Abstract
The invention relates to an optoelectronic component (100) having a semiconductor chip (2) for generating a primary radiation in the blue spectral range, a conversion element (4) which is arranged in the beam path of the semiconductor chip and is designed to generate a secondary radiation from the primary radiation, wherein the conversion element (4) comprises at least one first phosphor (9) and a second phosphor (10), wherein the first phosphor (9) is Sr(Sr.sub.1xCa.sub.x)Si.sub.2Al.sub.2N.sub.6:Eu.sup.2+ and/or (Sr.sub.1yCa.sub.y)[LiAl.sub.3N.sub.4]:Eu.sup.2+, where 0x1 and 0y1, wherein a total radiation (G) exiting from the component (100) is white mixed light.
Claims
1. An optoelectronic component comprising a semiconductor chip for generating a primary radiation in the blue spectral range, a conversion element which is arranged in the beam path of the semiconductor chip and is designed to generate secondary radiation from the primary radiation, wherein the conversion element comprises at least one first phosphor and a second phosphor, wherein the first phosphor is Sr(Sr.sub.1xCa.sub.x)Si.sub.2Al.sub.2N.sub.6:Eu.sup.2+ and/or (Sr.sub.1yCa.sub.y)[LiAl.sub.3N.sub.4]:Eu.sup.2+ with 0x1 and 0y1, wherein a total radiation (G) exiting from the component is white mixed light.
2. The optoelectronic component according to claim 1, wherein the first phosphor is Sr(Sr.sub.1xCa.sub.x)Si.sub.2Al.sub.2N.sub.6:Eu.sup.2+ having a colour locus Cx between 0.655 and 0.685 and Cy between 0.300 and 0.350 and/or wherein the emission spectrum of the first phosphor Sr(Sr.sub.1xCa.sub.x)Si.sub.2Al.sub.2N.sub.6:Eu.sup.2+ has a maximum full width at half maximum of 82 nm.
3. The optoelectronic component according to claim 1, wherein the first phosphor (Sr.sub.1yCa.sub.y)[LiAl.sub.3N.sub.4]:Eu.sup.2+ has a color locus Cx between 0.680 and 0.715 and Cy between 0.280 and 0.320, and/or wherein the emission spectrum of the first phosphor (Sr.sub.1yCa.sub.y)[LiAl.sub.3N.sub.4]:Eu.sup.2+ has a maximum full width at half maximum of 55 nm.
4. The optoelectronic component according to claim 1, wherein an emitted radiation of the first phosphor has a dominance wavelength in the range of 590 nm to 640 nm.
5. The optoelectronic component according to claim 1, wherein the conversion element has a second phosphor selected from the group consisting of (Ba,Sr).sub.2SiO.sub.4, beta-SiAlON, (Y,Lu).sub.3(Al,Ga).sub.5O.sub.12 and BaSiON, wherein the second phosphor is doped with rare earths and is designed for emitting radiation having a peak wavelength in the spectral range between 510 nm and 590 nm.
6. The optoelectronic component according to claim 1, wherein the second phosphor is a beta-SiAlON.
7. The optoelectronic component according to claim 1, wherein the first phosphor and the second phosphor are dispersed in a matrix material and are arranged directly downstream of a radiation exit area of the semiconductor chip.
8. The optoelectronic component according to claim 1, wherein the conversion element is formed as a layer system comprising at least two layers, wherein the first layer comprises the first phosphor and the second layer comprises the second phosphor, wherein the first layer is arranged between the semiconductor chip and the second layer.
9. The optoelectronic component according to claim 1, wherein the conversion element is formed as a layer system comprising at least two layers, wherein the first layer comprises the first phosphor and the second layer comprises the second phosphor, wherein the second layer is arranged between the semiconductor chip and the first layer.
10. The optoelectronic component according to claim 1, which has a further semiconductor chip, which is designed to generate a further primary radiation in the blue spectral range, wherein the semiconductor chips are arranged in a common recess, wherein the conversion element is formed as a potting and surrounds both semiconductor chips in a form-fitting manner.
11. The optoelectronic component according to claim 1, wherein the blue spectral range has a peak wavelength maximum between 380 nm and 480 nm.
