WO2015082552A1

WO2015082552A1 - Conversion element and method for producing a conversion element

Info

Publication number: WO2015082552A1
Application number: PCT/EP2014/076425
Authority: WO
Inventors: Dominik Pentlehner; Benjamin Claus Krummacher
Original assignee: Osram Oled Gmbh
Priority date: 2013-12-05
Filing date: 2014-12-03
Publication date: 2015-06-11
Also published as: DE102013113533A1

Abstract

The invention relates to a conversion element (5) which comprises at least one luminophore having an anisotropic molecular structure, wherein the molecules of the luminophore each have at least one transition dipole moment (7), wherein the transition dipole moments (7) in sum have an anisotropic orientation within the conversion element (5), wherein the luminophore is designed to convert an electromagnetic primary radiation, generated by a radiation source, into an electromagnetic secondary radiation, the electromagnetic secondary radiation having an anisotropic directionality. The invention also relates to a method for producing such a conversion element (5).

Description

description

Conversion element and method for producing a

conversion element

A conversion element is specified. In addition, a method for producing such a

Specified conversion element. One problem to be solved is to specify a conversion element which has a high light extraction efficiency. Furthermore, an object to be solved is to specify a method for producing such a conversion element. According to at least one embodiment, this includes

Conversion element at least one phosphor having an anisotropic molecular structure. The molecules of the phosphor each have at least one transition dipole moment. The transition dipole moments of the individual molecules have an anisotropic orientation within the sum

Conversion element. The phosphor is to

configured to convert an electromagnetic primary radiation generated by a radiation source into an electromagnetic secondary radiation. The electromagnetic secondary radiation has an anisotropic directionality.

The fact that the molecules of the phosphor each have at least one transitional dipole moment concludes here and in the

It does not follow that every molecule is more

Transition dipole moments may have. In particular, that is

Transition dipole moment meant for the relevant transition. For example, is the transition from the singlet ground state So pertaining to the singlet S i state, then the transition dipole moment is meant for this transition.

In the context of the present application, an anisotropic molecular structure is understood to mean that the molecules used are unsymmetrical or at least not

have spherically symmetric molecular structure. In particular, the molecules do not form a substantially spherical one

Molecular structure, but a rather elongated

Molecular structure. The at least one transition dipole moment can form along the longitudinal molecular axis of the individual molecules.

The transitional dipole moment has a fixed direction in the

Coordinate system of the phosphor (molecular coordinate system). This means, in particular, that aligning the phosphor in the room also aligns its transitional dipole moment. The term transition dipole moment is referred to in particular: "IUPAC Compendium of Chemical Terminology, Second Edition (The" Gold Book "), 1997 and IUPAC Compendium of Chemical Terminology, PAC, 2007, 79, 293 (1997). Glossary of terms used in photochemistry, third edition (IUPAC Recommendations 2006)) on page 434, DOI: 10.1351 / goldbook T06460 The disclosure of the documents is incorporated by reference.

That the transition dipole moments of the molecules of the phosphor in the sum of anisotropic alignment within the

Conversion element, is here and below meant that the majority of the phosphor molecules a

Preferred direction, ie in particular at least 50%, 60%, 70%, 80%, 90% or 95% and at most 100% of all molecules of the phosphor. The transition dipole moments have a certain orientation in the conversion element. This is relevant because of the absorption and / or

Emission process is a dipole transition.

As a measure of the orientation of molecules of the

Orientation factor Κ _θ = <cos ² 6>. To the

Term orientation factor is particularly referred to: IUPAC. Compendium of Chemical Terminology, PAC, 2007, 79, 293 (Glossary of terms used in photochemistry, third edition (IUPAC Recommendations 2006), at page 371, DOI:

10.1351 / goldbook.MT07422. The disclosure of the

Document is added by reference.

In particular, the fact that the transition dipole moments of the molecules of the phosphor have anisotropic orientation in the sum means that the orientation factor Κ _{θ is} not equal to 1/3. In particular, if Κ _θ <1/3, that is

Transient dipole moment preferably in the layer of

Conversion element arranged. The angle Θ is the angle between the respective transition dipole moment of the molecules of the phosphor and a layer normal n, wherein the

Layer normal n perpendicular to the layer of

Conversion element is arranged. The orientation factor Κ _θ is averaged over all phosphor molecules. In particular, <cos ² 6> is less than 0.2; 0.1; 0.015; 0.001 or 0. The smaller Κ _θ , the larger the

Absorption probability.

