a typical YAG:Ce and SCASN:Eu phosphor material, where R(λ) is the reflection spectrum of the phosphor powder under irradiation with white light. Fig. Figure 2 shows 1-R(λ) of a typical representative from the class of chlorosilicates CasMg(SiO4)4Cl2:Eu, SiONe (MSi2O2N2:Eu) and nitridodoor thiosilicates (Sr,Ba)2Si(O,N)4:Lu,Eu, where R(λ) is the reflection spectrum of the phosphor powder under irradiation with white light. Fig. 3 shows 1-R(λ) of Y3Al5O 12 Ce(1.8%) (YAG 1) and Y3(Al 0,9 Ga 0,1 )50 12 :Ce(3.4%) (YAGaG 1), where R(λ) is the reflection spectrum of the phosphor powder under irradiation with white light. Typical peak wavelengths for typical blue LEDs with λ dom452.5 nm (447.5 nm), λ dom 457.5 nm (453 nm) and λ dom 462.5 nm (458.5 nm) are also specified. Fig. Figure 4 shows the normalized emission spectra of Y3Al5O 12 Ce(1.8%) (YAG 1) and Y3(Al 0,9 Ga 0,1 )50 12 :Ce(3,4%) (YAGaG 1). Fig. 5 shows 1-R(λ) of Y3Al5O 12 :Ce(3%) (YAG 2) and (Y 0,9 Tb 0,1 )3(Al 0,9 Ga 0,1 )50 12 Ce(4.5%) (YAGaG 2), where R(λ) is the reflection spectrum of the phosphor powder under irradiation with white light. Typical peak wavelengths for typical blue LEDs with λ dam 452.5 nm (447.5 nm), λ dam 457.5 nm (453 nm) and λ dam 462.5 nm (458.5 nm) are also specified. Fig. Figure 6 shows the normalized emission spectra of Y3Al5O 12 :Ce(3%) (YAG 2) and (Y 0,9 Tb 0,1 )3(Al 0,9 Ga 0,1 )50 12 :Ce(4.5%) (YAGaG 2). Fig. Figure 7 shows 1-R(λ) of Y3Al5O 12 :Ce(2.2%) (YAG3) and (Lu 0,35 Y 0,65 )3Al5O 12 Ce(4.3%) (LuYAG3, where R(λ) is the reflection spectrum of the phosphor powder under irradiation with white light. Typical peak wavelengths for typical blue LEDs with λ dam 452.5 nm (447.5 nm), λ dam 457.5 nm (453 nm) and λ dam 462.5 nm (458.5 nm) are also specified. Fig. Figure 8 shows the normalized emission spectra of Y3Al5O 12 :Ce(2.2%) (YAG3) and (Lu 0,35 Y 0,65 )3Al5O 12 :Ce(4,3%) (LuYAG3). Fig. Figure 9 shows 1-R(λ) of SrSi2O2N2:Eu(10%) (Sr-SiAION 4) and (Y 0,15 Lu 0,95 )Al5O 12 Ce(3%) (LuYAG 4), where R(λ) is the reflection spectrum of the phosphor powder under irradiation with white light. Typical peak wavelengths for typical blue LEDs with λ dom 452.5 nm (447.5 nm), λ dom 457.5 nm (453 nm) and λ dom462.5 nm (458.5 nm) are also specified. Fig. Figure 10 shows the normalized emission spectra of SrSi2O2N2:Eu(10%) (Sr-SiON 4) and (Y 0,15 Lu 0,95 )Al5O 12 :Ce(3%) (LuYAG 4). Fig. Figure 11 shows the color point shift for LEDs with a SCASN phosphor in combination with a) only YAG, b) only YAGaG and c) a mixture of YAG and YAGaG for varying λ. dom of the blue semiconductor chip from 452.5 nm to 462.5 nm. The open symbols show 452.5, 455.0, 456.0, 457.0, 457.5, 458.0, 459.0, 460.0 and 462.5 nm chip λ dom The phosphor mixture was selected to achieve 3000 K on Planck (Cx = 0.4369, Cy = 0.4041) at 457.5 nm chip λ dam to achieve this. The phosphors correspond to the phosphors from Fig. 3 and Fig. 4. The data were analyzed using phosphors from Fig. 3 and Fig. 4 calculated. Fig. Figure 12 shows the color point shift for LEDs with a SCASN phosphor in combination with a) only YAG, b) only YAGaG and c) a mixture of YAG and YAGaG for varying λ. dom of the blue semiconductor chip from 452.5 nm to 462.5 nm. The open symbols show 452.5, 455.0, 456.0, 457.0, 457.5, 458.0, 459.0, 460.0 and 462.5 nm chip λ dom The phosphor mixture was selected to achieve 5000 K on Planck (Cx = 0.3451, Cy = 0.3516) at 457.5 nm chip λ dam to achieve this. The phosphors correspond to the phosphors from Fig. 3 and Fig. 4. The data were analyzed using phosphors from Fig. 3 and Fig. 4 calculated.

