Hermetic encapsulation of organic electro-optical elements

Translation of description of equivalent WO 03088370 A2

p0001Hermetic encapsulation of organic electro-optical elements

p0002description

p0003The invention relates generally to organic electro-optical elements, and a method for their preparation. In particular, the invention relates to a process for the preparation hermetically encapsulated organic electro-optical elements, and a hermetically encapsulated electro-optical element.

p0004Organic light-emitting diodes (OLEDs) are the subject of intensive development work, as they compared to other lighting and display means have versatile advantages. For example, OLEDs can be very thin and even made flexible. Opposite LCDs OLEDs also have the advantage of being self-luminous.

p0005The problem with OLEDs but especially their so far very limited lifespan. It is hardly succeeded in extending the service life of OLEDs on more than 5000 operating hours. For OLEDs are generally used metal cathode with a low work function. Commonly aspects include metallic Calziu. Such

p0006However, materials with a low work function are generally reactive. Chemical reactions of the metal layer and related work function changes are considered one of the main factors of life limited. In particular, the reaction with air, or with the existing moisture in the air as water here is responsible for the degradation of the metal electrode of an OLED.

p0007In US 5,882,761 it is proposed to solve the problem, an OLED, wherein the OLED structures are covered with an arched metal sheet. In addition, the OLED has described therein a desiccant or

p0008Getterreservoir on. The desiccant reservoir and the OLED structures are separated by a porous tape apart. The metal sheet is bonded to the glass carrier by means of an ultraviolet adhesive. The disadvantage here is that organic layers such as the bonding site between

p0009Sheet metal and glass support, for small gas molecules are relatively easy penetrable. The adhesion thus provides a transport channel, in particular for atmospheric oxygen and water. With this, it is only a question of time before the drying agent is exhausted and the degradation of

p0010Metal electrode used. Further, this type of encapsulation material properties of OLED technology as the encapsulation extremely thin or flexible components impractical.

p0011As getter materials are among other liquids known as described in JP 7211456, US 5821692, or US 5,962,962th In EP 0776147 furthermore describes the use of solid materials is described as a getter. Gases can, as disclosed in WO 9903112, are used as Gettermedium for organic devices. All such solutions known from the prior art is, however, common that the effect of the getter aterials decreases with continuous gas accumulation, so that a permanent protection is not given from degradation. The invention is therefore based on the object to slow the degradation of organic electro-optical elements, such as OLEDs, or to increase their service life.

p0012This object is achieved already at very surprisingly simple manner by a method for manufacturing an organic electro-optical element, and an organic electro-optical element according to the independent claims. Advantageous developments are specified in the respective dependent claims.

p0013Accordingly, the inventive method for manufacturing an organic electro-optical element comprising the steps of:

p0014-providing A substrate,

p0015-Aufbringen A first conductive layer, -Aufbringen at least one layer (15), which comprises at least one organic electro-optical material -Aufbringen a second conductive layer, and the step of

p0016- Depositing at least one layer (7, 71,72, ... 7N) with a vitreous structure.

p0017Layers with a vitreous structure are known for their extraordinarily good barrier effect. As layer with a vitreous structure is meant in this context a layer lacking long-range order of the material with a vitreous structure constituent elements and / or substances while existing short-range order of the materials and / or elements. As layer with a vitreous structure ie a glassy, ​​amorphous layer is called. Such layers accordingly include not only glasses. Rather, glassy layers, in addition to glasses also, for example, organic materials, alloys or amorphous element layers include. Opposite non-vitreous, ie essentially microcrystalline, polycrystalline or crystalline layers, the applied by the inventive films are characterized, among other things due to the amorphous structure by the absence of grain boundaries. Such grain boundaries are but just responsible for much higher permeability rate for small molecules, such as oxygen or water through crystalline or polycrystalline media.

p0018A particularly preferred embodiment of the invention provides in particular that the depositing at least one layer with a vitreous structure comprises the step of depositing a glass, in particular of an inorganic glass.

p0019With regard to the barrier properties of evaporation-coating for the

p0020Encapsulation of components and other substrates is also on the applications DE 202 05 830.1, filed on 15.04.2002,

p0021DE 102 22 964.3, filed on 23.05.2002;

p0022DE 102 22 609.1, filed on 23.05.2002;

p0023DE 102 22 958.9, filed on 23.05.2002;

p0024DE 102 52 787.3, filed on 13.11.2002; DE 103 01 559.0, filed on 16.01.2003; referenced by the same applicant, the disclosure of which is hereby expressly incorporated by reference.

p0025With regard to the barrier properties of Aufdampfglasschichten Measurements have shown that in

p0026Layer thicknesses of the evaporation-in the range of 8 microns to 18 microns helium leak rate of less than 10^"7 mbar 1 s^_1 or less than 10^{~ 8} mbar 1 s^_1 be safely reached. The measurements in layers with a layer thickness of 8 microns and 18 microns even helium leak rates of between 0 and 2xl0^{~ 9} mbar 1 s^_1 result, these upper limits are affected by the inaccuracy of the experiments already substantially.

p0027Many glasses are known which do not, measurable permeability for all gases except helium show already with layer thicknesses of 50 microns. A compilation of diffusion rates through glasses is found for example in "Handbook of Gas Diffusion in Solids and Melts". However, helium itself is not influenced because of its inertness and the layers of the OLED is for the lifetime of OLEDs, therefore, not important.

p0028Particularly suitable for a hermetic encapsulation of in particular is a layer having a vitreous structure which comprises an alkali-containing glass. The alkali ions fill gaps on the glass frame and thus ensure dense layers with very low permeability.