That the secondary electromagnetic radiation has anisotropic directionality is here and below

understood that the electromagnetic secondary radiation has a preferred direction. In particular, this can be

mean that the electromagnetic secondary radiation has a preferred main emission direction. In particular, the main radiation direction is perpendicular to the layer plane of the conversion element with a maximum deviation of +/- 5, +/- 10, +/- 20 ° or +/- 45 ° from this vertical position. In particular, main emission direction means that the

Electromagnetic secondary radiation in the direction away from the radiation source, so not to the radiation source, radiates. In particular, at least 50%, 60%, 70%, 80%, 90% or 95% and up to 100% of the total electromagnetic radiation has the main emission direction. The

Electromagnetic secondary radiation can be

Have wavelength maximum, which in the range of

visible light, for example from 520 nm to 750 nm, in particular from 550 nm to 650 nm.

In addition, at least a part of the electromagnetic secondary radiation can be radiated toward the radiation source, which initially reflects at the radiation source, for example an electrode, and finally into the radiation source

Main emission direction away from the radiation source is emitted. This additionally increases the light efficiency and decoupling of the radiation source.

According to at least one embodiment, the

at least one electromagnetic primary radiation

Wavelength maximum in the range of visible light,

for example, of at least 425 nm or 460 nm and

at most 480 nm or 620 nm.

The inventors have recognized that by aligning the transition dipole moment of the phosphor molecules in the Conversion element, the absorption probability of the primary electromagnetic radiation can be increased.

In particular, this means that additionally more electromagnetic secondary radiation can be emitted by the phosphor molecules in comparison to phosphor molecules which have no

Have orientation of the transition dipole moment. If more photons in the form of the primary electromagnetic radiation are absorbed by the phosphor molecules due to the alignment of their transition dipole moments, less can be

Fluorescent material used to be the same

To achieve absorption probability, which would have phosphors that no alignment of the

Have transition dipole moments. The efficiency of an organic light emitting diode can by

Alignment of the phosphor molecules can be increased because the converted light is no longer emitted isotropically, as in non-aligned phosphor molecules, but anisotropic in Hauptabstrahlrichtung, preferably perpendicular to the layer plane of the conversion element or perpendicular to

Surface of the organic light emitting diode. The radiated from the one surface of the conversion layer

Electromagnetic secondary radiation leaves the organic light-emitting diode, that is, it is decoupled, and the secondary electromagnetic radiation emitted by the other surface is directed into the organic light-emitting diode. This directed into the organic light emitting electromagnetic

Secondary radiation has a smaller aperture angle than in the case of non-aligned phosphor molecules and is therefore more likely to be coupled out after reflection at the reflective electrode. In accordance with at least one embodiment, this is

Conversion element formed as a layer. In particular, the layer thickness of the conversion element is at least 5 nm, 50 nm, 100 nm and at most 500 nm, 1 μm or 10 mm, for example 30 μm. In particular, more molecules of the phosphor have a transition dipole moment having a parallel orientation to the layer plane of the conversion element than a transition dipole moment having orthogonal

Alignment to the layer plane. Parallel alignment here excludes a deviation of at most +/- 5 °, +/- 10 °, +/- 20 ° or +/- 45 °, for example +/- 30 °, to the parallel

Alignment to the layer plane of the conversion element with. Orthogonal alignment here includes a deviation of at most +/- 5 °, +/- 10 ° or +/- 30 ° from the orthogonal orientation.

This means in particular that the conversion element is formed as a layer, where: <cos ² 6> is less than 1/3. In particular, <cos ² 6> is less than 0.25; 0.225; 0.2 0.155 or 0. The angle Θ is the angle between the respective transition dipole moment of the molecules of the phosphor and a layer normal n, wherein the layer normal n is arranged perpendicular to the layer of the conversion element. In accordance with at least one embodiment, the majority of the transition dipole moments are the molecules of the phosphor

aligned parallel to each other and / or in a plane. Majority of transitional dipole moments relates to the

Total of transitional dipole moments in the

Conversion element. In particular, majority means that more than 50%, in particular more than 70%, particularly preferably more than 80% of all transition dipole moments are arranged parallel to one another and / or in a plane to each other. In particular, this means that more than 50%, in particular more than 70%, particularly preferably more than 80% of

Phosphor molecules or the Übergangsdipolmomente in space are arranged parallel to each other and / or in a plane.

In accordance with at least one embodiment, more than 80% of all transition dipole moments of the phosphor are aligned parallel to the layer plane of the conversion element. The parallel alignment can be a maximum deviation of +/- 5 °, +/- 10 °, +/- 20 ° or +/- 30 ° from this parallel

Alignment to the layer plane of the conversion element

exhibit .

