Phosphor, method of manufacturing phosphor, and radiation-emitting component

Abstract

A phosphor is disclosed, the phosphor having a host material including an oxide, an activator element having a rare earth element with a first valence, and a rare earth element with a second valence, the second valence being greater than the first valence. Methods of making the phosphor and radiation-emitting components are also disclosed.

Description

[Technical Field]

[0001] A phosphor, a method for making the phosphor, and a radiation-emitting component are presented. Summary of the Invention [Problem to be solved by the invention]

[0002] The object of at least one embodiment is to provide a phosphor having improved properties. The object of at least one further embodiment is to provide a method for producing a phosphor having improved properties. The object of at least one further embodiment is to provide a radiation-emitting component having improved properties. These objects are solved by the phosphor, the method, and the radiation-emitting component according to the independent claims.

[0003] 1 illustrates a phosphor, according to at least one embodiment, the phosphor having a host material including an oxide, an activator element having a rare earth element with a first valence, and a rare earth element with a second valence, the second valence being greater than the first valence.

[0004] Thus, the phosphors described herein contain the same rare earth element with two different valences: a first valence and a second valence.

[0005] Hereinafter, the term "phosphor" is understood to mean a wavelength conversion material, or conversion material for short, i.e. a material designed to absorb and emit electromagnetic radiation. In particular, phosphors absorb electromagnetic radiation that has a wavelength maximum different from the electromagnetic radiation that they emit. For example, phosphors absorb radiation that has a wavelength maximum at a wavelength smaller than their emission maximum, and thus emit radiation with an emission maximum that is red-shifted. In the context of the present invention, pure scattering or pure absorption is not understood as wavelength conversion.

[0006] Hereinafter, the term "host material" is understood to mean a crystalline material, such as a ceramic material, into which a rare-earth element is introduced. A phosphor is thus, for example, a ceramic material. In particular, the host material typically forms a host lattice consisting of periodically repeating three-dimensional unit cells. In other words, a unit cell is the smallest repeating unit of a crystalline host lattice. In the unit cell, the rare-earth element with the first valence and the rare-earth element with the second valence, which are elements contained in the host material, each occupy a defined position, the so-called Wyckoff position.

[0007] In the present invention, the term "valence" of a particular element refers to how many elements with a single opposite charge are required in a chemical compound to achieve charge balance. Therefore, the term "valence" encompasses the number of charges of an element. Hereinafter, the first valence and the second valence are understood as two different valences. For example, the first valence is a valence of 3, and the second valence is a valence of 4. Thus, rare earth elements may exist in trivalent and tetravalent forms in phosphors. In particular, trivalent rare earth elements carry three times the positive charge, and tetravalent rare earth elements carry four times the positive charge.

[0008] The rare earth element with the first valence acts as an activator element in the phosphor. The activator element changes the electronic structure of the host material in such a way that electromagnetic radiation in a first wavelength range can be absorbed by the phosphor. This so-called primary radiation can excite electronic transitions in the phosphor that can return to the base state by emitting electromagnetic radiation in a second wavelength range, also known as secondary radiation. The activator element introduced into the host material is therefore responsible for the wavelength conversion properties of the phosphor. The secondary radiation has wavelengths in particular in the visible spectral range.

[0009] Some rare earth elements exist in oxidized form, i.e., with a second, higher valence. In particular, rare earth elements with a second valence do not function as activator elements or cause the conversion of primary radiation into secondary radiation in the visible spectrum of electromagnetic radiation. Hereafter, to distinguish between rare earth elements with a first valence and those with a second valence, only rare earth elements with a first valence will be referred to as activator elements.

[0010] In the present invention, rare earth elements include chemical elements of Group 3 of the periodic table as well as the lanthanides. The rare earth elements in the present invention are typically selected from the group consisting of scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium.

[0011] The inventors have recognized that the quantum efficiency of a phosphor and, with it, the brightness of the electromagnetic radiation emitted by a component containing the phosphor, can be reduced by the presence of a rare earth element, particularly a rare earth element with a second valence, which is not an activator element unlike the rare earth element with a first valence or which produces a secondary emission outside the visible spectral range. Thus, by appropriately varying the ratio of rare earth elements with a first valence to rare earth elements with a second valence, the brightness of a radiation-emitting component using the phosphor, such as an LED (light-emitting diode), can be continuously adjusted to the application requirements.

[0012] In so-called module system platforms for LEDs, individual components are interchangeable. The aim is to provide a module system that can accommodate as many different LED dielectrics as possible, including different colors, white positions, and especially brightness levels. To date, a wide brightness range has been achieved primarily through different chip sizes and types. Due to the specific design of the chips and, in some cases, the small individual volume of the individual dielectrics, complex chip portfolios must be available to ensure that the module system platform remains usable over a particularly long period—for example, more than 10 years. This is particularly important in the automotive sector. This results in chip costs increasing by two to three times compared to standard chips.

[0013] Previously, it was not possible to produce different LED brightness levels with one chip type without changing the operating current or modifying the chip in terms of its path, shape, or function. Such changes could be achieved, for example, through a narrower light exit path or through the addition of black materials, such as carbon black particles, within the light exit path. Carbon black particles in particular change the visual impression of the exterior, which is usually undesirable.

