EP3390274A1

EP3390274A1 - Conversion element, optoelectronic component provided therewith, and method for manufacturing a conversion element

Info

Publication number: EP3390274A1
Application number: EP16805118.3A
Authority: EP
Inventors: Georg DIRSCHERL
Original assignee: Osram Opto Semiconductors GmbH
Current assignee: Ams Osram International GmbH
Priority date: 2015-12-14
Filing date: 2016-12-01
Publication date: 2018-10-24
Also published as: KR20180093895A; JP2019501407A; DE102015121720A1; US20180371312A1; WO2017102360A1; CN108367916A

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.

Description

description

CONVERSION ELEMENT, OPTOELECTRONIC COMPONENT THEREWITH, AND METHOD FOR PRODUCING A CONVERSION ELEMENT

The invention relates to a conversion element. Further

The invention relates to an optoelectronic component, which in particular comprises a conversion element. Furthermore, the invention relates to a method for producing a

Conversion element.

Conversion elements often have conversion materials, for example quantum dots. The conversion materials convert the radiation emitted by a radiation source into radiation of changed, for example, longer wavelength. The conversion materials are typically dispersed in a polymer-based matrix material to convert the conversion material in a processable form

receive. However, polymer-based matrix materials have the disadvantage that they are permeable to moisture and / or oxygen and / or acidic gases from the environment. Furthermore, polymer-based matrix materials have a low

Aging stability on. On the other hand, a homogeneous and controllable distribution of the conversion materials in the matrix material is difficult to set.

An object of the invention is to provide a conversion element having improved properties.

In particular, a conversion element is to be provided which is free of a polymer as matrix material and thus has a high aging stability. In addition, the conversion element should have a high efficiency. Furthermore, an object of the invention is an optoelectronic component to provide improved properties.

It is a further object of the invention to provide a method of manufacturing a conversion element comprising a conversion element having improved properties

generated.

These objects are achieved by a conversion element according to independent claim 1. Advantageous embodiments and further developments of the invention are the subject of

dependent claims 2 to 12. Furthermore, these objects are achieved by an optoelectronic component according to claim 13. Furthermore, these objects are achieved by a method for producing a conversion element according to claim 14. Advantageous embodiments and further developments of the method are the subject of the dependent claims 15 to 17.

In at least one embodiment, the conversion element comprises or has quantum dots. The quantum dots are designed for wavelength conversion of radiation. The quantum dots each have a surface. At least two surfaces of quantum dots, in particular

adjacent quantum dots are connected to each other at least via a linker. The linker is used for spacing the quantum dots. This forms a network of quantum dots and linkers. In particular, the network is a

two-dimensional and / or three-dimensional network. Network is understood here and below as meaning that the quantum dots form the so-called nodes of the network and the linkers form the connecting lines between the networks

Quantum dots. In particular, the quantum dots and the linkers are linked to one another via chemical bonds, in particular via covalent and / or coordinative bonds. In accordance with at least one embodiment of the conversion element, the conversion element has or consists of quantum dots. The quantum dots are arranged for wavelength conversion or wavelength conversion.

The wavelength-converting quantum dots are in particular a sensitive conversion material, ie a conversion material sensitive to oxygen, moisture and / or acidic gases. Preferably, the quantum dots are nanoparticles, that is

Particles with a size in the nanometer range with a

Particle diameter ds o, for example, between at least 1 nm and at most 1000 nm. The quantum dots comprise a semiconductor core having wavelength-converting properties. In particular, the core of the quantum dots comprises or consists of a II / IV or I I I / V semiconductor.

For example, the quantum dots are selected from a group comprising InP, CdS, CdSe, InGaAs, GalnP and CuInSe2. The semiconductor core may be of one or more

Layers should be coated as a coating. The coating may be organic and / or inorganic. In other words, the semiconductor core may be completely or almost completely covered by further layers on its outer surface or surface.