In accordance with at least one embodiment, this is

Conversion element as a layer with a layer thickness of at least 5 nm, 10 nm, 100 nm, 1 ym or 10 mm formed and arranged directly on the radiation source. In particular, the conversion element is direct, ie with a

direct mechanical contact, arranged on a main surface of the radiation source. In particular, the

Main surface of the radiation source formed planar. The layer thickness of the conversion element can have a value between 5 nm and 200 nm. According to at least one embodiment, the

Radiation source an organic light emitting diode. The organic light-emitting diode has a first electrode, which is arranged on a substrate. The organic light-emitting diode has a second electrode. The organic light-emitting diode has a light-generating organic layer stack between the electrodes and a conversion element. The conversion element is in direct contact with the at least partially transparent second electrode at one

Layers stack facing away side arranged.

Alternatively, there need be no compelling direct contact between the first and / or second electrode and the conversion element. For example, the conversion element can be arranged indirectly on the at least partially transparent second electrode on a side facing away from the layer stack. Indirectly, in this context

mean that the first and / or second electrode and the conversion element have at least one indirect mechanical contact with each other. It can be a further layer or it can be arranged further layers between the first and / or second electrode and the conversion element.

The radiation source is according to at least one

Embodiment a natural light source, such as the sun, northern lights or lightning and / or a man-made artificial light source, such as oil lamps, lamps, bulbs, lasers, picture tubes or a light emitting diode. In particular, the radiation source is an organic light-emitting diode (OLED) or light-emitting diode (LED), for example a luminescence conversion light-emitting diode (LUCOLED) or luminescence conversion organic light-emitting diode (LUCOOLED).

According to at least one embodiment, the

Radiation source a light guide. The light guide can couple light, for example from a blue LED, over a side surface.

In accordance with at least one embodiment, this is

Conversion element as a layer with a layer thickness of at least 5 nm, 100 nm, 500 nm or 1 ym and at most 5 ym or 10 mm and spatially spaced from the radiation source. The layer thickness of the conversion element can have a value between 5 nm and 200 nm. In particular, the radiation source and the conversion element have a

spatial distance of at least 5 nm or 10 nm. But the spatial distance can also be much larger, that is, a distance between the earth or the conversion element and the sun as a radiation source. The conversion element can be arranged directly on a solar cell, wherein the solar cell is adapted to that of the

Conversion element emitted electromagnetic

To absorb secondary radiation and to convert completely or at least partially into electrical energy.

In particular, the radiation source is the sun. By

Arranging a conversion element on the solar cell can increase the efficiency of solar cells in the corresponding solar cell

Wavelength range can be increased.

According to at least one embodiment, the conversion element emits more than 90% of the total electro ^¬ magnetic secondary radiation with a maximum deviation of +/- 5 °, +/- 10 °, + / - 20 ° or +/- 30 ° from a vertical Alignment to the layer plane of the

Conversion element.

In accordance with at least one embodiment, the phosphor is a substituted or unsubstituted coumarin. Alternatively or additionally, the phosphor may be a substituted or unsubstituted perylene. Unsubstituted herein means that the coumarin is present as 1, 2-benzopyrone and / or perylene as peri-dinaphthylene in the conversion element. Substituted here means that 1, 2-benzopyrone and / or peri-dinaphthylene further radicals, for example alkyl,

Aryl, heteroaryl and / or alkoxy radicals.

Alternatively or additionally, the phosphor can

Laser dye having an anisotropic molecular structure, for example, a rhodamine or its derivatives and / or a Bodipy dye.

Alternatively or additionally, the phosphor can a

quasi-planar compound, for example, a substituted or unsubstituted porphyrin, phthalocyanine, chlorins or metal complexes of porphyrin, phthalocyanine or chlorins. Alternatively or additionally, the phosphor can

quasi-planar transition metal complex, in particular with Pt (II) or Pd (II) as the transition metal central atom.

In accordance with at least one embodiment, the phosphor may be an inorganic dye, an organic dye and / or a quantum dot.

In accordance with at least one embodiment, this is

Conversion element formed as a film. In particular, the film has a film thickness of at least 5 μm, 10 μm or 50 μm and at most 100 μm, 250 mm or 500 μm. Of the

Phosphor may be in a matrix material of the film

be embedded. In particular, the matrix material

Polyethylene, polycarbonate, polymethyl methacrylate (PMMA), polystyrene, silicone and / or epoxy resin or comprises

at least one of these components. In addition, further matrix materials may be present in the film. The film can be stretched. Stretching refers to here and in the Following that the film is deformed to produce an anisotropic property of the film. By stretching, alignment of the transition dipole moments of the phosphor in the conversion element can be created, resulting in anisotropic directionality of the electromagnetic

Secondary radiation leads.

