DE102014223507A1 - Organic light emitting device and method of making an organic light emitting device - Google Patents

Abstract

The invention relates to an organic light-emitting component which has on a substrate (1) a transparent first electrode (2) with an electrical contact region (3) for electrically contacting the first electrode (2) and a second electrode (5). Arranged between the first and the second electrode (2, 5) is an organic functional layer stack (4) having at least one organic light-emitting layer which is adapted to emit light during operation of the organic light-emitting component, the transparent first electrode (4) 2) has a decreasing transverse conductivity and an increasing transparency as a function of a lateral distance to the electrical contact region (3). Furthermore, methods for producing the organic light-emitting component are given.

Description

An organic light emitting device and method for producing an organic light emitting device are disclosed.

While in a small organic light emitting diode (OLED) without further precautions, a sufficiently homogeneous lateral luminance distribution can be achieved, have large-area OLEDs with at least one large-area transparent electrode, the problem that the electrical conductivity of this is very limited. Due to the resulting voltage drop across the transparent electrode, there is an inhomogeneous luminance distribution. If the large-area transparent electrode, for example peripherally electrically contacted at the edge, so there is a lower luminance in the center of the component than at the edge, since due to the limited lateral conductivity of the transparent electrode, a portion of the applied voltage drops across the electrode and therefore the range in the center of the luminous area is effectively operated at a lower voltage than areas near the contacts at the edge of the luminous area.

In order to avoid this problem, it is known in the prior art to use so-called "bus bars" or "grid lines", that is to say via the transparent electrode extending additional conductor webs which support the current distribution in the transparent electrode. The disadvantage of such wire webs lies in their lack of transparency, which gives non-luminous areas within the component and thus reduces the active area of an OLED. In addition, the cable webs can have a disadvantageous optical effect, since it may be possible that the luminous area no longer appears homogeneous, but is penetrated by the pattern of the cable webs.

At least one object of certain embodiments is to specify an organic light-emitting component in which the disadvantages described above can at least be reduced. Other objects of certain embodiments are to provide methods of making an organic light emitting device.

These objects are achieved by an object and by methods having the features of the independent claims. Advantageous embodiments and further developments of the subject matter and of the methods are characterized in the dependent claims and furthermore emerge from the following descriptions and the drawings.

In accordance with at least one embodiment, an organic light-emitting component has at least one transparent first electrode and a second electrode, between which an organic functional layer stack is arranged. The organic functional layer stack has at least one organic light-emitting layer in the form of an organic electroluminescent layer, which is designed to generate light during operation of the organic light-emitting component. The organic light-emitting component may in particular be designed as an organic light-emitting diode (OLED).

By "transparent" is here and below referred to a layer that is transparent to visible light. In this case, the transparent layer can be transparent or at least partially light-scattering and / or partially light-absorbing, so that the transparent layer can be translucent, for example, also diffuse or milky. Particularly preferably, a layer designated here as transparent has the lowest possible absorption of light.

The organic functional layer stack may comprise layers with organic polymers, organic oligomers, organic monomers, organic small, non-polymeric molecules ("small molecules") or combinations thereof. Suitable materials for the organic light-emitting layer are materials which have a light emission due to fluorescence or phosphorescence, for example polyfluorene, polythiophene or polyphenylene or derivatives, compounds, mixtures or copolymers thereof. The organic functional layer stack may also include a plurality of organic light emitting layers disposed between the electrodes. The organic functional layer stack may comprise further organic functional layers, for example charge carrier injection layers, charge carrier transport layers and / or charge carrier blocking layers.

According to a further embodiment, the organic light-emitting component has a substrate on which the electrodes, ie the transparent first electrode and the second electrode, and the organic functional layer stacks are applied. The substrate may comprise, for example, one or more materials in the form of a layer, a plate, a foil or a laminate, which are selected from glass, quartz, plastic, metal, silicon wafers. Particularly preferably, the substrate glass or / and plastic, for example in the form of a glass layer, glass sheet, glass plate, plastic layer, plastic film, plastic plate or a glass-plastic laminate, or is therefrom. In addition, the substrate, for example, in the case of plastic as the substrate material, one or more barrier layers have, with which the plastic material is sealed.

With regard to the basic structure of an organic light-emitting component, in this case for example with regard to the structure, the layer composition and the materials of the organic functional layer stack, reference is made to the document WO 2010/066245 A1 which is hereby expressly incorporated by reference, particularly with regard to the structure, the layer composition and the materials of the organic functional layer stack.