p0029In particular, borosilicate glasses are particularly suitable materials for the layer with a vitreous structure. This may also have alkali metal ions, to reduce the permeability.

p0030The term of an organic electro-optical material according to the invention comprises both an organic material having elektrolummeszente properties and thus is suitable for the structure of an OLED, as also comprises an organic material which photovoltaic properties. In the following, for simplicity of the

p0031OLED term generally used due to the äguivalenten structure for light modifying elements, ie both light-emitting and also for photovoltaic elements. As the organic electro-optical material comprises a plurality, substances known in the art can be used. Among other things can be used, metal-organic materials, in particular metal-organic complexes like triplet emitters or lanthanide complexes. For example, tris (8-hydroxyquinolino) aluminum (Alq3) or MEH-PPV (poly (2-methoxy, 5- (2-ethyl hexyloxy) paraphenylene vinylene (MEH-PPV) used 'as electroluminescent material. The layer may also include an organic or inorganic matrix layer with emitters such as

p0032is doped as an organic fluorescent dyes, electro-optical material. As inorganic matrix, among other porous titanium dioxide was used.

p0033More elektrolummeszente substances are for example in US 6,107,452, EP 0573549, EP 800563 Al, EP 800563 Bl and EP 1006169 AI described, which are incorporated by reference in the present application. Although known in the art, should also be on the structure of the OLEDs described in these documents and this

p0034Description provided as the content of this application.

p0035By depositing the invention also an intimate connection of the layer with a vitreous structure to the underlying material is provided without resulting voids or gases penetrable junctions because the layer grows directly on the underlying surface. Layers with a vitreous structure, ie largely without crystalline portion or subregions are also characterized by a better tolerance to mechanical stresses compared to crystalline materials. This means that the very good barrier effects of such materials are retained even when deformations within the mechanical stress limits of the material. The inventive method allows hence the flexible OLEDs with long service life.

p0036The deposition of the layer with a vitreous structure comprises according to the invention, the vacuum or Niederdruckabscheiden the layer, or the deposition of the layer by vacuum or low pressure coating. Good to be able to all vacuum coating processes. Accordingly, the deposition of the layer with a vitreous structure inter alia PVD or CVD method may be employed. Several deposition methods can be combined. Vacuum coating method or low pressure coating method such as PVD or CVD deposition include advantageous because these methods can be carried out in vacuum or in a dry atmosphere and so prevent contamination of moisture-sensitive OLED layers in the coating.

p0037The deposition of the at least one layer with a vitreous structure takes place according to a particularly preferred embodiment, by vapor deposition. By evaporating high growth rates of the layers can be achieved, and thus makes the inventive method in this variant particularly fast economical for large quantities.

p0038Advantageously, the deposition of the layer with a vitreous structure by vapor deposition further comprises the step of plasma ion-assisted vapor deposition (PIAD) include. Additionally, an ion beam onto the substrate to be coated is directed. The ion beam can be generated by a plasma source, for example by ionization of a suitable gas. Due to the gas ions emitted from the evaporation source particles are further accelerated. This leads to very dense and low-defect deposited layers.

p0039The step of depositing the layer with a vitreous structure can more preferably include the step of depositing a Aufdampfglases. Such glasses are materials that can be deposited by vapor deposition. It has been found that evaporation-coating exhibit excellent Verkapselungseigenschaften. These glasses can next to the preferred depositing by vapor deposition but of course also by other vacuum or

p0040Low-pressure coating processes are separated.

p0041Particularly suitable for the vapor deposition case is, for example, electron beam evaporation. For this purpose, an electron beam is directed at a target, which electron proposed by impacts their kinetic energy to the target, which heats up as a result. By heating the target material is finally evaporated. The vaporized material then impinges on the surface to be coated and deposited there from as a layer with a vitreous structure.

p0042The step of evaporating a layer with a vitreous structure may also include at least the step of Coverdampfens from two evaporation sources. In this way, for example, the stoichiometry of the deposited layer on the evaporation rates of the sources can be adjusted. In particular, the step of Coverdampfens may also include the step of varying, in particular periodically varying the rate of deposition at least one of the evaporation sources. By varying the

p0043Deposition rates, the material properties of the layer with a vitreous structure in the direction perpendicular be influenced and adapted to the vapor-deposited surface. Thus, by variation of the layer stoichiometry as the thermal expansion coefficient of the layer to which the coated surface to be adjusted so that thermal stresses are avoided or reduced between the surface material and the vapor-deposited layer. A periodic variation of the deposition rates, for example, are used to establish periodic refractive index variations in the deposited layer perpendicular to the coated surface.

p0044However, the deposition by vapor deposition generally requires special evaporation materials with relatively high vapor pressures. As for specific OLED applications, materials with low vapor pressures and connected to the generally high melting temperatures may be suitable, the step of depositing may include at least one layer with a vitreous structure by means of physical and / or chemical vapor deposition also advantageously comprises the step of sputtering a layer having vitreous structure or the sputtering comprise. Here, the sputtering of layers and the deposition by sputtering is understood to be one of the PVD process. The sputtering of layers can be in contrast to the vapor deposition carried out with high-boiling materials.

