DE102015101598A1 - A radiation-emitting optoelectronic device and method for producing a radiation-emitting optoelectronic device - Google Patents

Abstract

The invention relates to a radiation-emitting optoelectronic device which comprises a housing body (1), at least one optoelectronic radiation-emitting semiconductor (2) and a radiation-transmissive element (3) different from the housing body (1). The housing body (1) surrounds the at least one optoelectronic radiation-emitting semiconductor (2) at least in places. The radiation-transmissive element (3) is arranged in the beam path of the radiation-emitting semiconductor (2) and has a fluoropolymer. Furthermore, the invention relates to a method for producing a radiation-emitting optoelectronic device.

Description

The present invention relates to a radiation-emitting optoelectronic device and to a method for producing a radiation-emitting optoelectronic device.

The object of the invention is to provide a radiation-emitting optoelectronic device, which is characterized by a particularly high stability and a long service life.

This object is achieved by a radiation-emitting optoelectronic device according to claim 1. Further embodiments of the device according to the invention and a method for producing a radiation-emitting optoelectronic device are the subject of further claims.

The invention according to the main claim 1 is a radiation-emitting optoelectronic device comprising a housing body ( 1 ), at least one optoelectronic radiation-emitting semiconductor ( 2 ) and one from the housing body ( 1 ) various radiation-transmissive element ( 3 ). The housing body ( 1 ) surrounds the at least one optoelectronic radiation-emitting semiconductor ( 2 ) at least in places. The radiation-transmissive element ( 3 ) is in the beam path of the radiation-emitting semiconductor ( 2 ) and comprises a fluoropolymer.

The radiation-transmissive element can be located, for example, in the region of the main radiation exit surface of the radiation-emitting optoelectronic device. Fluoropolymers are to be understood in particular as meaning organic fluoropolymers comprising carbon-fluorine bonds and a skeleton comprising carbon-carbon bonds.

In conventional radiation-emitting optoelectronic devices, radiation-permeable elements in the region of the main radiation exit surface, which are different from the housing body, are silicones, polymers or even vitreous materials.

While vitreous materials have good robustness, they are usually associated with high costs and expensive to manufacture.

Epoxies and conventional polymers are in widespread use. However, they only have limited lifetimes. High temperatures, such as are found in many radiation-emitting optoelectronic devices in combination with radiation of at least partially high intensity and high energy (for example short-wavelength blue light with about 420 nm wavelength or ultraviolet radiation with wavelengths below 410 nm), lead to polymer degradation, ie the cleavage of covalent bonds in the polymer chains. This is often noticeable in operation by a yellowing of the radiation-transmissive element, as well as by a loss of brightness of the entire radiation-emitting optoelectronic device.

Radiation-transmissive elements may also consist of silicones in conventional radiation-emitting optoelectronic devices, which are often more stable than, for example, epoxy-based materials, but whose stability is nevertheless insufficient for many applications. In particular, they are not sufficiently resistant to high-energy radiation such as ultraviolet radiation.

For the radiation-transmissive element, there are high demands on the transparency or radiolucency not only for visible light, but in a broad spectral range. The spectral range may include electromagnetic radiation, which may include, for example, infrared radiation, visible light and in particular also ultraviolet radiation (UV radiation).

Due to the high transparency or radiolucency of radiation-transmissive elements for a broad spectral range, the radiation emitted by the optoelectronic semiconductor acts on the entire radiation-transmissive element and not only on its surface as in the case of radiopaque or even reflective components. This leads to particularly high demands on the stability to high-energy radiation such as UV radiation.

Radiation-emitting optoelectronic devices according to the invention - comprising a radiation-transmissive element comprising an organic fluoropolymer - are particularly durable. They also allow a comparatively constant radiation emission over a long period of operation, since they are much less prone to yellowing than conventional polymers. Due to the high stability, no further additives have to be used for stabilization, which in turn represent an additional yellowing risk.

Organic fluoropolymers have an extremely strong C-F bond (460 KJ / mol). The fluorine groups also shield the polymer backbone, having C-C bonds, to the outside. For this reason, fluoropolymers are suitable for long-term use temperatures of about 260 ° C. This is well above temperatures of about 150 ° C as they can occur in radiation-emitting optoelectronic components, for example in LEDs. In addition, fluoropolymers are also resistant to a wide range of chemicals and have low flammability. In addition, there is a very high transparency and radiolucency even against short-wave radiation, such as UV radiation.

The high thermal stability of fluoropolymers can be experimentally demonstrated by the fact that they often have no high mass loss, often less than one percent by weight, even at very high temperatures of up to 488 ° C. Their properties are also largely constant over a wide temperature range of up to -260 ° C to + 260 ° C up to plus 300 ° C.