[0014] One method for brightness gradation of LEDs known in the art is, for example, by adjusting different chip sizes. Further darkening is also known, for example, by specially designing the bond pads. This approach increases production costs, since only a small number of LEDs need to be designed for different brightnesses, which makes manufacturing the individual LED chips very expensive.

[0015] Furthermore, in order to minimize the effect on the color of the emitted radiation, it is possible in principle to introduce additional non-converting materials into the LED that absorb radiation but lack quantum efficiency. However, this creates the problem that the original conversion material and the additional non-converting material lacking quantum efficiency do not have exactly the same excitation optimum due to the different compositions of the original conversion material and the additional non-converting material lacking quantum efficiency. Therefore, LEDs with additional non-converting materials have different total absorptions, which requires laborious adjustment of the color position of the emitted radiation by adjusting the conversion material mixture. Therefore, it was previously impossible to produce and guarantee a reproducible, reduced quantum efficiency of the converter, since this could only be achieved by introducing foreign elements that would introduce unwanted absorption and change the emission color.

[0016] In contrast, the use of the phosphors described herein allows for reproducible adjustment of the brightness of the emitted radiation of a radiation-emitting component, such as an LED, since the high absorption remains unchanged, i.e., the position of the absorption maximum is maintained when the efficiency is high, while simultaneously ensuring a reduced quantum yield. The color of the emitted radiation from the radiation-emitting component is therefore unaffected, and the required brightness can be continuously adjusted. The composition of the phosphor remains essentially unchanged, with only some of the rare earth elements having a changed valence, allowing only the brightness of the emitted radiation to be adjusted while maintaining the phosphor's properties. Therefore, laborious adjustments to the phosphor mixture to precisely adjust the color position when the brightness is changed are not necessary. The visual impression of the appearance of a component containing the phosphor also remains unchanged, unlike, for example, when carbon black particles or pigments are used.

[0017] This offers many advantages in application. For example, the phosphors described herein can be used alone or in a mixture with a base phosphor, which differs from the phosphor only in that it does not contain a rare earth element with a second valence. This allows the brightness of a phosphor-containing component, such as an LED, to be flexibly and seamlessly adjusted while maintaining the color position, e.g., the white color position. Since all properties of the phosphor, in addition to brightness, are maintained compared to the base phosphor, particularly the position of the absorption maximum, the effort required for color position control is reduced or avoided.

[0018] Therefore, seamlessly adjusting brightness eliminates the need for different sizes and types of components, such as LED chips. This reduces the complexity of the component portfolio, especially when long-term availability is required, such as for automotive products. Harmonizing the portfolio in this way can also lead to further cost savings, as only one or a few component types need to be offered in large volumes.

[0019] According to at least one embodiment, the host material is a garnet. The use of garnet as a host material, when appropriately doped with activator elements, can provide phosphors with high quantum yields, e.g., greater than 95%. Hereinafter, garnets are referred to as phosphors having the general formula (Y, Lu, Gd, Tb)3(Al 1-x ,Ga x )5O 12 where 0≦x≦1. The elements listed in the first bracket may be present individually or in combination with one another, depending on the type of garnet. Specific examples of garnets include, for example, oxides of the general formula Y3Al5O 12 Yttrium aluminum garnet (YAG) with the general formula Lu3Al5O 12 It is lutetium aluminum garnet (LuAG) with

[0020] Hereinafter, phosphors and host materials are indicated by molecular formulas, where the elements listed in the molecular formulas are present in charged form. Therefore, hereinafter, elements and / or atoms in the molecular formulas of phosphors or host materials refer to ions in the form of cations and anions, even if not explicitly stated otherwise. This also applies to element symbols, even when element symbols are written without charge numbers for clarity.

[0021] In a given molecular formula, the phosphor or host material can contain further elements, for example in the form of impurities, which may total up to 5 mol %, in particular up to 1 mol %, preferably up to 0.1 mol %.

[0022] According to at least one further embodiment, the rare earth element is cerium (Ce). Thus, when Ce is present in a first valence, it can exist in the phosphor as an activator element. When Ce is present in a second valence, it can exist as a non-activator element, or at least can provide secondary emissions outside the visible spectral range. Ce as an activator element, especially in combination with a garnet as a host lattice, results in stable phosphors with high quantum efficiency.

[0023] According to at least one further embodiment, the first valence is 3 and the second valence is 4. Thus, in the phosphor, Ce is 3+ and Ce 4+ Therefore, Ce with a lower first valence exists as 3+ is present as an enhancer component.