p0045however layers having glassy structures can advantageously be prepared also by other methods, such as chemical vapor deposition, for example by means of plasma-induced, chemical vapor deposition (PCVD). Suitable in this respect is also particularly the plasma pulse-induced chemical

p0046Vapor deposition (PICVD) at which the plasma is generated is not constant over time, but is pulsed, which involves inter alia, a lower heat load on the member to be coated with it. The deposition of the layer with a vitreous structure may further comprise the step of Coabscheidens an organic material in an advantageous embodiment of the method. The Coabscheiden, or the simultaneous deposition of the organic material together with the coating material forming a layer with a vitreous structure may, for example, by co-evaporation or deposition from the residual gas atmosphere. The molecules of the organic material are thereby incorporated into the layer with a vitreous structure with. The organic material can influence the layer properties in many positive ways. As an example, to a higher flexibility of the coating to mechanical stress, the adjustment of optical and mechanical properties, improved adhesion by the film is about deposited as a gradient with changing the organic content, changing the packing density and the layer structure, and the influence of the chemical properties of the layer, called in particular by the addition of hydrophobic materials or getter.

p0047the layers are applied so advantageous that one of the conductive layers has a lower work function than the other conductive layer. Due to the

p0048Difference in work function of serving as electrodes first and second conductive layers between which the layer which comprises an organic electro-optical material, electrons with the correct polarity of the applied voltage to the electrodes at the acting as the cathode layer in unoccupied electronic states of the organic, electro-optical material is injected. Simultaneously injected from the anode acting as a layer having a lower work function defect electrons or holes, whereby in the organic material by Recombination of the electrons emitted in the hole-light quanta.

p0049many additional functional layers are used for the production of OLEDs, which are applied in particular between the first and second conductive layers. Accordingly, the method can advantageously also include the step of applying at least one hole injection layer and / or a potential matching layer and / or a

p0050include electron-blocking layer and / or a hole blocking layer and / or an electric conductor layer and / or a hole transport layer and / or an electron injection layer. Particularly high quantum or light yields are achieved by depositing the layers in order of preference potential matching layer / hole injection layer / electron blocking layer / layer which comprises at least one electro-optical material / hole blocking layer / electron transport layer / electron injection layer / potential matching layer.

p0051The sequence of the functional layers of the organic electro-optical element will hereinafter be referred to simply as the OLED layer structure. This comprises in particular the first and second conductive layer and the layer comprising an organic electro-optical material. In addition, the OLED layer structure also comprise, for example, the above mentioned further functional layers.

p0052In order to allow the light exit or light entry, it is advantageous if one of the conductive layers is at least partially transparent. Suitable for this purpose is, inter alia, indium tin oxide or fluorine-doped tin oxide (Sn0₂: F). A further advantage of the process is that the order of the applied layers is not mandatory. Generally, OLEDs are fabricated by forming a transparent conductive layer is deposited on a transparent substrate or a transparent substrate, on which then the layer comprising an organic electro-optic material is deposited. This structure is then covered by a conductive layer, which may for example have a lower work function compared with the transparent conductive layer as a further electrode. The emitted light can be coupled off in this case, the transparent support or.

p0053According to a preferred embodiment of the method the step of depositing is performed at least a layer having a vitreous structure after application of the at least one layer which comprises at least one organic electro-optical material and the first and second conductive layers. If these layers are applied from the same side of the support her, or deposited, so there is the layer which comprises at least one organic, electro-optical material between the support and the layer with a vitreous structure. In this manner, the OLED layer between the carrier structure and layer is encapsulated with a vitreous structure.

p0054Since the present invention applied layers with a vitreous structure, for example, also can be transparent itself, but it is also possible for the layer sequence to be arranged so that the transparent conductive layer is applied to the layer with the organic electro-optical material on the support. In this way, an OLED not, for example, be made transparent carrier, the light passes through the layer with a vitreous structure and the transparent conductive layer in this case.

p0055Advantageously, one or both of the conductive layers as well as the layer comprising an organic electro-optical material, is applied structured or be deposited. In particular, these layers also laterally, ie along the surface can be prepared structured. By such

p0056Patterning, a plurality of characteristics of such elements can be influenced. For example, light passageway openings can be created in a conductive layer. Furthermore, a layer arrangement is possible in which the layers need not necessarily be applied over each other. Rather, it is possible that, for example, patterned layers can also engage. For example, can also be applied like a comb structured the first and / or the second conductive layer. The layer which comprises at least one organic, electro-optical material, then can be located wholly or partly between the comb structures, for example. Structuring is also useful for pixelated structures, which are operated by individual circuit elements, or for the production of an organic electro-optical element as an active-matrix display.

p0057Particularly suitable for a hermetic encapsulation of OLEDs are layers with a vitreous structure, comprising an at least binary-component system. Such layers are generally characterized by very low permeability rates, since they, unlike, for example, quartz glass hardly tendency to form crystalline regions show and also have dense structures. Such at least binary component systems can, for example, from composed of at least two metal oxides or silicon dioxide and one or more metal oxides.

p0058Furthermore, the method may also be configured so that the step of depositing the at least one layer is carried out with a vitreous structure prior to application of one of the conductive layers. This is the layer with a vitreous structure between the carrier and the OLED layer structure. Such a variant of the method provides an OLED in which also the diffusion through the

p0059Substrate, or the carrier is suppressed through the OLED layer structure inside. This also allows a hermetic encapsulation on the support side of the OLED can be achieved. This is, for example, for flexible OLEDs advantageous if the carrier comprises a flexible plastic material, typically a high permeability for small gas molecules. The vitreous layer can also fulfill the function of education or Einkoppelschicht for the light emitted by the OLED light in order to increase the yield of OLED by refractive index matching.