Furthermore, the organic light-emitting component has an electrical contact region for electrical contacting of the first electrode. In addition, an electrical contact region may also be provided for electrically contacting the second electrode, wherein the electrical contact region for contacting the second electrode may have one or more features, which are described below generally and in conjunction with the electrical contact region for contacting the transparent first electrode are.

An electrical contact region for the electrical contacting or for the electrical connection of an electrode may include and / or hereinafter be, for example, an electrical supply line, a conductor track, an electrical connection pad, a contact wire and / or a bonding pad and be suitable for electrically connecting an electrode to a voltage supply. and / or power supply. In this case, the electrical contact region can also be formed by a part of the electrode. In particular, the electrical contact region may be arranged such that there is no direct electrical contact between the electrical contact region and the organic functional layer stack. An electrical contact region may be arranged in particular in the lateral direction next to the organic functional layer stack. In particular, this may mean that an electrical contact region for the electrical contacting of an electrode is in direct electrical contact only with this electrode, that is, not with the organic functional layer stack and not with the other electrode.

A lateral direction is here and hereinafter referred to as a direction which is parallel to the main extension direction of the layers of the organic light-emitting component, that is to say in particular parallel to the main extension plane of the transparent first electrode. The electrical contact region for contacting the first electrode thus lies in a plan view of the organic light-emitting component and thus on the luminous surface of the organic light-emitting component next to the transparent first electrode.

The electrical contact region may have a point, line or area-like contact surface with the transparent first electrode. In particular, a line surface or surface-like contact surface may extend along and / or also partially on a part of the first electrode. In this case, the electrical contact region may have one or more regions which are connected to one another or are in electrical contact with the first electrode separately from one another. The electrical contact region may also at least partially or completely surround the transparent first electrode. In particular, the electrical contact region can contact the first electrode at at least two side edges. The electrical contact region can thus be configured such that it completely or at least substantially completely surrounds the first electrode. It may mean that the electrical contact region contacts virtually the entire edge of the transparent first electrode, in which case regions of the electrical contact region may be kept free, for example those regions in which an electrical contact region extends to make contact with the second electrode.

According to a further embodiment, the transparent first electrode has a decreasing transverse conductivity and an increasing transparency as a function of a lateral distance to the electrical contact region. A lateral distance of a point of the first electrode from the electrical contact region may in this case for example denote a mean lateral distance, which is averaged over the lateral distances of a part or all of the electrical contact points of the contact region and the corresponding point of the first electrode. In this case, an arithmetic, a geometric or a suitable other summing or integrating averaging method with imaginary discrete contact points of finite size or with infinitesimal small assumed contact points are used. Alternatively, a lateral distance of a point of the first electrode to the electrical contact region may be given by the distance of the point of the first electrode to the nearest contact point of the contact region.

• – Leitfähigkeit im Randbereich: größer oder gleich 0,02 S/m, bevorzugt größer oder gleich 0,05 S/m, und kleiner oder gleich 1 S/m, bevorzugt kleiner oder gleich 0,2 S/m;
• – Leitfähigkeit im Mittenbereich: größer oder gleich 0,002 S/m, bevorzugt größer oder gleich 0,01, und kleiner oder gleich 0,1 S/m, bevorzugt kleiner oder gleich 0,05 S/m;
• – Verhältnis der Leitfähigkeit im Randbereich zur Leitfähigkeit im Mittenbereich: größer oder gleich 2, bevorzugt größer oder gleich 5, und kleiner oder gleich 20, bevorzugt kleiner oder gleich 10;
• – Transparenz (ohne Substrat) im Randbereich: größer oder gleich 70%, bevorzugt größer oder gleich 90%, und kleiner oder gleich 99%, bevorzugt kleiner oder gleich 95%;
• – Transparenz (ohne Substrat) im Mittenbereich: größer oder gleich 95%, bevorzugt größer oder gleich 98%, und kleiner oder gleich 99,9%, bevorzugt kleiner oder gleich 99,5%;
• – Dicke (für Indiumzinnoxid als Material der ersten Elektrode) im Randbereich: größer oder gleich 50 nm, bevorzugt größer oder gleich 100 nm, und kleiner oder gleich 2000 nm, bevorzugt kleiner oder gleich 500 nm;
• – Dicke (für Indiumzinnoxid als Material der ersten Elektrode) im Mittenbereich: größer oder gleich 5 nm, bevorzugt größer oder gleich 50 nm, und kleiner oder gleich 200 nm, bevorzugt kleiner oder gleich 100 nm.