[0024] Ce as an activator element 3+ Garnet phosphors having the activator element Ce can have a quantum yield of over 95% at about 460 nm, depending on the composition of the garnet, and a remission of less than 10% in the blue spectral region of electromagnetic radiation. 3+is activated by photons, especially blue photons, and exhibits a 4f1-5d0 <-> 4f0-5d1 transition, which typically emits light in the visible spectral region upon relaxation. For example, when YAG is used as a garnet, emission in the yellow spectral region with a peak maximum in the wavelength range of 540 nm to 580 nm and a half-width in the range of 110 nm to 130 nm is observed in the doped system YAG:Ce 3+ is released at

[0025] Furthermore, Ce 4+ Introduce or partially introduce Ce 3+ Ce 4+ Converting to Ce 3+ Compared to the base phosphor containing only Ce, there is no change in the emission in the visible spectral region, but the high absorption and the position of the absorption maximum in the blue spectral region are maintained. 3+ For phosphors containing Ce as a fluorine atom, the color locus of a radiation-emitting component containing the phosphors described herein does not change. For example, the white color locus of an LED may be changed by adding Ce as a fluorine atom to the phosphor. 4+ Furthermore, the presence of Ce in the phosphor is not affected. 4+ As the percentage of Ce increases, the absorption also increases in the UV region, i.e., in the range of 300 nm to 400 nm. Higher absorption in the UV region absorbs a shorter wavelength fraction of the primary radiation, which does not contribute to brightness but can accelerate the aging of packaging materials such as silicone or epoxy. Therefore, partially Ce 3+ Ce 4+ For example, by replacing 3+ Ce 4+ By oxidizing to Ce, while maintaining the high absorption and the precise position of the absorption maximum, 4+ The quantum yield or quantum efficiency of the phosphor can be adjusted arbitrarily between 0% and 100%, particularly between 20% and 100%, for example between 50% and 100%, of the quantum yield of a comparative phosphor (base phosphor) that does not contain the proportion of . Furthermore, the life of parts containing the phosphor can be extended.

[0026] According to at least one further embodiment, the phosphor has the general formula (Y, Lu, Gd, Tb)3(Al 1-x , Ga x )5O 12 :Ce y 3+ Ce 1-y 4+ (where 0 ≦ x ≦ 1 and 0 < y < 1). Thus, the host material is a garnet of the formula (Y, Lu, Gd, Tb)3(Al 1-x , Ga x )5O 12 , and the activator element, i.e., the rare earth element having a first valence, is Ce 3+ , and the rare earth element having a second valence is Ce 4+ . According to at least one embodiment, the phosphor does not contain a divalent co-dopant, particularly Mg 2+ . The co-dopant is hereinafter understood as an element that is further introduced into the host material in addition to the activator element or the rare earth element having a second valence.

[0027] According to at least one further embodiment, the phosphor has an absorption region with an absorption maximum, and the absorption maximum has a position that is essentially the same as the position of the absorption maximum of the base phosphor, and the base phosphor differs from the phosphor only in that it does not contain a rare earth element having a second valence.

[0028] Hereinafter, "essentially the same" shall mean that the two sizes being compared are exactly the same, differ only within the margin of measurement inaccuracy, or differ only to an extent not recognizable by an external observer. "Essentially the same" also includes deviations of up to 5%, particularly up to 2%, for example up to 1%.

[0029] Hereinafter, the base phosphor is understood to mean a composition that differs from the phosphor described herein only in that it does not contain a rare earth element having a second valence.

[0030] Therefore, in the base phosphor, the activator elements are not partially replaced by rare earth elements with a second valence, so the base phosphor does not have a reduced quantum yield as in the phosphors described herein. The higher the proportion of rare earth elements with a second valence, the lower the proportion of activator elements, and the lower the quantum yield of the phosphor. For example, if a phosphor has the formula (Y, Lu, Gd, Tb)3(Al 1-x , Ga x )5O 12 :Ce y 3+ Ce 1-y 4+ The base phosphor is (Y, Lu, Gd, Tb)3(Al 1-x , Ga x )5O 12 :Ce 3+ However, because the composition of the phosphor and base phosphor are otherwise identical, the position of the absorption maximum remains unchanged, and thereby the color position of the phosphor, as determined using, for example, fluorescence spectroscopy, remains unaffected.

[0031] According to at least one embodiment, the absorption region of the phosphor is at least in the UV to blue wavelength region of the electromagnetic spectrum. Thus, the absorption region of the phosphor is in the range of 300 nm to 500 nm. The absorption maximum may be, for example, in the range of 440 nm to 470 nm.

[0032] According to at least one further embodiment, the phosphor has a reduced quantum efficiency compared to the quantum efficiency of the base phosphor, which differs from the phosphor only in that it does not contain a rare earth element with a second valence. Thus, the base phosphor does not have the reduced quantum yield of the phosphors described herein. The higher the proportion of rare earth elements with a second valence in the phosphor, the lower the proportion of activator elements, and the lower the quantum yield of the phosphor. For example, when a phosphor has the formula (Y, Lu, Gd, Tb)3(Al 1-x , Ga x )5O 12 :Ce y 3+ Ce 1-y 4+The base phosphor is (Y, Lu, Gd, Tb)3(Al 1-x , Ga x )5O 12 :Ce 3+ is.

[0033] According to at least one further embodiment, the electromagnetic radiation emitted by the phosphor has a dominant wavelength that is essentially the same as the dominant wavelength of the base phosphor, and the base phosphor differs from the phosphor only in that it does not contain a rare earth element with a second valence. For example, the phosphor may have a formula of (Y, Lu, Gd, Tb)3(Al 1-x , Ga x )5O 12 :Ce y 3+ Ce 1-y 4+ The base phosphor is (Y, Lu, Gd, Tb)3(Al 1-x , Ga x )5O 12 :Ce 3+ is.