p0060The at least one layer with a vitreous structure can also be applied to the support side which of the side on which the layer is applied, comprising an organic electro-optical material is opposed. Thus, the layer is applied to the support side, on which during normal layer structure of the OLED, the light is coupled out into the environment. Again, with a vitreous structure increase the extraction efficiency, a refractive index-matching means of the film, especially because otherwise a large refractive index jump with correspondingly strong back reflections occur at the interface material / air. In addition, even such a layer to create a diffusion barrier for the lifetime of the OLED extension. A great advantage for the properties of OLEDs is also a development of the method for their preparation, wherein the step of applying a layer having a vitreous structure by means of physical and / or chemical vapor deposition includes the step of applying a multilayer film. The multiple layers of such a layer may for example have different chemical compositions, so that can be about barrier effects of individual layers to certain harmful gases for the life of tailoring. The mechanical properties such as flexibility, adhesion or intrinsic layer voltage can be increased for example by introducing more flexible interlayers. Not all layers of the multilayer film have to have a glass-like structure. Rather layers glassy material layer with other layers of different chemical composition, such as metal layers or organic layers, such as in particular polymer layers are combined to adjust the chemical and physical layer characteristics to the requirements. Accordingly, in this development of the method the step of applying a multilayer film comprising the step of applying a multilayer film with different chemical

p0061Compositions and / or- different mechanical properties of at least two of the layers. Here may also different manufacturing processes for the layers, such as by gluing, dip coating_. or spin coating are combined with each other and with the deposition of at least one layer with a vitreous structure.

p0062In particular, the multiple layers can also be applied so that at least two of the layers have different refractive indices. This can, by applying various layer materials can be achieved. However, it is also possible to influence the refractive index by the choice of the process parameters during application, such as the vapor deposition rate. Such a multilayer film having a varying refractive index is particularly suitable for a refractive index matching.

p0063Many deposition of layers with a vitreous structure leads to a certain heat load of the OLED layer structure which can have negative effects on the layers. In particular, the heat stress in CVD or PVD coatings can affect the coating composition. To reduce the impact of heat stress, at least one Vorverkapselungsschicht can additionally be applied. Such Vorverkapselungsbeschichtung example, can reduce the heat transfer and prevent heating of the OLED layers.

p0064In addition, a suitable Vorverkapselungsbeschichtung example, can prevent the layer penetrated another layer with a vitreous structure when applied by PVD or CVD coating or chemically altered. This may be the case for example with the second conductive layer, if it is made of very soft or reactive metals such as calcium.

p0065The method may also advantageously comprise the step of applying a cover. In order to protect the very thin layer generally having a vitreous structure, or the other layers of the OLED from being damaged, may thereto be applied on the layer with a vitreous structure, the cover. but also may also be a layer having a vitreous structure are applied such that the contact surface between the cover and the carrier is sealed by the layer having a vitreous structure, and is hermetically sealed. For this purpose, the step of depositing comprises at least one layer with a vitreous structure the step of covering the boundary of the bearing surface of the cover with at least a layer having a vitreous structure. This can not only solve the task of a hermetic seal, but the layer, such as the evaporation-coating can also be used to secure the cover, similar to a glass solder. The term of the contact surface is not to be understood in the strict sense as the surface formed on the contact points of other components with the cover. For example, since the OLED layer structure is generally slightly raised, a smaller distance between the cover and the respective pad, as the carrier may occur in adjacent areas adjacent to the OLED layer structure. These areas are, however, also be understood as a bearing surface. The support surface can thus be understood as the projection of the side of the cover on the base, which faces the base.

p0066Advantageously, the process according to the invention may further be improved in that it additionally comprises the step of applying at least one adhesive layer, in particular an adhesive layer to which is applied at least one layer with a vitreous structure comprises. Such a layer may, in particular the

p0067improve adhesion properties of the layer with a vitreous structure on plastic surfaces, which is beneficial to the mechanical stability of the layer structure under thermal or mechanical stress such as a bending load. In this way, a faster closed layer generated and it can be smoother layers with lower porosity reach.

p0068The invention also contemplates to provide an organic photoelectric element which is in particular produced by the method described above.

p0069An inventive element accordingly comprises: -a support, -a first conductive layer,

p0070-at least one layer which comprises at least one organic electro-optical material and

p0071-a second conductive layer, and

p0072-a deposited layer with a vitreous structure

p0073As mentioned above with respect to the manufacturing method described for OLEDs, a layer having a vitreous structure is particularly suitable as a diffusion barrier for small molecules, thus providing an effective protection against the degradation of the element prepared. Characterized in that the layer is deposited on a surface of the element, between the layer and the surface of a connection without intermediate or transition layers, which is favorable particularly for a hermetic seal. Preferably, the layer by means of CVD and / or PVD coating, for instance by sputtering, evaporation, or PICVD PCVD on the surface is deposited.

p0074Preferably, one of the conductive layers on a lower work function than the other conductive layer to provide a work function difference between the layers. In the case of a light emitting element a voltage to the conductive layers, electrons are, starting from the layer having a lower work function upon application into unoccupied energy states injected. By recombination of electron holes that are injected from the layer with a higher work function, then photons are emitted.

p0075To increase the quantum efficiency of an OLED according to the invention, the OLED may additionally comprise further functional layers. Advantageously, for example, at least one hole injection layer and / or at least a potential matching layer and / or at least one electron-blocking layer and / or at least one hole blocking layer and / or at least one electron conductor layer and / or at least one hole conductor layer and / or at least one Elektroneninj ektionsschicht.

p0076In order to allow the exit of the emitted light quanta, it is advantageous if one of the conductive layers is at least partially transparent for the light emitted by the organic electro-optical material layer having light. These required features can be met, inter alia, when the first conductive layer of indium tin oxide or fluorine-doped tin oxide.