Fluoropolymers have a high stability in a broad spectral range compared to short-wave electromagnetic radiation. For example, they are also stable to UV radiation and even withstand a continuous irradiation with high-energy UV radiation. This high long-term stability with respect to short-wave radiation is surprisingly also given for fluoropolymers which have a high transmission to high-energy radiation (for example ultraviolet radiation with wavelengths in the range from 410 to 230 nm). For such short wavelength radiation transmissive fluoropolymers, the radiation is not already reflected or absorbed by the outer layers of the polymeric material.

Radiation-permeable fluoropolymers are surprisingly also suitable at high temperature (in some cases well above 150 ° C.), in the simultaneous presence of short-wave radiation, such as UV radiation, due to their stability, but in particular their constant radiation transmission for radiation-transmissive elements of radiation-emitting optoelectronic devices. Even in the area of the largest radiation exposure, the area of the main radiation exit surface, they are stable and radiolucent over long periods of operation.

Radiolucent elements also have significantly higher requirements for radiopacity (for a wide radiation range, e.g., also for UV radiation) over a long period of operation than for other components of the radiation-emitting device, e.g. Housing components that are not in the area of the main radiation exit surface. However, fluoropolymers can also be used for such applications.

In contrast to conventional optoelectronic devices, the radiation-emitting optoelectronic devices according to the invention are therefore characterized by a longer service life, a lower tendency to yellowing and thus lower brightness losses.

In the following, various embodiments of the present invention will be discussed:

In one embodiment of the radiation-emitting optoelectronic device according to the invention, the radiation-transmissive element consists of the fluoropolymer.

In a different embodiment of the radiation-emitting optoelectronic device according to the invention, the radiation-transmissive element comprises the fluoropolymer and at least one additive. The additive may be e.g. to trade a dye. In particular, the additive may be a wavelength conversion substance which can at least partially convert the radiation emitted by the radiation-emitting optoelectronic semiconductor into radiation of longer wavelength, that is to say with lower energy.

In a particularly preferred embodiment of the radiation-emitting optoelectronic device according to the invention, the radiation-transmissive element is a potting material. Here, the potting material on the fluoropolymer or may consist of the fluoropolymer.

The requirements for stability, in particular the requirements for a consistently good transmission over a broad radiation spectrum up to UV radiation are for Potting materials particularly high, since the potting material and the radiation-emitting optoelectronic semiconductor can be in direct contact with each other. The potting material experiences here an additional increase in temperature (eg due to a Stokes shift). In particular, the dissipation of heat via the potting and the housing takes place very slowly, which can lead to elevated temperatures in the region of the potting material.

Due to the fact that the radiation-transmissive element is a potting material, it is also possible to manufacture the radiation-emitting components according to the invention with little effort and thus cost-effectively.

In a different development of the invention, the radiation-transmissive element is spaced from the radiation-emitting semiconductor (often referred to as "remote application"). Thus, for example, there may be a cavity between the radiation-transmissive element and the radiation-emitting semiconductor. In this way, e.g. the thermal load can be reduced by avoiding direct contact with the semiconductor.

In a particularly preferred embodiment of the radiation-emitting optoelectronic device according to the invention, the radiation-emitting semiconductor at least partially emits ultraviolet radiation. Ultraviolet radiation-emitting opto-electronic devices, such as e.g. UV LEDs are used for a variety of possible applications. They are used, for example, for sterilization purposes, for example for the sterilization of surfaces or water. Another field of application is dentistry, such as the hardening of dental fillings. However, UV radiation-emitting optoelectronic devices are also used in optical sensors. A variety of analysis techniques in the field of forensics as well as human or veterinary medicine, for example for the examination of body fluids, e.g. for protein analysis, rely on UV radiation emitting devices. There are also devices for use in light therapy. Additionally, UV radiation emitting devices play an important role in a variety of printing techniques. In addition, a number of phosphor-based radiation-emitting devices can be operated particularly efficiently with UV-LED pumps.

The stability requirements here are particularly high compared to the high-energy UV radiation. In addition, despite the action of the short-wave UV radiation having wavelengths of less than 410 nm, the radiolucent element must have a high transmission with respect to UV radiation over the entire service life.

The inventors have recognized that radiolucent elements comprising fluoropolymers meet this high requirement. Conventional polymers, however, are usually not sufficiently stable and usually not radiolucent in the UV range.

The transmission for UV radiation is significantly higher for fluoropolymers than for conventional polymers. Conventional polymers typically have an absorption edge at about 350-400 nm, i. at wavelengths smaller than 350 nm, no appreciable transmission takes place. Fluoropolymers, as used in the case of the present invention, often have a transmission of more than 90%, often greater than or equal to 94%, even at wavelengths in the range of 250 nm to 300 nm, in contrast to conventional polymers.