In accordance with at least one embodiment, this is

Conversion element formed as a film, wherein the

Conversion element comprises at least one matrix material and embedded therein a phosphor. The phosphor can in particular be chemically bonded to the matrix material. In particular, chromophore groups of the phosphor are attached to the matrix material, for example a polymer. The film may be stretched so that the film is an anisotropic

Has property and has a thickness of at least 5 ym, 10 ym or 50 ym and at most 100 ym, 250 ym or 500 ym.

According to at least one embodiment, the

Conversion element on an additional phosphor.

In particular, more than 80%, for example 85% or 95% of all transition dipole moments of the molecules of the first and the additional phosphor are aligned parallel to one another. First fluorescent is also used as a phosphor in this

Registration designated.

According to at least one embodiment, the

Conversion element several layers, so at least two layers. The layers can be arranged directly on one another. The layers each have at least one luminescent substance or a mixture of phosphors with an anisotropic molecular structure. The phosphors of

adjacent layers may differ from each other. This can be mixed with advantage from the

electromagnetic secondary radiation of the phosphor at least one layer and the electromagnetic

Secondary radiation of the phosphor can be generated at least the adjacent layer, wherein the mixed light has an anisotropic directionality.

Furthermore, a method for producing such a conversion element is specified.

The embodiments and definitions of the conversion element also apply to the method for producing such a conversion element and vice versa. In accordance with at least one embodiment, the method for producing a conversion element for solar cells

and / or organic light emitting diodes used.

In accordance with at least one embodiment, the method comprises the following method steps:

Providing the radiation source or the solar cell,

Bl) applying the conversion element to the

Radiation source or the solar cell, wherein the phosphor is evaporated in a vacuum and is deposited on the radiation source or the solar cell, so that an anisotropic alignment of the phosphor molecules takes place.

Alternatively, the method instead of the

Process step B1 the process step B2) B2) Applying the conversion element to the

Radiation source or the solar cell, wherein the phosphor is embedded in a matrix material and is applied by injection molding on the radiation source or the solar cell, so that anisotropic alignment of the

Phosphorus molecules take place.

According to at least one embodiment is in

Process step Bl) after and / or during the

Deposition process, the deposited phosphor and / or the surface of the radiation source or the solar cell brought to a room temperature elevated temperature or maintained at such temperature. According to at least one embodiment, that in the

Process step Bl or B2 generated conversion element are formed as a film. In particular, the film is produced prefabricated ^¬, that in a spatial distance to the radiation source ^¬ or solar cell. Subsequently, the film on the radiation source or solar cell up or

attached, in particular glued.

According to at least one embodiment, the

Conversion element are generated by vapor deposition of small molecules. As a result, an anisotropic alignment of the phosphor molecules within the conversion element can be produced.

The inventors have recognized that by introducing a phosphor having an anisotropic molecular structure, an increased likelihood of absorption of the

converting electromagnetic primary radiation can be increased. The emission of the converted Secondary electromagnetic radiation may have anisotropic directionality. In particular, that will

Conversion element in an optoelectronic device, such as an organic light emitting diode used.

As a result, the efficiency or the

Lichtauskoppeleffizienz the optoelectronic device can be increased. If one wishes to achieve the same degree of conversion as in conventional conversion elements, therefore, according to this invention, less phosphor material can be used for the same absorption probability. This saves material and therefore costs.

The anisotropic directionality, for example, an emission bundled with respect to the direction of the main emission direction of the optical component, can furthermore be used to avoid losses due to total reflection or

Waveguide in a luminescence conversion light emitting diode (LUCOLED) or luminescence conversion organic light emitting diode (LUCOOLED) can be used.

Decisive for the use of the conversion element it that the phosphor is the electromagnetic

Primary radiation absorbs, efficiently converts and the converted electromagnetic secondary radiation the

desired property in particular the desired anis

Directionality, polarization and / or color has.

The probability of absorption of

Primary electromagnetic radiation depends on its frequency, the phosphor material and its orientation in space. In particular, the probability of absorption depends on the orientation of the transition dipole moment of the phosphor molecules. In particular, the absorption probability maximum, if the transitional dipole moment parallel to

Polarization of the exciting original light, so the electromagnetic primary radiation is aligned. The transition dipole moment has a fixed direction in the coordinate system of the phosphor (molecular coordinate system). This means, in particular, that aligning the phosphor in the room also aligns its transitional dipole moment. In particular, the polarization direction can always be perpendicular to the propagation direction of the light. This means that the absorption of light by the phosphor is at its maximum when the transition dipole moment is perpendicular to the propagation direction of the primary electromagnetic radiation or parallel to the layer plane of the conversion element. The Probability ^¬ absorption can be affected by aligning the phosphor ^¬ molecules, in particular, the