The semiconductor core can be a single crystal or

polycrystalline agglomerate. According to at least one embodiment, the

Quantum dots have an average diameter of 3 to 10 nm, more preferably from 3 to 5 nm. By varying the size of the quantum dots can specifically Wavelength of the converting radiation are varied and thus adapted for respective applications. The quantum dots can be spherical or

be formed rod-shaped.

A first encapsulating layer of a quantum dot is, for example, an inorganic material such as

For example, zinc sulfide, cadmium sulfide and / or

Cadmium selenide formed and serves to generate the

Quantum dot potential. The first sheath layer and the semiconductor core may be of at least a second one

enveloping layer to be almost completely enclosed on the exposed surface. In particular, the first coating layer is an inorganic ligand shell, which in particular has an average diameter including the semiconductor core of 1 to 10 nm. The second cladding layer may be formed, for example, with an organic material such as cystamine or cysteine, and sometimes serves to improve the solubility of the quantum dots in, for example, a matrix material and / or a solvent. In this case, it is possible that due to the second covering layer a spatially uniform distribution of the quantum dots in a matrix material

is improved. The matrix material can be formed, for example, with at least one of the following substances: acrylate, silicone, hybrid material, such as Ormocer, for example

Ormoclear, polydimethylsiloxane (PDMS), polydivinylsiloxane, for example from PLT, Pacific Light Technologies, or mixtures thereof.

Acrylo-functionalized quantum dots, such as Ormoclear, can be obtained, for example, from Nanoco. When dispersing the quantum dots in an inorganic or organic matrix material often results in the problem that the matrix material is not very stable. It is also a transparent two-component mixture. Furthermore, the matrix material is permeable to moisture and environmental influences, for example acidic gases. In addition, an optimum distance between the individual quantum dots can not be set sufficiently sufficiently so that a quenching of the emitted radiation is increased. this leads to

Efficiency losses of the conversion element.

Alternatively, quantum dot sols or quantum dot dispersions can be used to generate a conversion element. The solvent is removed from a quantum dot dispersion, ie a mixture of quantum dots and solvent, and the quantum efficiency is determined. However, this is very low, since the distance between the individual quantum dots is low due to the

Quantum dot agglomeration. As a result, the emission of the quantum dots is partially or completely extinguished, ie quenched.

The quantum dots of the conversion element each have a surface. The surface can be the surface of the

Be semiconductor. Alternatively, the surface may also be the surface of the first covering layer or a

another covering layer, for example the second covering layer. At least two surfaces, in particular more than two surfaces, of adjacent quantum dots are connected to one another via at least one linker or a plurality of linkers. As a linker or spacer

(English for spacers) is understood here and below a molecular compound that is between at least two Is arranged surfaces of the quantum dots, in particular covalently and / or coordinatively on the surfaces of the

Quantum dots is bound, and thus the quantum dots spaced from each other.

According to at least one embodiment, the quantum dots are selected from a group comprising InP, CdS, CdSe and CuInSe2 and / or wherein the quantum dots are free from an inorganic or organic coating. In other words, the quantum dots then have no further enveloping layer except the semiconductor core.

According to at least one embodiment, the distance

of adjacent quantum dots at least 20 nm, 15 nm, 14 nm, 13 nm, 12 nm, 11 nm, 10 nm, 9 nm, 8 nm or 7 nm and / or at most 30 nm, 40 nm, 50 nm, 100 nm one

Quench the emission reduced or prevented. The spacing of adjacent quantum dots can be adjusted, for example, by the chain length of the linker.

The linker binds chemically to the surface of the respective quantum dot. In particular, the chemical attachment of the linker to the surface of the respective

Quantum dots covalent and / or coordinative. In accordance with at least one embodiment, the linker has at least two

reactive groups. The reactive groups are each terminally attached to the linker. In particular, the reactive groups each bind covalently and / or coordinatively to the respective surface of the corresponding quantum dot.

