OLED and methods for manufacturing an OLED

Abstract

OLED comprising: - a substrate (1), - an organic layer stack (6) with at least one active light-emitting layer suitable for generating electromagnetic radiation, wherein the organic layer stack (6) is arranged between a first electrode (5) and a second electrode (7), and - a buffer layer (3) arranged between the substrate (1) and the first electrode (5), wherein the buffer layer (3) is formed from an organic material, wherein - a polymeric planarization layer (2) is applied in direct contact to the substrate (1), - the buffer layer (3) is applied in direct contact to the planarization layer (2), and - the first electrode (5) is applied in direct contact to the buffer layer (3), - the second electrode (7) terminates on the substrate.- the buffer layer (3) extends along a side surface of the polymeric planarization layer (2) and the organic layer stack (6) extends along a side surface of the first electrode (5), such that the second electrode (7) is electrically insulated from the first electrode (5).

Description

An organic light emitting diode (OLED) and a method for manufacturing an OLED are provided.An OLED is disclosed, for example, in the publication WO 2013 / 072250 A1.The document KR 10 2010 0 022 373 A is directed to an inverted electroluminescent display in which the operating voltage is reduced.The document DE 103 10 341 A1 is directed to a multilayer mirror for a lighting device and a method for the production thereof.CN 104 979 490 A relates to a flexible organic light-emitting diode and a method for producing the same.The publication DE 11 2004 000 938 B4 discloses a flexible multilayer packaging material and electronic components with the packaging material.An object of the present invention is to specify an OLED having an improved luminous area. A process for producing an OLED of this type is also to be specified.These objects are achieved by the independent claims.Advantageous embodiments and developments of the OLEDs and of the methods are each specified in the dependent claims.An OLED comprises a substrate and an organic layer stack comprising at least one light-emitting layer suitable for generating electromagnetic radiation. The organic layer stack is arranged between a first electrode and a second electrode.The organic layer stack may include or be formed from organic semiconductor materials. Organic semiconductors are semiconductors which are based on organic materials and have semiconducting properties.Suitable materials for the at least one organic light-emitting layer are materials which have radiation emission on the basis of fluorescence or phosphorescence, such as, for example, 2- or 2,5-substituted poly-p-phenylenevinylene, and metal complexes, for example iridium complexes such as blue-phosphorescent FlrPic (bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)iridium III), green-phosphorescent Ir(ppy)3(tris(2-phenylpyridine)iridium III), Red-phosphorescent Ru (dtb-bpy)3*2(PF6) (tris[4,4'-di-tert-butyl-(2,2')-bipyridin]ruthenium(III)komplex) and blue-fluorescent DPAVBi (4,4-bis[4-(di-p-tolylamino)styryl]biphenyl), green-fluorescent TTPA (9,10-bis[N,N-di-(p-tolyl)amino]anthracene) and red-fluorescent DCM2 (4-dicyanomethylene)-2-methyl-6-julolideyl-9-enyl-4H-pyran).In addition to one or more light-emitting organic layers, the organic layer stack may also have further organic layers, such as hole-transport layers and electron-transport layers, for example.It may thus be advantageous if the organic layer stack comprises one or more organic layers which are designed as hole transport layers in order to enable effective hole injection into the at least one light-emitting layer. Materials which may prove advantageous for a hole transport layer are, for example, tertiary amines or carbazole derivatives.Furthermore, the following materials may be suitable for the hole transport layers, for example:N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine (NPB),N,N'-bis(naphthalen-2-yl)-N,N'-bis(phenyl)-benzidine (β-NPB),N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-benzidine (TPD),N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-9,9-spirobifluorene (spiro-TPD),N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)-9,9-spirobifluorene (spiro-NPB),N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-9,9-dimethylfluorene (DMFL-TPD),N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)-9,9-dimethylfluorene (DMFL-NPB),N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-9,9-diphenylfluorene (DPFL-TPD),N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)-9,9-diphenylfluorene (DPFL-NPB),2,2',7,7'-tetrakis(N,N-diphenylamino)-9,9'-spirobifluorene (spiro-TAD),9,9-Bis[4-(N,N-bis-biphenyl-4-yl-amino)phenyl]-9H-fluorene (BPAPF),9,9-Bis[4-(N,N-bis-naphthalen-2-yl-amino)phenyl]-9H-fluorene (NPAPF),9,9-Bis[4-(N,N'-bis-naphthalen-2-yl-N,N'-bis-phenyl-amino)-phenyl]-9H-fluorene (NPBAPF),2,2',7,7'-tetrakis[N-naphthalenyl(phenyl)amino]-9,9-spirobifluorene (spiro-2NPB),N,N'-bis(phenanthren-9-yl)-N,N'-bis(phenyl)-benzidine (PAPB), 2,7-bis[N,N-bis(9,9-spiro-bifluorene-2-yl)-amino]-9,9-spiro-bifluorene (spiro-S),2,2'-Bis[N,N-bis(biphenyl-4-vl)amino]-9,9-spirobifluorene (2,2'-spiro-DBP),2,2'-Bis(N,N-diphenyl-amino)-9,9-spirobifluorene (spiro-BPA).The hole transport layers may include a dopant. The dopant used may be, for example, a metal oxide, an organometallic compound, an organic material or a mixture thereof, for example WO 3, MoO 3, V 2 O 5, Re 2 O 7 and Re 2 O 5, di-rhodium tetratrifluoroacetate (Rh 2( TFA) 4) or the isoelectronic ruthenium compound Ru2(TER)2(CO)2or an organic material which has aromatic functional groups or is an aromatic organic material, For example, aromatic materials having a distinct number of fluorine and / or cyanide (CN) substituents.Furthermore, the organic layer stack may have one or more functional layers which are formed as electron transport layers. In addition, the layer stack can also have electron- and / or hole-blocking layers.For example, the electron-conducting layer may comprise an electron-transport layer comprising, for example, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) or 4,7-diphenyl-1,10-phenanthroline (BPhen). This material can preferably comprise a dopant selected from Li, Cs 2 CO 3, Cs 3 Po 4 or a molecular doping.The first electrode and / or the second electrode can contain a transparent conductive oxide or consist of a transparent conductive oxide, for example.Transparent conductive oxides (TCOs for "transparent conductive oxides") are generally metal oxides, such as, for example, zinc oxide, tin oxide, cadmium oxide, titanium oxide, indium oxide or indium tin oxide (ITO). Besides binary metal oxygen compounds, such as ZnO, SnO 2 or In 2 O 3 ternary metal oxygen compounds, such as Zn 2 SnO 4, ZnSnO 3, MgIn 2 O 4, GaInO 3, also belong, Zn 2 In 2 O 5 or In 4 Sn 3 O 12 or mixtures of different transparent conductive oxides to form the group of TCOs. Furthermore, the TCOs do not necessarily correspond to a stoichiometric composition and can furthermore also be p- and n-doped.Furthermore, it is also possible for the first and / or the second electrode to comprise a metal or to be formed from a metal. Suitable metal for one of the electrodes is, for example, one of the following materials:Aluminum, barium, indium, silver, gold, magnesium, calcium, lithium.The OLED includes a buffer layer disposed between the substrate and the first electrode, the buffer layer being formed of an organic material. The buffer layer, like the organic layer stack, can also be formed from an organic semiconductor material. The buffer layer is preferably formed from an organic material which is also or can be comprised by the organic layer stack.According to one embodiment of the OLED, a lateral extent of the organic layer stack and a lateral extent of the buffer layer are the same within the scope of the production tolerances. For example, the buffer layer and the organic layer stack have the same basic shape within the scope of the manufacturing tolerances. The buffer layer and the organic layer stack are preferably arranged congruently within the scope of the manufacturing tolerances. Within the scope of manufacturing tolerances, it can mean here that the deviations are less than or equal to 600 micrometers, preferably less than or equal to 400 micrometers, and particularly preferably less than or equal to 200 micrometers.According to a preferred embodiment, the substrate is a metal substrate. Particularly preferably, the metal substrate is flexible. With the aid of a flexible substrate, a flexible OLED can advantageously be produced.The metal substrate comprises, for example, one of the following materials or is formed from one of the following materials: steel, aluminum, copper. For example, the metal substrate comprises an alloy with aluminum or copper as the main component or is formed from such an alloy.A metal substrate may have a roughness of a few nanometers to several micrometers. In the present case, the metal substrate has, for example, a roughness of less than or equal to 1 micrometer. For example, the metal substrate has a roughness between 600 nanometers and 800 nanometers. Therefore, in a metal substrate, a planarization layer described below is particularly preferably used.Furthermore, it is also possible for the substrate to be formed by a plastic film. Particularly preferably, the plastic film is