WO2022101241A2

WO2022101241A2 - Assembly comprising organic light-emitting diodes on a flexible substrate

Info

Publication number: WO2022101241A2
Application number: PCT/EP2021/081188
Authority: WO
Inventors: Thomas Emde; Ralph Wichtendahl
Original assignee: Lightpat Gmbh
Priority date: 2020-11-16
Filing date: 2021-11-10
Publication date: 2022-05-19
Also published as: WO2022101241A3; DE102020130230A1

Abstract

The present invention relates to an assembly comprising organic light-emitting diodes (OLED) with a layer structure that comprises: --a flexible substrate (F1), --at least one barrier layer (S1) applied to the substrate, --at least one transparent electrode (E1), --a light-emitting layer sequence (O1) comprising organic materials (OLED stack), --at least one return electrode (R1), --at least one top encapsulation layer which seals the layer structure against the influence of moisture and oxygen, --wherein, according to the invention, the top encapsulation layer is used simultaneously as the return electrode (R1) and consists of an electrically conductive material. The solution according to the invention allows simplified process control by direct encapsulation. The encapsulation layer according to the invention can be applied in particular over the whole surface, and can advantageously consist of highly water-vapour-diffusion-tight materials, in particular of metals, which are also electrically conductive.

Description

Light-emitting diodes on a flexible substrate

The present invention relates to an arrangement comprising organic light-emitting diodes (OLED) with a layer structure comprising: a flexible substrate, at least one barrier layer applied to the substrate, at least one transparent electrode, a light-emitting layer sequence comprising organic materials (OLED stack), at least one rear electrode , at least one top encapsulation layer that seals the layer structure against the influence of moisture and oxygen.

State of the art

DE 10 2014 202 945 B4 discloses a planar organic electronic component, in particular an organic light-emitting diode, which can be produced using the so-called roll-to-roll method. Here, a base electrode is applied to the substrate, followed by a passivation layer, then the OLED layer and then a second electrode layer, which serves as the back electrode. The entire layer sequence is covered with an encapsulation layer. The base electrode and the back electrode are each connected to electrical contacts. The ground electrode is applied directly to the substrate here. The passivation layer is above and not below the ground electrode. The encapsulation layer protects the active layers against mechanical influences and against the penetration of water and oxygen. The passivation layer consists of a resin applied by flexographic printing, which is cured by UV radiation or thermally. In this known OLED, the encapsulation layer must consist of an electrically non-conductive material.

EP 3 035 404 A1 describes barrier layers for OLEDs that are produced using the roll-to-roll process. In this case, an organic layer is applied to a substrate, which lies between two barrier layers. A groove is cut into this multi-layered barrier layer and filled with a sealing material, which can have high conductivity. An electrically conductive resistor (referred to as shunt 47) is then placed across the layers and bonded to the sealing material. A first electrode layer is then applied to the multi-layer barrier layer, an electro-optical layer is deposited over the first electrode, a second electrode layer is deposited on top of this and finally a sealing layer as the top layer, with the lower electrode layer being led out of the sealing and being connected to the conductor, connected to the sealing material. The top layer, which seals the layer structure of the active, light-emitting layers, must consist of an electrically non-conductive material.

A central problem, especially with large-area OLEDs, is the combination of the front electrode, which should have a very high level of transparency, but which must also be very conductive at the same time. According to the prior art, this is often solved by using series-connected elements. These also impose different electrical potentials on the backside, which in turn requires electrical isolation on the backside from the backside barrier.

Very good barrier layers are required on the front and on the back, of which at least one must be transparent. The two barrier sides must also be joined together along the edges so that no water and oxygen molecules can diffuse between them. Typically, metals are very impervious to water vapor diffusion, but this contradicts the requirement of an electrically non-conductive backside barrier mentioned above.

Previous approaches to OLEDs, which are manufactured using the roll-to-roll process, preferably use active areas that are structured into individual cells, which are then connected in series in order to limit the maximum current intensities.

For example, glass, thin glass (thin glass is a very thin rolled glass layer of preferably about 10 to 100 μm, which in turn is partially applied to carrier foils) or plastic foils (PET, PEN) with various ceramic very thin layers can be used as a transparent barrier (e.g Al2O3, SiN, SiOxNy), advantageously applied in a multi-layer sequence with thin organic leveling layers, in which the leveling layers have the task To decouple layer defects from each other and to bind partially diffused water through introduced getter materials.

The second barrier can either be one of the transparent materials described above, or an opaque layer. These are often caused by thicker layers, such as those used for the transparent layers. Metal foils laminated in foils on both sides are also common, which work very well on the surface, but always allow water vapor diffusion at the edges through the lower lamination foil(s).

Evaporated aluminum metal layers are not used as a barrier because they tend to form small holes (pinholes) during growth. Other materials (e.g. silver) have so far only been tested for water vapor diffusion in very thin, still transparent layers that are stabilized on both sides with dielectrics.

Barrier encapsulations have so far often been produced by laminating several barrier systems. The component to be protected is glued in between the barriers. Liquid adhesives or PSA foils are used for lamination. The systematic disadvantage of this lamination is the large amount of foreign materials (adhesives, protective and carrier films) that are inserted between the effective barrier layers, apart from the actually sensitive layer, which, in addition to the properties required by the lamination, is also chemically inert to the must be a wear layer (OLED stack) and itself must not contain any water or adhering atmospheric water.

Typically, the scheme of OLEDs to be fabricated calls for a transparent and/or non-conductive back barrier.