In at least one embodiment, the reactive group is a phosphonate group and / or sulfate group. In other words, the linker or spacer can be attached to its Side chain ends each having a reactive group. The reactive groups may be spaced from each other by alkyl groups, alkene groups of appropriate chain length. In accordance with at least one embodiment, the linker is formed from at least two pre-linkers. Each of the pre-linkers has a functional group. The functional group is crosslinkable or hydrosilylatable. This can after the

Crosslinked or hydrosilylation of the two pre-linkers of the linker can be generated or is by cross-linking or

Hydrosilylated generated. In other words, during the production of the conversion element, the quantum dots have a pre-linker. The pre-linker points to the one

Chain end a reactive group, for example one

Phosphonate group, on. This phosphonate group binds covalently and / or coordinately to the corresponding surface of the respective quantum dot. At the free chain end of the corresponding pre-linker a functional group is arranged. The functional group is, for example, a vinyl group, acrylic group and / or Si-H group. The

functional group of the respective pre-linker, which is attached to the corresponding surface of the respective quantum dot, covalently bonds with a second pre-linker via its functional group, for example by polymerization or hydrosilylation. As a polymerization, for example, radical, cationic or

anionic polymerization into consideration. Thus, the linker is generated from two pre-linkers by connecting the pre-linker via its functional groups.

In accordance with at least one embodiment, this is

Conversion element free of an inorganic and / or organic matrix material. In other words, that indicates Conversion element no matrix material, in particular

polymer-based matrix material, on. It can therefore be dispensed with the matrix material, since the respective

Quantum dots are chemically linked via the linker.

In at least one embodiment, the linker comprises a carbon chain having at least 32 carbon atoms, more preferably between and including 32 carbon atoms and at most including 40 carbon atoms. Alternatively or additionally, the linker may be a silyl chain

at least including 32 carbon atoms and / or at most including 40 carbon atoms. Alternatively or additionally, the linker may be a

Carbon chain, for example as described above, additionally having ester groups and / or aromatic groups in the carbon chain. Alternatively or additionally, the linker may have a silyl chain, for example as described above, which additionally contains ester groups, H, alkoxy, -OMe, -O-CH 2 -CH 3, -O-CH 2 -CH 2 -CH 3 and / or aromatic groups in having the silyl chain. In particular, the corresponding carbon chains and / or

Silyl chains between the two reactive groups of the linker arranged. Accordingly, the pre-linker may have at least one carbon chain with at least 16 inclusive

Have carbon atoms up to 20 carbon atoms. Alternatively or additionally, the pre-linker may have a silyl chain with at least 16 inclusive

Have silicon atoms and / or a maximum of 20 silicon atoms. Thus, a distance between the quantum dots can be generated, which reduces or prevents quenching of the converting radiation. Alternatively or additionally, the linker PDMS

(Polydimethylsiloxane), PDPS (polydiphenylsiloxane),

Having polydimethylsiloxane or Polydiphenylsiloxanketten, wherein the chains may be substituted with methyl and / or phenyl side groups.

In accordance with at least one embodiment, the pre-linker has the formula C =C- (SiR ₂ -O) n-PO (OH) ₂ with n = 16, 17, 18 or 20 and R =CH ₃ and / or phenyl.

According to at least one embodiment, the

Carbon chain and / or silyl chain in addition to side chains which are selected from: H, alkoxy, -O-CH 2 -CH 3, -O-CH 2 -CH 2 -CH 3, methyl (Me), phenyl (Ph), O-Me, O- Ph.

In accordance with at least one embodiment, the functional group is crosslinkable or hydrosilylbar. In other words, the functional group becomes during the production of the

Conversions element crosslinked and / or hydrosilylated.

Alternatively or additionally, the functional group is selected from a group comprising vinyl, allyl, haloallyl, acrylate, methacrylate, Si-H and epoxy. In accordance with at least one embodiment, this is

Conversion element a single-phase system or single-phase system. In other words, the quantum dots that are linked together via the linkers form only one phase. This does not create miscibility problems, as it does

for example, in a system of quantum dots

dispersed in conventional matrix materials. According to at least one embodiment, the surface of a respective quantum dot or at least 80% of the

Surfaces at least three and not more than five linkers that are covalently or coordinatively attached to the surface of the

Quantum dots are bound.