flexible. For example, the plastic film comprises one of the following materials or is formed from one of the following materials: PET, PEN, polyimide, PEEK. In the case of a plastic film as substrate, a planarization layer is also preferably used in order to compensate for roughness of the surface.According to a preferred embodiment, the organic layer stack and the buffer layer comprise small molecules or are formed from small molecules. In other words, the material which is preferably comprised both by the buffer layer and by the organic layer stack is small molecules.The class of small molecules is low molecular weight compounds of low molecular weight, especially in comparison with long-chain polymers. In particular, low molecular chemical compounds and short chain organic molecules having conjugated double bonds are referred to as small molecules. As a rule, small molecules can be deposited in layers by vacuum-assisted processes, such as, for example, vapor deposition. In contrast, long-chain polymers are generally processed in solution and applied in layers, for example by printing or centrifugal coating. Suitable materials of the small molecule class for individual layers of the organic layer stack, which are likewise suitable for forming the buffer layer, are already mentioned further above.Particularly preferably, the buffer layer is formed from a material which is used in the organic layer stack and simultaneously directly adjoins the first electrode. For example, a hole-conducting organic layer directly adjoins the first electrode. The buffer layer is therefore particularly preferably formed from a material which can also be used for a hole-conducting layer. Furthermore, the material for the hole-conducting layer should preferably be capable of being vapor-deposited at a high rate.According to a preferred embodiment of the OLED, the buffer layer is formed from a material which can be deposited by vapor deposition.Alternatively, it is also possible for the buffer layer to be formed from a material which can be applied by wet deposition.Furthermore, materials which comprise metal complexes or consist of metal complexes are suitable for the buffer layer. These materials generally have the advantage of being particularly cost-effective.Materials which comprise Cu complexes, Zn complexes or Bi complexes or consist of one of these complexes are particularly suitable in this case. Such materials are described, for example, in the following publications: WO 2011 / 033 023 A1, DE 10 2010 062 877 A1.Furthermore, suitable Zn-carboxylate complexes are described as p-dopants, for example, in the publication DE 10 2014 114 224 A1, while the publication DE 10 2014 114 231 A1 describes suitable organometallic benzoate complexes having perfluoroalkyl substituents.Finally, the document WO 2013 / 182 389 A2 describes polynuclear main group metal complexes as p-dopants, while the document DE 10 2011 084 639 A1 is directed to low-electron copper-azomethine complexes.Finally, the documents US 2011 / 089 408 A1 and US 2014 / 107 364 A1 describe suitable polynuclear Cu(I) complexes and Cu(II) complexes.In particular, organic dopants can also be vapor-deposited as pure substance in order to form the buffer layer. Furthermore, it is also possible for the proportion of the p-dopant to be formed comparatively high and for a matrix of the p-dopant to serve only to prevent crystallization of the layer and to promote good layer growth.Particularly preferably, the buffer layer is in direct contact with the first electrode. In other words, the buffer layer and the first electrode have a common interface. Particularly preferably, the layer of the organic layer stack directly adjoining the first electrode is formed from the same material from which the buffer layer is also formed. This offers the advantage that the first electrode is in direct contact on both sides with an identical or a similar material and thus also only has to be adapted to this material. For example, it is advantageous if the first electrode and the organic material of the buffer layer and of the organic layer stack are adapted with regard to adhesion, growth behavior and chemical and mechanical properties.According to a further embodiment, a polymeric planarization layer is arranged between the substrate and the buffer layer. The polymeric planarization layer comprises or consists particularly preferably of a polymer. In other words, the planarization layer is formed from a polymer, unlike the buffer layer, which is preferably formed from small molecules. Preferably, the polymeric planarization layer is applied in direct contact to the substrate. Due to the long-chain molecular structure of the polymers, the polymeric planarization