According to the prior art, the disadvantages mentioned are often solved by direct encapsulation. This is characterized by the fact that the second barrier is applied directly to the first barrier and the layer sequence built up on it (OLED, display, OPV, CIGS-PV). This avoids an intermediate layer of adhesive. In order to insulate electrically and topologically against unevenness and the potential differences described above, these direct encapsulations are designed with an underlying non-conductive planarization layer and the barriers with ALD, CVD, PECVD or sputtering deposited Al2O3, SiO, SiN, SiOxNy, again advantageously as a multi-layer system (known as Vitex structure).

Direct encapsulation requires a fairly complex process sequence, which is already being carried out on an industrial scale in display production, but not yet successfully carried out in cost-saving and large-area roll-to-roll production. The difficulty in roll-to-roll production is the need for a continuous process with the same process speeds for all components. If several layers of the same type are to be applied and the underlying layer must not be touched in between, for example by being rolled up, the corresponding coating devices must be available several times in the system.

Finally, the cut between two roll-to-roll products often presents a technical problem, since the lateral sealing of the barrier must also be guaranteed along the cut line.

The problem of the transverse conductivity of the transparent electrode is often solved by introduced or applied conductor tracks, if not by circumventing it with the help of series connection. Usually, however, the cable reinforcement should be as invisible as possible and the conductor tracks are not used as a decorative element.

Proceeding from the prior art mentioned above, the object of the present invention is to provide an arrangement comprising organic light-emitting diodes with the features mentioned at the outset, which allows simplified process control with direct encapsulation during production, and thereby in particular cost-effective production, also over large areas OLEDs for the lighting sector enabled.

The solution to the above problem is provided by an arrangement comprising organic light-emitting diodes of the type mentioned at the beginning with the features of claim 1. The features mentioned in the subclaims relate to preferred developments of the solution to the problem according to the invention.

Approach of the present invention

According to the invention, the encapsulation layer simultaneously serves as a back electrode and consists of an electrically conductive material. The solution according to the invention enables a simplified process control through direct encapsulation. The encapsulation layer according to the invention can in particular be applied over the entire surface and advantageously consist of very water vapor diffusion-tight materials, in particular metals, which are also electrically conductive, so that the encapsulation layer can simultaneously serve as a back electrode. The present invention thus opens up a cost-effective roll-to-roll production option for a new application of large-area OLEDs.

In the production of the large-area OLED, a process sequence is used according to the invention that allows direct encapsulation using electrically conductive materials.

In particular, according to a development of the invention, a metallic layer or a combination of metallic layers is used whose property is not to form any pinholes or preferably to close pinholes formed from the previous layer, for example as a second barrier layer in a direct encapsulation.

According to a development of the invention, the uppermost encapsulation layer preferably comprises at least one metallic layer, in particular made of Ag, Al, Cu or Au, and/or it comprises at least one ceramic layer.

According to a preferred development of the invention, the encapsulation layer and rear electrode (R1) comprises a layer sequence of a plurality of metallic layers and/or a layer sequence of a plurality of ceramic materials.

According to the invention, the layer conductivity of the encapsulation layer and rear electrode (R1) is preferably greater than that of the transparent electrode (E1) without conduction reinforcement by a conductive track (L1). The application of a metallic wire reinforcement on the transparent electrode can be advantageously used as a decorative element for the OLED.

According to the invention, metal layer systems or alternatively, for example, a metal foil can be used as the second barrier layer in a laminated barrier layer arrangement. According to a preferred development of the invention, the encapsulation layer and rear electrode (R1) is interrupted in a contact area towards the outer edge and the potential of the transparent electrode (E1) is routed to the outside and/or the encapsulation layer and rear electrode (R1) is in other areas uninterrupted towards the outer edge.

According to a preferred development of the invention, a continuous conductive area of the transparent electrode (E1) is narrower than the light-emitting layer sequence (01) in the direction of the width of the OLED. The entire inner transparent electrode E1 is thus electrically insulated from the back electrode R1 lying above it.

According to a preferred development of the invention, in some areas the transparent electrode has two areas (E1) and (E2) that are electrically insulated from one another, viewed in the direction of the width of the OLED, and which are separated from one another by an area (E5) in which no transparent electrode is provided is, wherein in a contact area, the transparent electrode (E1) is continuous in the width direction.

According to a preferred development of the invention, at least one, preferably several, non-transparent conductive tracks (L1) are applied to the transparent electrode (E1) and/or non-transparent conductive tracks (L1) are attached to the barrier layer (S1 ) upset.

According to a preferred development of the invention, additional conductive tracks (L2) are provided for connecting the front electrode (E2), which are not electrically conductively connected to the area (E1) of the transparent electrode and/or additional conductive tracks (L3) are provided, which are connected in a contacting area to an interrupted area of the outer rear electrode (R1) and applied to the transparent electrode (E2).

According to a preferred development of the invention, the light-emitting layer sequence (01) completely covers the continuous, narrower conductive area of the transparent electrode (E1), but in a contacting area the light-emitting layer sequence (01) covers the transparent electrode that is continuous in the width direction over its width not completely covered. According to a preferred development of the invention, the arrangement also comprises a non-conductive layer (B1), which covers at least the edge area of the light-emitting layer sequence (01) when viewed across the width in the contacting area and at least up to the edge of the back electrode (01) when viewed across the width in the contacting area. R1) extends where it is interrupted, with the back electrode (R1) being applied to the non-conductive layer (B1).

According to a preferred development of the invention, the non-conductive layer (B1) in the contacting area extends into the area of a further conductive track (L3) and the non-conductive layer (B1) preferably extends up to an area of the rear electrode (R3) that is separated from a region (R1) of the rear electrode by a break.