The inventor has recognized that the chemical attachment of the quantum dots via bimodal linkers, ie linkers having at least two reactive groups, makes it possible to dispense with an additional inorganic and / or organic matrix material. By the chain length of the corresponding linker can also be the necessary distance from adjacent

Quantum dots are set and thus a quenching of the emission can be prevented. Furthermore, short chains of the linker, for example, chains having a chain length of 16 to 20 atoms, can lead to maximization of the inorganic content, resulting in an increase in the blue light content of the emitted radiation and in temperature stability. A lower organic content reduces the

Yellowing of the conversion element. Long chains of the linker, for example chains with a chain length of> 20 atoms, can adjust and adjust the polymer-like toughness. Further, by the conversion element no scattering at the interfaces between a quantum dot and the

Matrix material, as in the conventional

Conversion elements is described present, so that the conversion element has a high transparency.

Furthermore, a conversion element can be provided which has a high degree of filling of quantum dots. The higher the degree of filling of the quantum dots, the thinner it can be Conversion element can be generated. In particular, the layer thickness of a molded as a layer

Conversion element of 1 to 5 ym be. In addition to the

Design freedom provides a thinner layer of

Conversion element and a better heat dissipation and therefore protects in particular temperature-labile quantum dots.

Furthermore, no macrophase separation can be observed by the conversion element described here, since this is a one-phase system and not just a two-phase system comprising a quantum dot and an inorganic or organic matrix material with an increase in the degree of filling.

It will continue to be an optoelectronic device

specified. In particular, the optoelectronic

Component to a conversion element described here. That is, all features described and disclosed for the conversion element are also disclosed for the optoelectronic device and vice versa.

According to at least one embodiment, this includes

Optoelectronic component, a conversion element and a semiconductor layer sequence. The semiconductor layer sequence is capable of emitting radiation. The conversion element is arranged in the beam path of the semiconductor layer sequence and converts the radiation emitted by the semiconductor layer sequence during operation into radiation with a different wavelength. The conversion of the radiation emitted by the semiconductor layer sequence, for example from the blue one

Spectral range, in radiation of changed wavelength, for example in the red or green spectral range, may be complete or partial. For partial conversion mixed-colored light, in particular white light, can be generated.

In accordance with at least one embodiment, the optoelectronic component is a light-emitting diode, or LED for short. The optoelectronic component is then preferably designed to emit blue or white light.

The optoelectronic component comprises at least one optoelectronic semiconductor chip, which the

Semiconductor layer sequence has. The

Semiconductor layer sequence of the semiconductor chip based

preferably on a III-V compound semiconductor material. The semiconductor material is preferably a

Nitride compound semiconductor material such as Al _n _In] __ _n _ _m Ga _m N, or a phosphide compound semiconductor material such as Al _n _In] __ _n _ _m Ga _m P, where in each case 0 ^ n 1, 0 ^ m 1 and n + m <1. May be the semiconductor material is Al _x _Ga] __ _x As well act with 0 ^ x ^ 1. Here, the

Semiconductor layer sequence dopants and additional

Have constituents. For the sake of simplicity, however, only the essential constituents of the crystal lattice of the semiconductor layer sequence, ie Al, As, Ga, In, N or P, are given, even if these can be partially replaced and / or supplemented by small amounts of further substances.

The semiconductor layer sequence includes an active layer with at least one pn junction and / or with one or more quantum well structures. In the operation of the LED or the semiconductor chip becomes in the active layer a

generates electromagnetic radiation. A wavelength or a wavelength maximum of the radiation is preferably in the ultraviolet and / or visible and / or infrared Spectral range, in particular at wavelengths between 420 nm and 800 nm inclusive, for example between 440 nm and 480 nm inclusive. The conversion element is in the beam path of the

Semiconductor layer sequence arranged. In particular, the conversion element converts the UV, IR or visible radiation emitted by the semiconductor layer sequence into radiation having a modified, for example a longer wavelength,

For example, in red, green, orange light

completely or partially.