In another development of the radiation-emitting optoelectronic device according to the invention, the radiation-emitting semiconductor at least partially emits UV radiation in the range of 400-320 nm (near UV light, abbreviation UVA). Furthermore, the radiation-emitting semiconductor can also at least partially emit UV radiation in the range of 320-290 nm (average UV, abbreviation UVB) or even UV radiation in the range of 290-100 nm (far UV, abbreviation UVC).

Radiation-permeable elements comprising fluoropolymers are more stable than conventional polymers and more radiolucent than conventional polymers over the aforementioned types of UV radiation, and often even against even shorter wavelength UV radiation (e.g., vacuum UV or even extreme UV).

A further preferred embodiment of the radiation-emitting optoelectronic device according to the invention has a housing body, which likewise comprises at least one fluoropolymer, wherein the housing body is in contact with the radiation-transmissive element.

The fact that both housing body as well as the radiolucent element equally comprise a fluoropolymer, the stability of the radiation-emitting optoelectronic devices can be further increased. For example, it is possible for degradation to occur at the contact points between the radiation-transmissive element and the housing body due to high temperatures and high-energy radiation in some radiation-emitting optoelectronic devices, and these points therefore represent a weak point in the overall arrangement. By manufacturing both components, housing body and radiation-transmissive element, each of fluoropolymers with similar chemical properties, a particularly intimate connection of the components is possible, which can have a positive effect on the overall service life. Also, a yellowing in the area of the contact points could possibly be avoided.

In a further embodiment, the housing body is made of a fluoropolymer.

It is also possible that both the housing body and the radiation-transmissive element have the same fluoropolymer or consist of the same fluoropolymer. When using the same fluoropolymer, it is possible to make the compound of the two components particularly stable.

Alternatively, it is also possible for the radiation-emitting element to comprise a fluoropolymer or to consist of a fluoropolymer, while the housing body has a fluoropolymer merely as matrix material, into which further materials, for example radiation-reflecting particles of inorganic oxides, such as TiO ₂ , can be introduced. In this way, the housing material can be colored white and thus highly reflective. For example, the housing can also have porous fluoropolymers which have a particularly high reflection, for example greater than 90%, for example 95%. For example, a radiolucent fluoropolymer for the radiolucent element may be combined with a reflective fluoropolymer for the housing.

wobei die Substituenten X₁ bis X₄ jeweils unabhängig voneinander ausgewählt sind aus der Gruppe umfassend:

• – Wasserstoff,
• – Halogen, insbesondere Chlor und Fluor,
• – R
• – OR wobei der Rest R jeweils ein Kohlenwasserstoffrest C₁-C₁₀ oder ein fluorierter Kohlenwasserstoffrest C₁-C₁₀ sein kann,

und wobei zumindest einer der Substituenten X₁ bis X₄ Fluor ist.In a preferred embodiment of the radiation-emitting optoelectronic device according to the invention, the fluoropolymer has a first repeating structural unit A of the following general formula:

wherein the substituents X ₁ to X _{4 are} each independently selected from the group comprising:

• - hydrogen,
• Halogen, in particular chlorine and fluorine,
• - R
• OR wherein the radical R may in each case be a hydrocarbon radical C ₁ -C ₁₀ or a fluorinated hydrocarbon radical C ₁ -C ₁₀ ,

and wherein at least one of the substituents X ₁ to X _{4 is} fluorine.

Here and below, the symbol "*" stands for binding sites of the recurring structural unit, which are connected to the next recurring structural unit. In addition, at the end of the polymer chain end groups can close the polymer, which may for example be selected from the same group of substituents as the substituents X ₁ to X ₄ . But there are also other common end groups conceivable.

The inventors of the present invention have recognized that polymers having said repeating structural unit A are particularly suitable for the radiation-emitting optoelectronic devices according to the invention.

In particular, it is preferred if at least two of the radicals X ₁ -X _{4 are} fluorine atoms. Still more preferably, if at least three or exactly three of the radicals X ₁ -X ₄ fluorine atoms. In another particularly preferred embodiment, four of the radicals are fluorine atoms. Overall, the stability increases with increasing number of fluorine atoms.

R can be a hydrocarbon radical C ₁ -C ₁₀ , it being preferred for R to be a hydrocarbon radical C ₁ -C ₅ , in particular C ₁ -C ₃ . The hydrocarbon radical may be, for example, saturated, unsaturated, normal or branched and cyclic hydrocarbon radicals, in particular alkyl radicals. But also aromatic residues are conceivable. R can be unsubstituted or substituted.