The transparent first electrode is thus characterized by a varying transverse conductivity and a varying transparency as a function of the lateral distance to the electrical contact region. In other words, in a first region near the electrical contact region, the first electrode has a higher transverse conductivity and a lower transparency than in a second region, which is farther from the electrical contact region than the first region. In the case of an electrical contact region which completely or substantially surrounds the transparent first electrode, this means, in particular, that the transverse conductivity of the first electrode is less in the region of the component center than at the component edge, while the transparency in the region of the component center is greater in comparison to the component edge. In this case, the following parameters may in particular be particularly advantageous for the first electrode, with regions of the first electrode near or in contact with the contact region being designated as the edge region and regions of the first electrode being as far apart as possible from the entire contact region as center region:

• - Conductivity in the edge region: greater than or equal to 0.02 S / m, preferably greater than or equal to 0.05 S / m, and less than or equal to 1 S / m, preferably less than or equal to 0.2 S / m;
• Conductivity in the middle range: greater than or equal to 0.002 S / m, preferably greater than or equal to 0.01, and less than or equal to 0.1 S / m, preferably less than or equal to 0.05 S / m;
• Ratio of the conductivity in the edge region to the conductivity in the middle region: greater than or equal to 2, preferably greater than or equal to 5, and less than or equal to 20, preferably less than or equal to 10;
• Transparency (without substrate) in the edge region: greater than or equal to 70%, preferably greater than or equal to 90%, and less than or equal to 99%, preferably less than or equal to 95%;
• Transparency (without substrate) in the middle region: greater than or equal to 95%, preferably greater than or equal to 98%, and less than or equal to 99.9%, preferably less than or equal to 99.5%;
• Thickness (for indium tin oxide as material of the first electrode) in the edge region: greater than or equal to 50 nm, preferably greater than or equal to 100 nm, and less than or equal to 2000 nm, preferably less than or equal to 500 nm;
• Thickness (for indium tin oxide as material of the first electrode) in the central region: greater than or equal to 5 nm, preferably greater than or equal to 50 nm, and less than or equal to 200 nm, preferably less than or equal to 100 nm.

The indicating conductivity values can apply in particular to the transverse conductivity of the first electrode. When selecting the parameters for the edge region and the center region from the specified parameter ranges, these are to be selected so that the transparency of the first electrode in the edge region is smaller than the transparency of the first electrode in the middle region and that the conductivity of the first electrode, ie in particular their Transverse conductivity is greater in the edge area than in the center area. The transparency preferably applies with regard to a transmission of light generated in the component. The parameter ranges for the conductivity, the thickness and the transparency can be independent of each other, adjustable by the geometric design and the choice of material for the first electrode. For an electrical contact region that does not completely or substantially completely surround the first electrode, corresponding values from the specified parameter ranges may apply to regions of the first electrode that are near or closest to the contact region and farthest from the contact region.

In the organic light-emitting device described here, and particularly in the transparent first electrode having the varying transverse conductivity and the varying transparency, it can be advantageously used that the conductivity and the transparency of the transparent first electrode are not independent of each other. Rather, increased transparency requires reduced conductivity and vice versa. Advantageously, however, the fact that the first electrode has to carry a larger lateral current at the edge of the component, that is to say in the vicinity of the electrical contact region, than in regions further away from the electrical contact region, can be used in the first electrode described here. In the case of an electrical contact region enclosing the first electrode, this can easily be illustrated by the fact that in the middle of the component, only the current which also energizes the center of the luminous area flows laterally through the first electrode, while at the edge of the component or the first electrode lateral to one, the current flows through the first electrode, which energizes the edge region of the active luminous surface, as well as the current which energizes the center of the component and thus the center of the luminous surface.

In the case of the organic light-emitting component described here, the transparent first electrode thus has the highest possible conductivity in regions near the electrical contact region, ie at the edge, in order to minimize the voltage drop across the electrode to regions remote from the electrical contact region in these regions. In contrast, the first electrode has a comparatively lower conductivity in regions farther away from the electrical contact region. The minimized voltage drop in the edge region can reduce the difference between the electrical voltages that are close to the electrical contact region and those further away from the electrical contact region, which can already improve the homogeneity of the luminance.

As a result of greater transparency being present at the same time in regions with a lower transverse conductivity, a lower absorption of the light generated in the organic light-emitting component can also be achieved in these regions, which can further improve the homogeneity of the luminance. In the case of the organic light-emitting component described here, it is thus possible to increase the luminance homogeneity within the luminous area in comparison to conventional large-area OLEDs without the use of conventional busbars such as "busbars".