In accordance with at least one embodiment, this is

Conversion element arranged directly on the semiconductor layer sequence of the semiconductor chip. With direct will here and in the

Understood below, that the conversion element is applied directly, so that no further layers or elements between the semiconductor layer sequence and the

Conversion element are arranged. This does not exclude that between the semiconductor layer sequence and the

Conversion element is arranged a connecting means, such as an adhesive.

Alternatively, the conversion element of the

Semiconductor chip spaced. It can then more

Elements or layers may be arranged between the semiconductor layer sequence and the conversion element. As another

Layers can be used, for example, as adhesive layers.

The invention further relates to a method for producing a conversion element. Preferably, with the

Process the conversion element described above produced. That is, all features disclosed for the conversion element are also for the method for

Production of a conversion element disclosed and

vice versa. The same applies to the optoelectronic

Component, in particular an above-described

Conversion element includes.

In accordance with at least one embodiment, the method for producing a conversion element comprises the steps:

A) providing at least two quantum dots,

in particular more than two quantum dots, each having a surface, B) functionalizing the at least two surfaces, each with a pre-linker, wherein the respective pre-linker directly to the surface of the respective quantum dot

covalently or coordinatively attached, wherein the pre-linker terminally has a functional group,

C) Activation of the functional group, so that at least two or exactly two pre-linkers are joined together to form a linker that forms the two surfaces of the

Connects quantum dots together so that the linker and the quantum dots form a network.

In accordance with at least one embodiment, step C) takes place by means of an initiator, by UV radiation or thermally. As an initiator, for example, Lucirin TPO-L can be used. Alternatively, the functional groups can also be activated thermally, for example at a temperature of 60 ° C to 180 ° C. In at least one embodiment, the pre-linker has a carbon chain of at least 16 inclusive

Carbon atoms and / or at most including 20

Carbon atoms on the terminal one each

Phosphonate group or sulfate group as a reactive group and have a functional group. The carbon chain binds directly via the phosphonate group and / or sulfate group to the surface of a quantum dot. Via the functional group, the carbon chain is connected chemically, in particular covalently, with another pre-linker of an adjacent surface of another quantum dot. The covalent bond can be by hydrosilylation or polymerization, for example by radical

Polymerization, carried out.

In accordance with at least one embodiment, the pre-linker has a silyl chain with at least 16 inclusive

Silicon atoms and / or at most including 20

Silicon atoms on. At the end of the silyl chain, a phosphonate group or sulfate group is arranged as a reactive group and a functional group. Via the phosphonate group or sulfate group, the silyl chain can be attached directly to the surface of a quantum dot.

In particular, the silyl chain via the functional group is connected to another pre-linker of an adjacent surface of another quantum dot. The connection between the functional groups can be effected by polymerization, ie crosslinking, or hydrosilylation. Further advantages, advantageous embodiments and

Further developments emerge from the following in

Compound described with the figures

Exemplary embodiments. FIGS. 1A to 1C each show quantum dots according to a

Embodiment, Figures 2A and 2B each have a conversion element according to an embodiment, Figures 3A to 3C each have a conversion element according to an embodiment, Figures 4A to 4C each have a conversion element according to an embodiment and Figures 5A to 5G each have a schematic

Sectional view of an optoelectronic

Component according to one embodiment. In the exemplary embodiments and figures, identical, identical or identically acting elements can each be provided with the same reference numerals. The illustrated elements and their proportions with each other are not to be regarded as true to scale. Rather, individual elements, such as layers, components, components and areas for exaggerated representability and / or better understanding can be displayed exaggerated.