It is particularly preferred if R is a fluorinated hydrocarbon radical C ₁ -C ₁₀ , for example a fluorinated hydrocarbon radical having up to five (C ₁ -C ₅ ) or more preferably having up to three carbon atoms (C ₁ -C ₃ ). R can, for example, have the general formula -C _n F _{2n + 1} (with n less than or equal to 10, preferably n less than or equal to 5, or with n less than or equal to 3). For example, the radical R can thus be a CF ₃ group, a C ₂ F ₅ group or a C ₃ F ₇ group. But not completely fluorinated groups or longer chains are conceivable. The higher the degree of fluorination, the more stable the fluoropolymer in general.

It is particularly preferred in general if R is a perfluorinated hydrocarbon radical. The introduction of a radical R or OR for at least one or exactly one of the substituents X ₁ to X ₄ leads to a better processability of the fluoropolymer, in particular the fluoropolymer is thereby better castable. This opens up processing through a variety of thermoplastic processes and is also crucial for the use of fluoropolymers as part of potting materials, for example.

Processing by casting, injection molding, film or tube extrusion are but a few examples of possible processing techniques. Such fluoropolymers thus have advantages over conventional fluoropolymers in processing and in particular enable large-scale production.

In a preferred embodiment, A is a repeating structural unit selected from the group of repeating structural units of the following general formulas:

In a particularly preferred embodiment, the fluoropolymer is a fluoropolymer suitable for injection molding. Particular preference is given to meltable fluorine-containing thermoplastics as fluoropolymers. These polymers are easy to process by injection molding or extrusion.

In another embodiment, the fluoropolymer is injection-moldable modified polytetrafluoroethylene (PTFE). (Conventional PTFE is not suitable for injection molding.) PTFE is thermoset when heated, but does not flow sufficiently after melting the crystalline areas and therefore can not be thermoplastic.) An example of a thermoplastic, injection moldable on modified PTFE based fluoropolymer is the fluoropolymer brand name Moldflon ^® Elring Klinger.

umfasst,
wobei die Substituenten Y₁ bis Y₄ jeweils unabhängig voneinander ausgewählt sind aus der Gruppe umfassend:

• – Wasserstoff,
• – Halogene, insbesondere Chlor und Fluor,
• – R,
• – OR, wobei der Rest R jeweils ein Kohlenwasserstoffrest oder ein fluorierter Kohlenwasserstoffrest C₁-C₁₀ sein kann

oder wobei die Struktureinheit B die Formel

aufweisen kann. In another particularly preferred embodiment of the invention, the fluoropolymer is a copolymer which, in addition to the first structural unit A, has at least one further structural unit B of the general formula which is different from the first structural unit A.

includes,
wherein the substituents Y ₁ to Y _{4 are} each independently selected from the group comprising:

• - hydrogen,
• Halogens, in particular chlorine and fluorine,
• - R,
• - OR, wherein the radical R may each be a hydrocarbon radical or a fluorinated hydrocarbon radical C ₁ -C ₁₀

or wherein the structural unit B is the formula

can have.

The inventors of the present invention have found that copolymers of the described form having two different repeating structural units A and B are particularly suitable for radiation-transmissive elements for radiation-emitting optoelectronic devices according to the invention. The use of copolymers of the form described makes it possible to obtain fluoropolymers which are particularly suitable for casting. The diversity of the structural units A and B allows the properties of the copolymer to be flexibly adapted and e.g. to optimize pourability or to adjust other properties of the polymer (e.g., flexibility, chemical resistance, temperature resistance, refractoriness, mechanical strength, low temperature processability, optical properties).

Optoelectronic devices of the form described are to be made with a particularly low cost and thus inexpensive to produce. At the same time they are characterized by a high transmission over a wide radiation spectrum, e.g. also in the UV range, which also existed during continuous operation despite the radiation exposure and high temperatures.

In particular, in the case that at least one or exactly one of the four substituents Y ₁ to Y _{4 is} a group R or a group OR, the pourability of the polymer is considerably improved.

For R, in principle, the same radicals are conceivable, as already described for the structural unit A. The effects for certain radicals R listed in connection with the structural unit A are also applicable with regard to the structural unit B. It is again particularly preferred in this case if R is a fluorinated or even perfluorinated hydrocarbon radical, for example of the general formula -C _n F _{2n + 1} (where n is less than or equal to 10, preferably n is less than or equal to 5, or n is less than or equal to 3 ). For example, R may be -CF ₃ , -C ₂ F ₅ or -C ₃ F ₇ .

und wobei die Struktureinheit B ausgewählt ist aus der Gruppe umfassend:

wobei R jeweils ein Kohlenwasserstoffrest C₁-C₁₀ oder ein fluorierter Kohlenwasserstoffrest C₁-C₁₀ sein kann. In a further embodiment of the radiation-emitting optoelectronic device according to the invention, the fluoropolymer is a copolymer having a first structural unit A and a second structural unit B, wherein the structural unit A is selected from the group comprising:

and wherein the structural unit B is selected from the group comprising:

where each R can be a hydrocarbon radical C ₁ -C ₁₀ or a fluorinated hydrocarbon radical C ₁ -C ₁₀ .