The transparent first electrode can be designed, for example, as an anode and thus serve as a hole-injecting material. By way of example, the transparent first electrode may comprise a transparent conductive oxide or consist of a transparent conductive oxide. Transparent conductive oxides (TCOs) are transparent conductive materials, typically metal oxides such as zinc oxide, tin oxide, cadmium oxide, titanium oxide, indium oxide, indium tin oxide (ITO) or aluminum zinc oxide (AZO). In addition to binary metal-oxygen compounds such as ZnO, SnO ₂ or In ₂ O _3, ternary metal-oxygen compounds, such as Zn ₂ SnO _4, CdSnO _3, ZnSnO _3, MgIn ₂ O _4, GaInO _3, Zn ₂ In ₂ O ₅ or In ₄ Sn ₃ O ₁₂ or mixtures of different transparent conductive oxides to the group of TCOs. Furthermore, the TCOs do not necessarily correspond to a stoichiometric composition and may also be p- or n-doped. Furthermore, the transparent first electrode may comprise or be made of silver nanowires (SNW) or nanoparticles of a TCO.

In addition, the transparent first electrode can have or be formed by a thin metal layer whose thickness is sufficiently low so that the metal is at least partially transparent. Such an electrode may be referred to as a thin metal electrode (TME) or a thin metal film electrode (TMF) and may include, or be comprised of Ag or an Ag alloy, such as an Ag-Mg alloy. Furthermore, combinations of said materials, for example in the form of multiple layers, are possible.

The transparent first electrode may be applied by various methods depending on the material chosen, for example in the case of a TCO or a thin metal film by sputtering or thermal evaporation and in the case of silver nanowires or TCO nanoparticles, for example by a solvent-based process such as a printing process ,

The second electrode may be designed as a cathode and thus serve as an electron injecting material. In particular, aluminum, barium, indium, silver, gold, magnesium, calcium or lithium, as well as compounds, combinations and alloys thereof, may be advantageous as the cathode material. By means of a sufficient thickness of one or more of the materials mentioned, the second electrode can be designed to be reflective. Alternatively or additionally, the second electrode can also have one of the abovementioned TCOs or a layer sequence with or consisting of one or more TCO layers and one or more metal layers. The second electrode may also be transparent. In this case, the second electrode may have features that are described above and below for the first electrode.

Alternatively, the first electrode may also be designed as a cathode and the second electrode as an anode.

The first and / or the second electrode may each be formed over a large area and contiguous. As a result, a large-area radiation of the electromagnetic radiation generated in the active region can be made possible. "Large area" may mean for the organic radiation-emitting component described here that the organic radiation-emitting component has an area greater than or equal to a few square millimeters, preferably greater than or equal to one square centimeter, and particularly preferably greater than or equal to one square decimeter.

According to a further embodiment, the first electrode is arranged between the substrate and the organic functional layer stack. In this case, the substrate is also transparent. Thus, in this case, the light generated in the organic functional layer stack during operation of the device may be radiated through the substrate and the first electrode, and the organic light emitting device is implemented as a so-called "bottom emitter".

Furthermore, the transparent first electrode can also be arranged above the organic functional layer stack as viewed from the substrate. In this case, the light generated in the organic functional layer stack during operation of the component can in this case be emitted in a radiation direction away from the substrate and the organic light emitting component is designed as a so-called "top emitter".

If the second electrode is also designed to be transparent, the organic light-emitting component can also be embodied as emitting on both sides.

According to another embodiment, the transverse conductivity and the transparency of the first electrode vary gradually and thus continuously. Alternatively, the transverse conductivity and transparency may vary in steps.

According to a further embodiment, the first electrode has a thickness which decreases as a function of the lateral distance to the electrical contact region.

By varying the layer thickness, the conductivity as well as the transparency of the transparent first electrode can be modified simultaneously. A greater thickness means in this case a higher conductivity and a higher absorption or a lower transparency, while a smaller thickness correspondingly causes a lower transverse conductivity and thus a higher transparency. The thickness can be continuously reduced depending on the lateral distance to the electrical contact region. Alternatively, it is also possible that the thickness gradually decreases as a function of the lateral distance to the electrical contact region.