p0077The at least one layer with a vitreous structure may also include not only on the side of the support on which the layer which comprises the organic electro-optic material. Rather, the layer may be provided with a vitreous structure also on the side of the support, which is opposite to this side. In this way, can be limited by the carrier on the one hand, the diffusion of gas molecules, on the other hand, for example, the optical properties of OLEDs can be influenced favorably by about the layer with a vitreous structure creates a refractive index matching. The at least one layer with a vitreous structure may further comprise, along the direction perpendicular to the coated surface has a varying composition and / or a varying refractive index. By varying the composition normal to the surface, the layer in this direction corresponding varying material properties, such as^' have a varying coefficients of thermal expansion or refractive index. The refractive index may, however, also different, are affected for example by the morphology of the layer. In particular, the composition and / or the refractive index can also vary periodically. A layer with a vitreous structure and a periodically varying refractive index is particularly well suited to light off or inject into the element.

p0078The at least one layer with a vitreous structure may also be arranged particularly advantageously between the carrier and the first or second conductive layer. With this

p0079Arrangement, the diffusion of gas molecules is also suppressed through the carrier. Also can be prepared in this manner, a refractive index matching between the OLED layer structure and the support.

p0080The organic electro-optical element may also include a multi-ply layer which comprises at least a layer having a vitreous structure. This can be both for the optical properties, or in particular for the training or coupling of light, as well as for the mechanical properties such as the bending tolerance can be advantageous.

p0081A particularly favorable embodiment and Einkopplungsvermögen for light may be achieved in particular if the layers of the have multiple layer different refractive indices.

p0082In addition, the OLED can also have at least one Vorverkapselungsschicht which as

p0083can serve thermal barrier coating and reduces the heat load of the OLED during the coating with the layer or layers with a vitreous structure. A

p0084Vorverkapselungsbeschichtung can- also serve to provide the layer with a vitreous structure a stable surface.

p0085To protect the layer with a vitreous structure or the other layers, in particular from mechanical damage the OLED may further include a cover advantageously.

p0086The OLED may additionally comprise advantageously at least one bonding layer, which preferably to at least adjacent a layer with a vitreous structure. improved adhesion of the layer is achieved with a vitreous structure by such a bonding layer. This higher growth rates and comparatively smoother layers can be reached during the deposition. Moreover, such adhesive layer serve to release intrinsic layer stresses.

p0087An inventive electro-optical element may also have advantageously structured layers. For example, the first and / or the second conductive and / or the at least one layer which comprises at least one organic electro-optical material may be structured to incorporate additional functionality in one or more of these layers. Specifically, the first and / or second conductive layer can comb-like structure be. The finger electrodes of the comb-structured layers, for example, mesh, so that a voltage between present on a plane conductive layers can be applied or tapped.

p0088Equally, however, other structures of the layers are useful. For example, the conductive layers may in different levels on the substrate arranged in mutually intersecting lines, respectively having conductor tracks which allow a single pixel drive-connected pixel structures, particularly for display applications. In this case, which is located between the conductive layers layer which comprises at least an electro-optical material, is excited in the vicinity of a crossing point of two of driven conductor tracks of the conductive layers locally electroluminescence. A corresponding photovoltaic array can conversely be used for local signal sampling for sensor applications, such as an image pickup.

p0089It is also within the scope of the invention to provide an apparatus for performing the above-described

p0090to provide manufacturing method and / or a photoelectric element according to the invention. Such a device has, in addition to equipment for the manufacturing of the OLED layer structure in addition to a coating apparatus for depositing at least one layer with a vitreous structure.

p0091The invention is described in more detail below using preferred embodiments and with reference to the accompanying drawings in more detail. Here, the same reference numerals in the drawings, the same or like parts. Show it :

p0092Fig. 1 a first embodiment of an OLED according to the invention, Fig. 2 shows another embodiment of an OLED according to the invention with an inverse layer structure, Fig. 3 shows an embodiment of an OLED with

p0093Vorverkapselungsschicht, Fig. 4A to 4D embodiments with additional cover to protect the OLED layer structure, Fig. 5 shows an embodiment of the OLED with arrangement of the layer with a vitreous structure between OLED layer structure and support, Fig. 6 shows an embodiment with multilayer

p0094Encapsulation of the OLED multilayer structure, FIG. 7 shows an embodiment with multi-layer

p0095Encapsulation of the OLED layer structure and different refractive indices of individual layers,

p0096Figs. 8A and 8B, the profile of the refractive index in a

p0097Layer with a vitreous structure according to two additional embodiments of an OLED, Fig. 9 shows an embodiment of an OLED with comb-patterned conductive layers,

p0098FIG. 10 is a comparison of two samples with Si0₂-, Or evaporation-coated calcium strips 11 is a graph of the optical density of encapsulated calcium-strips as a function of time, Figure 12 is a comparison of the efficiency of different encapsulated OLEDs, and FIG 13, the luminous intensity different encapsulated OLED elements... function of the Length of stay in a climate chamber.

p0099Fig. 1 shows in schematic cross-sectional view of a first embodiment of an OLED according to the invention, indicated as a whole with 1. The OLED comprises a substrate 3, on which on one side a 9 OLED layer structure 5 is applied. The layer structure 5 comprises a first conductive layer 13, a layer 15 which comprises at least one organic electro-optical material, and a second conductive layer 17. The layer structure 5 of the OLED is covered with a layer 7 with a vitreous structure which by means of PVD - and / or CVD coating was applied. The layer 7 creates a hermetic encapsulation of the OLED layer structure 5, in particular to small gas molecules of the natural atmosphere, such as water or oxygen because of its low permeability. In this way, the degradation of the OLED according to the invention is reduced significantly by chemical reactions of reactive gases with materials of the layer structure, which results in an increased lifetime of the OLED. As the material of the layer 7 is particularly inorganic glass has been found to be low because of its low permeability. Particularly low permeability show particular alkaline glasses, which are in particular also borosilicate glasses.