FIGS. 1A to 1C each show a schematic

Side view of a quantum dot according to a

Embodiment. The quantum dot 1 may, as shown in FIG. 1A, comprise or consist of a semiconductor core 1a. If the quantum dot 1 consists of a semiconductor core - li ^¬ la or includes this, then the surface is ld of the

Quantum dot 1 the outer surface or surface of the

Semiconductor core la. The semiconductor core la can

have wavelength converting properties. Of the

Semiconductor core la may, for example, be cadmium selenide,

Cadmium sulfide, indium phosphide and copper indium selenide. The quantum dot 1 can be free from another

Coating, for example, an inorganic and / or organic coating, as shown in Figures 1B and IC be.

FIG. 1B shows a quantum dot 1 which is next to the

Semiconductor core la has an enveloping first layer 1b. For example, the enveloping first layer 1b may be formed of zinc sulfide. The quantum dot 1 may have an average diameter of 1 to 10 nm. In comparison, the quantum dot 1 of Figure 1A may have an average diameter of 5 nm. The figure IC shows a quantum dot 1, in addition to the

Semiconductor core la and the first enveloping layer lb additionally a further second enveloping layer lc

can have. The further enveloping layer 1c may be an organic coating, for example of silicone, acrylate or a mixture thereof. If one speaks of the surface 1 d of a respective quantum dot 1, then according to FIG. 1B this corresponds to the surface of the first enveloping layer 1b and according to FIG. 1C to the surface of the second enveloping layer 1c.

FIGS. 2A and 2B each show a schematic

Side view of a conversion element according to a

Embodiment. FIG. 2A shows a quantum dot 1, at to which a pre-linker 8 is connected. Pre-linker 8 has a reactive group 8b, here a reactive phosphonate group. The reactive group 8b can covalently and / or coordinately bind to the surface ld 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, Si-H and / or epoxy. Between the functional group 8a and the reactive group 8b is a chain 8c, in this example a

Carbon chain with 18 carbon atoms, arranged. As functional group 8a, a vinyl group is shown by way of example here.

FIG. 2B shows two quantum dots 1, which are connected via a

Linker 7 are connected to each other for spacing or connected. The linker 7 has two reactive groups 7a at the chain ends (not shown here). The reactive groups 7 a, which are, for example, a phosphonate group or sulfate group, are bonded to the surface 1 d 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. Additionally, ether groups and / or aromatic moieties may be part of the chain. This can be a

defined distance between the corresponding ones

Quantum dots 1 are generated by the linker 7.

In particular, the distance is less than or equal to 10 nm, for example 7 nm. Figure 3A shows a possible chain of a linker 7 or pre-linker 8. For example, the linker 7 a

Be carbon chain. Furthermore, the carbon chain may additionally contain one or more ether groups and / or have aromatic groups. At the side ends, the pre-linker 8 has a functional group X, 8b. The

functional group X, 8b may be a vinyl, acrylate,

Methacrylate, halogenated, ie in particular fluorinated, allyl group or epoxy group. At the other end of the respective chain of the pre-linker 7 or linker 7, this may have a reactive group Y, 8a which is, for example, a phosphonate or sulfate group. FIG. 3C shows the reaction of two pre-linkers 8 to a linker 7. The functional groups X of the corresponding pre-linkers 8 react with one another and form a linker 7, the functional groups X crosslinking or hydrosilylating and a covalent bond between the pre-linker 8 is formed.

FIG. 4A shows a conversion element, in particular a schematic view of the connection of the quantum dots 1 with pre-linkers 8. In this embodiment, two

Quantum dots 1 via two pre-linker 8, ie

a total of four pre-linkers 8, linked together covalently and / or coordinatively. This creates a distance d between the quantum dots 1 of at least 10 nm, for example 15 nm.

FIG. 4B shows a two-dimensional network of

Quantum dots 1 and linkers 7. Here form the

Quantum dots 1, the corresponding nodes of the

Network and the linker 7, the connecting lines between the nodes or quantum dots. 1

FIG. 4C shows a three-dimensional network

Quantum dots 1 and linkers 7. FIG. 5 shows schematic side views of optoelectronic components 100 according to various embodiments

Embodiments. In particular, the optoelectronic component is a light-emitting diode, in short LED. According to FIG. 1A, the light source 3 is a light-emitting diode chip which is applied to a carrier 2. Immediately above the LED chip 3 is the conversion element 4. Direct applied here does not exclude that a connecting means, such as an adhesive, is located between the respective components. Optionally, the light source 3 and the conversion element 4 are laterally surrounded by a reflector casting 6.