Absorption probability increased. It may also be that the electromagnetic

Primary radiation is already polarized by nature. The absorption probability is maximum when the phosphor is oriented to be

Transitional dipole moment parallel to the main axis of the

Polarization ellipse stands. In particular, that should

Transition dipole moment in linearly polarized light parallel to the polarization direction and in elliptically polarized light parallel to the main axis of the ellipse. This can be the case, for example, if an electroluminescent emitter is already anisotropically oriented in an organic light-emitting diode (OLED). The emission direction may also be dependent on the orientation of the transition dipole moment. The intensity of the emission of secondary electromagnetic radiation is maximum parallel to the transition dipole moment. By aligning the

Phosphor can thus influence the emission characteristics of the conversion element as a whole.

Aligning the phosphor can be next to the

Probability of absorption and the

Abstrahlcharakteristik the conversion element also on the polarization of both the not yet absorbed light, so the electromagnetic primary radiation, as well as the converted light, so the electromagnetic secondary radiation effect. In particular, the portion with a polarization direction is preferably absorbed by the electromagnetic primary radiation parallel to the transition dipole moment of the phosphor, that is to say the

Polarization direction of the transmitted light, so the electromagnetic secondary radiation is rotated in the direction perpendicular to the transition dipole moment. In particular, in the case of unpolarized electromagnetic primary radiation, the electromagnetic secondary radiation is polarized. The phosphor converted by the electromagnetic

Secondary radiation is preferred with a

Polarization direction emitted parallel to the transition dipole moment, that is, the converted light has a polarization. The polarization of the unconverted primary radiation can also be increased, namely

perpendicular to the transitional dipole moment of the conversion element. In particular, if the primary radiation is unpolarized, the unconverted primary radiation is polarized, perpendicular to the transition dipole moment of the conversion element. The transition dipole moments of absorption and emission of the phosphor can be the same. In particular, the transition dipole moments of absorption and emission can be arranged parallel to one another. Alternatively, the transition dipole moments of absorption and emission may also have different directions. This is particularly the case only when the phosphor is excited by absorption into a different state than that from which it emits. In this case, the phosphor having the anisotropic molecular structure functions as both a color converter and a polarization rotator. Different states can

electronic states, for example singlet or triplet, for triplet emitters or else different singlets for fluorescent dyes, but also different vibronic states of the same electronic state.

The change, for example, the increase in the polarization of the electromagnetic primary radiation is always advantageous when polarized light is to be generated. The degree of polarization can be further increased by the use of polarizers. Overall, the efficiency of the

Producing polarized light higher when the light is already polarized in front of the polarizer. One possible application is the generation of polarized light for

Display applications, for example, to achieve 3D effects.

The polarization direction of the electromagnetic

Primary radiation and secondary radiation can be influenced by a conversion element described here,

especially increase. This is an advantage if polarized light is to be generated. In addition, the reflectivity of some surfaces is dependent on the degree of polarization, i.

by combination of an aligned conversion element with such a surface, eg as a reflective

Electrode, the degree of polarization can be further increased.

In addition to the use of phosphors with an anisotropic molecular structure can also be determined by the choice of

Phosphor material, the phosphor particle size distribution and / or increased by a matrix material in the conversion element, the conversion efficiency. In particular, such materials are used as matrix materials

used, which show the highest possible transmission. The converter particle size, the refractive index and the

Matrix material can the radiation characteristics of the

Determine particles of scattered light. It can be set between, for example, strongly forward or, for example, approximately isotropic. The particle size can determine the ratio of absorption / conversion and scattering. For example, in a conversion LED by using a coarse-grained mixture compared to a strongly scattering fine-grained mixture, a higher absorption probability and a directional

Abstrahlcharakteristik the Streuanteils be generated.

In accordance with at least one embodiment, the phosphor is introduced in one layer or in different layers. In particular, the phosphor is arranged in a layer above an organic light-emitting diode. In particular, the conversion element is arranged on the organic light-emitting diode. On in this context means one

direct or indirect mechanical contact with the organic light-emitting diode.

Hereinafter, a described conversion element and a method described herein for producing a Conversion element with reference to the drawing using exemplary embodiments explained in more detail. Same

Reference numerals indicate the same elements in the individual figures. However, they are not to scale

rather, individual elements may be exaggerated for clarity.