[0034] To determine the dominant wavelength of the electromagnetic radiation emitted by a phosphor, a line is drawn on the CIE standard diagram starting from the white point and passing through the color locus of the electromagnetic radiation. The intersection of the line with the spectral color line that bounds the CIE standard diagram represents the dominant wavelength of the electromagnetic radiation. In general, the dominant wavelength is different from the wavelength of the emission maximum.

[0035] The dominant wavelength of the phosphor unchanged compared to the base phosphor is determined, for example, by fluorescence spectroscopy, and the color position of the phosphor is determined by the presence of a rare earth element with a first valence, e.g., Ce. 3+ with a rare earth element having a second valence, such as Ce 4+ This means that it is not affected by partial replacement by

[0036] According to at least one further embodiment, the electromagnetic radiation emitted by the phosphor has a half-width that is essentially the same as the half-width of the base phosphor, and the base phosphor differs from the phosphor only in that it does not contain a rare earth element with a second valence. For example, the phosphor may have a formula (Y, Lu, Gd, Tb)3(Al1-x , Ga x )5O 12 :Ce y 3+ Ce 1-y 4+ When having (Y, Lu, Gd, Tb)3(Al 1-x , Ga x )5O 12 :Ce 3+ It is. The almost unchanged half-value width is conditioned by the almost unchanged emission behavior of the phosphor compared to the base phosphor.

[0037] According to at least one further embodiment, further specification parameters of the phosphor are also essentially unchanged compared to the base phosphor as described above. Further specification parameters include, for example, the particle size, morphology, scattering properties and body color of the phosphor powder.

[0038] According to at least one further embodiment, the phosphor has a brightness that decreases as the proportion of rare earth elements having a second valence in the phosphor increases. For the phosphor (Y, Lu, Gd, Tb)3(Al 1-x , Ga x )5O 12 :Ce y 3+ Ce 1-y 4+ (where 0 ≦ x ≦ 1 and 0 < y < 1), the brightness is greater when y is large than when y is small. Therefore, the brightness of the phosphor described in this specification cannot be continuously adjusted.

[0039] Furthermore, a method for manufacturing the phosphor is shown. This method is suitable for manufacturing the phosphor as described in this specification. Therefore, all features disclosed in relation to the phosphor are also applicable to this method, and vice versa.

[0040] According to at least one embodiment, the method is - A step of providing a base phosphor, wherein the base phosphor is - A host material containing an oxide, and an activator element having a rare earth element with a first valence; having providing a base phosphor; - oxidizing the base phosphor to a phosphor, the phosphor comprising: a host material comprising an oxide; an activator element having a rare earth element with a first valence; a rare earth element having a second valence, the second valence being greater than the first valence; having oxidizing the base phosphor to a phosphor; Includes.

[0041] Thus, by oxidizing a portion of the activator elements to rare earth elements of a second valence, the method allows for the refinement of a base phosphor into a phosphor with reduced, continuously tunable quantum efficiency. The more rare earth elements of a first valence are oxidized to rare earth elements of a second valence, the more the quantum efficiency is reduced, and with it the brightness of the emitted radiation.

[0042] The production of the phosphors is significantly less expensive than the production of the base phosphors, and in particular does not require expensive raw materials such as gallium or scandium oxide, so does not significantly increase the production costs of the phosphors and components containing them. Thus, the phosphors described herein can be cost-effectively produced and provided with reproducibly reduced quantum efficiencies.

[0043] Cost-effective phosphor production involves simple post-processing of the base phosphor. This method also allows for additional cost savings, since a single base phosphor can be used to produce a range of refined phosphor brightnesses depending on the application, rather than providing additional phosphors or other heterogeneous elements with low quantum efficiency to reduce the brightness of the phosphor. Therefore, there is no additional cost for providing different phosphors and, therefore, for creating new formulations to adjust the color position of the emitted radiation.

[0044] According to at least one embodiment, the oxidation is carried out by heating. According to at least one embodiment, the oxidation is carried out at a temperature in the range of 350°C to 1400°C, in particular in the range of 600°C to 1200°C, for example in the range of 600°C to 1000°C. This allows the method to be carried out at moderate to high temperatures, and the oxidation is carried out by post-sintering the base phosphor to form the phosphor. The higher the temperature selected, the greater the amount of oxidized Ce in the resulting phosphor. 4+ The resulting brightness of the emitted radiation can therefore be controlled by the temperature in this method.

[0045] According to at least one further embodiment, the oxidation is carried out in air or oxygen. Thus, the oxidation or post-sintering of the base phosphor takes place under oxidizing conditions.

[0046] According to at least one embodiment, the oxidation is carried out for a period of at least 1 hour and at most 5 hours, for example 3 hours.

[0047] According to at least one further embodiment, the base phosphor (Y, Lu, Gd, Tb)3(Al 1-x , Ga x )5O 12 :Ce 3+ where 0≦x≦1, and a phosphor (Y, Lu, Gd, Tb)3(Al1-x , Ga x )5O 12 :Ce y 3+ Ce 1-y 4+ (where 0 ≤ x ≤ 1 and 0 < y < 1) is oxidized.

[0048] According to at least one embodiment, divalent co-dopants, especially Mg 2+ are not used in this method.