According to a preferred development of the invention, the non-conductive layer (B1) is applied before the light-emitting layer sequence (01) is deposited and is partially covered by the latter.

According to a preferred development of the invention, the arrangement according to the invention is characterized in particular by the following layer sequence: a flexible substrate (F1), at least one barrier layer (S1) applied to the flexible substrate (F1), at least one transparent layer applied to the barrier layer (S1). Electrode (E1), at least one conductive track (L1, L2, L3) applied to the transparent electrodes (E1, E2), a light-emitting layer sequence (01) applied to the conductive track and comprising organic materials (OLED stack), at least one encapsulation layer and rear electrode (R1, R3) applied to the light-emitting layer sequence (01), or by the following layer sequence: a flexible substrate (F1), at least one barrier layer (S1) applied to the flexible substrate (F1), at least one the barrier layer (S1) applied conductive track (L1, L2, L3), at least one on the conductive Track (L1, L2, L3) applied transparent electrode (E1), on the transparent electrode (E1) applied light-emitting layer sequence (01) comprising organic materials (OLED stack), at least one encapsulation layer and rear electrode (R1, R3) applied to the light-emitting layer sequence (01), wherein the light-emitting layer sequence (01) is narrower than the layer structure, viewed in the direction of the width of the layer structure, preferably by using a shadow mask during application all in all.

According to a preferred development of the invention, the arrangement is designed as a large-area OLED in thin-layer encapsulation on a transparent, rollable substrate.

According to a preferred development of the invention, the light-emitting layer sequence (01) is not structured in the longitudinal direction (strip direction) of the flexible substrate (F1) and/or the transparent electrode (E1) or the rear electrode (R1) is not structured in the longitudinal direction or the transparent one Electrode (E1) and the rear electrode (R1) are not structured in the longitudinal direction.

Materials and deposition methods preferably used according to the invention

Materials and deposition methods that are preferably used according to the invention are listed below.

F: Substrate or carrier film, typically PET, PEN or rollable thin glass, as part of a known transparent barrier film.

S: Barrier films known per se can serve as the barrier layer, typically made of SiO, SiOxNy, SiN, Al2O3 or similar ceramic layers. The films are distinguished by a surface in the direction of the active layer which itself does not contain water, ie in particular it does not have a protective layer made of PET.

E: The transparent electrode is preferably applied directly to the transparent barrier using thin-film deposition methods, preferably by sputtering (PVD), preferably ITO (indium tin oxide) or DMD (dielectric-metal-dielectric, the dielectric being, for example, MgO or Al2O3, and the metal is Ag, for example).

L: These conductive tracks are made, for example, by printing (inkjet printing, gravure printing, screen printing) with conductive ink. The conductive ink consists preferably of Cu, Ag or Ni suspensions and is characterized by low surface roughness, freedom from solvents after the drying process and layer thicknesses of 0.1 pm to 10 pm. Alternatively, the conductive tracks are implemented by evaporating metals (such as, but not limited to, Ag, Al, Au, Cu) through structured masks.

Alternatively, the conductive tracks can be implemented by fine wires laid in or under E1.

B: In an advantageous embodiment of the invention, a partial area of the transparent electrode can also be covered with a non-conductive layer. A material is used that does not itself contain any dissolved water, is chemically inert to the OLED stack (O) and has a low water vapor diffusion coefficient. Polymers that can be coated in the same process as (L) and achieve similar layer thicknesses are particularly suitable.

This layer can be made of a lacquer, for example, which in turn advantageously contains getter particles, which in turn bind diffusing water and thus slow down the progress of the diffusion front laterally so that it takes longer than the desired service life of the product to cross the overlapping area. The paint is advantageously applied by inkjet or controllable slit nozzles in an inert atmosphere or vacuum (20 to 100 mbar) to avoid water vapor deposits and in particular in the case of paints with getter particles.

Alternatively, the separating layer can be applied, for example, with a non-conductive vapor-deposited thin layer that inhibits water vapor diffusion and is 20 to 2000 nm thick. Since this layer is only applied very locally and outside the product's field of vision, there is a particular freedom of choice in the materials and their layer thickness. Methods with charged particles can also be used here, since the active OLED layer can be destroyed at these points, provided it retains its insulating effect (e.g. ALD, sputtering, PVD, CVD, PECVD: Al2O3, SiO, SiN, SiON, SiOCH, parylene). This layer can advantageously be made of a lacquer which is characterized by a low water vapor diffusion coefficient.

O: Active layer or layer sequence made of organic materials that are suitable for producing an organic light-emitting diode (known as an OLED stack). This layer can be made of monomers or polymers, for example, and by thermal Evaporation in vacuo or from liquid coating (slit nozzle, pressure, ink-jet) applied.

A sufficiently conductive planarization layer, which is applied in exactly the same way as the OLED layers, can advantageously also be used as the bottom and/or top layer of the OLED layer sequence.

R: The back electrode thus forms the second barrier layer at the same time. Metals (for example Al, Ag, Cu, Au), co-evaporation of metals and layer sequences of metals are preferably used for this purpose, but layer sequences with ceramic materials are also used. They are preferably distinguished by a layer conductivity which is better than the layer conductivity of the transparent electrode (E) without line reinforcement (L). The layer thickness of the individual layers is preferably between 10 and 2000 nm. The bottom layer that makes contact with the OLED preferably consists of Al or Cu.

A possible second layer preferably consists of a material which is characterized by a greater surface energy than the underlying metal and thus preferentially grows on the defects in the underlying layer.