Show it:

Figures 1 to 4 are each a schematic side view of a conversion element according to a

Embodiment and a radiation source or an organic light-emitting diode according to an embodiment, Figures 5A, 5B and 5C each have a schematic

Side view of a conversion element according to one embodiment, Figure 6 is a schematic plan view of a

Conversion element according to one embodiment, Figure 7A is a chemical structural formula of a phosphor according to one embodiment, Figure 7B associated with this phosphor of Figure 7A

Absorption and emission spectrum according to an embodiment, FIG. 8 shows a chemical structural formula of a phosphor according to an embodiment, Figures 9a to 9m chemical structural formulas of several phosphors according to an embodiment, and Figure 10 alignment of phosphors in one

Matrix material according to one embodiment.

In Figure 1 is a conversion element 5 according to a

Embodiment shown. The conversion element 5 is in direct contact with an organic light-emitting diode 6

or a radiation source 10 is arranged.

In particular, the conversion element 5 is in direct contact on an at least partially transparent second

Electrode 4 is arranged. The organic light emitting diode 6

or the radiation source 10 has a first electrode 2, which is arranged on a substrate 1, on. Furthermore, the organic light-emitting diode 6 or the radiation source 10 has an organic layer stack 3 and a second electrode 4. The organic layer stack 3 is disposed between the first electrode 2 and the second electrode 4 and for emission of electromagnetic

Primary radiation (not shown here) set up. The first electrode 2 may be an anode made of a transparent conductive oxide, TCO for short. For example, the first electrode 2 comprises or consists of indium tin oxide. Alternatively, the first electrode 2 may be reflective and comprise a metal such as silver, aluminum, cadmium, barium, indium, magnesium, calcium, lithium or gold. Additional functional layers like

Charge carrier injection layers or barrier layers are not shown in FIG. 1, but may additionally be comprised by an organic light-emitting diode 6. On a side facing away from the substrate 1 of the organic layer sequence 3, a second electrode 4 is applied, which is preferably designed as a cathode and a metal such as silver, aluminum, cadmium, barium, indium, magnesium,

Calcium, lithium or gold or consists of one or more of said metals. The second electrode 4 may in this case be composed of several partial layers. It is also possible that the second electrode 4

is radiation-transmissive and a material, in particular a transparent conductive oxide, such as ITO, comprises or consists thereof. The conversion element 5, which is applied to the second electrode 4, schematically has a phosphor in Figure 1 with an anisotropic

Molecular structure on. In particular, the phosphor has a transitional dipole moment 7, which is shown schematically in FIG. 1 by a phosphor molecule with a transitional dipole moment 7. The transitional dipole moment 7 shown is parallel to the layer plane of the conversion element 14

aligned. Layer plane of the conversion element 14 means here the main surface of the conversion element 5, which is applied directly to the second electrode 4. The electromagnetic primary radiation emitted by the organic layer stack 3 can be absorbed by the conversion element 5 and converted into an electromagnetic secondary radiation. Due to the preferred direction of

Transient dipole moments 7 of the molecules of the phosphor in the conversion element 5 have the electromagnetic

Secondary radiation an anisotropic directionality 8 on.

In particular, the electromagnetic secondary radiation has a preferred direction, which is radiated substantially perpendicular to the main surface of the conversion element. In essence, that means more than 80% of

electromagnetic secondary radiation perpendicular to Layer of the conversion element 5 is emitted with a deviation of +/- 45 ° to the vertical orientation.

The organic light emitting diode 6 can also more than one

Have phosphor. In particular, the phosphors in different layers of the conversion element 5

be arranged. Different phosphors may also have differently aligned transition dipole moments 7, e.g. with transition dipole moments 7 parallel, or in the same plane, but perpendicular to each other. In the latter case, the two phosphors preferably emit light polarized perpendicular to one another.

Alternatively, the conversion element 5 a layer

have, wherein a phosphor is disposed above the organic light emitting diode 6.

Apart from the conversion element 5, the organic light-emitting diode 6 disposed above the second electrode 4 also has a scattering layer (not shown here), one or more filters (not shown here), one

Encapsulation layer (not shown here) and / or a

Substrate (not shown here) have. These layers may be arranged in all different orders and combined with each other, e.g. by

Introducing scattering particles into the conversion element.

FIG. 2 is a schematic side view of a

Conversion element 5 and a radiation source 10th

or an organic light-emitting diode 6 according to one embodiment. FIG. 2 differs from FIG. 1 in that, between the conversion element 5 and the second electrode 4 of FIG Slide 9 is arranged. In particular, the film 9 is adapted to decouple the electromagnetic primary radiation from the organic light emitting diode 6 and in the

Coupling conversion element 5. This can be the

Absorption probability of the electromagnetic

Primary radiation in the conversion element 5 or in the

Fluorescent can be increased. In addition, the emission of the electromagnetic secondary radiation can be increased. The film 9 can be called here and in the following also Auskoppelfolie. The decoupling film 9 comprises a material, for example polycarbonate, polymethylmethacrylate (PMMA), polystyrene, silicone and / or epoxy resin.