[0049] Furthermore, a radiation-emitting component is shown. The radiation-emitting component is designed and intended to include the phosphor described herein. Accordingly, all features disclosed in connection with the phosphor apply also to the radiation-emitting component and vice versa.

[0050] According to at least one embodiment, the radiation-emitting component - a semiconductor chip that emits electromagnetic radiation in a first wavelength range during operation, and - a conversion element having the phosphor described herein, the phosphor converting electromagnetic radiation in the first wavelength range into electromagnetic radiation in a second wavelength range that is partially different from the first wavelength range, includes.

[0051] The electromagnetic radiation in the first wavelength range forms the emission spectrum of the semiconductor chip and is also referred to as primary radiation.

[0052] The semiconductor chip is, for example, a light-emitting diode chip or a laser diode chip. Accordingly, this component can be a light-emitting diode (LED) or a laser. Preferably, the semiconductor chip has an epitaxially grown semiconductor stack having an active region suitable for generating electromagnetic radiation. For this purpose, the active zone has, for example, a pn junction, a double heterostructure, a single quantum well structure or a multiple quantum well structure.

[0053] During operation, the semiconductor chip can emit electromagnetic radiation, for example, from the ultraviolet spectral region and / or from the visible spectral region, in particular from the blue spectral region, so that the primary radiation has a wavelength, for example, in the range of 300 nm to 500 nm, in particular 400 nm to 460 nm.

[0054] The conversion element is in particular arranged at the radiation exit surface of the semiconductor chip, for example located in the beam path of the semiconductor chip, so that at least a portion of the radiation emitted by the semiconductor chip impinges on the conversion element.

[0055] The phosphor in the conversion element converts electromagnetic radiation in a first wavelength range into electromagnetic radiation in a second wavelength range, which forms the emission spectrum of the phosphor and is also called secondary radiation.

[0056] The electromagnetic radiation in the second wavelength range is at least partially different from the first wavelength range. The phosphor contained in or constituting the conversion element provides the conversion element with wavelength conversion properties. For example, the conversion element only partially converts the electromagnetic radiation of the semiconductor chip into electromagnetic radiation in the second wavelength range, while another part of the electromagnetic radiation of the semiconductor chip is transmitted by the conversion element. In this case, the radiation-emitting component emits mixed light composed of electromagnetic radiation in the first wavelength range and electromagnetic radiation in the second wavelength range. The mixed light includes, for example, white light. Complete conversion is referred to as complete conversion if the primary radiation is completely converted through the conversion element and / or if no transmission of the primary radiation occurs through the conversion element. In this case, the radiation-emitting component emits secondary radiation emitted by the conversion element.

[0057] Because the quantum efficiency of the phosphor can be adjusted depending on the proportion of rare earth elements with a second valence, the desired final brightness of the radiation-emitting component can be continuously adjusted based on the properties of the phosphors described herein, while the brightness of the primary radiation emitted by the semiconductor chip remains the same. The color locus of all emitted radiation is maintained, and there is no need to develop a new method for preparing the phosphor mixture to adjust the color locus.

[0058] Thus, a broad spectrum of brightness can be provided using only one type and size of semiconductor chip and, at the same time, radiation-emitting component. In particular, special chip types required for specific applications, such as the automotive sector, can be procured or manufactured on a large scale, and the desired brightness can be adjusted using appropriate phosphors with reproducibly reduced quantum efficiencies. This reduces the additional costs previously incurred due to the need to offer various chip types. Therefore, by using the phosphors described herein, a chip portfolio can be harmonized without changing the radiation-emitting component's specifications, particularly with regard to the emission color and the visual impression of the appearance. The visual impression of the component's appearance, which remains unchanged by the introduction of the phosphors described herein, cannot be achieved with carbon black particles or other pigments.

[0059] According to at least one embodiment, the conversion element comprises only a phosphor. Thus, the phosphor is used as the sole phosphor in the conversion element. The phosphors described herein allow for continuous adjustment of the desired brightness of the radiation-emitting component depending on the proportion of rare earth elements with the second valence.

[0060] According to at least one embodiment, the conversion element further comprises a base phosphor, which differs from the phosphor only in that it does not contain rare earth elements with a second valence. Thus, the conversion element includes a mixture of an unpurified base phosphor and a purified phosphor with a reduced quantum efficiency, allowing for flexible and seamless adjustment of the brightness of the radiation-emitting component. Depending on the phosphors selected and the ratio of base phosphor to phosphor, the quantum efficiency can be adjusted between 50% and 100% of the quantum efficiency of the base phosphor, while maintaining the absorption and absorption maximum position of the base phosphor.

[0061] Regardless of whether the phosphor is used alone or used together with a base phosphor in the conversion element, the color position of the base phosphor is maintained. In order for the radiation-emitting component containing the phosphor and optionally the base phosphor to have the same color position as the radiation-emitting component in which only the base phosphor is present, the amount of the added phosphor and / or the mixing ratio of the phosphor and the base phosphor can be adjusted accordingly.

[0062] According to at least one embodiment, the conversion element comprises (Y, Lu, Gd, Tb)3(Al 1-x , Ga x )5O 12 :Ce y 3+ Ce 1-y 4+ (where 0 ≤ x ≤ 1 and 0 < y < 1) as a single phosphor.