In addition, the defects of the following layer of the rear electrode R can advantageously be decoupled from the preceding layer, also by means of a non-conductive layer, this layer in turn preferably having a layer thickness of 10 to 2000 nm if it is applied in a thin-layer process (ALD: Al2O3, CVD: SiO, SiOCH, SIN, SiON).

Alternatively, this layer in turn has a layer thickness of 100 to 10,000 nm if it is applied as a lacquer layer in a liquid deposition process (by means of ink jet, slot nozzle, gravure printing, screen printing; thermally or UV-curing lacquers).

At least one point, preferably outside the active area of the OLED, the metallic layers of the rear electrode and barrier R (encapsulation layer) are electrically connected to one another by omitting the non-conductive sub-layers of R .

Process sequence and structuring preferred according to the invention

Preferred process sequences and structuring in the production of OLED arrangements according to the invention are explained in more detail below. The ones used here Reference numbers refer to the accompanying drawings. Two areas can be distinguished for the lateral structuring: a) the normal edge area, which is characterized by the fact that the rear electrode R1 is not interrupted towards the outer edge and b) the contacting area, which is characterized by the fact that the rear electrode R1 is towards the outer edge is interrupted and the potential of the transparent front electrode E1 is led to the outside.

On a carrier film (F) with a full-surface barrier (S), the electrode (E) is designed on the side of the transparent barrier (S) in such a way that the continuous conductive area is smaller than the active layer (01) that will later cover the full surface. This means that the entire inner transparent electrode (E1) is electrically isolated from the back electrode R1 above it, with the exception of the contact points.

The electrode is structured using shadow masks during deposition, so that there is no other area apart from the transparent electrode E1 (see Figure 2), alternatively by means of laser ablation or alternatively lithographically (chemical etching through appropriately structured resist masks with subsequent removal of the resist mask), with an area E5 of the electrode is removed and there are thus two areas E1 and E2 that are electrically isolated from one another (cf. FIG. 1).

In contrast, the electrode E1 is continuous in the contacting area. In order to achieve sufficient conductivity, non-transparent, conductive tracks (L1) are applied to the electrode E1. The tracks can be applied in any form, but must not leave the area of the electrode E1 and in particular must not bridge the isolation trenches E5. The conductive tracks are used to design the component.

Alternatively, the conductive tracks L can also be applied in front of the transparent electrode E. Other conductive structures L2 (connection of the front electrode) and L3 can optionally be applied outside of the area, advantageously in particular at the points where the electrical contacts will later be attached. For the connection of the rear electrode, L2 is not electrically connected to E1, L1 and L3.

The active layer sequence of the OLED (O) is applied to the electrode E1, which has thus increased electrical transverse conductivity, in such a way that this active layer covers the part of the electrode E1 that is in contact with the luminous area at all points except for the contacting area, ( see figures 1 and 2)

In the contact area, the electrode E1, advantageously also the conductive structures or tracks L1 to L3, are continuous (see Figures 3, 4, 5 and 6)

At the contacting area, an area can advantageously be covered by a non-conductive layer B, which overlaps at least the area from the edge of the OLED layer to the edge of the rear electrode R1 applied later (see FIGS. 4, 5 and 6).

According to an optional variant of the invention, the additional non-conductive layer B can advantageously extend outwards into the area of the connection L3 and advantageously also up to the back electrode R3 (see FIG. 6).

Alternatively, the non-conductive layer B can also be applied before the OLED layer O is deposited (see, for example, FIGS. 5 and 6).

A second electrode R, which represents the second electrical connection of the active layer of the OLED, is applied on the side opposite the transparent barrier. This electrode completely covers the layers E1 and O with the exception of the contacting of E1.

At the contact, E1 does not reach the edge of 01 or an advantageously used B1.

The electrode is preferably structured using shadow masks during the deposition, alternatively using laser ablation or lithography (chemical etching through appropriately structured resist masks with subsequent removal of the resist mask). In this way, a foil that can be contacted externally with the front (E1) and rear electrode (R3) was created, which glows on the inner surface. The contacting with cables (K1 and K2) and further protection of the active film are carried out using known methods (e.g. soldering, crimping, conductive PSA; encapsulation with other classic films in wet or PSA lamination).

Alternatively, the isolation trench is protected by covering it with a barrier film equipped with a diffusion-inhibiting PSA (self-adhesive film).

A metal foil or metal-plastic foil laminate is advantageously laminated onto the entire surface using a continuous PSA.

Concrete embodiments of the present invention

The present invention is explained in more detail below on the basis of specific exemplary embodiments with reference to the accompanying drawings. show:

FIG. 1 shows a schematically simplified cross section through a first exemplary arrangement according to the invention outside of the contacting area;

FIG. 2 shows a further, schematically simplified cross section through a second exemplary arrangement according to the invention outside of the contacting area;

FIG. 3 shows a schematically simplified cross section through a further exemplary arrangement according to the invention outside of the contacting area;

FIG. 3a shows a schematically simplified cross section through an exemplary arrangement according to the invention in the contacting area;

FIG. 4 shows a schematically simplified cross section through a fourth exemplary arrangement according to the invention in the contacting area;

FIG. 5 shows a schematically simplified cross section through a fifth exemplary arrangement according to the invention in the contacting area; FIG. 6 shows a schematically simplified cross section through a sixth exemplary arrangement according to the invention in the contacting area;

FIG. 7 shows a schematically simplified plan view of an exemplary embodiment according to the invention;

FIG. 8 shows a schematically simplified plan view of an alternative exemplary embodiment according to the invention;

FIG. 9 shows a schematically simplified plan view of a further alternative exemplary embodiment according to the invention;

FIG. 10 shows a schematically simplified plan view of a further alternative exemplary embodiment according to the invention.