In the exemplary embodiment, as shown in FIG. 1B, the optoelectronic component 100 additionally has a lens 5. The lens 5 may be arranged directly downstream of the conversion element 4.

In Figure 5C it can be seen that the conversion element 4 directly on the LED chip or on the

Semiconductor layer sequence 3 of the optoelectronic component 100 is arranged. In contrast to FIG. 5A, the reflector casting 6 is missing. In the exemplary embodiment, as shown in FIG. 1B, the conversion element 4 surrounds the entire surface of the body

Semiconductor chips or the light source 3. In particular, the conversion element 4 has a constant thickness around the light source 3 around.

According to FIG. 1C, the light source or the semiconductor chip 3 is arranged in a recess 10 of an optoelectronic component 100. The recess 10 can with a casting 9, for example, made of silicone, be filled. The potting 9 is directly downstream of the conversion element 4. The

Optoelectronic component 100 also has a housing 21. In other words, the conversion element 4 is spatially spaced from the light source 3.

FIG. 1F shows that the conversion element 4 surrounds the semiconductor chip or light source 3 like a cap, as a result of which the conversion element 4 has a uniform thick layer in all directions. The conversion element 4 and the light source 3 can in a recess of a

Housing 21 of an optoelectronic device 100th

be arranged and surrounded by a potting 9. The embodiment of Figure IG shows

Optoelectronic device 100, in which the

Conversion element 4, the light source 3 all around, so from its entire surface, positive and cohesive

enveloped.

The ones described in connection with the figures

Embodiments and their features can according to

Further embodiments are also combined with each other, even if such combinations are not explicitly shown in the figures. Furthermore, the embodiments described in connection with the figures, additional or alternative features as described in

general part. The invention is not by the description based on the

Embodiments limited to these. Rather, the invention encompasses every new feature as well as every combination of features, which in particular any combination of features in The patent claims, even if this feature or this combination itself is not explicitly in the

Claims or embodiments is given. This patent application claims the priority of German Patent Application 10 2015 121 720.1, the disclosure of which is hereby incorporated by reference.

Reference sign list

100 optoelectronic component

d distance

1 quantum dot or quantum dots

la semiconductor core

lb first coating layer

lc second jacketing layer

ld surface of the quantum dot

2 carriers

3 semiconductor chip, semiconductor layer sequence, light source

4 conversion element

5 lens

6 Reflection potting

7 linkers

7a reactive group

8 pre-linkers

8a reactive group

8b functional group

8c carbon chain and / or silyl chain

9 potting

10 recess

21 housing

Claims

claims

Conversion element (4) comprising

Quantum dots (1) arranged for wavelength conversion of radiation,

wherein the quantum dots (1) each have a surface (ld), wherein at least two surfaces (ld)

adjacent quantum dots (1) via at least one linker (7) for spacing the quantum dots (1) are connected, so that a network of quantum dots

(1) and linker (7) is formed.

Second conversion element (4) according to claim 1,

wherein the linker (7) has at least two reactive groups (7a), each at the respective surface

(ld) of the quantum dot (1) are covalently or coordinate bonded.

3. conversion element (4) according to one of the preceding

Claims,

wherein the reactive group (7) is a phosphonate group or sulfate group.

4. conversion element (4) according to one of the preceding

Claims,

wherein the linker (7) is formed from at least two pre-linkers (8), each pre-linker (8) having a

having functional group (8b) which are crosslinkable or hydrosilylatable, so that after crosslinking or hydrosilylation of the two pre-linker (8) of the linker (7) is generated.

5. conversion element (4) according to one of the preceding claims,

wherein the conversion element (4) free of a

inorganic and / or organic matrix material.