[0063] According to at least one further embodiment, the conversion element comprises the phosphor (Y, Lu, Gd, Tb)3(Al 1-x , Ga x )5O 12 :Ce y 3+ Ce 1-y 4+ (where 0 ≤ x ≤ 1 and 0 < y < 1) and a base phosphor (Y, Lu, Gd, Tb)3(Al 1x , Ga x )5O 12 :Ce 3+ (where 0 ≤ x ≤ 1) and consists of a mixture.

[0064] According to at least one embodiment, the ratio of the phosphor to the base phosphor in the conversion element is selected from 100:0, 80:20, and 60:40.

[0065] The phosphor and optionally the base phosphor can be embedded in a matrix material, and the phosphor and optionally the base phosphor are present in particulate form. According to one embodiment, the matrix material is selected from the group including polymers and glasses. Examples of polymers that can be selected include polystyrene, polysiloxane, polysilazane, PMMA, polycarbonate, polyacrylate, polytetrafluoroethylene, polyvinyl, silicone resin, silicone, epoxy resin, and transparent synthetic rubber. Examples of glasses that can be selected include silicates, water glass, and quartz glass.

[0066] According to at least one embodiment, the conversion element is designed as an encapsulation element. For this purpose, the phosphor and, if applicable, the base phosphor can be embedded in a matrix material. The encapsulation element can be arranged, for example, in a recess in the housing and surround the semiconductor chip. According to an embodiment, the encapsulation element is a volume encapsulation in which the phosphor and, if applicable, the base phosphor are uniformly distributed in the matrix material. Alternatively, according to a further embodiment, the phosphor and, if applicable, the base phosphor are present in a sedimented form in the encapsulation element. Thus, within the encapsulation element, there is a concentration gradient of the phosphor and, if applicable, the base phosphor in the matrix material, with the concentration of the phosphor and, if applicable, the base phosphor decreasing with increasing distance from the semiconductor chip.

[0067] According to at least one embodiment, the conversion element is designed as a conversion layer. The conversion layer can be provided in direct or indirect contact with the semiconductor chip. In the case of indirect contact, the conversion layer can be provided on the semiconductor chip, in particular on the radiation exit surface of the semiconductor chip, for example by means of an adhesive layer, or an encapsulant can be present between the semiconductor chip and the conversion element.

[0068] According to a further embodiment, the semiconductor chip, the optional conversion element, and optionally the adhesive layer can all be surrounded by an encapsulant, and for example the semiconductor chip, the conversion element, and optionally the adhesive layer are arranged in a recess of the housing, in which the encapsulant is further arranged.

[0069] The encapsulant may have a transmittance of at least 85%, preferably 95%, for the primary and / or secondary radiation.Furthermore, the encapsulant may have silicone or epoxy resin as material.

[0070] According to at least one embodiment, two or more phosphors as described herein having different compositions are present in the conversion element, in which case additional base phosphors associated with each may also be present in the conversion element.

[0071] Further advantageous embodiments and further configurations of the phosphors, components and methods will become apparent from the examples described below in conjunction with the figures. [Brief explanation of the drawings]

[0072] [Figure 1] 1 shows a schematic cross-sectional view of a radiation-emitting component according to an embodiment; [Figure 2A] 1 shows a schematic cross-sectional view of a radiation-emitting component according to an embodiment; [Figure 2B] 1 shows a schematic cross-sectional view of a radiation-emitting component according to an embodiment; [Figure 3] 1 shows a reflectance spectrum of a phosphor according to an example. [Figure 4] 1 shows a reflectance spectrum of a phosphor according to an example. DETAILED DESCRIPTION OF THE INVENTION

[0073] In the figures, identical, similar or similarly acting elements are provided with the same reference numerals. The figures and the size ratios of the elements shown therein should not be taken to scale. Rather, individual elements, in particular layer thicknesses, may be shown exaggeratedly large for better illustration and / or for better understanding.

[0074] 1 shows a schematic cross-section of a radiation-emitting component according to an embodiment. The radiation-emitting component 100 comprises a semiconductor chip 10. During operation, the semiconductor chip 10 emits electromagnetic radiation in a first wavelength range (primary radiation) from a radiation exit surface 11. The semiconductor chip 10 comprises an epitaxially grown semiconductor layer stack with an active region suitable for generating electromagnetic radiation. The primary radiation has a wavelength in the blue and / or ultraviolet range, for example. The semiconductor chip 10 is in particular an LED chip.

[0075] The component further comprises a conversion element 20. The conversion element 20 comprises a matrix material in which phosphor 1, in particular particles of phosphor 1, are embedded, or the conversion element 20 comprises a ceramic formed from phosphor 1 or consists of a ceramic formed from phosphor 1. Alternatively, the conversion element 20 comprises a matrix material in which phosphor 1 and base phosphor 2, in particular particles of phosphor 1 and base phosphor 2, are embedded, or the conversion element 20 comprises a ceramic formed from phosphor 1 and base phosphor 2 or consists of a ceramic formed from phosphor 1 and base phosphor 2.