In turn, R may in each case comprise the radicals already described above.

Copolymers of the form described are not only UV-stable, thermally stable, chemically resistant and at the same time permanently permeable to UV radiation, but at the same time they are characterized by their good castability and processability and thus make the presentation particularly easy to manufacture and cost-effective radiation-emitting optoelectronic devices.

umfasst. Copolymere mit dieser Struktureinheit A sind besonders stabil und strahlendurchlässig. Particularly preferred is an embodiment in which the radiation-transmissive element comprises a copolymer having as structural unit A a unit of the formula

includes. Copolymers with this structural unit A are particularly stable and radiolucent.

In one embodiment, the polymer is a block copolymer.

In a further embodiment of the invention, the fluoropolymer is a copolymer which is a random copolymer. That the structural units A and B are statistically distributed.

In one embodiment of the invention, the copolymer is a periodic copolymer in which the structural units A and B are in a recurring regular order (eg... AAAA-B-AAAA-B-AAAA -... etc.).

In a further and at the same time particularly preferred embodiment, the copolymer has an alternating sequence of the structural units A and B (ie... A-B-A-B-A-B -...).

In particular, alternating copolymers are distinguished by a particularly good combination of good UV radiation permeability, stability and processability.

In a further embodiment of the invention, the fluoropolymer has a further structural unit C which differs in each case from the structural units A and B and which can be described by the same general formula as structural unit B.

• – Ethylen-Chlortrifluorethylen-Copolymer (ECTFE),
• – Ethylen-Tetrafluorethylen-Copolymer (ETFE),
• – Perfluoralkoxy-Polymere (PFA),
• – Fluoriertes-Ethylen-Propylene-Copolymer(FEP),
• – Polyvinylfluorid (PVF),
• – Polychlortrifluorethylen (PCTFE),
• – Copolymer aus Tetrafluorethylen, Hexafluorpropylen und Vinylidenfluorid (THV),
• – Copolymer aus Tetrafluorethylen und 2,2 Bis(trifluor methyl)-4,5-Difluor-1,3-Dioxolan (PTFE-AF)

handelt. A preferred embodiment of the present invention uses as a radiation-transmissive element, a radiation-transmissive element comprising a fluoropolymer, which is a

• Ethylene-chlorotrifluoroethylene copolymer (ECTFE),
• Ethylene tetrafluoroethylene copolymer (ETFE),
• Perfluoroalkoxy polymers (PFA),
• Fluorinated ethylene-propylene copolymer (FEP),
• Polyvinyl fluoride (PVF),
• - polychlorotrifluoroethylene (PCTFE),
• Copolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (THV),
• Copolymer of tetrafluoroethylene and 2,2-bis (trifluoromethyl) -4,5-difluoro-1,3-dioxolane (PTFE-AF)

is.

The radiation-transmissive element can also comprise mixtures of the stated polymers or consist of one or more of the stated polymers. In addition, it is possible that the radiation-transmissive element has modified forms of said polymers.

auf. Particularly suitable as a radiation-transmissive element for radiation-emitting optoelectronic devices according to the present invention are radiation-transmissive elements comprising the polymer ECTFE. ECTFE is a fluoropolymer obtained by copolymerization of chlorotrifluoroethylene and ethylene. It thus has as structural unit A

on.

auf.As structural unit B, it has

on.

The structural units can be present, for example, in alternating sequence.

Particularly suitable as a radiation-transmissive element for radiation-emitting optoelectronic devices according to the present invention are also radiation-transmissive elements comprising the polymer ETFE, which is a copolymer of tetrafluoroethylene and ethylene. The polymer has as structural unit A:

auf.Structural unit B is ETFE

on.

ETFE has a particularly high UV radiation permeability and also has high temperature resistance, good chemical resistance and high mechanical strength.

aufweist und die Struktureinheit B

aufweist.Radiation-emitting optoelectronic devices are also preferred, wherein the radiation-transmissive element comprises PFA or similar polymers. It is particularly preferred in this case if the structural unit A

and the structural unit B

having.

R is defined as already described for the general formula of the structural units A and B.

PFA has good chemical resistance, thermal resistance and high fire resistance.

