WO2010136411A1

WO2010136411A1 - Chloroaluminate compound, process for the preparation thereof, radiation-emitting device comprising the chloroaluminate compound and process for producing the radiation-emitting device

Info

Publication number: WO2010136411A1
Application number: PCT/EP2010/057076
Authority: WO
Inventors: Ute Liepold
Original assignee: Osram Opto Semiconductors Gmbh
Priority date: 2009-05-25
Filing date: 2010-05-21
Publication date: 2010-12-02
Also published as: DE102009037861A1; WO2010136411A8

Abstract

Chloroaluminate compound having the general formula: Me1 3-x-yEuxMnyAl2O5Cl2,where Me1 is at least one element selected from among: Mg, Ca, Sr, Ba or any combinations thereof and: 0 < x < 3; 0 = y < 3; x + y < 3.

Description

description

A chloroaluminate compound, a process for the production thereof, a radiation-emitting device comprising the chloroaluminate compound, and a process for producing the radiation-emitting device

This patent application claims the priorities of German patent applications 10 2009 022 561.7 and 10 2009 037 861.8, the disclosure of which is hereby incorporated by reference.

A chloroaluminate compound according to claim 1 is provided, such as a radiation emitting device comprising the chloroaluminate compound. Further, a process for producing the chloroaluminate compound as well as a process for producing the radiation-emitting device are given.

A widespread problem of radiation-emitting devices, for example white LEDs, is that the brightness and efficiency of the semiconductor chip are dependent on the current supply. If the radiation-emitting device comprises a phosphor, the chip and phosphor react differently to temperature increases, which may be the result of a higher electrical voltage, which changes the proportion of the primary radiation emitted directly by the chip and the secondary radiation converted by the phosphor relative to one another. This in turn can result in that the color impression of the of the

Radiation-emitting device emitted radiation can change depending on the current. An object of the embodiments of the radiation-emitting device is to provide a radiation-emitting device whose light color is largely independent of the respective brightness of the semiconductor chip.

Another object is to provide a phosphor which can be used for such radiation-emitting devices.

The object is achieved by a chloroaluminate compound according to claim 1. Further embodiments of the chloroaluminate compound and a radiation-emitting device with the chloroaluminate compound are the subject of further claims. Furthermore, a method for producing the chloroaluminate compound and the radiation-emitting device is also claimed.

One embodiment of the invention relates to a chloroaluminate compound according to the general formula:

Me ¹ SX- _Y Eu _x Mn ₇ Al ₂ O ₅ Cl ₂ where Me ^{1 represents} at least one element selected from: Mg, Ca, Sr, Ba, or any combination thereof, and 0> x <3; 0 ≤ y <3; x + y <3.

A chloroaluminate compound of the stated composition can be excited by UV radiation, emitting radiation in the visible range. Due to the fact that the exciting radiation can be largely outside the visible range, it does not contribute, or only slightly, to the color location of the radiation emitted by a radiation-emitting device, the color locus being represented by the color coordinates of the CIE system can be defined. Thus, the color location is wholly or largely independent of the brightness of the radiation source with which the phosphor is excited. The luminescence properties can be influenced, for example, by the proportion of Eu and / or Mn.

According to a further embodiment of the invention, Me ^{1 is} the following sub-formula:

(S _ri _ _z _z Me ^2), whereby the following formula results:

(Sr ₁₎ Me ² J 3 -X- _Y Eu _x Mn ₇ Al ₂ O ₅ Cl ₂ where Me ^{2 represents} at least one element selected from: Mg, Ca, Ba, and 0 ≤ z <1.

The Sr obtained in the compound may be at least partially replaced by one or more of Mg, Ca, Ba. By partially exchanging the Sr, the luminescence properties such as excitation range or even luminescence color can be influenced. For example, the replacement of Sr for Ca results in a slight shift and the replacement of Sr for Ba results in a greater shift of the emission spectrum to shorter wavelengths.