12. A background lighting for a display, which comprises at least one optoelectronic component according to claim 1.
13. A method for producing an optoelectronic component according to claim 1, comprising the following steps: A) Provision of a semiconductor chip for generating a primary radiation in the blue spectral range, B) Provision of a conversion element which is arranged in the beam path of the semiconductor chip and is designed to generate secondary radiation from the primary radiation, wherein the conversion element has at least one first and second phosphor, wherein the first phosphor is Sr(Sr.sub.1xCa.sub.x)Si.sub.2Al.sub.2N.sub.6:Eu.sup.2+ and/or (Sr.sub.1yCa.sub.y)[LiAl.sub.3N.sub.4]:Eu.sup.2+, where 0x1 and 0y1, wherein the component emits white mixed light at least during operation.
Description
[0047] Further advantages, advantageous embodiments and developments will become apparent from the exemplary embodiments described below in conjunction with the figures.
[0048] In the figures:
[0049] FIGS. 1 to 7A each show a sectional illustration of an optoelectronic component according to an embodiment,
[0050] FIG. 7B shows a plan view of an optoelectronic component of FIG. 7A according to an embodiment,
[0051] FIGS. 8A and 8B show emission spectra according to an embodiment,
[0052] FIGS. 9A to 10B show CIE colour diagrams and the associated data according to an embodiment.
[0053] In the exemplary embodiments and figures, identical or identically acting elements can in each case be provided with the same reference symbols. The elements illustrated and their size relationships among one another are not to be regarded as true to scale. Rather, individual elements such as, for example, layers, components and regions are represented with an exaggerated size for better representability and/or for a better understanding.
[0054] FIG. 1 shows a schematic side view of an optoelectronic component according to an embodiment. The optoelectronic component 100 has a substrate 1. The substrate 1 can be, for example, a semiconductor or ceramic wafer, for example a shaped material made of sapphire, silicon, germanium, silicon nitride, aluminium oxide, titanium dioxide, a luminescent ceramic, such as, for example, YAG. Furthermore, it is possible for the substrate to be a printed circuit board, PCB, a metallic lead frame or other type of connection support. At least one semiconductor chip 2 can be arranged on the substrate 1. The semiconductor chip comprises in particular a III-V compound semiconductor material, for example gallium nitride. The semiconductor chip 2 is preferably designed to emit radiation from the blue spectral range during operation of the optoelectronic component, for example between 440 nm and 480 nm. A conversion element 4 is arranged downstream of the semiconductor chip 2. The conversion element 4 is arranged in the beam path of the semiconductor chip 2 and is designed for converting the primary radiation emitted by the semiconductor chip into a secondary radiation having a changed, usually longer, wavelength. An adhesive layer 3 can optionally be present between the conversion element 4 and the semiconductor chip 2. The adhesive layer 3 can be of a high-refractive or a low-refractive material. The conversion element 4 can have a first phosphor 9 and a second phosphor 10. The first phosphor 9, such as Sr(Sr.sub.1xCa.sub.x)Si.sub.2Al.sub.2N.sub.6:Eu.sup.2+ and/or (Sr.sub.1yCa.sub.y)[LiAl.sub.3N.sub.4]:Eu.sup.2+, where 0x1 and 0y1, and the second phosphor 10, such as beta-SiAlON, can be embedded in a matrix material, for example in silicone or epoxy. Depending on the selection of the matrix material and on the refractive index thereof, the adhesive layer 3 can be selected. The optoelectronic component 100 can furthermore optionally have a reflection element 5, for example made of titanium dioxide. The reflection element 5 surrounds both the side surfaces of the semiconductor chip 2 and the side surfaces of the conversion element 4. The optoelectronic component 100 is designed to emit white mixed light as the total radiation G.
[0055] FIG. 2 shows a schematic side view of an optoelectronic component according to an embodiment. The optoelectronic component 100 of FIG. 2 differs from that of FIG. 1 in that the component has no substrate 1. The component 100 of FIG. 2 is thus substrate-free and has contact webs 6. The semiconductor chip 2 is formed here in particular as a top emitter or as a sapphire flip-chip, i.e. has the contact webs 6, which are required for contacting, on a side surface.
[0056] FIG. 3 shows a schematic side view of an optoelectronic component according to an embodiment. The component as shown in FIG. 3 differs from the component 100 of FIG. 1 in that it additionally has a lens 7. The lens can be formed, for example, from silicone and directly to the conversion element, i.e. in direct mechanical and electrical contact.