According to a further embodiment, in a method for producing an organic light-emitting component, the transparent first electrode is applied by means of vapor deposition or sputtering with a thickness which decreases as a function of the lateral distance to the electrical contact region. In this case, during the application of the first electrode, masks can be used to produce areas of the transparent first electrode of different thicknesses. By using different masks, it can be achieved that in each case only partial regions of the electrode surface of the first electrode are formed or deposited on regions on which electrode material has already been applied using another mask. As an alternative to this, it is also possible for a uniformly thick layer to be applied laterally homogeneously, followed by structuring in the form of back structuring, in which the varying thickness of the transparent first electrode is produced.

According to a further embodiment, in a method for producing an organic light-emitting component, the transparent first electrode is made of solution by means of a printing process with a degree of coverage which decreases as a function of the lateral distance to the electrical contact region and / or with an electric field as a function of the lateral distance Applied contact area reducing thickness. Printing methods are suitable, as described above, in particular in connection with solution-processed electrode materials such as, for example, TCO nanoparticles or silver nanowires. The varying degree of coverage may be achieved, for example, by decreasing the number and / or decreasing size and / or decreasing density of printed areas of electrode material. The printed areas may be drops, for example in the case of ink-jet printing (inkjet printing), or else be generated by the well depth and / or density in a gravure printing process.

The organic light-emitting component can furthermore have an encapsulation in the form of a glass cover and / or a thin-film encapsulation, in order to protect the first and second electrode and the organic functional layer stack from moisture and / or oxidizing substances such as oxygen, for example.

Further advantages, advantageous embodiments and developments emerge from the embodiments described below in conjunction with the figures.

Show it:

1A and 1B schematic representations of an organic light emitting device according to an embodiment,

2 a schematic representation of an organic light emitting device according to another embodiment,

3 a substrate having a transparent first electrode for an organic light emitting device according to another embodiment, and

4 to 6 an organic light-emitting component and comparative simulations of the lateral stress distribution and the lateral luminance distribution according to a further 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, but individual elements, such as layers, components, components and areas, for better presentation and / or better understanding may be exaggerated.

In the 1A and 1B is an embodiment of an organic light emitting device 100 shown. In 1A this is a plan view of the organic light emitting device 100 shown while the 1B a sectional view through the organic light emitting device 100 equally along the sectional plane AA and the sectional plane BB represents. The following description refers equally to the 1A and 1B ,

The organic light emitting device 100 is designed as an organic light emitting diode (OLED) and has a substrate 1 on top of which a transparent first electrode 2 and a second electrode 5 are arranged. Between the electrodes 2 . 5 is an organic functional layer stack 4 arranged with at least one or more organic light emitting layers, which are adapted to, during operation of the organic light emitting device 100 Generate light by electroluminescence.

The substrate 1 is like the first electrode 2 formed transparently so that in the organic functional layer stack 4 during operation of the organic light emitting device 100 generated light can be emitted through this outward. As an alternative to such a configuration referred to as bottom emitter, the transparent first electrode 2 also from the substrate 1 seen above the organic functional layer stack 4 be arranged so that the organic light-emitting device 100 in this case is designed as a so-called top emitter.

The substrate 1 can in the embodiment shown in particular glass and / or plastic and be formed, for example, as a film or plate made of or with glass and / or plastic or a glass-plastic laminate.

The organic functional layer stack 4 For example, in addition to one or more organic light-emitting layers, further organic functional layers may be included, such as charge carrier transport layers and / or charge carrier blocking layers, such as one or more hole transport layers and / or one or more electron transport layers and / or one or more hole blocking layers and / or one or more electron blocking layers other organic functional layers.

The transparent first electrode 2 In the embodiment shown, a transparent conductive oxide (TCO) such as indium tin oxide (ITO) on the substrate 1 is applied. Additionally or alternatively, other transparent electrically conductive materials such as other TCOs mentioned above in the general part are also possible. The second electrode 5 is reflective in the embodiment shown and has a metal, as described above in the general part.

Furthermore, the organic light-emitting component 100 an electrical contact area 3 for electrically contacting the transparent first electrode 2 on. The second electrode 5 is via electrical contact areas 6 electrically contacted. The electrical contact area 3 to the electric Contacting the first electrode 2 is at the edges of the transparent first electrode 2 formed and forms a substantially transparent first electrode 2 enclosing electrical contact, by means of which the transparent first electrode 2 contacted on almost all sides electrically. Only in areas where the electrical contact area 6 the second electrode 5 guided laterally outward, the electrical contact area 3 for contacting the first electrode 2 be interrupted. Alternatively, it may also be possible that between the electrical contact areas 6 for contacting the second electrode 5 and the electrical contact area 3 for contacting the first electrode 2 an electrically insulating layer is arranged, so that in this case the electrical contact area 3 for contacting the first electrode 2 encircling and the first electrode 2 can be completely enclosed.