For example, a corresponding polymer can be obtained by copolymerization of tetrafluoroethylene and perfluorovinylpropyl ether. PFA-based polymers have a fluorinated alkoxy substituent that increases the plasticisability of the polymer. The oxygen functionality also enhances the transparency of the material, for example the transmission of UV radiation as desired for potting materials of the present invention. In PFA based fluoropolymers with particularly good processability include those sold under the brand name "Hyflon ^® PFA" by Solvay Fluoropolymers. In many cases, comparable properties have other under the brand name "Hyflon ^®" sold Fluoropolymers on (eg "Hyflon ^® MFA").

Instead of introducing an alkoxy substituent, it is also possible to increase the ductility and thus the castability of corresponding polymers by introducing an alkyl, in particular a fluorinated, alkyl substituent. This is done, for example, in FEP, which is a copolymer of tetrafluoroethylene and a different monomer unit based on an at least partially fluorinated olefin (eg hexafluoropropylene). FEP polymers have as structural unit A:

The structural unit B is:

R is in turn defined as already described for the general formula of the structural units A and B.

FEP polymers have a particularly good UV radiation permeability chemical and thermal resistance and high fire resistance. They also allow particularly smooth surfaces.

aufweist.Also suitable as a fluoropolymer in a radiation-emitting device according to the invention is polyvinyl fluoride (PVF), which is the recurring structural unit A

having.

aufweist.Also suitable as the fluoropolymer is polychlorotrifluoroethylene (PCTFE), which as the repeating structural unit A

having.

als Struktureinheit B

und als eine dritte davon verschiedene wiederkehrende Struktureinheit C

auf.In addition, the polymer is particularly suitable as a fluoropolymer in radiation-emitting optoelectronic devices. THV stands for the copolymer formed by copolymerization of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride. It has as structural unit A

as structural unit B

and as a third of them, a different recurring structural unit C

on.

THV is thus a copolymer comprising three different repeating structural units. It has particularly advantageous optical properties, high flexibility and is very easy to process even at low temperatures. In particular, the good processability even at low temperatures of the THV is a particular advantage over many conventional fluoropolymers when used in the radiation-emitting optoelectronic devices according to the invention.

auf.Also particularly suitable as a fluoropolymer in radiation-emitting optoelectronic devices according to the invention is the polymer PTFE-AF, which is a copolymer of tetrafluoroethylene and 2,2-bis (trifluoromethyl) -4,5-difluoro-1,3-dioxolane. PTFE AF has as repeating structural unit A

on.

auf.Another recurring structural unit B is PTFE-AF

on.

Also PTFE AF shows particularly good UV ray transmission and processability.

The polymers listed are examples of particularly suitable fluoropolymers, which in each case are fluorine-containing thermoplastics. Meltable fluorine-containing thermoplastics can be manufactured by means of injection molding and extrusion, making them particularly suitable for use in large-scale processes. The fluoropolymers mentioned are common commercially available polymers and are thus readily available. Modified forms of the listed polymers can also be used in the present invention. As will be shown by the example of PFA, there are often a large number of modifications of the respective polymers. Thus, PFA has commercially available modifications "PFA N" with improved adhesion properties, "PFA FLEX" with increased ductility and "PFA UHP" has a particularly high purity. PFA FLEX and PFA UHP also each show an improved transmission and a lower "crack susceptibility" (ie a lower tendency to form undesirable cracks or gaps) and are thus particularly suitable for radiolucent elements. Radiation-permeable elements comprising said polymers also generally show a significantly lower tendency to yellow than conventional polymers.

However, the invention is not limited to the above fluoropolymers.

In a further embodiment, the average molecular mass of the fluoropolymers of the radiation-transmissive element of the radiation-emitting optoelectronic device according to the invention in the range of 1000 g / mol to 10,000,000 g / mol, in particular between 1000 g / mol and 1,000,000 g / mol, more preferably between 2000 g / mol and 800,000 g / mol, and most preferably between 4000 g / mol and 500,000 g / mol.

Another preferred embodiment of the radiation-emitting optoelectronic device according to the invention is designed as a light-emitting diode (LED) which emits UV light. It is therefore a UV LED.

• – an einer zu einem Trägerelement hin gewandten ersten Hauptfläche des Gehäusekörpers einer strahlungserzeugenden Epitaxieschichtenfolge ist eine reflektierende Schicht aufgebracht oder ausgebildet, die zumindest einen Teil der in der Epitaxieschichtenfolge erzeugten elektromagnetischen Strahlung in diese zurückreflektiert;
• – die Epitaxieschichtenfolge weist eine Dicke im Bereich von 20 µm oder weniger, insbesondere im Bereich von 10 µm auf; und
• – die Epitaxieschichtenfolge enthält mindestens eine Halbleiterschicht – also einen strahlungsemittierenden optoeletkronischen Halbleiter – mit zumindest einer Fläche, die eine Durchmischungsstruktur aufweist, die im Idealfall zu einer annähernd ergodischen Verteilung des Lichtes in der epitaktischen Epitaxieschichtenfolge führt, d.h. sie weist ein möglichst ergodisch stochastisches Streuverhalten auf.