A first possible exemplary embodiment of the present invention is explained in more detail below, initially with reference to FIG. The figure shows a schematically simplified cross section through an exemplary arrangement according to the invention outside of the contacting area, the layer structure of which is explained below. The substrate denoted by F1 can be, for example, a thin glass which is flexible and can therefore be unrolled from a roll (not shown) and rolled up again onto a roll after the coating. This coating method, which is known per se, is also referred to as roll-to-roll and has the advantage that it enables the production of comparatively large-area OLEDs, which are a preferred subject matter of the present invention. The illustration according to FIG. 1 is not to scale, ie the proportions and the relative layer thicknesses in the drawing do not have to correspond to the actual proportions. A barrier layer S1, for example a barrier film, which can consist of SiO, SiOxNy, SiN, Al2O3 or similar ceramic layers, is first applied to the substrate F1. The transparent electrode E1 is applied to this barrier layer S1, which electrode can be applied in particular using a thin-film method, preferably by sputtering (PVD), and which can consist of ITO (indium tin oxide) or DMD (dielectric-metal-dielectric), for example , where the dielectric can be, for example, MgO or Al2O3 and the metal can be, for example, Ag. As can be seen from Figure 1, the transparent electrode E1 is interrupted at a point denoted by E5, so that seen across the width (in the transverse direction) there are two separate areas of this lower electrode, namely an area E1 on the right in the drawing, the inside and an area E2 on the left in the drawing, which is on the outside. The purpose of this separation of the transparent lower electrode is to separate the inner region E1 of the transparent electrode from the rear electrode R1. In order to increase the conductivity of the transparent electrode E1, conductive tracks L1 are applied to it. There can be several of these conductive tracks L1, which are spaced apart and which can consist of a non-transparent material, so that they are visible to the viewer when the OLED is switched on, but this is deliberately sought within the scope of the present invention in order to pass through the conductive Tracks L1 to create visible decorative elements that structure the light-emitting surface of the OLED. These conductive tracks L1 must not bridge the isolation trench E5, which interrupts the transparent electrode.

The active layer, i.e. the OLED layer sequence 01, is then applied, which can have a layer structure known per se, usually at least comprising a hole conduction layer, an emitter layer that contains the organic dye and an electron conduction layer, this between the two electrodes lie. The substances used specifically for these layers are not critical within the scope of the present invention and are therefore not explained in more detail at this point. It can be seen in FIG. 1 that the light-emitting OLED layer sequence 01 does not extend over the entire width of the arrangement in the region illustrated in FIG. On the inside in the drawing on the right the layer sequence 01 is continued beyond the representation, but on the outside in the drawing on the left the layer sequence 01 ends at some distance from the edge. The right-hand area E1 of the transparent electrode is completely covered by the layer sequence 01, as are the two conductive tracks L1, which increase the conductivity. On the outer area E2 of the transparent electrode, which is separated from the area E1 by the isolation trench E5, there is also a conductive track L2, which, however, ends in front of the isolation trench E5 so that the latter is not bridged. The OLED layer sequence 01 covers the isolation trench E5 and extends to the left (outside) beyond the second region E2 of the transparent electrode and the conductive track L2. The entire arrangement of the layers S1, E1, E2 and O1 described above is covered by the rear electrode R1 and is thus encapsulated towards the top of the layer structure. The back electrode R1 consists of an electrically conductive, for example a metallic, material and thus takes over this top layer R1 according to the invention, in addition to the function of the back electrode, at the same time that of the encapsulation layer or barrier layer, which protects the underlying layers against moisture and oxygen.

If in the present invention the two sides of the layer structure shown in cross section are referred to as "outside" and "inside", then "outside" means that side of the material web shown in section over which the OLED arrangement is electrically connected is contacted, while the other side (seen in the transverse direction) is labeled "inside". For this reason, the layer structure is asymmetrical, as the drawings show.

A second, somewhat modified variant of the layer structure of an arrangement according to the invention is explained in more detail below with reference to FIG. The substrate F1, the barrier layer S1, the light-emitting layer sequence 01 and the back electrode and encapsulation layer R1 are basically the same as in the embodiment variant described above with reference to FIG. 1, so that reference can be made to the statements there. However, in contrast to the variant of FIG. 1, in the variant according to FIG. 2, the transparent electrode E1 is narrower as seen in the transverse direction. No transparent electrode is provided in the area lying on the outside; instead, a conductive track L2 is applied directly to the lower barrier layer S1 and is covered by the rear electrode R1. The|[1] layer sequence 01 extends outwards as far as the conductive track L2. Conductive tracks L1 are also applied to the transparent electrode E1 present in the inner area, but they do not extend beyond the end of the transparent electrode E1. The rear electrode R1 covers the entire width of the arrangement of the layers described above on the top side, so that complete encapsulation is provided. The layer sequence 01 is thus covered by the back electrode not only on the top side but also in its outer edge region. The layer sequence 01 lies completely over the transparent electrode E1 and extends outwards so far that it overlaps the conductor track L2, but the layer sequence 01 does not extend across the entire width of the arrangement in the transverse direction, as in FIG.

A cross section according to a variant of the invention in the area of a normal edge of the layer arrangement (outside the contacting area) is explained in more detail below with reference to FIG. Here the OLED layer arrangement 01 extends across the entire width in the transverse direction. The lower electrode layer E1 extends however, in the transverse direction only on the inner area of the layer arrangement. Conductive tracks L1 are arranged on the lower electrode E1. In the area on the outside, in which there is no lower electrode E1, a non-conductive layer B1 is applied directly to the lower barrier layer S1. The rear electrode and encapsulation layer R1 can here extend continuously over the entire OLED layer arrangement in the transverse direction of the arrangement.

