CONVERSION ELEMENT, OPTOELECTRONIC COMPONENT PROVIDED THEREWITH, AND METHOD FOR MANUFACTURING A CONVERSION ELEMENT

Abstract

The invention relates to a conversion element (4) comprising quantum dots (1) designed to convert the wavelength of radiation; each of the quantum dots (1) has a surface (1d), and at least two surfaces (1d) of adjacent quantum dots (1) are connected via at least one linker (7), provided for keeping the quantum dots (1) at a distance from each other, such that a network of quantum dots (1) and linkers (7) is formed.

Claims

1. A conversion element comprising quantum dots, which are designed for wavelength conversion of radiation, wherein the quantum dots each have a surface, wherein at least two surfaces of adjacent quantum dots have at least one linker for spacing the quantum dots, such that a network of quantum dots and linkers is formed, wherein the linker has at least two reactive groups, each of which is covalently or coordinatively bound on the respective surface of the quantum dot.

2. (canceled)

3. The conversion element according to claim 1, wherein the reactive group is a phosphonate group or sulfate group.

4. The conversion element according to claim 1, wherein the linker is formed from at least two pre-linkers, wherein each pre-linker has a functional group which can be cross-linked or hydrosilylatable, so that after the cross-linking or hydrosilylation of the two pre-linkers the linker is formed.

5. The conversion element according to claim 1, wherein the conversion element is free of an inorganic and/or organic matrix material.

6. The conversion element according to claim 1, wherein the distance (d) between adjacent quantum dots is at least 10 nm.

7. The conversion element according to claim 1, wherein the linker comprises a: a) carbon chain having at least 32 carbon atoms, b) silyl chain having at least 32 carbon atoms, c) carbon chain having ester groups in the carbon chain, d) carbon chain having aromatic groups in the carbon chain, e) silyl chain with ester groups in the silyl chain, or f) silyl chain having aromatic groups in the silyl chain, g) polydimethylsiloxane chain or polydiphenylsiloxane chain, wherein the respective chain a) to g) is arranged between the two reactive groups.

8. The conversion element according to claim 1, wherein the carbon chain and/or silyl chain additionally comprises side chains, which are selected from: H, alkoxy, OMe, OCH.sub.2CH.sub.3, OCH.sub.2CH.sub.2CH.sub.3.

9. The conversion element according to claim 1, wherein the functional group can be cross-linked or hydrosilylatable and is selected from a group consisting of vinyl, allyl, haloallyl, acrylate, methacrylate, SiH and epoxy.

10. The conversion element according to claim 1, wherein the quantum dots are selected from a group consisting of InP, CdS, CdSe and CuInSe.sub.2 and/or wherein the quantum dots are free of an inorganic or organic coating.

11. The conversion element according to claim 1, wherein the conversion element is a single-phase system.

12. The conversion element according to claim 1, wherein at least three and at most five linkers are linked covalently or coordinatively to a surface of a quantum dot.

13. An optoelectronic component with a conversion element according to claim 1 comprising: a semiconductor layer sequence which is capable of emitting radiation, wherein the conversion element is arranged in the beam path of the semiconductor layer sequence and converts during operation the radiation emitted by the semiconductor layer sequence into radiation having a changed wavelength.

14. A method for producing a conversion element according to claim 1 comprising the steps of: A) providing at least two quantum dots, each having a surface, B) functionalizing the at least two surfaces with in each case one pre-linker, wherein the respective pre-linker is directly covalently or coordinatively linked to the surface of the respective quantum dot, wherein the pre-linker has a functional group at its end, c) activating the functional group, such that the at least two pre-linkers are connected to one another and form a linker, which connects the two surfaces of the quantum dots, so that the linker and the quantum dots form a network.

15. The method according to claim 14, wherein step C) is carried out by means of an initiator, by means of UV radiation or thermally.

16. The method according to claim 14, wherein the pre-linker has a carbon chain having at least 16 carbon atoms, which in each case have a phosphonate group or sulfate group as a reactive group at their end and a functional group, wherein the carbon chain is directly bonded to the surface of a quantum dot via the phosphonate group or sulfate group, and wherein the carbon chain is bonded via the functional group to a further pre-linker of an adjacent surface of a further quantum dot.