[0101] Fig. Figure 1 shows the typical absorption properties (represented by a plot of 1-R(λ)) of a garnet phosphor (YAG:Ce) and an aluminonitridisosilicate phosphor (SCASN:Eu) in the wavelength range of blue light. While the absorption of the SCASN phosphor remains nearly stable, the absorption of the YAG changes drastically over a narrow wavelength range. Thus, even small changes in the wavelength of the blue light emitted by the semiconductor chip, due to, for example, temperature changes and / or operating current changes, can result in a significantly altered blue light absorption by the garnet phosphor and lead to a subsequent color shift of the optoelectronic semiconductor device.

[0102] Fig. Figure 2 shows the absorption properties (represented by a plot of 1-R(λ)) of a typical representative from the class of chlorosilicates Ca8Mg(SiO4)4Cl2:Eu, SiONe (MSi2O2N2:Eu) and nitridodoor thosilicates (Sr,Ba)2Si(O,N)4:Lu,Eu, with an absorption that slowly decreases for longer blue LED wavelengths.

[0103] Fig. Figure 3 shows the absorption properties (represented by a plot of 1-R(λ)) and Fig. Figure 4 shows the normalized emission spectra of two typical yellow garnet phosphor materials, a YAG and a YAGaG material with the same emission color but different absorption maxima. The absorption maximum of YAG 1 lies in the longer wavelength range compared to the absorption maximum of YAGaG 1.

[0104] Fig. Figure 5 shows the absorption properties (represented by a plot of 1-R(λ)) and Fig. Figure 6 shows the normalized emission spectra of two typical yellow garnet phosphor materials, a YAG and a YAGaG material with the same emission color but different absorption maxima. The absorption maximum of YAG₂ lies in the longer wavelength range compared to the absorption maximum of YAGaG₂.

[0105] Fig. Figure 7 shows the absorption properties (represented by a plot of 1-R(λ)) and Fig. Figure 8 shows the normalized emission spectra of two typical yellow garnet phosphor materials, a YAG and a YAGaG material with the same emission color but different absorption maxima. The absorption maximum of YAG 3 lies in the longer wavelength range compared to the absorption maximum of LuYAG 3.

[0106] Fig. Figure 9 shows the absorption properties (represented by a plot of 1-R(λ)) and Fig. Figure 10 shows the normalized emission spectra of two typical yellow-green phosphors: an Sr-SiON₄ SrSi₂O₂N₂:Eu (10%) and a LuYAG material with very similar emission colors but different absorption maxima. The absorption maximum of LuYAG₄ lies in the longer wavelength range compared to the absorption maximum of SiON₄.

[0107] Fig. 11 and Fig. Figure 12 shows the color point shift for LEDs with a SCASN phosphor. When only a YAG phosphor is used in combination with a SCASN phosphor material, the excitation light slowly shifts into the absorption maximum of the YAG phosphor as the excitation wavelength of the blue light changes from λ. damThe wavelength changes from 452.5 nm to 462.5 nm. This increases the proportion of blue light absorbed by the YAG phosphor. Simultaneously, the proportion of yellow light in the converted light also increases. This leads to a color shift towards a yellow color point, as shown by the curves with open circle symbols in Fig. 11 and Fig. 12 displayed.

[0108] If only a YAGaG phosphor is used in combination with a SCASN phosphor material, the excitation light slowly shifts out of the absorption maximum of the YAGaG phosphor when the excitation wavelength of the blue light changes from λ damThe wavelength changes from 452.5 nm to 462.5 nm. This reduces the proportion of blue light absorbed by the YAGaG phosphor. Simultaneously, the proportion of yellow light in the converted light is also reduced. This results in a color shift towards a bluer color point, as shown by the curves with open square symbols in Fig. 11 and Fig. 12 displayed.

[0109] When a combination of YAG and YAGaG phosphors is used in combination with a SCASN phosphor material, the excitation light slowly shifts out of the absorption maximum of the YAGaG phosphor to almost the same extent as it shifts into the excitation maximum of the YAG phosphor when the excitation wavelength of the blue light changes from λ domThe wavelength changes from 452.5 nm to 462.5 nm. This results in a color point shift, primarily defined by the change in the blue wavelength (with small imbalances between shifting into and out of the corresponding absorption maxima, resulting in an additional small oscillation between a bluer and yellower color point), as shown by the curves with open triangle symbols in Fig. 11 and Fig. 12 displayed.