[0057] FIG. 4 shows a schematic side view of an optoelectronic component according to an embodiment. The component 100 of FIG. 4 differs from the component 100 of FIG. 1, for example, in that the conversion element 4 is formed as a layer system 41, 42. The conversion element 4 has a first layer 41, which has at least the first phosphor, and a second layer, which has at least the second phosphor. The two layers are spatially separated from one another by a further adhesive layer, which may optionally be present. In the case of the component 100 of FIG. 4, the second layer 42 is arranged between the first layer 41 and the semiconductor chip 2. The second layer 42 is designed, in particular, to emit radiation from the green spectral region or range. The first layer 41 is designed in particular to emit radiation from the red spectral range. The semiconductor chip 2 is designed in particular to emit primary radiation from the blue spectral range, so that the total radiation G is a combination of the primary radiation of the semiconductor chip 2 and the two secondary radiations of the layers 41, 42 of the conversion element 4. The total radiation G is then in particular white mixed light.
[0058] FIG. 5 shows a side view of an optoelectronic component according to an embodiment. The optoelectronic component 100 of FIG. 5 differs from the optoelectronic component 100 of FIG. 4 in that the layers 41, 42 of the conversion element 4 are interchanged. In other words, the first layer 41 in the component 100 of FIG. 5 is now arranged between the semiconductor chip 2 and the second layer 42. In other words, the red-emitting first layer 41 of the conversion element 4 is thus arranged downstream of the semiconductor chip 2 and the green, yellow or green-yellow emitting second layer 42 of the conversion element 4 are arranged downstream of the red-emitting first layer 41.
[0059] FIG. 6 shows a schematic side view of an optoelectronic component 100 according to an embodiment. The optoelectronic component 100 of FIG. 6 is almost identical to the optoelectronic component 100 of FIG. 1, except that the component of FIG. 6 additionally has a protective diode (ESD) 8. Said protective diode 8 can optionally be present in the component and can be spaced laterally from the semiconductor chip 2. The protective diode 8 can be arranged on the substrate 1 within the recess 4 of a component. The reflection element can be part of a housing.
[0060] FIG. 7A shows a schematic side view of an optoelectronic component 100 according to an embodiment. The component of FIG. 7A differs from the component 100 of FIG. 6 in that the component 100 has a further semiconductor chip 21. In other words, the component 100 now has two semiconductor chips 2, 21. The two semiconductor chips 2, 21 are spaced apart laterally from one another and are arranged on the substrate 1. Furthermore, a protective diode (ESD) 8 may optionally be present. The two semiconductor chips 2, 21 can be arranged in a common recess 12. In this case, the conversion element is designed as a potting and preferably has the first phosphor and the second phosphor dispersed in a matrix material (not shown here).
[0061] FIG. 7B shows a plan view of an optoelectronic component. In particular, FIG. 7B shows the plan view of a protective diode 8, onto the radiation exit area of the semiconductor chip 2 and onto the radiation exit area of the semiconductor chip 21.
[0062] FIGS. 8A and 8B show emission spectra according to an embodiment and in each case one example of the transmission profile of a blue 8-1, green 8-2 and red 8-3 colour filter. The relative intensity I.sub.rel is shown in both figures as a function of the wavelength in nm. FIGS. 8A and 8B each show the overall emission, that is to say the emission of primary radiation and secondary radiation, of a semiconductor chip in conjunction with a first and a second phosphor 8-4. In the case of FIGS. 8A and 8B, the second, in this case green-emitting phosphor is in each case a beta-SiAlON. In the case of FIG. 8A, the first phosphor is Sr(Ca,Sr)Si.sub.2Al.sub.2N.sub.6:Eu.sup.2+. In the case of FIG. 8B, the first phosphor is (Sr,Ca)[LiAl.sub.3Ni.sub.4]:Eu.sup.2+. Conventional LCD filter systems consist of three (blue, green and red) or four (blue, green, yellow and red) colour filters.