layer is particularly well suited to compensating for unevennesses of the substrate.For example, the polymeric planarization layer may include or consist of one of the following materials: epoxy resin, acrylate resin, polyurethane resin, polyamide resin, polyimide resin, silicone resin.The polymeric planarization layer has a thickness between 0.2 micrometers and 30 micrometers, inclusive, depending on the polymer, the method of application, and the roughness of the substrate, for example. Preferably, the polymeric planarization layer has a thickness between 1 micrometer and 15 micrometers inclusive, and more preferably between 2 micrometers and 10 micrometers inclusive.The buffer layer has a thickness of between 10 nanometers and 1.2 micrometers, inclusive, for example. Preferably, the buffer layer has a thickness between 100 nanometers and 800 nanometers inclusive, and more preferably between 200 nanometers and 600 nanometers inclusive.According to a particularly preferred embodiment of the OLED, the planarization layer is applied in direct contact to the substrate and the buffer layer is applied in direct contact to the planarization layer. Finally, the first electrode is preferably applied in direct contact to the buffer layer. Particularly preferably, the organic layer stack is then in turn applied in direct contact to the first electrode. In this embodiment, the polymeric planarization layer may advantageously accommodate the asperities of the substrate, while the buffer layer in direct contact with the first electrode is particularly compatible with the electrode material.The buffer layer advantageously protects the first electrode arranged on it, for example from outgassing, such as volatile organic compounds (VOCs) or also solvents from the polymeric planarization layer. Furthermore, it is also possible for the buffer layer to protect the first electrode from contaminants, such as halogenated contaminants from polymer synthesis, or from additives, such as catalysts or crosslinking initiators, from the polymeric planarization layer. In addition, the buffer layer can protect the first electrode from water residues from the polymeric planarization layer or from particles which have accumulated on the polymeric planarization layer before the substrate is introduced into the electrode / organic coating installation.An idea of the present application is to use, besides a polymeric planarization layer having a comparatively high thickness, an organic buffer layer formed of a material that is or could be used in the organic layer stack. In particular, the organic layer stack and the buffer layer may be formed of small molecules. The buffer layer advantageously isolates the sensitive electrode from the polymeric planarization layer and protects it from volatile organic components and solvent residues that may be present in the polymeric buffer layer. In this way, defects in the luminous surface of the OLED, so-called dark spots, can be at least reduced. In addition, smaller particles may be covered or planarized by the buffer layer.According to a further embodiment of the OLED, the material of the organic layer stack extends along a side surface of the first electrode as far as the substrate and electrically isolates the first electrode from the second electrode. In this embodiment, the second electrode particularly preferably extends laterally over the underlying organic material as far as the substrate. If the substrate is designed to be electrically conductive, as is the case, for example, with a metal substrate, this can be used to achieve simple external electrical contacting of the second electrode. Furthermore, it is also possible for the second electrode to extend only as far as the polymeric planarization layer. In this embodiment, the first electrode and / or the second electrode can have a rectangular basic shape which has a bulge on one side. The bulge projects laterally out of the organic layer stack and the buffer layer. The respective electrode can be electrically contacted from the outside via the bulge.According to one embodiment of the OLED, it is provided to emit radiation generated during operation of the OLED through the substrate (bottom emitter). In this embodiment, the buffer layer preferably has a refractive index of at least 1.6 and particularly preferably of at least 1.8. In this way, the decoupling from the OLED can be increased.In a method of making an OLED, a substrate is provided. Then, a buffer layer is deposited. Preferably, the buffer layer is deposited by evaporation. A comparatively high vapor deposition rate is particularly preferably used for this purpose, since this allows thick layers with short process times.For example, the