6. Conversion element (4) according to one of the preceding claims,

wherein the distance (d) of adjacent quantum dots (1) is at least 10 nm.

7. Conversion element (4) according to one of the preceding claims,

wherein the linker (7) has a:

a) carbon chain (8c) with at least 32

Carbon atoms,

b) silyl chain (8c) with at least 32 carbon atoms, c) carbon chain (8c) with ester groups in the

Carbon chain,

d) carbon chain (8c) with aromatic groups in the carbon chain,

e) silyl chain (8c) with ester groups in the silyl chain, or

f) Silyl chain (8c) with aromatic groups in the

Silylkette,

g) polydimethylsiloxane chain (8c) or

Polydiphenylsiloxane chain (8c),

wherein the respective chain (8c) a) to g) are arranged between the two reactive groups (8a).

8. Conversion element (4) according to one of the preceding claims, wherein the carbon chain and / or silyl chain (8c) additionally has side chains selected from: H, alkoxy, -OMe, -O-CH ₂ -CH ₃ , -O-CH ₂ -CH ₂ -CH ₃ .

9. conversion element (4) according to one of the preceding

Claims,

wherein the functional group (8b) is crosslinkable or hydrosilylable and is selected from a group comprising vinyl, allyl, haloallyl, acrylate, methacrylate, Si-H and epoxy.

10. Conversion element (4) according to one of the preceding

Claims,

wherein the quantum dots (1) are selected from a group comprising InP, CdS, CdSe and CuInSe ₂ and / or wherein the quantum dots (1) are free from an inorganic or organic coating (lb, lc).

11. Conversion element (4) according to one of the preceding

Claims,

wherein the conversion element (4) is a single-phase system.

12. conversion element (4) according to one of the preceding

Claims,

wherein at least three and at most five linkers (7) are covalently or coordinatively attached to a surface (ld) of a quantum dot (1). 13. Optoelectronic component (100) with a

Conversion element (4) according to one of claims 1 to 12 comprising: a semiconductor layer sequence (3) capable of emitting radiation,

wherein the conversion element (4) is arranged in the beam path of the semiconductor layer sequence (3) and the radiation emitted by the semiconductor layer sequence (3) in the

Operation converted into radiation with changed wavelength.

Process for producing a conversion element (4) according to one of Claims 1 to 12, comprising the steps:

A) providing at least two quantum dots (1), each having a surface (ld),

B) functionalizing the at least two surfaces (ld) each with a pre-linker (8),

wherein the respective pre-linker (8) directly to the

Surface (ld) of the respective quantum dot (1) is covalently or coordinately connected, wherein the pre-linker (8) terminally has a functional group (8a),

C) activation of the functional group (8a) such that the at least two pre-linkers (8) are joined together to form a linker (7) comprising the two

Surface (ld) of the quantum dots (1) connects to each other, so that the linker (7) and the quantum dots (1) form a network.

15. The method according to claim 14,

wherein step C) takes place by means of an initiator, by UV radiation or thermally.

16. The method according to claim 14,

wherein the pre-linker (8) has a carbon chain with at least 16 carbon atoms, the terminally each having a phosphonate group or sulfate group as a reactive group (8b) and a functional group (8a), wherein the carbon chain via the phosphonate group or sulfate group directly to the 5 surface (ld) of a quantum dot (1) and wherein the carbon chain via the functional group (8a) with another pre-linker (8) of an adjacent surface (ld) of another

Quantum dot (1) is covalently connected.

10

17. The method according to claim 14,

wherein the at least one pre-linker (8) comprises a silyl chain

has at least 16 Si atoms which terminally each have a phosphonate group or sulfate group as a reactive group (8b)

15 and a functional group (8a), wherein the

Silyl chain via the phosphonate group or sulfate group directly to the surface (ld) of a quantum dot (1)

and wherein the silyl chain via the functional group (8a) with a further pre-linker (8) of a

20 adjacent surface (ld) of another quantum dot (1) is connected.