p0100Preferably, the layer with a vitreous structure thereby comprises a vapor-deposition, which was deposited by evaporation on the element. 1

p0101The layer 15 comprising an organic electro-optical material will hereinafter for simplicity referred to as organic light emitting layer. However, this layer can be used as light-absorbing, photovoltaic layer of the photovoltaic element be formed.

p0102To be particularly suitable, the evaporation-type has 8329 Schott proved, having that following composition by weight: Si0₂ 84.1% B₂0₃ 11.0%

p0103N / A₂0 "2, 0%]

p0104K₂0 * 0, 3% (^■ (In the layer 3.3%)

p0105Li₂0 * 0, 3% J

p0106A1₂0₃ »2.6% (in the layer <= 0.5%)

p0107The values ​​in parentheses are the weight fractions of the respective components in the vapor-deposited layer.

p0108The electrical resistance of this borosilicate glass is approximately 10¹⁰ Ω / cm (at 100 ° C). This glass also has a refractive index of about 1.469 in pure form. The dielectric constant ε is about 4.7 (at 25 ° C,

p01091MHz), tan .delta is about 45 x 10^"4 (At 25 ° C, 1 MHz). Through the evaporation process and the different volatility of the components of this system is slightly different stoichiometries between the target material and the deposited layer arise. The deviations in the deposited layer are given in parentheses.

p0110Another suitable evaporation-coating, which is hereinafter referred to as Glas2, has the following composition in percent by weight: Components: Glas2

p0111Si0₂ 71%

p0112B₂0₃ 26%

p0113N / A₂0 0.5%

p0114Li₂0 0.5%

p0115K₂0 1.0%

p0116A1₂0₃ 1.0%

p0117These two particularly preferred borosilicate glasses used have the properties listed in the table below:

p0118<img id="imgf000027_0001" he="102" wi="154" file="imgf000027_0001.tif" img-format="tif" img-content="table" orientation="portrait" inline="yes" />

p0119By applying the layer 7 by vacuum deposition, such as CVD and / or PVD is formed an intimate connection of the layer 7 with both the surface of the layer structure 5, and with the carrier itself in regions adjacent to the OLED layer structure. This will also Permeabilitätskanäle at the edge regions of the OLED Layer structure is avoided, which are encapsulated in previously known OLEDs about by bonds. Preferably, the layer 7 by vapor deposition, in particular by means of electron beam evaporation of a glass target with one of the compositions indicated above, deposited.

p0120It has been found to produce particularly dense and low-defect layers as advantageous a GSP Source (APS = "advanced plas a source") to use and a plasma ion assisted deposition to make ion-aided deposition in particular by plasma.

p0121The carrier in this embodiment comprises a transparent substrate. Of the organic light emitting layer 15, light emitted passes first through the first conductive

p0122Layer 13 and then passes through the boundary surface to the surroundings on the side 11 of the transparent support.

p0123The first conductive layer 13 in this embodiment comprises a transparent conductive material such as indium tin oxide in order to allow the passage of light.

p0124The second conductive layer comprises a material having a lower work function than that of the first conductive layer, wherein in the case of indium-tin-oxide layer whose work function is about 4.9 eV. As the material for the second conductive layer in particular calcium is suitable. Calcium is very reactive and react in particular with the atmospheric oxygen, as well as the in the air^' as

p0125Moisture water contained. In particular for the protection of this layer is important a hermetic encapsulation of the OLED layer structure for preventing degradation. This embodiment of an OLED comprising the layer sequence carrier / first conductive layer / organic light emitting layer / second conductive layer. This corresponds to the standard structure of OLEDs. By applying a layer with a vitreous structure, the same time the OLED layer structure 5 effectively encapsulated, but also a structure having an inverse layer sequence can be realized. This variant is shown in Fig. 2. . In the embodiment shown in Figure 2, the layer sequence is accordingly: carrier / second conductive layer / organic light emitting layer / first conductive layer. In this embodiment, the carrier can also comprise an opaque material. 3 The light emitted from the organic light emitting layer 15, light then passes after passing through the first conductive layer 13 through the layer 7 with a vitreous structure at the outer side 19 from.

p0126In Fig. 3 is shown with a Vorverkapselungsschicht 21 schematically illustrates an embodiment. These

p0127Vorverkapselungsschicht serves, inter alia, to provide a stable surface for the layer 7 with a vitreous structure. The second conductive layer 17 preferably comprises a very soft metal calcium. The Vorverkapselungsschicht 21 prevents that this layer is penetrated by molecules of the layer 7th In addition, the layer 21 also constitutes a thermal barrier coating, which prevents their low thermal conductivity, that large heat outputs are transmitted during application of the layer 7 with a vitreous structure on the OLED layer structure.

p0128In Figures 4A to 4D embodiments of the organic electro-optical element 1 are shown with additional cover 23rd The cover 23 serves to protect especially against mechanical damage. Since the Layers 13 to 17 of the element 1 may be relatively soft, the layer 7 is connected in the field of OLED layer structure 5 with a not very stable base, so that the layer 7 to mechanical influences can be sensitive. The cover 23 may be advantageous bonded to the OLED. In the embodiment shown in Fig. 4A, the cover 23 is connected via a synthetic resin or plastic layer 25 with the other components of the element. The resin or plastic layer 25 is capable of compensating for unevenness on the surface, such as the excellent OLED layer structure.