deposition rate is between 0.1 angstroms / second and 100 angstroms / second inclusive. Preferably, the deposition rate is between 1 Angstroms / second and 50 Angstroms / second, inclusive, and more preferably between 5 Angstroms / second and 15 Angstroms / second, inclusive.Alternatively, it is conceivable that the buffer layer is deposited by wet deposition.The buffer layer is preferably deposited on or over the substrate, i.e. either the buffer layer is applied in direct contact to the substrate or one or more layers are located between the buffer layer and the substrate. With suitable materials for the buffer layer, crosslinking by means of UV irradiation is conceivable.Finally, an organic layer stack is deposited by vapor deposition, which is arranged between a first electrode and a second electrode, wherein the buffer layer is formed from an organic material.The buffer layer is preferably formed from an organic semiconductor material, for example from small molecules. Particularly preferably, the buffer layer is formed from an organic material which is also comprised by the organic layer stack.Particularly preferably, the buffer layer and the organic layer stack are vapor-deposited through the same mask. This is possible in particular if the buffer layer is formed from a material which is also comprised by the organic layer stack or could be used in the organic layer stack. The use of the same mask advantageously leads to a simplified production method and makes it possible to precisely position the buffer layer relative to the organic layer stack.Particularly preferably, the buffer layer and the organic layer stack are deposited in the same apparatus, particularly preferably without the workpiece leaving the apparatus in the meantime. In this way, contamination of the later OLED by harmful substances or particles during production can be at least reduced.According to a particularly preferred embodiment of the method, a polymeric planarization layer is applied to the substrate. The buffer layer is applied to the polymeric planarization layer and the first electrode is applied to the polymeric planarization layer.Features and embodiments disclosed herein only in connection with the OLED may also be formed in the manufacturing process and vice versa.Further advantageous embodiments and developments of the invention are evident from the exemplary embodiments and examples described below in connection with the figures.The schematic sectional representations of FIGS. 1 to 6 describe in more detail an exemplary embodiment of a method for producing an OLED.FIG. 7 shows a schematic sectional illustration of an OLED according to an exemplary embodiment.FIG. 8 shows a schematic plan view of the OLED according to the exemplary embodiment of FIG. 7.FIG. 9 shows a schematic sectional illustration of an OLED according to an example.FIG. 10 shows a schematic plan view of the OLED according to the example of FIG. 9.Identical, similar or identically acting elements are provided with the same reference numerals in the figures. The figures and the proportions of the elements shown in the figures with respect to one another are not to be considered as true to scale. Rather, individual elements, in particular layer thicknesses, can be represented with exaggerated size for better clarity and / or for better understanding.In the embodiment according to FIGS. 1 to 6, a flexible metal substrate 1, for example made of steel, is provided in a first step (FIG. 1 ).In a next step, which is schematically illustrated in FIG. 2, a polymeric planarization layer 2 is applied to the substrate 1. The planarization layer 2 is formed of a polymer. For example, the polymeric planarization layer 2 is deposited on the substrate 1 by one of the following methods: printing, such as screen printing or gravure printing, ink jetting, spin coating, spin coating, slot die coating, dispensing.For example, the polymeric planarization layer 2 can be applied to the substrate 1 in a structured manner, each structural element later being part of a finished OLED. For this purpose, the polymeric planarization layer 2 is first applied over the entire surface of the entire substrate 1, for example by centrifugal coating or a spin coating, and is then structured by exposure and development. Alternatively, it is also possible to leave the polymeric planarization layer 2 over the entire surface of the substrate 1.In a next step, schematically illustrated in FIG. 3, a buffer layer 3 is deposited in direct contact on the polymeric planarization layer 2. For this purpose, a mask 4 is used which covers locations of the substrate 1 that are not to be provided with the buffer layer 3. The buffer layer 3 is preferably formed from