[0076] The matrix material is selected from polymers such as polystyrene, polysiloxane, polysilazane, PMMA, polycarbonate, polyacrylate, polytetrafluoroethylene, polyvinyl, silicone resin, silicone, epoxy resin and transparent synthetic rubber, and from glasses such as silicates, water glass and quartz glass.

[0077] In operation, phosphor 1 and possibly base phosphor 2 convert electromagnetic radiation in a first wavelength range into electromagnetic radiation in a second wavelength range (secondary radiation). If the primary radiation is not completely converted by the conversion element, the component emits mixed light made up of the primary and secondary radiation.

[0078] The conversion element 20, designated here as conversion layer, can be provided directly on the semiconductor chip 10 or attached to the semiconductor chip 10, for example by means of an adhesive layer (not explicitly shown here).

[0079] The semiconductor chip 10 with the conversion element 20 arranged thereon is placed in a recess in the housing 30. The housing 30 has beveled sides facing the semiconductor chip 10, which may be designed to be reflective. As shown here, the semiconductor chip 10 and the conversion element 20 may be surrounded by an encapsulant 40 in the housing 30. However, the presence of the encapsulant 40 is not essential. The encapsulant may be made of, for example, silicone or epoxy resin and has a transmittance of at least 85%, preferably 95%, for the electromagnetic radiation of the active region.

[0080] Alternatively, the housing 30 may not have side walls and therefore no cutouts, but may be designed as a carrier (not shown here).

[0081] 2A shows a further embodiment of a radiation-emitting component. For elements with the same reference numbers, the explanation given with reference to FIG. 1 applies. In this embodiment, the conversion element 20 is not arranged directly on the semiconductor chip 10, but on the side of the encapsulation 40 facing away from the semiconductor chip 10, at a distance from the latter. Here too, the conversion element 20 is designed as a conversion layer.

[0082] FIG. 2B shows a further embodiment of the radiation-emitting component. For elements with the same reference numerals, the explanations given with reference to FIGS. 1 and 2A apply. In this embodiment, the conversion element 20 is designed as an encapsulation element and is arranged in a cutout of the housing 30. The conversion element 20 thereby surrounds the semiconductor chip 10. The encapsulation element may be designed as a volume encapsulation in which the phosphor 1 and optionally the base phosphor 2 are present homogeneously distributed in a matrix material. Alternatively, the phosphor 1 and optionally the base phosphor 2 may be present in precipitated form. The concentration of the phosphor 1 and optionally the base phosphor 2 in the matrix material is then high near the semiconductor chip 10 and decreases with increasing distance from the semiconductor chip 10.

[0083] The components shown in Figures 1 and 2 are, for example, LEDs. For clarity, further elements such as electrical contacts are not shown in Figures 1 and 2.

[0084] Hereinafter, phosphor 1 described in this specification and a method for producing the same will be described using examples.

[0085] As starting material, the base phosphor according to Example B1 (2.0 mol % Ce 3+ YAG:Ce containing 3+ ) and Example B2 (2.8 mol% Ce 3+ YAG:Ce containing 3+ ) are prepared. Each of these base phosphors is made of oxide YAlO as an oxide or host material. 12 and the rare earth element Ce as an activator element having a first valence of 3+.

[0086] The base phosphors B1 and B2 are post-sintered. For this purpose, they are heated in air at various temperatures for 3 hours, thereby oxidizing them to phosphor 1. Depending on the applied temperature, the phosphors according to examples L1 to L4 are derived from base phosphor B1, while phosphors L5 and L6 are derived from base phosphor B2.

[0087] In the following Tables 1 and 2, the manufacturing temperature T and the relative quantum efficiency QE compared to each base phosphor are shown. rel , minimum reflectance R at wavelengths of 450 nm to 470 nm 450-470 , relative brightness H rel , the half-width FWHM and dominant wavelength λ of the associated emission spectrum dom At the same time, Examples L1 to L6 are listed. [Table 1] [Table 2]

[0088] The associated reflectance spectra are shown in Figures 3 and 4. Figure 3 shows the reflectance spectra of base phosphor B1 and phosphors L1-L4, and Figure 4 shows the reflectance spectra of base phosphor B2 and phosphors L5 and L6. In each, reflectance R in % is plotted against wavelength λ in nm.

[0089] As the temperature increases during the oxidation of the base phosphor, the relative quantum efficiency and, with it, the relative brightness of the phosphor decreases, which is due to the activator element Ce. 3+ The content of Ce in each phosphor decreases. 4+ It can be clearly seen that this is due to the increase in the content of

[0090] At the same time, the absorption behavior of the base phosphor is preserved in the phosphor, which in particular results in a minimum reflectance R at wavelengths of 450 nm and 470 nm. 450-470 This can be seen in the spectra of Figures 3 and 4, where the curves completely overlap in the range between 450 nm and 470 nm.

[0091] Furthermore, the luminescence behavior of the resulting phosphor is also preserved, as can be seen from the almost unchanged half-width of the emission spectrum.

[0092] The dominant wavelength λ of the phosphor compared with each base phosphor dom are essentially the same, indicating that the base phosphor can be oxidized to the phosphor without changing the color locus of the emitted radiation.

[0093] Thus, the phosphors described herein are well suited for use in components that are to be provided in a range of brightnesses.