A further exemplary embodiment of the present invention is explained in more detail below with reference to FIG. 3a. This is a sectional view in the transverse direction through an arrangement according to the invention in the contacting area. Here, too, a barrier layer S1 is first applied to the substrate F1, to which the layer E1 of the transparent lower electrode is then applied. A comparison with FIGS. 1 and 2 shows that the layer structure in the contacting area according to FIG. 3a differs somewhat from that outside of the contacting area. First of all, the transparent electrode E1 is not interrupted here in the transverse direction of the arrangement, but instead runs through. Here, too, conductive tracks L1 can be applied to the electrode layer E1 in order to increase the conductivity and to create decorative areas (patterns or the like). Here, too, the light-emitting layer sequence 01 with the organic layer extends in the transverse direction only over a partial region of the arrangement, similarly to outside of the contacting region. Unlike in Figures 1 and 2, the back electrode does not extend continuously across the width in the transverse direction in the contacting area, but the back electrode is divided into two areas, one of which area R1 (on the right in the drawing) starting from the inner side approximately to the end of the light-emitting layer sequence 01. If the edge area is not encapsulated here, as in the example in FIG. 3a, this is not a problem since this structure only affects the contacting area and a certain loss of activity in the contacting area can therefore be accepted. It should be noted that the invention is primarily concerned with large-area OLEDs for lighting purposes and not with OLED displays, so that a loss of activity in the edge area is comparatively unproblematic in relation to the total area of the OLED.

After an interruption in the transverse direction, the rear electrode R1 emanating from the inside, which also serves for encapsulation, is followed by a second region R3 of the rear electrode lying on the outside (on the left in the drawing). It can thus be seen from FIG. 3a that the rear electrode R1, R3 remote from the substrate is seen in the transverse direction in the contacting region is interrupted, while the lower transparent electrode E1 close to the substrate is continuous here in the transverse direction.

FIG. 4, to which reference is made below, shows an embodiment variant that is somewhat modified compared to FIG. 3a, again seen in a cross section that lies in the contacting area. Deviating from the variants described with reference to FIGS. 1 and 2, an additional non-conductive layer B1 is provided here, which is deposited over the OLED layer sequence 01 and covers a partial area of the transparent electrode E1. Polymers that are chemically inert to the OLED layer sequence are particularly suitable for this non-conductive layer B1. Preferred properties and materials for this non-conductive layer B1 are mentioned above in the explanation of the materials used. This non-conductive layer B1 also covers the edge region of the OLED layer sequence 01 and is covered by the conductive rear electrode layer R1 serving as the encapsulation layer. Here, too, the back electrode is interrupted, seen in the transverse direction, so that two regions R1 and R3 that are separate from one another arise. The lower barrier layer S1 on the substrate film F1 and the lower transparent electrode E1 are continuous in the transverse direction in the contacting region shown in FIG. Conductive tracks L1 can be applied to the transparent electrode E1 in the region covered by the OLED layer sequence 01 in order to increase the conductivity of the transparent electrode.

FIG. 5 shows the contact area of a further variant that differs somewhat from the previously described embodiments. In contrast to the variant described above with reference to FIG. 4, in the exemplary embodiment in FIG. 5 the nonconductive layer B1 is deposited on the transparent electrode E1 and the OLED layer sequence 01 is deposited after the nonconductive layer B1 so that it covers it. In the separated outer area R3 there is a conductive track L3 on the lower transparent electrode E1 (front electrode) which lies below the outer area R3 of the rear electrode, again to increase the conductivity of the electrode. Otherwise, the structure of the layers in the exemplary embodiment in FIG. 5 is similar to that in the variant in FIG. 4 described above.

A further exemplary embodiment of the invention is explained below with reference to FIG. Similar to the example in FIG. 5, there is a continuous barrier layer S1 on the substrate and a transparent electrode E1 continuous in the transverse direction on this. The structure of the light-emitting OLED Layer sequence 01 corresponds to the example described above, as does the rear electrode, which is divided into two separate regions R1 and R3 and simultaneously serves as an encapsulation layer. Deviating from the example in Figure 5, however, in Figure 6 the non-conductive layer B1 is larger in its extension in the transverse direction, so that the layer B1 extends from the OLED layer sequence 01 that overlaps it on the outside to below the region R3 of the rear electrode and extends up to the conductive track L3, so that here the non-conductive layer B1 quasi bridges the gap between the two areas R1 and R3 of the rear electrode and is covered by both areas. As in the previously described exemplary embodiments according to FIGS. 4 and 5, the active layer sequence of the OLED stack is completely covered by the inner region R1 of the rear electrode. As in the variant of FIG. 5, a conductive track L3 is located below a partial area of the non-conductive layer B1.