In another embodiment of the invention, the chloroaluminate compound may be represented by the general formula:

Sr ₃ -XEu _x Al ₂ O ₅ Cl ₂ , where 0 <x <3.

The chloroaluminate compound according to the general formula Sr ₃ - _x Eu _x Al ₂ O ₅ Cl ₂ can be excited in the UV range and in the short-wave visible range up to approximately 470 nm. Very good is the connection in the UV range and in the short-wave Visible range to about 425 nm excite. In the latter range, the reflectivity with respect to the excitation radiation is less than 30 percent. This means that only a small amount of radiation is reflected by the conversion material, and a large proportion is absorbed and thus can be converted. The chloroaluminate compound shows intense orange-yellow luminescence. The emission spectrum extends from the blue-green spectral range to the IR and has a half-width of about 167 nm. The orange-yellow emission of the chloroaluminate compound has a very high half-width, which is approximately in the range of 167 nm. The emission ranges from green to the near IR range.

The maximum of the emission is about 616 nm. For a composition according to the formula Sr ₂ , 9Euo, iAl ₂ 0 ₅ Cl 2, the color coordinates are approximately at C _x = 0.537 and c _y = 0.448 with a 360 nm excitation and a measurement range of 380 to 800 nm. Color coordinates are to be understood as the color coordinates according to the CIE system. The dominant wavelength of this phosphor is 585 nm. The dominant wavelength is the wavelength which can be determined as follows: In the CIE color diagram, a line is drawn from the white point to the color locus (c _x , c _y ) of the phosphor and up to the horseshoe-shaped line of the chart. On the horseshoe-shaped line, the wavelengths of the visible spectral range are plotted. The wavelength at which the extended connecting line meets the horseshoe-shaped line is the dominant wavelength.

In the three embodiments described above, a range for the parameter x of 0.015 ≦ x ≦ 0.3 is preferred, and 0.015 ≦ x ≦ 0.15 is particularly preferred. A fraction of less than 0.015 for x would only lead to a weak emission. With a proportion of greater than 0.15 can already use a deletion of the emission, ie the emitted radiation is absorbed by the conversion material again.

In addition to the chloroaluminate compound itself, a radiation emitting device comprising the chloroaluminate compound is also claimed.

An embodiment of the radiation-emitting device in this case comprises a radiation source which emits a primary radiation and a conversion material which is arranged in the beam path of the radiation source. Here, the conversion material comprises at least one of the above-described chloroaluminate compounds.

The radiation source emits a primary radiation which is at least partially converted by the conversion material into a secondary radiation. The conversion material in this case comprises a chloroaluminate compound according to the invention. The radiation emitted by the radiation-emitting device can be both pure secondary radiation if the primary radiation is completely converted into secondary radiation. But it may also be mixed light, which results from the mixture of secondary radiation and unconverted primary radiation. The primary radiation emitted by the radiation source can here be matched to the absorption region of the conversion material.

In a further embodiment of the radiation-emitting device, the radiation source emits a primary Radiation in a wavelength range of 180 nm to 470 nm, wherein the range 280 to 470 nm is preferred

Such primary radiation can be readily absorbed by the chloroaluminate compound. Thus, a large proportion of the primary radiation can be converted into the secondary radiation.

In a further embodiment of the radiation-emitting device, the conversion material converts the primary radiation into a secondary radiation which lies in the visible spectral range from 450 nm to 780 nm, preferably in the range from 450 nm to 700 nm.

Thus, the primary radiation in the UV or short-wave visible range is converted into secondary radiation having a broad emission spectrum with respect to the visible region.

In a further embodiment, the spectrum of the secondary radiation has an intensity maximum in the wavelength range from 600 nm to 630 nm.

Because the chloroaluminate compound has an intensity maximum in the orange range, it is possible to produce white light by combining the secondary radiation with a certain proportion of blue primary radiation.

In a further embodiment, the conversion material has a reflectivity of less than 30% with respect to a primary radiation from the wavelength range from 180 nm to 420 nm. Due to the low reflectivity of the conversion material is able to absorb a high proportion of the primary radiation and convert.