[0094] The features and embodiments described in connection with the figures can be combined with each other to form further embodiments, even if not all combinations are explicitly described. Furthermore, the embodiments described in connection with the figures can alternatively or additionally have further features according to the description in the general part.

[0095] The invention is not limited to the examples described herein, but rather includes each and every novel feature and each and every combination of features, and in particular each and every combination of features in the claims, even if those features or combinations themselves are not explicitly recited in the claims or examples.

[0096] This patent application claims priority from German Patent Application No. 102022126567.6, the disclosure of which is incorporated herein by reference. [Explanation of symbols]

[0097] 1. Phosphor 2. Base Phosphor 10 Semiconductor chips 11 Radiation exit surface 20 Conversion Factors 30 Housing 40 Encapsulating material 100 Radiation-emitting parts B1 Base phosphor according to the embodiment B2 Base phosphor according to the embodiment L1 Phosphor according to the embodiment L2 Phosphor according to the embodiment L3 Phosphor according to the embodiment L4 Phosphor according to the embodiment L5 Phosphor according to the embodiment L6 Phosphor according to the embodiment

Claims

1. a host material comprising an oxide; an activator element having a rare earth element with a first valence; the rare earth element having a second valence, the second valence being greater than the first valence; A phosphor having the formula: The phosphor is general formula, (Y,L#,Gd,Tb) ３ (Al) １－ｘ ,Ga ｘ ) ５ O １２ :Yes ｙ ３＋ Yes １－ｙ ４＋ (Wherein, 0≦x≦1 and 0<y<1) having Phosphor.

2. the host material is a garnet; The phosphor according to claim 1 .

3. The rare earth element is cerium (Ce). The phosphor according to claim 1 or 2.

4. the first valence is 3 and the second valence is 4; The phosphor according to claim 3 .

5. does not contain divalent co-dopants; The phosphor according to any one of claims 1 to 4.

6. having an absorption region with an absorption maximum, the absorption maximum has a position that is essentially the same as the position of the absorption maximum of the base phosphor; the base phosphor differs from the phosphor only in that it does not contain the rare earth element having the second valence; The phosphor according to any one of claims 1 to 5.

7. the absorption region of the phosphor is at least in the UV to blue wavelength region of the electromagnetic spectrum; The phosphor according to claim 6.

8. the phosphor has a reduced quantum efficiency compared to the quantum efficiency of a base phosphor; the base phosphor differs from the phosphor only in that it does not contain the rare earth element having the second valence; The phosphor according to any one of claims 1 to 7.

9. the electromagnetic radiation emitted by the phosphor has a dominant wavelength that is essentially the same as the dominant wavelength of the base phosphor; the base phosphor differs from the phosphor only in that it does not contain the rare earth element having the second valence; The phosphor according to any one of claims 1 to 8.

10. the electromagnetic radiation emitted by the phosphor has a half-width that is essentially the same as the half-width of the base phosphor; the base phosphor differs from the phosphor only in that it does not contain the rare earth element having the second valence; The phosphor according to any one of claims 1 to 9.

11. the phosphor has a brightness that decreases as the proportion of the rare earth element having a second valence in the phosphor increases. The phosphor according to any one of claims 1 to 10.

12. - providing a base phosphor, said base phosphor comprising: a host material comprising an oxide; an activator element having a rare earth element with a first valence; having providing a base phosphor; - oxidizing the base phosphor to a phosphor, the phosphor being said host material comprising an oxide; said activator element having a rare earth element with a first valence; the rare earth element having a second valence, the second valence being greater than the first valence; having oxidizing the base phosphor to a phosphor; having A method for producing a phosphor, comprising: The phosphor is general formula, (Y,L#,Gd,Tb) ３ (Al) １－ｘ ,Ga ｘ ) ５ O １２ :Yes ｙ ３＋ Yes １－ｙ ４＋ (Wherein, 0≦x≦1 and 0<y<1) having A method for manufacturing phosphors.

13. The oxidation is carried out at a temperature in the range of 350°C to 1400°C. The method of claim 12.

14. The oxidation is carried out in air or oxygen, and / or the oxidation is carried out for a period of at least 1 hour and at most 5 hours.

14. The method of claim 12 or 13.

15. The base phosphor (Y, Lu, Gd, Tb) ３ (Al １－ｘ , Ga ｘ ) ５ O １２ : Ce ３＋ (wherein 0≦x≦1), wherein the phosphor (Y, Lu, Gd, Tb) ３ (Al １－ｘ , Ga ｘ ) ５ O １２ : Ce ｙ ３＋ Ce １－ｙ ４＋ wherein 0≦x≦1 and 0<y<1, The method according to any one of claims 12 to 14.

16. No divalent codopants are used; The method according to any one of claims 12 to 15.

17. a semiconductor chip that emits electromagnetic radiation in a first wavelength range during operation; a conversion element comprising a phosphor according to any one of claims 1 to 11, said phosphor converting electromagnetic radiation in said first wavelength range into electromagnetic radiation in a second wavelength range which is partially different from said first wavelength range; and Equipped with Radiation-emitting parts.

18. the conversion element further comprises a base phosphor; the base phosphor differs from the phosphor only in that it does not contain the rare earth element having the second valence; 18. The radiation-emitting component of claim 17.

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