FIG. 7 shows a possible exemplary embodiment of the invention in a schematically simplified plan view. The feed direction of the tape transport in roll-to-roll production is from bottom to top according to the arrow on the right in the drawing. FIG. 7 shows the contact area with the two contacts K1 and K2 for contacting the two electrodes E1 and R1 of the layer structure. For the sake of visual simplification, the layers of the layered structure are partially shown lying one on top of the other, with the hatching corresponding to those from the sectional views so that they can be assigned. It can be seen in FIG. 7 that contact is made with the lower transparent electrode E1 on the outside via the contact K1, which is on the left in the drawing. The line of intersection to the neighboring module of the quasi-endless OLED layer arrangement runs transversely on the upper side. It can be seen in FIG. 7 that the back electrode and encapsulation layer is divided into two separate areas R1 and R3, the contact K2 being connected to the area R1 of the back electrode lying further inwards. In the contacting area according to FIG. 7, the lower electrode E1 extends over the entire width of the layer arrangement, as also for example in the example in FIG. 3, so that the lower electrode E1 can be contacted on the outside via the contact K1. In the tape transport direction, on the other hand, the lower electrode E1 ends at a certain distance from the transverse edge and cutting line to the neighboring module, with the upper rear electrode and encapsulation layer R1 being contacted here via the contact K2.

A further alternative exemplary embodiment of the present invention is explained in more detail below with reference to the schematic top view of FIG. In the The illustration according to FIG. 8 clearly shows that the layer structure, seen in section, differs in the “normal” area from the contacting area, as has already been explained with reference to the various sectional drawings in FIGS. 1 and 2 on the one hand and FIGS. 3 to 6 on the other. It can be seen that in the exemplary embodiment according to FIG. 8, where there is no contact, the back electrode and encapsulation layer R1 runs across the entire width of the arrangement, and both the lower electrode E1 and the OLED layer sequence 01 extend over most of the width of the arrangement extend, that is, here neither the lower electrode E1 nor the rear electrode R1 are interrupted in the direction of the width of the arrangement. In the contacting area (in the drawing at the top), on the other hand, the back electrode R1 does not extend all the way to the left edge, but rather ends a little earlier and is contacted there by the contact K2. The lower electrode E1 extends further to the left in the (in the drawing) upper corner region than the rear electrode R1, namely up to a conductor track L2, which can be seen in the upper left corner of the drawing and which in turn is electrically connected to the contact K1 , via which the OLED is connected. In the corner region mentioned, the OLED layer sequence would therefore not be covered by the encapsulation layer which would otherwise be present and which also serves as the rear electrode R1. This is accepted, however, since a deterioration in the light yield in this comparatively small area can be accepted.

In the exemplary embodiment according to FIG. 8, it can also be seen that numerous conductor tracks L1 are applied to the lower electrode E1, which are arranged in the manner of a decorative print and result in a decorative pattern. As explained above, these conductor tracks L1 are used, on the one hand, to increase the conductivity of the lower electrode and, on the other hand, they enable the light-emitting OLED surface to be designed in a decorative manner. Where there are no conductors, the material is transparent and light is emitted. The OLED surface is covered where the conductor tracks are, which reduces the overall light output of the surface. However, this is irrelevant because the light-emitting surface of this type of OLED produced by roll-to-roll is sufficiently large and thus sufficient light yield is achieved over the entire surface and because with these OLED arrangements the optimization of the illuminance is not the priority stands.

In the embodiment variant according to FIG. 9, to which reference is made below, the structure of the OLED arrangement is largely similar to that according to FIG. 8. Only the contacting in the corner area (top left in the drawing) is somewhat different differently, since an area is also provided here, which is provided with a non-conductive layer B1, as has already been described above for the embodiment variant according to FIG. The conductor track L1 is connected to the lower electrode E1 on the inside, viewed in the transverse direction, and then extends further outwards in the transverse direction, where it is connected to the contact K1. In order to insulate the conductor track (and thus the lower electrode connected to it) from the rear electrode R1, a non-conductive layer B1 is provided here, since, unlike in the exemplary embodiment described above with reference to FIG. 8, the rear electrode R1 in FIG. 9 is in the corner area is not interrupted. Even if the rear electrode R1 is interrupted, the two electrodes can be electrically isolated from one another by inserting a non-conductive layer B1 in the corresponding areas. In this variant too, as described above for FIG. 8, numerous conductor tracks L1 are applied, which form a decorative pattern on the surface of the light-emitting arrangement.

FIG. 10 shows a further exemplary embodiment variant in plan view, in which the rear electrode R1 is not interrupted in the transverse direction, unlike in FIG. For this purpose, a non-conductive layer B1 is provided here, which is in the (in the drawing) upper edge area, i.e. where the transition to the next OLED arrangement in the transport direction is provided and where the contacting of the respective OLED arrangement takes place, extends across the entire width of the assembly in the transverse direction. As you can see, the area of the non-conductive layer in the outer area (on the left in the drawing) also extends a bit in the longitudinal direction, so that a conductor track L1 can be arranged there, which is routed to the lower electrode E1. so that it can be contacted via conductor track L1. This conductor track L1 extends outwards from the layer arrangement and is angled so that it then extends in the tape transport direction. This conductor track L1 is routed to the area outside of the rear electrode R1, which covers the layer arrangement, and is covered by the non-conductive layer B1 where the rear electrode is located, so that the conductor track L1 can be connected on the outside to the contact K1, by means of which the lower Electrode is contacted. The rear electrode R1 can be contacted a little further inside (seen in the transverse direction) via the contact K2. In the region of the line of intersection to the neighboring module, the lower electrode E1 is insulated from the rear electrode R1 by the non-conductive layer B1, which extends there over the entire width.