For example, the LED may be a thin-film light-emitting diode chip. A thin-film light-emitting diode chip is characterized in particular by the following characteristic features:

• On a first main surface of the housing body facing a carrier element of a radiation-generating epitaxial layer sequence, a reflective layer is applied or formed which reflects back at least part of the electromagnetic radiation generated in the epitaxial layer sequence;
• - The epitaxial layer sequence has a thickness in the range of 20 microns or less, in particular in the range of 10 microns; and
• - The epitaxial layer sequence contains at least one semiconductor layer - that is, a radiation-emitting optoeletkronischen semiconductor - with at least one surface having a mixing structure, which leads to an almost ergodic distribution of light in the epitaxial epitaxial layer sequence, that is, it has a possible ergodisch stochastic scattering behavior.

A basic principle of a thin-film light-emitting diode chip is, for example, in I. Schnitzer et al., Appl. Phys. Lett. 63 (16), 18 October 1993, 2174-2176 described, the disclosure of which is hereby incorporated by reference.

The invention furthermore relates to a method for producing a radiation-emitting optoelectronic device, wherein the radiation-transmissive element is a potting material ( 3 ), comprising the steps:

Step A: Presenting a housing body ( 1 ) and the radiation-emitting semiconductor ( 2 ).

Step B: Potting the Semiconductor ( 2 ) with the potting material ( 3 ).

By using a pourable potting the manufacturing process can be designed without great technical effort and thus cost. A direct connection of the components of the housing body, which at least partially surrounds the radiation-emitting semiconductor, with the potting material is easily produced by casting. Also enclosing the semiconductor with the Potting material, both of which are in direct contact with each other can be implemented. The process is time-saving and suitable for the industrial scale.

Further details, features and advantages of the subject matter of the invention will become apparent from the following description of the figures and embodiments.

In the figures shows:

1 5 shows the simplified, schematic side view of a radiation-emitting optoelectronic device according to the invention, wherein the radiation-transmissive element (FIG. 3 ) is a potting material.

2 2 shows the simplified schematic side view of a radiation-emitting optoelectronic device according to the invention, wherein the radiation-transmissive element (FIG. 3 ) to the radiation-emitting semiconductor ( 2 ) is spaced.

3 Measurements of the transmission of electromagnetic radiation from infrared radiation to UV radiation for an ETFE fluoropolymer (brand name: Fluon), glass, as well as the polymer polycarbonate.

In the following, the respective figures or embodiments are described in more detail for illustration.

1 shows a simplified schematic representation of a radiation-emitting optoelectronic device according to an embodiment of the present invention, comprising a housing body ( 1 ), at least one optoelectronic radiation-emitting semiconductor ( 2 ), as well as from the housing body ( 1 ) various radiation-transmissive element ( 3 ), wherein the housing body ( 1 ) the at least one optoelectronic radiation-emitting semiconductor ( 2 ) at least in places surrounds. The radiation-transmissive element ( 3 ) is in the beam path of the radiation-emitting semiconductor ( 2 ) arranged. It may be located in particular in the area of the main radiation exit surface. The radiation transmissive element is a potting material comprising a fluoropolymer. It can be in direct contact with both the housing body ( 1 ) and in particular in direct contact with the radiation-emitting semiconductor ( 2 ) stand. The device may also include other typical elements for radiation-emitting opto-electronic devices, such as corresponding substrates, traces, heat-sinks, and reflective layers and other common devices as may be found in corresponding radiation-emitting optoelectronic devices, such as LEDs.

2 also shows a simplified schematic representation of a radiation-emitting optoelectronic device according to another embodiment of the present invention, comprising a housing body ( 1 ), at least one optoelectronic radiation-emitting semiconductor ( 2 ), as well as from the housing body ( 1 ) various radiation-transmissive element ( 3 ), wherein the housing body ( 1 ) the at least one optoelectronic radiation-emitting semiconductor ( 2 ) at least in places surrounds. The radiation-transmissive element ( 3 ) is in the beam path of the radiation-emitting semiconductor ( 2 ) arranged. It may be located in particular in the area of the main radiation exit surface. The radiation-transmissive element ( 3 ) of the embodiment shown is to the radiation-emitting semiconductor ( 2 ) spaced. Between the radiation-transmissive element ( 3 ) and the radiation-emitting semiconductor ( 2 ) may be, for example, a cavity. The radiation-transmissive element may, for example, be a platelet, for example a wavelength conversion platelet.