Alternatively to the illustrated embodiment of the electrical contact area 3 as a circumferential electrical contact area this can be the first electrode 2 also only in parts of the edge of the first electrode 2 contact, for example, only on one side or, as in the case of electrical contact areas 6 for contacting the second electrode 5 , on opposite sides. For the following description in terms of the transverse conductivity and the transparency of the first electrode 2 then applies accordingly.

The transparent first electrode 2 has as a function of a lateral distance to the electrical contact region 3 a decreasing transverse conductivity and an increasing transparency. In the exemplary embodiment shown, this is achieved in particular by a varying thickness of the first electrode 2 reached, which depends on the lateral distance to the electrical contact area 3 reduced. In particular, the thickness of the first electrode decreases 2 depending on the lateral distance to the electrical contact area 3 continuously, essentially without steps.

In a method of manufacturing the organic light emitting device 100 For example, this may be a laterally homogeneous layer having a uniform thickness with the electrode material of the first electrode 2 are applied, which is then structured by back-structuring such that the thickness distribution shown is achieved. Due to the varying thickness of the first electrode can be achieved that this close to the electrical contact area 3 has a larger transverse conductivity and a lower transparency than in areas farther away from the electrical contact area 3 In the exemplary embodiment shown, that is, in areas closer to the center of the first electrode 2 and thus the luminous region of the organic light emitting device 100 ,

Over the electrodes 2 . 5 and the organic functional layer stack 4 can still be arranged an encapsulation arrangement, which is not shown for clarity. The encapsulation arrangement can be embodied, for example, in the form of a glass cover or in the form of a thin-layer encapsulation.

A glass lid, for example in the form of a glass substrate, which may have a cavity, may by means of an adhesive layer or a glass solder on the substrate 1 glued or with the substrate 1 be merged. A moisture absorbing material, a so-called "getter", for example with or from zeolite, can also be glued into the cavity in order to bind moisture or oxygen which can penetrate through the adhesive. Furthermore, an adhesive containing a getter material may also be used to secure the lid to the substrate.

In the present context, an encapsulation arrangement designed as a thin-layer encapsulation is understood to be a single-layer or multilayer device which is suitable for forming a barrier to atmospheric substances, in particular to moisture and oxygen and / or other harmful substances such as corrosive gases, for example hydrogen sulphide. For this purpose, the encapsulation arrangement can have one or more layers each having a thickness of less than or equal to a few 100 nm. In particular, the thin-layer encapsulation may comprise or consist of thin layers which are applied, for example, by means of an atomic layer deposition (ALD) method. Suitable materials for the layers of the encapsulation arrangement are, for example, aluminum oxide, zinc oxide, zirconium oxide, titanium oxide, hafnium oxide, lanthanum oxide, tantalum oxide. The encapsulation arrangement preferably has a layer sequence with a plurality of the thin layers, each having a thickness between an atomic layer and 10 nm, the boundaries being included.

As an alternative or in addition to thin layers produced by ALD, the encapsulation arrangement can have at least one or a plurality of further layers, ie, in particular, barrier layers and / or passivation layers, which are produced by thermal vapor deposition or by a plasma-assisted process, such as sputtering or plasma-assisted chemical vapor deposition. enhanced chemical vapor deposition ", PECVD). Suitable materials for this may be the abovementioned materials and silicon nitride, silicon oxide, silicon oxynitride, indium tin oxide, indium zinc oxide, aluminum-doped zinc oxide, aluminum oxide and mixtures and alloys of the materials mentioned. The one or more further layers may, for example, each have a thickness between 1 nm and 5 μm, and preferably between 1 nm and 400 nm, the limits being included.

Thin film encapsulations are for example in the documents WO 2009/095006 A1 and WO 2010/108894 A1 whose respective disclosure content is hereby incorporated in full in this regard by reference.

In 2 is another embodiment of an organic light emitting device 100 shown in which compared to the previous embodiment, the thickness of the first electrode 2 depending on the lateral distance to the electrical contact area 3 gradually reduced. In the method for producing such an organic light-emitting device 100 For example, a plurality of different masks can be used, by means of which a deposition, for example by vapor deposition or sputtering, takes place only in partial areas, so that the stepped profile shown can be produced.