F1 substrate or carrier film

S1 barrier layer or barrier film

E1 transparent electrode

E2 transparent electrode

E5 Interruption of the transparent electrode

L1 conductive track

L2 conductive track

L3 conductive track

B1 additional non-conductive layer

01 active layer sequence, OLED stack

R1 back electrode, barrier layer, encapsulation layer

R3 external area of the back electrode, barrier layer, encapsulation layer

K1 contact for the bottom electrode

K2 contact for the return electrode

Claims

23 patent claims

1. Arrangement comprising organic light-emitting diodes (OLED) with a layer structure comprising: a flexible substrate (F1), at least one barrier layer (S1) applied to the substrate, at least one transparent electrode (E1), a light-emitting layer sequence (01) comprising organic materials (OLED stack), at least one rear electrode (R1), at least one top encapsulation layer, which seals the layer structure against the influence of moisture and oxygen, characterized in that the top encapsulation layer also serves as a rear electrode (R1) and is made of an electrically conductive material consists.

2. Arrangement according to claim 1, characterized in that the top encapsulation layer comprises at least one metallic layer, in particular made of Ag, Al, Cu or Au, and/or comprises at least one ceramic layer.

3. Arrangement according to one of claims 1 or 2, characterized in that the layer conductivity of the encapsulation layer and rear electrode (R1) is greater than that of the transparent electrode (E1) without line reinforcement by a conductive track (L1).

4. Arrangement according to one of claims 1 to 3, characterized in that the encapsulation layer and rear electrode (R1) comprises a layer sequence of a plurality of metallic layers and/or a layer sequence of a plurality of ceramic materials.

5. Arrangement according to one of claims 1 to 4, characterized in that the encapsulation layer and rear electrode (R1) is interrupted in a contacting area towards the outer edge and the potential of the transparent electrode (E1) is routed to the outside and/or the encapsulation layer and Rear electrode (R1) is not interrupted in other areas towards the outer edge. Arrangement according to one of Claims 1 to 5, characterized in that a continuous conductive region of the transparent electrode (E1) is narrower than the light-emitting layer sequence (01) in the direction of the width of the OLED. Arrangement according to one of Claims 1 to 6, characterized in that in partial areas the transparent electrode has two areas (E1) and (E2) which are electrically insulated from one another and which are separated from one another by an area (E5), viewed in the direction of the width of the OLED, in which no transparent electrode is provided, wherein the transparent electrode (E1) is continuous in the width direction in a contact area. Arrangement according to one of Claims 1 to 7, characterized in that at least one, preferably several, non-transparent conductive tracks (L1) are applied to the transparent electrode (E1) and/or non-transparent conductive tracks (L1) under the transparent electrode (E1 ) are applied to the barrier layer (S1). Arrangement according to one of Claims 5, 7 or 8, characterized in that further conductive tracks (L2) are provided for connecting the front electrode (E1?), which are not electrically conductively connected to the region (E1) of the transparent electrode and/ or that further conductive tracks (L3) are provided, which are connected in a contacting area to an interrupted area of the outer rear electrode (R1) and applied to the transparent electrode (E1). Arrangement according to one of Claims 6 to 9, characterized in that the light-emitting layer sequence (01) completely covers the continuous, narrower conductive region of the transparent electrode (E1), but in a contacting region the light-emitting layer sequence (01) covers the width in the direction continuous transparent electrode not completely covered over its width. Arrangement according to one of claims 1 to 9, characterized in that it further comprises a non-conductive layer (B1), seen in the contacting area across the width at least the edge region of Covered by the light-emitting layer sequence (01) and, seen across the width, in the contacting region at least as far as the edge of the back electrode (R1), where it is interrupted, the back electrode (R1) being applied to the non-conductive layer (B1). Arrangement according to Claim 11, characterized in that the non-conductive layer (B1) in the contacting area extends into the area of a further conductive track (L3) and the non-conductive layer (B1) preferably extends up to an area of the rear electrode (R3) extends, which is separated by a break from a region (R1) of the rear electrode. Arrangement according to one of Claims 1 to 10 or 12, characterized in that the non-conductive layer (B1) is applied before the deposition of the light-emitting layer sequence (01) and is partially covered by the latter. Arrangement according to one of Claims 1 to 14, characterized by the following sequence of layers: a flexible substrate (F1), at least one barrier layer (S1) applied to the flexible substrate (F1), at least one transparent electrode ( E1), at least one conductive track (L1, L2, L3) applied to the transparent electrode (E1), a light-emitting layer sequence (01) applied to the conductive track and comprising organic materials (OLED stack), at least one light-emitting layer sequence applied to the conductive track Layer sequence (01) applied encapsulation layer and rear electrode (R1, R3), or the following layer sequence: a flexible substrate (F1), at least one barrier layer (S1) applied to the flexible substrate (F1), at least one barrier layer (S1) applied conductive track (L1, L2, L3), at least one on the conductive track (L1, L2, L3) applied transparent electrode (E1), a light-emitting layer sequence (01) applied to the transparent electrode (E1) and comprising organic materials (OLED stack), 26 at least one encapsulation layer and rear electrode (R1, R3) applied to the light-emitting layer sequence (01), wherein the light-emitting layer sequence (01) is narrower than the overall layer structure. Arrangement according to one of Claims 1 to 14, characterized in that this is designed as a large-area OLED in thin-layer encapsulation on a transparent, rollable substrate. Arrangement according to one of Claims 1 to 15, characterized in that the layer sequence (01) is not structured in the longitudinal direction (strip direction) of the flexible substrate (F1) and/or the transparent electrode (E1) or the rear electrode (R1) is not structured in the longitudinal direction is structured or the transparent electrode (E1) and the rear electrode (R1) are not structured in the longitudinal direction. Arrangement according to one of Claims 1 to 16, characterized in that the layer sequence (01) is interrupted in each case parallel to and in the vicinity of the cut edges outside the area of (E1) or in the area of (B1) (preferably by laser ablation), seen in the belt direction at the beginning and end of the modules.