3 shows measurements on three different materials, where the transmission (T) is the permeability of the electromagnetic radiation in percent (%) as a function of the wavelength (λ) of the emitted radiation in nanometers (nm). The measurement demonstrates that, especially for short wavelengths in the UV range, conventional materials have only a limited transmission. Due to their lack of UV radiation permeability, they are therefore unsuitable for use in UV radiation-emitting optoelectronic devices. In particular, radiation-transmissive elements comprising polycarbonates are not suitable for the transmission of UV radiation. The transmission in the UV range for glass substrates is slightly better than for polycarbonate, but here, too, for wavelengths just below 400 nm, for example at 350 nm, the transmission is already considerably limited. In contrast, the fluoropolymer, which is an ETFE polymer (brand name Fluon), is far more permeable to radiation in the UV range.

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 claims or exemplary embodiments.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• I. Schnitzer et al., Appl. Phys. Lett. 63 (16), 18 October 1993, 2174-2176 [0091]

Claims (12)

Radiation-emitting optoelectronic device - comprising - a housing body ( 1 ), - at least one optoelectronic radiation-emitting semiconductor ( 2 ), - one from the housing body ( 1 ) various radiation-transmissive element ( 3 ), - wherein the housing body ( 1 ) the at least one optoelectronic radiation-emitting semiconductor ( 2 ) surrounds at least in places, - wherein the radiation-transmissive element ( 3 ) in the beam path of the radiation-emitting semiconductor ( 2 ), and - wherein the radiation-transmissive element ( 3 ) has a fluoropolymer. A radiation-emitting optoelectronic device according to the preceding claim, wherein the radiation-transmissive element ( 3 ) is a potting material. A radiation-emitting optoelectronic device according to one of the preceding claims, wherein the radiation-transmissive element ( 3 ) to the radiation-emitting semiconductor ( 2 ) is spaced. A radiation-emitting optoelectronic device according to one of the preceding claims, wherein the radiation-emitting semiconductor ( 2 ) Emits UV radiation. A radiation-emitting optoelectronic device according to one of the preceding claims, wherein the housing body ( 1 ) also has a fluoropolymer and with the radiation-transmissive element ( 3 ) is in contact. A radiation-emitting optoelectronic device according to one of the preceding claims, wherein the housing body ( 1 ) and the radiation-transmissive element ( 3 ) have the same fluoropolymer. A radiation-emitting optoelectronic device according to one of the preceding claims, wherein the fluoropolymer comprises a first structural unit A of the following general formula:

wherein the substituents X ₁ to X _{4 are} each independently selected from the group comprising: - hydrogen, - halogens, in particular F and Cl, - R, - OR, where R is in each case a hydrocarbon radical C ₁ -C ₁₀ or a fluorinated hydrocarbon radical C ₁ -C ₁₀ , and wherein at least one of the substituents X ₁ to X _{4 is} fluorine. A radiation-emitting optoelectronic device according to the preceding claim, wherein the fluoropolymer is a copolymer comprising, in addition to the first structural unit A, at least one further structural unit B different from the structural unit A and having the following general formula:

wherein the substituents Y ₁ to Y _{4 are} each independently selected from the group comprising: - hydrogen, - halogens, in particular F and Cl, - R - OR where R is in each case a hydrocarbon radical C ₁ -C ₁₀ or a fluorinated hydrocarbon radical C ₁ - C ₁₀ can be or wherein the structural unit B has the formula

having. A radiation-emitting optoelectronic device according to one of the preceding claims, wherein the fluoropolymer is a copolymer having a first structural unit A and a second structural unit B, wherein the structural unit A is selected from the group comprising:

and wherein the structural unit B is selected from the group comprising:

where each R can be a hydrocarbon radical C ₁ -C ₁₀ or a fluorinated hydrocarbon radical C ₁ -C ₁₀ . A radiation-emitting optoelectronic device according to one of claims 6 or 7, wherein the copolymer has an alternating sequence comprising structural units A and B. Radiation-emitting optoelectronic device, wherein the fluoropolymer is a polymer selected from the group consisting of: ethylene-chlorotrifluoroethylene copolymer (ECTFE), ethylene-tetrafluoroethylene copolymer (ETFE), perfluoroalkoxy polymers (PFA), and fluorinated ethylene Propylene copolymer (FEP) - polyvinyl fluoride (PVF), - polychlorotrifluoroethylene (PCTFE), - copolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (THV), - copolymer of tetrafluoroethylene and 2,2-bis (trifluoromethyl) -4,5-difluoro-1 , 3-dioxolane (PTFE-AF). A method for producing a radiation-emitting optoelectronic device according to claim 2, comprising the steps A) presenting a housing body ( 1 ) and the radiation-emitting semiconductor ( 2 ), B) casting the semiconductor ( 2 ) with the potting material ( 3 ).

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