FIG. 3 schematically shows a side view of a

Conversion element 5, which directly on a

Radiation source 10 is arranged. In particular, the radiation source 10 is an organic light-emitting diode 6.

FIG. 4 shows a schematic side view of a conversion element 5 according to one embodiment. The

Conversion element 5 is arranged directly on the main surface of a solar cell 11. The conversion element 5 is arranged between a radiation source 10 and the solar cell 11. The radiation source 10 is for example the sun. The radiation source 10 is spatially spaced from the conversion element 5. The radiation source 10 can emit electromagnetic primary radiation, which is converted by the conversion element 5 into electromagnetic secondary radiation. The converted electromagnetic

Secondary radiation can be at least partially converted into electrical energy in the solar cell 11. By

Use of a conversion element 5 according to the invention with at least one anisotropic phosphor can thus be more electrical energy can be generated in comparison to a conventional conversion element, which has no anisotropic phosphor molecules. FIGS. 5A, 5B and 5C each show a schematic side view of a conversion element 5. The

Conversion element 5 comprises phosphor molecules each having a transition dipole moment 7. The phosphor molecules have an anisotropic molecular structure. The anisotropic

Molecular structure can be generated for example by different substituents. The transition dipole moments 7 are preferably arranged substantially parallel to the layer plane of the conversion element 5. The direction of the

Transient dipole moments of the individual molecules are either rectified or oppositely directed.

FIG. 5B shows, in comparison with FIGS. 5A and 5C, that the transition dipole moments have the same orientation relative to one another.

FIG. 6 shows a schematic top view of a

Conversion element 5 according to one embodiment. The

Conversion element 5 shows at least one phosphor which has an anisotropic molecular structure. Furthermore, FIG. 6 shows that a majority of the transition ^¬ dipolmomente the molecules of the phosphor is aligned parallel to each other. In particular, the mutually parallel transition dipole moments are arranged in a plane to one another (not shown here).

FIG. 7A shows a chemical structural formula of a

Phosphor according to one embodiment. The phosphor comprises 1,2-benzopyrone, also referred to as coumarin can be. In particular, coumarin is substituted.

In particular, 1,2-benzopyrone may have at least one

Substituted nitrogen and / and sulfur atom heteroaromatic be substituted. For example, the phosphor is

Coumarin 6, which is also known as 3- (2-benzotiazolyl) -7-

(Diethylamino) coumarin (Figure 7A).

FIG. 7B shows the absorption and emission spectrum associated with the phosphor of FIG. 7A in accordance with FIG

Embodiment. FIG. 7B shows the intensity I in a.U. as a function of the wavelength λ in nanometers. The first curve 12 shows the absorption spectrum of the coumarin 6. The second curve 13 shows the emission spectrum of the coumarin 6. The absorption spectrum 12 shows intensity maxima at about 300 nm and 450 nm. Coumarin 6 shows

Coulomb 6 has a transitional dipole moment and is therefore able to have a preferential direction in one

Conversion element 5 take.

FIG. 8 shows a chemical structural formula of a

Phosphor according to one embodiment. In particular, the phosphor is a substituted or unsubstituted perylene. Perylene can also be referred to as peri-dinaphthalene. Perylene may be substituted in particular. When

Substituents are aromatic, heteroaromatic, alkyl, alkoxy in question. Perylene exhibits a transitional dipole moment and can therefore assume a preferred direction in a conversion element 5 according to an embodiment.

FIGS. 9a to 9m show structural formulas of further phosphors according to further embodiments. The other phosphors can be used in a conversion element become. The further phosphors may be an electromagnetic generated by a radiation source (10)

Convert primary radiation into an electromagnetic secondary radiation, wherein the secondary electromagnetic radiation has an anisotropic directionality.

Figure 10 shows the orientation of phosphors as shown in Figures 9a to 9m in a stretched polyethylene film at room temperature. Here, the numbers 1 to 81 correspond to the numbers 1 to 81 of FIGS. 9a to 9m. By stretching the film, an orientation of the phosphor can be generated. In particular, take the

Fluorescent molecules enter a certain preferred direction in space.

By introducing a phosphor in a film,

For example, from polymer, a high degree of alignment of the molecules can be achieved in a simple manner. The invention described here is not by the

Description limited 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.

This patent application claims the priority of German Patent Application 10 2013 113 533.1, the disclosure of which is hereby incorporated by reference.