17. The method according to claim 14, wherein the at least one pre-linker comprises a silyl chain having at least 16 Si atoms, which in each case have a phosphonate group or sulfate group as a reactive group and a functional group, wherein the silyl chain is directly bonded to the surface of a quantum dot via the phosphonate group or sulfate group, and wherein the silyl chain is bonded via the functional group to a further pre-linker of an adjacent surface of a further quantum dot.

18. A conversion element comprising quantum dots, which are designed for wavelength conversion of radiation, wherein the quantum dots each have a surface, wherein at least two surfaces of adjacent quantum dots have at least one linker for spacing the quantum dots, such that a network of quantum dots and linkers is formed.

Description

[0053] In the figures:

[0054] FIGS. 1A to 1C each show quantum dots according to one embodiment,

[0055] FIGS. 2A and 2B each show a conversion element according to an embodiment,

[0056] FIGS. 3A to 3C each show a conversion element according to an embodiment,

[0057] FIGS. 4A to 4C each show a conversion element according to an embodiment and

[0058] FIGS. 5A to 5G each show a schematic sectional illustration of an optoelectronic component according to an embodiment.

[0059] 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.

[0060] FIGS. 1A to 1C each show a schematic side view of a quantum dot according to an embodiment. As shown in FIG. 1A, the quantum dot 1 can comprise or consist of a semiconductor core 1a. If the quantum dot 1 consists of a semiconductor core 1a or comprises the latter, the surface 1d of the quantum dot 1 is then the outer surface or surface of the semiconductor core 1a. The semiconductor core 1a can have wavelength-converting properties. The semiconductor core 1a can be formed, for example, from cadmium selenide, cadmium sulfide, indium phosphide and copper indium selenide. The quantum dot 1 can be free of a further coating, for example an inorganic and/or organic coating, as shown in FIGS. 1B and 1C.

[0061] FIG. 1B shows a quantum dot 1 which, in addition to the semiconductor core 1a, has an enveloping or sheathing first layer 1b. The enveloping first layer 1b can, for example, be formed from zinc sulphide. The quantum dot 1 can have an average diameter of 1 to 10 nm. In comparison thereto, the quantum dot 1 of FIG. 1A can have an average diameter of 5 nm.

[0062] FIG. 1C shows a quantum dot 1 which can additionally have a further second enveloping or sheathing layer 1c in addition to the semiconductor core 1a and the first sheathing layer 1b. The further enveloping layer 1c can be an organic coating, for example made of silicone, acrylate or a mixture thereof. If the surface 1d of a respective quantum dot 1 is discussed, this then corresponds to the surface of the first enveloping layer 1b according to FIG. 1B and to the surface of the second enveloping layer 1c according to FIG. 1C.

[0063] FIGS. 2A and 2B each show a schematic side view of a conversion element according to an embodiment. FIG. 2A shows a quantum dot 1 to which a pre-linker 8 is connected. The pre-linker 8 has a reactive group 8b, in this case a reactive phosphonate group. The reactive group 8b can bind covalently and/or coordinatively to the surface 1d of the quantum dot 1. The pre-linker 8 also has a functional group 8a. The functional group 8a can be, for example, vinyl, allyl, haloallyl, acrylate, methacrylate, SiH and/or epoxy. A chain 8c is arranged between the functional group 8a and the reactive group 8b, in this example a carbon chain having 18 carbon atoms. A vinyl group is shown here by way of example as the functional group 8a.

[0064] FIG. 2B shows two quantum dots 1, which are connected to one another via a linker 7 for spacing. The linker 7 has two reactive groups 7a at the chain ends (not shown here). The reactive groups 7a, which are, for example, a phosphonate group or sulfate group, are bound to the surface 1d of the respective quantum dot 1. The linker 7 has a chain between the reactive groups 7a. The chain can, for example, be a carbon chain and/or a silyl chain. In addition, ether groups and/or aromatic units may be part of the chain. A defined distance between the corresponding quantum dots 1 can thus be generated by the linker 7. In particular, the distance is less than or equal to 10 nm, for example 7 nm.