By way of example, the proportion by weight of the chloroaluminate compound in the conversion material allows the proportion of the primary light converted by the conversion material to be controlled. If an excessively high proportion of the chloroaluminate compound is chosen in relation to the matrix, it may be extinguished by complete absorption of the secondary radiation.

Embodiments are also conceivable in which the conversion material comprises, in addition to the chloroaluminate compound, further phosphors.

The conversion material can be introduced into a matrix in one embodiment. As a matrix material, for example, a silicone, an epoxy or other resin can be used. Embodiments are also conceivable in which the conversion material is introduced into a glass or a ceramic.

The matrix material is preferably permeable to the secondary radiation. Embodiments are conceivable in which the matrix material is also permeable to the primary radiation, but embodiments are also possible in which the matrix material partially absorbs the primary radiation.

An embodiment is also possible in which a filter is present in the beam path after the conversion material, which filters out the primary radiation which has not been converted by the conversion material. Of the For example, a filter may comprise a UV absorber such as TiO 2, but it may also be formed as a photonic crystal, for example.

In a further embodiment, the radiation-emitting device emits a mixed light of the primary radiation and the secondary radiation.

In the case where the primary radiation is not completely converted into secondary radiation, and the matrix material does not fully absorb the unconverted primary radiation, and the radiation-emitting device in the beam path does not have an additional filter that filters out the primary radiation, the radiation-emitting device also emits one in addition to the secondary radiation certain amount of primary radiation. By a targeted adjustment of the proportions of primary radiation and secondary radiation, which can be done for example via the proportion of the conversion material in the matrix, the wavelength of the mixed light, which is composed of primary radiation and secondary radiation, can be adjusted specifically. Thus, for example, using blue primary radiation, it is possible for the radiation-emitting device to emit white light.

In a further embodiment, the radiation source comprises a semiconductor diode.

The semiconductor diode can be used to emit the primary radiation in the UV or short-wave visible range. The semiconductor material may in this case be based, for example, on nitride compound semiconductors or phosphide compound semiconductors. But they are too Embodiments possible in which an organic LED (OLED) is used as the radiation source.

"Based on nitride compound semiconductors" in the present context means that the active epitaxial layer sequence or at least one layer thereof comprises a nitride III / V compound semiconductor material, preferably Al _n Ga _m In _n _m N, where O ≦ _n ≦ l, O ≤ m ≤ l and n + m ≤ 1. In this case, this material does not necessarily have to have a mathematically exact composition according to the above formula, but rather it may have one or more dopants and additional constituents which have the characteristic physical properties of Al _n Ga _m ini- _n _ _m N material does not substantially change. For simplicity, includes above formula, however, only the major components of the crystal lattice (Al, Ga, in, N), even though these can be replaced in part by small amounts of other substances.

In this context, "based on phosphide compound semiconductors" means that the semiconductor body, in particular the active region, preferably comprises Al _n Ga _m In _n _m p, where 0 ≦ _n ≦ l, 0 ≦ _m ≦ l and n + m ≦ 1, preferably with n ≠ 0 and / or m ≠ 0. In this case, this material does not necessarily have to have a mathematically exact composition according to the above formula Rather, it may comprise one or more dopants as well as additional constituents which substantially substantially preserve the physical properties of the material For the sake of simplicity, however, the above formula contains only the essential constituents of the crystal lattice (Al, Ga, In, P), even though these may be partially replaced by small amounts of other substances. In addition to the chloroaluminate compound itself, a process for its preparation is claimed.

A variant of the production process for the preparation of one of the chloroaluminate compound described above comprises the process steps:

A) providing a powder mixture comprising in each case a stoichiometric amount based on the composition Me ¹ S-XEu _x Al ₂ O ₅ Cl ₂ to Me ¹ CO ₃ and Me ¹ Cl ₂ , Al ₂ O ₃ , Eu ₂ O ₃ , B) homogenizing the powder mixture from A), and C) annealing the powder mixture from B).