p0129In the embodiment shown in Fig. 4B, the layer 7 having a vitreous structure was deposited so that the border of the contact surface of the cover is covered with. For this purpose the cover 23 has been applied prior to the layer 7 with a vitreous structure on the coated substrate. The layer 7 with a vitreous structure was then, so that the edge of the cover 23 is sealed by the layer 7 on the cover and over the edge of time, which defines the boundary curve of the support surface, is deposited. In this way it is prevented that gases penetrate between the cover and support, and the OLED layer structure can achieve the fifth

p0130In the embodiment shown in Fig. 4C was omitted adhesion of the cover to the base. Here, the layer 7 is used with a vitreous structure itself for mounting the cover 23. In addition to sealing the edges of the Andeckung is by the deposition of the layer with a vitreous structure, therefore also a compound of the cover, similar as achieved with a glass solder, but without the OLED need to layer structure of a particular heat stress expose. The layer 7 is not exemplified as a continuous layer, deposited only on the edges of the cover or of the edge curve of the support surface of the cover. Of course, the layer 7 may also similarly as in FIG. 4B, the entire surface of the coated side of the element to be deposited covering.

p0131Fig. 4D shows a further embodiment of a cover 23 provided with an element 1, wherein the outline curve of the support surface of the cover having a

p0132Layer 7 is covered with a vitreous structure. Here too, as in the embodiment shown with reference to FIG. 4C, in addition to a sealing and attachment of the cover obtained by means of the layer 7. In contrast, however, the layer 7 is evaporated onto the side member so that the edges of the element 1 are sealed.

p0133In the embodiment shown on the basis of Fig. 4E is a seal or a hermetic reached completion of the OLED layer structure and an attachment of a cover 23 by depositing from the side, which is opposite to the cover. Here too, the embodiments of FIGS. 4B, 4C and 4D together, the outline curve of the support surface of the cover 23 covered by the layer 7 with a vitreous structure.

p0134In Fig. 5, an embodiment is shown in which the layer having a vitreous structure prior to applying the first and second conductive layer and the organic light-emitting layer is applied on the carrier 3. This is the layer with a vitreous structure between the carrier and the OLED stack. In this way, the diffusion through the substrate, or the carrier and into the OLED layer structure into suppressed. By achieved with this arrangement, the layer 7 between OLED layer structure 5 and the carrier 3 encapsulation of the OLED from the side of the carrier 3 ago it is also possible that for the carrier 3, a penetrable for gas molecules material may be used. For example, can be used in this way, a plastic support, otherwise the gas molecules would migrate in the OLED layer structure through due to poor barrier properties of plastics. The use of plastic substrates is particularly suitable for flexible OLEDs.

p0135The OLED may further comprise an adhesive layer 10 for connecting the layer 7 with a vitreous structure with a plastic carrier. The bonding layer 10 adjoins the layer 7 with a vitreous structure and is located between the carrier 3 and layer 7. The bonding layer 10 provides a firm and durable connection of the layer 7 with a vitreous structure with the carrier 3, so that a separation of the layer 7 is prevented in particular when bending the OLED from the flexible support. 3 Of course, having such bonding layers also those described above, and the embodiments described below.

p0136In addition, 5 to complete the OLED layer structure hermetically a not shown in Fig. 5 further encapsulation, said encapsulation also preferred by applying a layer with a vitreous structure by means of CVD and / or PVD coating. The applied between the OLED layer structure 5 and the support 3 layer with a vitreous structure, besides, also additionally serve its function as a diffusion barrier as a refractive index matching between the OLED layer structure 5 and the support 3 to the decoupling of the organ pean layer 15 emitted light to improve.

p0137In OLEDs with flexible substrates 3, which are constructed as shown in Fig. 5, the layer 7 should run along the neutral axis of the structure, so that can not form cracks in this layer when bending the OLED, which increase the degradation again could. In FIG. 6, an embodiment is shown in which a multilayer film was deposited 27 to increase the flexibility of the structure. The multilayer film 27 is applied on the side of the carrier 9 between the carrier 3 and OLED layer structure 5th The multi-layer film 27 in this embodiment comprises N layers with a vitreous structure 71, 72, ..., 7N.

p0138Alternately to these layers 71, 72, ..., 7N are N flexible layers 81, 82, ..., 8N applied. The flexible layers 81, 82, ..., 8N, for example, comprise polymer layers. If the OLED is bent, so contact between the individual layers to shear forces. The shear forces are to 8N degraded due to the flexibility of the layers 81 by deformation of these layers. The same principle can of course be applied also on the opposite side of this page OLED layer structure to complete yet flexible encapsulation of the OLED layer structure. 5

p0139In the figures 5 and 6, the encapsulation of the OLED layer structure in each case on the side opposite the support not shown for clarity.

p0140Fig. 7 is similar to the embodiment shown in Fig. 6, an OLED according to the invention with multi-layer sheet 27, the layers 71, 72, ..., 7N with a vitreous structure, as well as other layers 81, 82, ..., 8N comprises. in the Unlike the embodiment shown in Fig. 6, the layers at the side 11 of the carrier 3 are here however applied, which of the side 9, on which the OLED layer structure 5 is applied is opposite. additionally shown an encapsulation of the OLED layer structure 5 is similar to the embodiments illustrated with reference to Figures 1 to 4 by a layer 7 with a vitreous structure.