Claims

claims

1st conversion element (5), the

at least one phosphor with an anisotropic

Having molecular structure, wherein the molecules of the

Phosphor each have at least one transition dipole moment (7), wherein the transition dipole moments (7) in the sum have an anisotropic orientation within the conversion element (5),

wherein the phosphor is adapted to an electromagnetic primary radiation generated by a radiation source (10) in an electromagnetic

To convert secondary radiation, the

Electromagnetic secondary radiation has an anisotropic directionality.

Second conversion element (5) according to claim 1,

wherein the radiation source (10) is an organic

Light-emitting diode (6) is,

wherein the organic light emitting diode (6) is a first

Electrode (2), which is arranged on a substrate (1), a second electrode (4) and a light

having generating organic layer stack (3) between the electrodes (3, 4), and

wherein the conversion element (5) is arranged in direct contact on the at least partially transparent second electrode (4) on a side facing away from the layer stack (3).

3. Conversion element (5) according to one of the preceding claims, wherein the conversion element (5) is formed as a layer, wherein: <cos ² 6> ^ 0.2; where Θ the Angle between the respective transitional dipole moment of the molecules of the phosphor and a layer normal (s) is, wherein the layer normal (s) is arranged perpendicular to the layer of the conversion element.

4. Conversion element (5) according to one of the preceding claims, wherein a majority of the transition dipole moments (7) of the molecules of the phosphor are arranged parallel to each other and in a plane.

5. Conversion element (5) according to one of the preceding claims, wherein more than 80% of all

Transition dipole moments (7) of the molecules of the phosphor a parallel alignment with a maximum deviation of ± 45 ° from this parallel orientation to

Layer surface of the conversion element (14).

6. Conversion element according to one of the previous

Claims, wherein the conversion element (5) as a layer with a layer thickness of at least 5 nm and at most

200 nm is formed and directly on the

Radiation source (10) is arranged, wherein the

Radiation source (10) is an organic light-emitting diode (6).

7. Conversion element (5) according to one of the preceding claims, wherein the conversion element (5) is formed as a layer having a layer thickness of at least 5 nm and at most 200 nm and from the radiation source (10) is spatially spaced, wherein the conversion element

(5) is disposed directly on a solar cell (11), wherein the solar cell (11) is adapted to that of the conversion element (5) converted To absorb electromagnetic secondary radiation and at least partially convert it into electrical energy.

8. Conversion element (5) according to one of the preceding claims, wherein the conversion element (5) emits more than 90% of the total secondary electromagnetic radiation with a maximum deviation of ± 30 ° from a vertical orientation to the layer plane of the conversion element (14).

A conversion element (5) according to any one of the preceding claims wherein the phosphor is selected from the group consisting of substituted or unsubstituted coumarin, substituted or unsubstituted perylene, a laser dye, a Bodipy dye, a quasi-planar compound and a quasiplanar

Transition metal complex comprises.

10. Conversion element (5) according to one of the preceding claims, wherein the conversion element (5) is formed as a film, wherein the phosphor is embedded in at least one matrix material, wherein the matrix material comprises or consists of polyethylene, wherein the film is stretched, so that the film has a thickness of at least 5 ym and at most 100 ym.

11. Conversion element (5) according to one of the preceding claims, wherein the conversion element (5) is formed as a film, which is a matrix material and therein

embedded embraces the phosphor, wherein the

Phosphor is chemically bonded to the matrix material, wherein the film is stretched, so that the film has a thickness of at least 5 ym and at most 100 ym.

12. Conversion element (5) according to one of the preceding claims, wherein the conversion element (5) comprises an additional phosphor, wherein more than 80% of all transition dipole moments (7) of the molecules of the first and the additional phosphor have a parallel alignment to each other.

13. A method for producing a conversion element (5) according to one of claims 1 to 12 on a

Radiation source (10) and / or a solar cell (11) with the following process steps:

A) providing the radiation source (10) or the solar cell (11),

Bl) applying the conversion element (5) on the

Radiation source (10) or the solar cell (11), wherein the phosphor is evaporated in a vacuum and the radiation source (10) or the solar cell (11)

is deposited so that an anisotropic alignment of the phosphor molecules takes place,

or

B2) applying the conversion element (5) on the

Radiation source (10) or the solar cell (11), wherein the phosphor is embedded in a matrix material and is applied by injection molding on the radiation source (10) or the solar cell (11), so that an anisotropic alignment of the phosphor molecules takes place.

14. The method of claim 13, wherein in step Bl) after and / or during the deposition step, the deposited phosphor or the surface of

Radiation source (10) or the solar cell (11) on a is brought to room temperature elevated temperature or maintained at such a temperature.