By appropriate choice of the amount of starting materials, the proportion of Eu is determined, with which the compound is doped. By appropriate selection of the carbonates or chlorides, the corresponding composition of Me ^{1 is} controlled, and the chloride content in the product. After homogenization of the powder mixture, the powder mixture is subsequently annealed.

In a further process variant, the powder mixture in process step A) additionally comprises MnO ₂ and the stoichiometric amounts thus relate to the composition Me ¹ SX- _Y Eu _x Mn ₇ Al ₂ O ₅ Cl ₂ .

In a further process variant, the temperature range for the annealing in process step C) is in the range from 1000 ^° C. to 1400 ^° C., preferably in the range from 1000 ^° C. to 1250 ^° C.

In a further process variant, the annealing in process step C) takes place in the forming gas stream. In addition to the process for producing the chloroaluminate compound, a process for producing a radiation-emitting device comprising such a chloroaluminate compound is also claimed.

A method variant for producing one of the radiation-emitting devices described above comprises the method steps: a) providing a radiation source emitting a primary radiation, b) introducing a conversion material into a matrix material, c) introducing the matrix material comprising the conversion material into the beam path of the radiation source in that at least part of the primary radiation is converted by the conversion material into a secondary radiation. Here, a material is used for the conversion material, which comprises a compound according to one of the above-described chloroaluminate compound.

In method step a), both an LED and an OLED can be used as the radiation source. For example, a silicone, an epoxide or another resin can be used as the matrix material in process step b). The introduction of the matrix material in method step c) can be effected for example by the direct application of the matrix material to the radiation exit surface of the radiation source. The application can take place in such a way that a layer is formed on the radiation source, but it can also take place in that the entire radiation source is poured into the matrix material. However, variants are also possible in which the matrix material, for example, as a layer on a transparent support is applied, and then the carrier is introduced with the matrix material in the beam path.

In the following, variants of the invention will be explained in more detail with reference to figures and exemplary embodiments.

Figure 1 shows a schematic side view of an embodiment in which the entire primary radiation is converted into secondary radiation.

Figure 2 shows a schematic side view of an embodiment in which only a portion of the primary radiation is converted into secondary radiation.

Figure 3 shows a schematic side view of an embodiment in which the matrix is formed as a layer on the radiation source.

Figure 4 shows a schematic side view of an embodiment in which the inner walls of the housing are chamfered.

FIG. 5 shows two emission spectra (I and II) in which the relative intensity (I _r ) was plotted against the wavelength (λ).

FIG. 6 shows two spectra (I and II) in which the reflectivity (R) was plotted against the wavelength (λ).

FIG. 1 shows a schematic side view of an exemplary embodiment of the radiation-emitting device 1. The radiation-emitting device 1 in this case comprises a housing 10 which is pot-shaped. On the inside of the bottom surface of the housing 10, two circuit boards 11 are arranged. On one of the two circuit boards 11, the radiation source 4 is arranged so that it occupies a centered position relative to the housing 10. The upper side of the radiation source 4 is electrically conductively connected via a bonding wire 12 to the printed circuit board 11 which is at a distance from the radiation source. Thus, the radiation source 4 is now in electrically conductive contact with each of the two circuit boards 11. By applying voltage to the two circuit boards 11, the radiation source 4 can emit primary radiation 2. The entire radiation source 4 is potted in the housing 10 with a matrix 13. In this case, the conversion material 5 is embedded in the matrix 13. The concentration of the conversion material 5 is in this case selected so that the entire emitted primary radiation 2 is converted by the conversion material 5 into secondary radiation 3. Due to the complete conversion of the primary radiation 2 into secondary radiation 3, the radiation-emitting device 1 emits exclusively secondary radiation 3 via its radiation exit surface 14. The complete conversion of the primary radiation 2 into secondary radiation 3 can be achieved, for example, via the corresponding concentration of the conversion material 5 in the matrix 13.