Depending on the formation of the organic functional layer stack and possible further layers, the thickness profile of the first electrode 2 in a height profile of the organic functional layer stack 4 and the second electrode 5 impact.

Alternatively to vapor deposition or sputtering, by means of which preferably a varying thickness of the first electrode 2 can be generated from or with a TCO, in particular solution-processed electrode materials such as TCO nanoparticles or silver nanowires can be applied by printing techniques. For example, as in 3 shown is the first electrode 2 be produced by an inkjet printing process in which a laterally varying number of printed areas 20 is applied in the form of a varying number of drops per area. Furthermore, it may also be possible that, for example, a gravure printing method is used, in which a varying size and / or a varying density of printed areas 20 can be generated by a varying cup depth or density within the printed electrode surface. It may thus be possible for the printing method to reduce the number and / or the size and / or the density of the printed areas as a function of the lateral distance from the electrical contact area 20 is reached. Depending on the print pattern, this can also be done as in 3 is shown, a varying thickness, that is, a thickness which decreases depending on the lateral distance to the electrical contact region can be achieved. As in connection with the 1A to 2 may be described, the thickness and / or the degree of coverage of the printed areas 20 change continuously or gradually.

In conjunction with the 4 to 6 a simulation by means of the simulation tool COMSOL of an organic light-emitting component is shown, the structure of which, purely by way of example, corresponds to the basic structure of the in 2 shown organic light emitting device 100 equivalent. The simulation was based on a square organic light-emitting component with an area of 105 mm × 105 mm, which has a circumscribed electrical contact. The transparent first electrode 2 points to a glass substrate 1 circumferential, inherently homogeneous regions, which have a different transverse conductivity and a different transparency from each other. In particular, the first electrode 2 formed step-shaped and has circumferential steps and surrounding areas with the thicknesses h3 = 385 nm, h2 = 330 nm, h1 = 275 nm, n = 220 nm, l1 = 165 nm, l2 = 110 nm and l3 = 55 nm. The region h3 forms an edge region of the first electrode 2 while the area l3 forms a central area. The electrical conductivities and the transmission values for the individual thickness ranges of the first electrode 2 were assumed to be inversely scaling with the layer thickness and were calculated directly from the layer thicknesses during the simulation. The stated layer thickness distribution is to be understood as merely exemplary and not restrictive. In particular, other parameter values for the thickness, the conductivity and the transparency of the first electrode can also be advantageous, for example selected from the parameter ranges given above in the general part.

The thus formed organic light emitting device was compared with conventional prior art OLED devices having a homogeneous, uniformly thick first electrode having a thickness corresponding to the region 12 with a resistivity of 16 ohms / sq and a transparency of 90.6% (including glass substrate), on the one hand an OLED device with busbars and on the other an OLED device without busbars was used.

In 5 on the left are the voltage distribution for the conventional device with uniformly thick first electrode without busbars, in the middle the voltage distribution for the conventional device with evenly thick electrode with busbars and right the voltage distribution for the organic light emitting device described here 100 shown. The scale on the far right indicates the voltage values in volts. In 6 is correspondingly left the luminance distribution for the conventional device with uniformly thick first electrode without busbars, in the middle the luminance distribution for the conventional device with uniformly thick electrode with busbars and right luminance distribution for the organic light emitting device described here 100 shown. The rightmost scale indicates the luminance values in candela per square meter. The simulation was based on an average luminance of 2000 cd / m ² in each component.

The following table shows the average operating voltage U in volts for the simulated components as parameters, the luminous efficacy η in lm / W, the maximum luminance Lum _max in cd / m ² , the minimum luminance Lum _min in cd / m ² and the uniformity H stated. The uniformity is calculated from the minimum and maximum luminance values Lum _max and Lum _min according to H = 1 - (Lum _max - Lum _min ) / (Lum _max + Lum _min ).

The simulated values of 5 and 6 consider both the influence of the transverse conductivity and the transparency on the voltage distribution or on the luminance distribution. parameter Device according to the prior art without busbars Component according to the prior art with busbars Component according to FIG. 4 U 5.85 5.76 5.77 η 40.0 39.6 39.3 _Max 2739 2278 2240 Lum _min 1423 1821 1713 H 68% 89% 87%

Like that 5 and 6 As well as the numerical values given in the table, with the simulated organic light emitting device a homogeneity of the voltage distribution and the luminance distribution can be achieved, which substantially corresponds to the values of a conventional OLED device with busbars, while a considerable improvement compared to a conventional OLED device without busbars can be achieved. In the case of a first electrode 2 , whose thickness does not vary in stages but continuously, it may be possible that a further improvement in homogeneity can be achieved. In the case of the organic light-emitting component described here, it is thus possible to homogenize the luminance distribution in comparison to conventional OLED components without having to use busbars.