small molecules.A first electrode 5 is then applied in direct contact to the buffer layer 3 (not shown). An organic layer stack 6 is vapor-deposited onto the first electrode 5, again by means of the mask 4 which has already been used in the deposition process of the buffer layer 3, said organic layer stack comprising an active light-generating layer which is suitable for emitting electromagnetic radiation. The organic layer stack 6, like the buffer layer 3, is preferably formed from small molecules. The organic layer stack 6 preferably comprises an organic material which is also comprised by the buffer layer 3 or from which the buffer layer 3 is formed.Finally, a second electrode 7 is deposited on the organic layer stack 6 (FIG. 5 ).In a next step, which is schematically illustrated in FIG. 6, the substrate 1 is divided along dividing lines 8, so that a plurality of OLEDs are formed. In principle, it is also conceivable for a single OLED to be produced on a substrate. In this case, this step is omitted.In FIGS. 1 to 6, the individual layers of the OLED are shown with the same lateral extent. It should be pointed out at this point that this represents a purely schematic simplification and does not necessarily have to be formed in the method described. Rather, the lateral extents of the individual layers can be different, as described below by way of example with reference to FIGS. 7 to 10.The OLED according to the exemplary embodiment of FIG. 7 has a substrate 1, on which a polymeric planarization layer 2 is applied in direct contact, which preferably consists of a polymer. The substrate 1 is preferably a flexible metal substrate, for example made of steel. A buffer layer 3 is applied to the polymeric planarization layer 2. The buffer layer 3 is formed of an organic material. The buffer layer 3 is preferably formed from small molecules.A first electrode 5, in the present case the anode, is applied to the buffer layer 3. The first electrode 5 extends along a side surface of the buffer layer 3 as far as the polymeric planarization layer 2.On the first electrode 5 there is deposited in direct contact an organic layer stack 6 comprising an active light generating layer suitable for emitting visible light. A material of the organic layer stack 6 extends over a side surface of the first electrode 5 as far as the buffer layer 3 and further over a side surface of the polymeric planarization layer 2 as far as the substrate 1.The second electrode 7, which in the present case is the cathode, also extends over the entire side surface of the underlying layer stack as far as the substrate 1.FIG. 8 shows a schematic plan view of the OLED according to the exemplary embodiment of FIG. 7 and in particular a delimitation of the lateral extent and the basic shapes of the individual layers of the OLED.The substrate 1, the polymeric planarization layer 2, the buffer layer 3, the first electrode 5, the organic layer stack 6, and the second electrode 7 have a rectangular basic shape in the present embodiment, as FIG. 8 shows.In the OLED according to the exemplary embodiment of FIGS. 7 and 8, the polymeric planarization layer 2 covers a central region of the substrate 1 over the full surface, while a narrow, encircling edge region of the substrate 1 is free of the polymeric planarization layer 2.The buffer layer 3 and the organic layer stack 6 have the same lateral extent and are arranged congruently one above the other. Therefore, FIG. 8 shows a common boundary which extends completely within the boundary of the polymeric planarization layer 2. The buffer layer 3 and the organic layer stack 6 are arranged within the polymeric planarization layer 2.The first electrode 5 and the second electrode 7, on the other hand, are arranged offset from each other. The first electrode 5 projects here on two opposite sides beyond the boundary of the second electrode 7 and the planarization layer 2, while the second electrode 7 projects on the other two sides beyond the boundary of the first electrode 5.Furthermore, the first electrode 5 and the second electrode 7 are each arranged offset with respect to the organic layer stack 6. The first electrode 5 and the second electrode 7 here protrude beyond the organic layer stack 6 on two different sides. At the regions which protrude laterally from the organic layer stack 6, the first electrode 5 and the second electrode 7 can each be electrically contacted from the outside.The OLED according to the example of FIGS. 9 and 10 comprises a first electrode 5 terminating on a main surface of the polymeric planarization layer 2.Like the schematic plan view of FIG. 10 on the OLED according to FIG. 9, the substrate 1, the polymeric planarization layer 2, the organic layer