p0141The multilayer film 27 is used here with the increase provided by the layers 71 to 7N barrier effect of refractive index matching to improve the coupling out of from the organic layer 15 emitted light at the interface of the OLED to the ambient. The individual layers 71 to 7N and 8N 81 to the multilayer film 27, therefore, have different refractive indices. In particular, the layer 27 is constructed so that the layers 71 have to 7N with a vitreous structure and the same refractive index layers 81 to 8N also same refractive indices. In this way, the refractive index alternates with the alternating arrangement of the layers from layer to layer.

p0142However, a variation of the refractive index may arise not only by combining different layers. Rather, it is also possible that a layer having a vitreous structure along the direction perpendicular to the coated surface varying composition and / or along this direction varying refractive index. In this case, a variation of the refractive index is preferably achieved also by varying the layer composition. However, a variation by a layer morphology along that direction changing, such as a varying density is also conceivable. Layers with variation of the refractive index by changing layer composition can be prepared by Deposition of the layer are produced by means of co-evaporation, wherein the evaporation rate at least one of

p0143Evaporation sources is modified during the deposition process. By periodically changing the deposition rate, for example, by periodically changing the performance of the sources as a corresponding layer may be formed with a vitreous structure, the coated surface to perpendicular a periodically varying refractive index.

p0144Such a course of the refractive index is exemplified in Figures 8A and 8B. The coordinate z characterizes the direction perpendicular to the coated surface. Both curves show a periodic variation of the refractive index in the z direction. The curve shown in Fig. 8B of the refractive index also includes in addition to the periodic variation on a decrease in the amplitude in the z-direction, which may be useful for training, or coupling efficiency of the element addition.

p0145In Fig. 9 finally shows a further embodiment of an OLED, or an organic electro-optical element is shown, having structured functional layers. In this embodiment, the conductive layers 13 and 17 are comb-like structure and are both located on the same plane on the support 3. The layers 13 and 17 each comprise finger electrodes 30 which are connected to at least one web 32nd The voltage supply, or the voltage tap in the case of a photovoltaic element is maintained via the webs 32. The layer 15 comprises at least one organic, electro-optical material is applied to the to the patterned layers 13 and 17, causing fluid to the layer 15 also is between the finger electrodes. The OLED layer structure thus produced is in this embodiment, the encapsulation again, similar to the embodiment illustrated on the basis of Fig. 1 with a layer 7 is covered with a vitreous structure.

p0146Of course, the illustrated above exemplary embodiments can also be combined in various ways, for example by layers are applied with a vitreous structure on multiple sides of the substrate. Among other things, the embodiment shown with reference of Fig. 7 with a coating on the side of the

p0147Substrate, facing the OLED layer structure 5, for example, be combined as in the embodiments of Figures 5 or 6th Likewise, nearly any other combination of the embodiments shown are possible. Also can be used in pixel displays all embodiments, for example, by a matrix arrangement of the elements described or by correspondingly structured conductive layers with intersecting conductor tracks.

p0148Fig. Figure 10 shows photographic images of the light transmission through two samples. The samples are glass substrates on which two calcium strips are applied. The substrates were then encapsulated on the side with the calcium strips. In the sample shown in Fig. 10 on the left side an evaporation-coating was applied to encapsulate in the right imaged sample is a silicon oxide layer was selected for encapsulation as a comparison.

p0149The photographs were taken after twenty hours of storage of the samples in air. Not degraded areas of

p0150Calziumschicht appear dark in the images. With the two images can be seen that the evaporation-coated Calziumstreifen are less heavily corroded. The degradation in the coated silicon oxide sample is over the entire surface more advanced than the comparative sample with evaporation-coating.

p0151Fig. Figure 11 shows the optical density of each with a plurality of Calziumstreifen evaporation-coating glass or silicon coated samples as a function of the duration of exposure of air. The samples on which measurements were carried out, besides resemble the samples shown in Fig. 10. Again Calziumstreifen were again deposited on a substrate, and the side with the strip then encapsulated by vapor deposition of a Aufdampfglas- or a silicon oxide layer.

p0152Based on the graph shown in Fig. 11 it is clear that the degradation of the Calziumstreifen when using

p0153Silica as encapsulation versus the combined

p0154Evaporation-encapsulated samples are significantly faster.

p0155In Fig. 12 is a bar graph is shown, showing a comparison of the efficiency of different encapsulated OLEDs. There were OLEDs, which were encapsulated with evaporation-coating, compared with OLEDs without encapsulation and OLEDs with a silicon oxide encapsulation. The efficiency measurements were measured shortly after the encapsulating at two different luminescence. The OLEDs were tested in a protective gas atmosphere in order to prevent in the unencapsulated OLEDs degradation.

p0156Based on the measurements shown in Fig. 12 it is clear that the deposition of vapor-deposition, in contrast to

p0157Silicon oxide substantially does not influence the quality of the manufactured OLED, since the efficiency of evaporation-coating glass with OLEDs encapsulated shows little difference to the non-encapsulated OLEDs. In contrast, the efficiency of the encapsulated with silicon oxide OLEDs is clearly lowered.

p0158Reference is made to Figure 13., Which shows a graph of light intensity of two different encapsulated OLED elements depending on the length of stay in a climate chamber. There an encapsulated with silicon oxide OLED were compared with an encapsulated with evaporation-OLED. The luminous intensity was measured by a photo element, wherein the measured values ​​are given in relative units. The luminosity was determined here at a constant operating current of OLEDs of 2mA.

p0159The samples were stored in a climate chamber at 85 ° C air temperature and 85% relative humidity. It turns out that the encapsulated with silicon oxide OLED in a climate chamber having only about a quarter of the original luminosity after ten days. In contrast, shows the encapsulated with evaporation-OLED even a slight increase in luminosity.

LIST OF REFERENCE NUMBERS

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