[0110] This behavior allows for the demand-based adjustment of a color point shift in response to changing excitation wavelengths of the blue light emitted by the semiconductor chip. In this way, the direction of the color shift can be adjusted to best suit a specific application.

[0111] Additionally, it is also possible to minimize the color point shift. For example, if two or more materials are selected whose absorption maxima are equidistant or nearly equidistant from the given excitation wavelength of the LED chip at shorter or longer wavelengths, small shifts in the excitation wavelength due to temperature and / or operating current changes result in smaller color point shifts than with conventional LEDs. If the distances between the open symbols, which each denote the same excitation wavelengths, are in Fig. 11 and Fig. In comparison to the other LEDs, the distances around the central point on Planck's curve are smaller for the variant with a mixture of YAG and YAGaG than for conventional LEDs with YAG alone or YAGaG alone. Therefore, the LED according to the invention exhibits a smaller shift in the color coordinates than conventional LEDs for the same change in excitation wavelength.

[0112] Using the aforementioned embodiments and variations thereof (including equidistant absorption maxima, non-equidistant absorption maxima, different mixing ratios of the phosphors, etc.), the color point shifts of optoelectronic semiconductor devices (e.g. LEDs) due to temperature changes and / or operating current changes can be minimized and / or shifted in a more preferred direction.

[0113] In general, the embodiments described herein can be used with all common phosphor materials exhibiting wavelength-dependent absorption in the range of the changing excitation wavelength for optoelectronic semiconductor devices (e.g., LEDs). Both combinations of materials from the same material class (e.g., two garnet phosphors or two aluminonitridisosilicate phosphors) and mixtures of materials from two of the more material classes (e.g., one garnet phosphor and one aluminonitridisosilicate phosphor) are conceivable within the scope of the present invention.

Claims

[1] Conversion element comprising: n different phosphors, where n≥3 and where each phosphor has an absorption spectrum and a normalized emission spectrum, wherein two of the at least three phosphors each have a different absorption spectrum and areas under the normalized emission spectra of the at least two phosphors overlap by at least x%, where x = 75, and wherein the two or at least three phosphors each exhibit wavelength-dependent absorption in the range of the changing excitation wavelength for optoelectronic semiconductor devices, and wherein two of the at least three phosphors have absorption maxima that are located at approximately the same distance from the present excitation wavelength of the semiconductor device at shorter or longer wavelengths, and wherein two of the at least three phosphors, each exhibiting a different absorption spectrum and with areas overlapping at least x% under the normalized emission spectra, are selected from the group consisting of the garnet phosphors (Y,Tb,Lu)3(Al,Ga)5O 12 :Ce 3+ ; and The third phosphor selected is from the group consisting of aluminonitridosilicates. [2] Conversion element according to claim 1, wherein x = 85, x = 95, particularly preferably x = 99. [3] Conversion element according to claim 1 or 2, wherein one-quarter of the at least three phosphors, each having a different absorption spectrum and the areas under the normalized emission spectra overlap by at least x%, is selected from the group consisting of nitride silicates, oxynitride silicates, aluminooxynitride silicates and oxysilicates. [4] Conversion element according to any one of the preceding claims, wherein the two of the at least three phosphors, each having a different absorption spectrum and the areas under the normalized emission spectra overlap by at least x%, are selected from the group consisting of Y3Al5O 12 :Ce 3+ and Y3(Al,Ga)6O 12 :Ce 3+ , Y3Al5O 12 :Ce 3+ and (Y,Tb)3(Al,Ga)5O 12 :Ce 3+ , Y3Al5O 12 :Ce 3+ and (Lu,Y)3Al5O 12 :Ce 3+ or Y3Al5O 12 :Ce 3+ and (Lu,Y)3(Al,Ga)5O 12 :Ce 3+ . [5] Optoelectronic semiconductor device comprising at least one conversion element according to any one of claims 1 to 4. [6] Method for producing a conversion element according to any one of claims 1 to 4, comprising: - Introducing n phosphors, where n≥3, into a matrix material, or - Mixing n phosphors, where n≥3, and sintering a ceramic from the mixture of the n phosphors; and - Manufacturing a conversion element according to any one of claims 1 to 4. [7] Method for manufacturing an optoelectronic semiconductor device according to claim 5, comprising: - Inserting the conversion element into the beam path of a radiation-emitting semiconductor chip; and - Manufacturing an optoelectronic semiconductor device according to claim 5. [8] Method for manufacturing an optoelectronic semiconductor device according to claim 7, wherein the radiation-emitting semiconductor chip emits primary radiation in the wavelength range between 300 nm and 570 nm, preferably in the range 350 nm to 500 nm, more preferably in the range 420 nm to 480 nm. [9] Use of a conversion element according to any one of claims 1 to 4 in a lighting device.

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