[0065] FIG. 3A shows a possible chain of a linker 7 or pre-linker 8. For example, the linker 7 can be a carbon chain. Furthermore, the carbon chain can additionally have one or more ether groups and/or aromatic groups. At the side ends, the pre-linker 8 has a functional group X, 8b. The functional group X, 8b can be a vinyl, acrylate, methacrylate, halogenated, i.e. in particular fluorinated, allyl group or epoxy group. At the other end of the respective chain of the pre-linker 8 or linker 7, the latter can have a reactive group Y, 8a, which is, for example, a phosphonate or sulfate group.

[0066] FIG. 3C shows the reaction of two pre-linkers 8 to form? a linker 7, wherein the functional groups X of the corresponding pre-linkers 8 react with one another and form a linker 7, wherein the functional groups X are crosslinked or hydrosilylated and a covalent bond is formed between the pre-linkers 8.

[0067] FIG. 4A shows a conversion element, in particular a schematic view of the connection of the quantum dots 1 to pre-linkers 8. In this embodiment, two quantum dots 1 are connected via two pre-linkers 8, i.e. a total of four pre-linkers 8 are linked covalently and/or coordinatively to one another. In this case, a distance d between the quantum dots 1 of at least 10 nm, for example 15 nm, is produced.

[0068] FIG. 4B shows a two-dimensional network of quantum dots 1 and linkers 7, wherein the quantum dots 1 form the corresponding nodes of the network and the linkers 7 form the connecting lines between the nodes or quantum dots 1.

[0069] FIG. 4C shows a three-dimensional network of quantum dots 1 and linkers 7.

[0070] FIGS. 5A to 5G show schematic side views of optoelectronic components 100 according to various embodiments. In particular, the optoelectronic component is a light-emitting diode, for short LED. According to FIG. 5A, the light source 3 is a light-emitting diode chip which is applied to a carrier 2. Directly above the light-emitting diode chip 3, the conversion element 4 is located. This does not exclude that a connecting element, such as an adhesive, is arranged between the respective components. Optionally, the light source 3 and the conversion element 4 are laterally surrounded by a reflector casting 6.

[0071] In the exemplary embodiment as shown in FIG. 5B, the optoelectronic component 100 additionally has a lens 5. The lens 5 can be arranged directly downstream of the conversion element 4.

[0072] In FIG. 5C it can be seen that the conversion element 4 is arranged directly on the light-emitting diode chip or is arranged on the semiconductor layer sequence 3 of the optoelectronic component 100. In this case, the reflector casting 6 is absent in comparison to FIG. 5A.

[0073] In the exemplary embodiment as shown in FIG. 5B, the conversion element 4 surrounds the entire surface of the semiconductor chip or the light source 3. In particular, the conversion element 4 has a constant thickness around the light source 3.

[0074] According to FIG. 5E, the light source or the semiconductor chip 3 is arranged in a recess 10 of an optoelectronic component 100. The recess 10 can be filled with a potting 9, for example made of silicone. The conversion element 4 is arranged directly downstream of the potting 9. The optoelectronic component 100 further comprises a housing 21. In other words, the conversion element is spatially separated from the light source.

[0075] FIG. 5F shows that the conversion element 4 surrounds the semiconductor chip or light source 3 in a cap-like manner, as a result of which the conversion element 4 has a uniform thickness in all directions. The conversion element 4 and the light source 3 can be arranged in a recess of a housing 21 of an optoelectronic component 100 and can be surrounded by a potting 9.

[0076] The exemplary embodiment of FIG. 5G shows an optoelectronic component 100 in which the conversion element 4 surrounds the light source 3, i.e. on its entire surfaces, in a form-fitting and material-to-material manner.

[0077] 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.

[0078] 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.

[0079] This patent application claims the priority of German patent application 10 2015 121 720.1, the disclosure content of which is hereby incorporated by reference.

REFERENCES

[0080] 100 optoelectronic component [0081] D distance [0082] 1 quantum dot or quantum dots [0083] 1a semiconductor core [0084] 1b first sheathing layer [0085] 1c second sheathing layer [0086] 1d surface of the quantum dot [0087] 2 support [0088] 3 semiconductor chip, semiconductor layer sequence, light source [0089] 4 conversion element [0090] 5 lens [0091] 6 reflection potting [0092] 7 linker [0093] 7a reactive group [0094] 8 pre-linker [0095] 8a reactive group [0096] 8b functional group [0097] 8c carbon chain and/or silyl chain [0098] 9 potting [0099] 10 recess [0100] 21 housing