stack 6 and the buffer layer 3 again have a rectangular basic shape. The arrangement of the substrate 1, the polymeric planarization layer 2, the organic layer stack 6 and the buffer layer 3 with respect to one another is also carried out, as in the exemplary embodiment according to FIGS. 7 and 8, wherein the planarization layer 2 has a smaller lateral extent.The shape of the first electrode 5 and the second electrode 7, however, in contrast to the exemplary embodiment of FIGS. 7 and 8, has a bulge on one side of the rectangular basic shape in each case. The first electrode 5 and the second electrode 7 are arranged in such a way that the respective bulge protrudes from the organic material of the buffer layer 3 and of the layer stack 6, so that each electrode 5, 7 can be electrically contacted from the outside via its bulge.List of reference characters1 Substrate 2 Polymeric planarization layer 3 Buffer layer 4 Mask 5 First electrode 6 Organic layer stack 7 Second electrode 8 Division lines

Claims

OLED comprising: - a substrate (1), - an organic layer stack (6) comprising at least one active light-generating layer suitable for generating electromagnetic radiation, wherein the organic layer stack (6) is arranged between a first electrode (5) and a second electrode (7), and - a buffer layer (3) arranged between the substrate (1) and the first electrode (5), wherein the buffer layer (3) is formed from an organic material, wherein - a polymeric planarization layer (2) is applied in direct contact to the substrate (1), - the buffer layer (3) is applied in direct contact to the planarization layer (2), and - the first electrode (5) is applied in direct contact to the buffer layer (3), - the second electrode (7) terminates on the substrate, the buffer layer (3) extends along a side surface of the polymeric planarization layer (2) and the organic layer stack (6) extends along a side surface of the first electrode (5), such that the second electrode (7) is electrically insulated from the first electrode (5).The OLED according to the preceding claim, wherein the buffer layer (3) is formed of an organic semiconductor material.The OLED according to any of the above claims, wherein the buffer layer (3) is formed from an organic material also comprised by the organic layer stack (6).The OLED according to any of the above claims, wherein the organic layer stack (6) and the buffer layer (3) comprise small molecules.The OLED according to any of the preceding claims, wherein the buffer layer (3) is formed of an organic material that can be deposited by evaporation.The OLED according to any one of claims 1 to 3, wherein the buffer layer (3) is formed of an organic material that can be deposited by wet deposition.The OLED according to any one of the preceding claims, wherein the buffer layer (3) is formed of a material comprising metal complexes.The OLED according to any of the above claims, wherein a lateral extension of the organic layer stack (6) and a lateral extension of the buffer layer (3) are equal.The OLED according to any of the preceding claims, wherein the substrate (1) is a flexible metal substrate or a flexible plastic film.The OLED of any of claims 1 to 7, which is configured to emit radiation generated during operation of the OLED through the substrate, wherein the buffer layer has a refractive index of at least 1.6.Method for producing an OLED, comprising the following steps: - providing a substrate (1), - depositing a buffer layer (3), - vapor depositing an organic layer stack (6) arranged between a first electrode (5) and a second electrode (7), wherein the buffer layer (3) is formed from an organic material, wherein - a polymeric planarization layer (2) is applied in direct contact to the substrate (1), - the buffer layer (3) is applied in direct contact to the planarization layer (2), and - the first electrode (5) is applied in direct contact to the buffer layer (3), - the second electrode (7) ends on the substrate, and - the buffer layer (3) extends along a side surface of the polymeric planarization layer (2) and the organic layer stack (6) extends along a side surface of the first electrode (5), so that the second electrode (7) is electrically insulated from the first electrode (5).Method according to the preceding claim, in which the buffer layer (3) is deposited by evaporation.Method according to the preceding claim, in which the buffer layer (3) and the organic layer stack (6) are vapour-deposited through the same mask (4).Method according to one of Claims 11 to 13, in which the buffer layer (3) comprises small molecules.Method according to claim 14, wherein the buffer layer (3) is deposited by wet deposition.

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