In the exemplary embodiment of a further radiation-emitting device illustrated in FIG. 2, the housing 10, the etching plates 11, the radiation source 4 and the bonding wire 12 are arranged analogously to the exemplary embodiment illustrated in FIG. However, here the concentration of the conversion material 5 in the matrix 13 is selected so that only part of the primary radiation 2 is converted into secondary radiation 3. Thus, the emits Radiation-emitting device 1, a mixed light 6 which is composed of the primary radiation 2 and the secondary radiation 3.

FIG. 3 shows the schematic side view of a further exemplary embodiment of the radiation-emitting device 1. The radiation source 4 is arranged here on a printed circuit board 11. The upper side of the radiation source 4 is electrically conductively connected via a bond wire 12 to a further printed circuit board 11. The radiation source 4 is thus electrically conductively connected to a printed circuit board 11 at the top or bottom, respectively. On the upper side of the radiation source 4, a conversion layer of the matrix 13 is arranged, in which the conversion material 5 is embedded. The primary radiation 2 emitted by the radiation source 4 is converted into secondary radiation 3 as it passes through the matrix 13 by the conversion material 5. The radiation-emitting device 1 thus emits exclusively the secondary radiation 3. Depending on the thickness of the conversion layer or concentration of the conversion material 5 in the conversion layer, partial conversion, ie the generation of mixed light of primary radiation 2 and secondary radiation 3, is also possible in this exemplary embodiment.

4 shows a schematic side view of a further embodiment of the radiation-emitting device 1. The radiation-emitting device 1 comprises a housing 10 with bevelled inner walls 15. The surface of the inner walls 15 may in this case be coated with a reflective material, so that the radiation is transmitted to the inner walls 15 hits is deflected upwards. The radiation source 4 is on one of the two circuit boards 11th arranged and electrically connected to a bonding wire 12 to the other circuit board. The housing 10 is filled with a matrix 13, in which the converter material 5 is embedded.

5 shows two emission spectra I and II in which in each case the relative intensity (I _r ) of the emission of two differently processed chloroaluminate phosphors is plotted against the wavelength (λ) in nm. The excitation of the phosphor was carried out here with a radiation of wavelength of 360 nm. Shown is an emission wavelength range of 450 nm to 800 nm for each of the phosphor emitted radiation. The spectrum I shows the spectrum of the chloroaluminate compound Sr ₂ , 9Euo, iAl ₂ 0 ₅ Cl2. This sample was prepared by annealing for 8 hours at 1250 ⁰ C and is almost phase pure. Curve II shows the spectrum of a chloroaluminate compound, which was processed at 1250 ⁰ C for 4 hours. This sample still has 10 to 20% foreign phases (Sri ₂ Ali ₄ θ33, SrCl ₂ ).

As can be seen in FIG. 5, the emission spectrum I in the illustrated wavelength range has a higher relative intensity (I _r ) than the emission spectrum II, which still has foreign phase components.

FIG. 6 shows two spectra I and II in which the reflectivity (R) is plotted against the wavelength (λ) in nm. In this experiment, the wavelength at which the phosphor is irradiated was varied from 300 nm to 800 nm, and the respective reflectivity for the corresponding wavelength was measured relative to corresponding values of a white standard with ~ 100% reflectivity. The measured samples of spectra I and II correspond to those the measured in Figure 5 for the corresponding emission spectra I and II substances.

As can be seen in Figure 6, the chloroaluminate compound Sr ₂ , gEuo, 1Al ₂ O ₅ Cl ₂ below 400 nm has a low reflectivity and thus a high absorption. In the range of 400 to 430 nm, the compound also has a significant absorption capacity. By contrast, the sample with the foreign phase fractions of 10 to 20 percent has a significantly higher reflectivity, as shown in Spectrum II.

In the following, a variant of the production method for Sr ₃ _ _x Eu _x Al ₂ 0 ₅ Cl _{2 will be} described.