The embodiments described in conjunction with the figures may alternatively or additionally comprise further features which are described above in the general part.

The invention is not limited by the description based on the embodiments of these. 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 patent 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 patent literature

• WO 2010/066245 A1 [0010]
• WO 2009/095006 A1 [0057]
• WO 2010/108894 A1 [0057]

Claims (16)

Organic light-emitting device, comprising: - on a substrate ( 1 ) a transparent first electrode ( 2 ) with an electrical contact area ( 3 ) for electrically contacting the first electrode ( 2 ) and a second electrode ( 5 ) and - between the first and the second electrode ( 2 . 5 ) an organic functional layer stack ( 4 ) having at least one organic light-emitting layer which is adapted to emit light during operation of the organic light-emitting component, the transparent first electrode ( 2 ) as a function of a lateral distance to the electrical contact region ( 3 ) has a decreasing transverse conductivity and an increased transparency. Component according to claim 1, wherein the transparent first electrode ( 3 ) between the organic functional layer stack ( 4 ) and the substrate ( 1 ) is arranged. Component according to claim 1 or 2, wherein the first electrode ( 2 ) has a thickness that depends on the lateral distance to the electrical contact region ( 3 ) decreased. Component according to one of the preceding claims, wherein the thickness in dependence on the lateral distance to the electrical contact region ( 3 ) decreased continuously. Component according to one of the preceding claims, wherein the thickness in dependence on the lateral distance to the electrical contact region ( 3 ) gradually reduced. Component according to one of the preceding claims, wherein the transparent first electrode ( 2 ) as a function of the lateral distance to the electrical contact region ( 3 ) has a reduced degree of coverage. Component according to one of the preceding claims, wherein the transparent first electrode ( 2 ) as a function of the lateral distance to the electrical contact region ( 3 ) a decreasing number and / or a decreasing size and / or a decreasing density of printed areas ( 20 ) having. Component according to one of the preceding claims, wherein the electrical contact area ( 3 ) the first electrode ( 2 ) and the first electrode ( 2 ) has a transverse conductivity of greater than or equal to 0.02 S / m and less than or equal to 1 S / m in an edge region and a transverse conductivity of greater than or equal to 0.002 S / m and less than or equal to 0.1 S / m in a central region. Component according to one of the preceding claims, wherein the electrical contact area ( 3 ) the first electrode ( 2 ) and the first electrode ( 2 ) has a transparency of greater than or equal to 70% and less than or equal to 99% in one edge region and a transparency of greater than or equal to 95% and less than or equal to 99.9% in a central region. Component according to one of the preceding claims, wherein the electrical contact area ( 3 ) the first electrode ( 2 ), the first electrode ( 2 ) is of indium tin oxide and has a thickness of greater than or equal to 50 nm and less than or equal to 2000 nm in a peripheral region and a thickness of greater than or equal to 5 nm and less than or equal to 200 nm in a central region. Component according to one of the preceding claims, wherein the electrical contact area ( 3 ) the first electrode ( 2 ) and the first electrode ( 2 ) has a ratio of a transverse conductivity in the edge region to a transverse conductivity in the middle region of greater than or equal to 2, preferably greater than or equal to 5, and less than or equal to 20, preferably less than or equal to 10. Process for producing an organic light-emitting component according to one of Claims 1 to 11, in which the transparent first electrode ( 2 ) by vapor deposition or sputtering with a depending on the lateral distance to the electrical contact area ( 3 ) reducing thickness is applied. Method according to claim 12, wherein during the application of the first electrode ( 2 ) Masks for producing areas of the transparent first electrode of different thicknesses ( 2 ) be used. Method according to Claim 12, in which for the production of the transparent first electrode ( 2 ) is applied a uniformly thick layer, which is then patterned. Process for producing an organic light-emitting component according to one of Claims 1 to 11, in which the transparent first electrode ( 2 ) from solution by means of a printing process with a function of the lateral distance to the electrical contact area ( 3 ) reducing the degree of coverage and / or depending on the lateral distance to the electrical contact area ( 3 ) reducing thickness is applied. The method of claim 15, wherein the printing process is inkjet printing or gravure printing.

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