[0063] The LCD filters generally have a half-width FWHM of typically 70 nm to 120 nm, in which the transmission can be electrically controlled. In this case, the transmitted light is obtained from the superposition of the transmission of the individual colour filters. Certain gaps thus arise at the transition points between the filters in the visible spectral range. Consequently, in the case of a broadband almost continuous spectrum, a certain portion of the emitted LED light is absorbed in the filters. In order to be able to obtain the maximum emitted light quantity from the component in the case of completely opened filters on the screen surface, it is therefore advantageous to use narrow-band phosphors, which emit in the region of the individual filter curves (FIGS. 8A and 8B). In this case, it is particularly important that the phosphors used, i.e. the first and second phosphors, in each case emit only within a filter region in order to be able to ensure the largest possible colour space, wherein the properties of an optoelectronic component can be adapted accordingly by different phosphors. The trend is more and more towards larger colour spaces, for example DCI-P3 or Rec2020. Therefore, spectrally particularly well-adapted phosphors are required which make this possible.
[0064] FIGS. 9A and 10A each show a CIE colour standard diagram. The CIEy is represented as a function of CIEx. 9-1 or 10-1 corresponds here to the colour space SRGB, 9-2 or 10-2 corresponds to the colour space DCI-P3, 9-3 or 10-3 corresponds to the colour space Adobe and 9-4 or 10-4 corresponds to the colour space Rec2020. In the images, the covered colour space is additionally represented by the LED and after the filter evaluation. This colour space that can be achieved by the component is almost perfectly congruent with the DCI-P3 colour space (9-2 or 10-2). These colour spaces are known to the person skilled in the art and are therefore not explained in more detail here. FIG. 9B shows in each case the corresponding covering of the described colour spaces in CxCy or uv coordinates by an optoelectronic component of an embodiment in which the primary radiation is generated by a blue-emitting semiconductor chip and the secondary radiation is generated by a first phosphor, which is Sr(Sr.sub.1xCa.sub.x)Si.sub.2Al.sub.2N.sub.6:Eu.sup.2+, and by a second phosphor, which is a beta-SiAlON in this case.
[0065] FIG. 10B shows in each case the corresponding coverage of the described colour spaces in CxCy or uv coordinates by means of an optoelectronic component of an embodiment in which the primary radiation is generated by a blue-emitting semiconductor chip and the secondary radiation is generated by a first phosphor, (Sr.sub.1yCa.sub.y)[LiAl.sub.3Ni.sub.4]:Eu.sup.2+, and by a second phosphor, which is a beta-SiAlON in this case.
[0066] FIGS. 9A and 9B show the data of a system comprising a semiconductor chip which emits primary radiation from the blue spectral range, of a second phosphor being beta-SiAlON and of a first phosphor being Sr(Sr.sub.1xCa.sub.x)Si.sub.2Al.sub.2N.sub.6:Eu.sup.2+. FIGS. 10A and 10B show the data of a system comprising a blue-emitting semiconductor chip 2, a beta-SiAlON as the second phosphor and a first phosphor of the type (Sr.sub.1yCa.sub.y)[LiAl.sub.3N.sub.4]Eu.sup.2+. The reference characters 9-5 and 10-5 designate the white point of the CIE colour standard diagram.
[0067] The exemplary embodiments described in conjunction with the figures and the features thereof can also be combined with one another in accordance with further exemplary embodiments, even if such combinations are not explicitly shown in the figures. Furthermore, the exemplary embodiments described in conjunction with the figures can have additional or alternative features according to the description in the general part.
[0068] The invention is not restricted to the exemplary embodiments by the description on the basis of the exemplary embodiments. Rather, the invention encompasses any new feature and also any combination of features, which includes in particular any combination of features in the patent claims, even if this feature or this combination itself is not explicitly specified in the patent claims or exemplary embodiments.
[0069] This patent application claims the priority of German patent application 10 2015 120 775. 3, the disclosure content of which is hereby incorporated by reference.
LIST OF REFERENCE NUMERALS
[0070] 100 optoelectronic component
[0071] 1 substrate
[0072] 2 semiconductor chip
[0073] 3 adhesive layer
[0074] 4 conversion element
[0075] 5 reflection element or housing
[0076] 6 contact webs
[0077] 7 lens
[0078] 8 protective electrode
[0079] 9 first phosphor
[0080] 10 second phosphor
[0081] 11 matrix material
[0082] G total emission
[0083] 12 recess
[0084] 21 further semiconductor chip
[0085] 31 further adhesive layer
[0086] 41 first layer
[0087] 42 second layer