In this variant, the starting powders are weighed in the following ratios: 1.9 mol SrCO ₃ , 1 mol SrCl ₂ × 6 H ₂ O, 1 mol Al ₂ O ₃ and 0.05 mol Eu ₂ O ₃ . The powder mixture is homogenized and then annealed in a corundum boat with lid at a temperature between 1000 ⁰ C and 1400 ⁰ C, preferably between 1100 ⁰ C and 1300 ⁰ C, for 12 hours in the Formiergasstrom. The result is a powder having the following composition: Sr ₂ , ₉ Euo, 1Al ₂ O ₅ Cl ₂ . The resulting powder can be excited with 366 nm electromagnetic radiation to emit white-orange light.

The invention is not limited by the description with reference to the embodiments. Rather, the invention encompasses any novel feature as well as any combination of features, including in particular any combination of features in the claims, even if this feature or combination itself is not explicitly stated in the patent claims or exemplary embodiments.

Claims

claims

1. Chloroaluminate compound according to the general formula:

A chloroaluminate compound according to claim 1, wherein Me ^{1 is} the following partial formula:

(S _ri _ _z _z Me ^2), whereby the following formula results:

(Sr ₁₎ Me ² J ₃ -x-yEu _x Mn _y Al ₂ O ₅ Cl ₂ where Me ^{2 represents} at least one element selected from: Mg, Ca, Ba, and 0 ≤ z <1.

3. chloroaluminate compound according to any one of the preceding claims, according to the general formula:

Sr ₃ -XEu _x Al ₂ O ₅ Cl ₂ .

4. chloroaluminate compound according to any one of the preceding claims, wherein: 0.015 ≤ x ≤ 0.3.

5. A radiation-emitting device (1), comprising:

a radiation source (4) emitting a primary radiation (2),

a conversion material (5) which is arranged in the beam path of the radiation source (4), wherein the conversion material (5) comprises a compound according to one of claims 1 to 3, and at least a portion of the primary radiation (2) is converted by the conversion material (5) into a secondary radiation (3).

6. radiation-emitting device (1) according to claim 5, wherein the radiation source (4) emits a primary radiation (2) in a wavelength range of 180 nm to 470 nm.

7. Radiation-emitting device (1) according to any one of claims 5 or 6, wherein the conversion material (5) converts the primary radiation (2) into secondary radiation (3), which ranges in the visible spectral range of a wavelength of 450 nm to 780 nm.

8. radiation-emitting device (1) according to claim 7, wherein the spectrum of the secondary radiation (3) in the wavelength range of 600 nm to 630 nm has an intensity maximum.

9. radiation-emitting device (1) according to one of claims 5 to 8, wherein the conversion material (5) with respect to a primary radiation (2) from the wavelength range of 180 nm to 420 nm has a reflectivity of less than 30%.

10. radiation-emitting device (1) according to one of claims 5 to 9, which emits a mixed light (6) from the primary radiation (2) and the secondary radiation (3).

11. The radiation-emitting device (1) according to any one of claims 4 to 10, wherein the radiation source (4) comprises a semiconductor diode.

12. A process for producing a chloroaluminate compound according to any one of claims 1 to 4, comprising the process steps:

A) providing a powder mixture comprising in each case a stoichiometric amount of Me ¹ CO ₃ and Me ¹ Cl ₂ , Al ₂ O ₃ , Eu ₂ O ₃ ,

B) homogenizing the powder mixture from A),

C) annealing the powder mixture from B).

13. The method of claim 12, wherein the powder mixture in step A) additionally comprises MnO ₂ .

14. The method according to any one of claims 12 or 13, wherein the annealing in step C) takes place at a temperature which is in the temperature range of 1000 ⁰ C to 1400 ⁰ C.

15. A method for producing a radiation-emitting device (1) according to one of claims 5 to 11, comprising the method steps: a) providing a radiation source (4) emitting a primary radiation (2), b) introducing a conversion material (5) into a Matrix material (13), c) introducing the matrix material (13), which comprises the conversion material (5) in the beam path of the radiation source (4), so that at least a portion of the primary radiation (2) by the conversion material (5) into a secondary radiation ( 3), using for the conversion material (5) a material comprising a compound according to any one of claims 1 to 3.