OPTOELECTRONIC COMPONENT, AND METHOD FOR CONTACTING AN OPTOELECTRONIC COMPONENT

Description

[0001] The invention relates to an optoelectronic component and a method for contacting such an optoelectronic component.

[0002] Optoelectronics comprises the fields of optics and semiconductor electronics. It particularly encompasses systems and processes that enable the conversion of electronically generated energy into light emissions or that convert light emissions into energy. Optoelectronic components, particularly organic optoelectronic components such as organic photovoltaic elements (OPVs) and organic light-emitting diodes (OLEDs), generate electrical energy or convert electrical energy into light emissions, which must be led out of or into the optoelectronic component for subsequent use. Busbars are used for this purpose. Busbars represent a point in an optoelectronic component where the converted energy is concentrated and transmitted in the form of electrical currents.

[0003] Organic optoelectronic components can be manufactured, for example, by evaporating the materials, printing polymers, or processing them from liquids. The basic structure of organic optoelectronic components is disclosed in WO2004083958 or WO2011138021.

[0004] Organic optoelectronic components, especially organic photovoltaic cells, exhibit a significantly reduced lifetime due to direct contact with air, oxygen, water, and / or moisture and therefore require encapsulation. Optoelectronic components are therefore typically coated or encapsulated with a protective layer to protect them from external influences, particularly to protect them mechanically and against environmental influences, such as moisture or oxygen diffusion. Encapsulation can be achieved using barrier films or direct encapsulation.

[0005] Organic optoelectronic components are structured using laser processes. These methods are used primarily for interconnecting individual photovoltaic cells on an optoelectronic component, as well as for electrically isolating photovoltaic cells. Laser structuring, particularly laser structuring of the electrodes, can result in bumps, so-called laser scribes, that are many times higher than the height of the layers in the flat topology of a layer system of an organic photovoltaic element. This makes it difficult to apply additional layers, especially a barrier layer, and can also damage an already applied layer during subsequent encapsulation.Known processes for integrating thin-film encapsulation are very sensitive to the topology of individual layers within the system, leading to height differences within a single layer. Therefore, most thin-film encapsulations incorporate a planarization layer before a barrier layer is applied.

[0006] When integrating thin-film encapsulation into photovoltaic elements, especially solar cells, contact must be established using busbars. This contact must also be established within the area containing the thin-film encapsulation, i.e., a barrier layer. A particular disadvantage of the current technology is that such contacting is very complex and costly.

[0007] Documents US 2018 / 090066 A1, US 2014 / 008636 A1, WO 2013 / 001780 A1, US 2017 / 358763 A1 and US 2015 / 076463 A1 disclose an optoelectronic component with a planarization layer provided with electrically conductive particles.

[0008] The object of the present invention is to provide an optoelectronic component and a method for producing such an optoelectronic component, wherein the disadvantages described in the prior art do not occur. The technical problem underlying the present invention consists in particular in, on the one hand, planarizing projections created by laser structuring the individual layers of an optoelectronic component so that a barrier layer can be applied in order to enable sealing or sealing by means of a thin layer, and on the other hand, providing an electrically conductive contact between a layer of the optoelectronic component, in particular an electrode layer, and a layer arranged above the barrier layer, in particular a busbar. The method should in particular be capable of being integrated into a roll-to-roll process.

[0009] The object is achieved by the subject matter of the independent claims. Advantageous embodiments emerge from the subclaims. The object is achieved in particular by providing an optoelectronic component, in particular a photovoltaic element, comprising a base electrode, a cover electrode, and a layer system with at least one photoactive layer, wherein the layer system is arranged between the base electrode and the cover electrode, a planarization layer arranged on the side of the base electrode and / or the cover electrode facing away from the layer system, at least one barrier layer arranged on the planarization layer, wherein the barrier layer is not electrically conductive and is formed over the entire layer system of the optoelectronic component, and at least one current collecting bar, wherein the at least one current collecting bar is arranged on the at least one barrier layer.The planarization layer comprises electrically conductive particles, wherein the electrically conductive particles are incorporated into the planarization layer, and wherein the electrically conductive particles electrically bridge the planarization layer through the at least one barrier layer, so that the base electrode and / or the cover electrode are electrically conductively contacted with the at least one current collecting bar. The optoelectronic component is, in particular, a photovoltaic element.

[0010] In a preferred embodiment of the invention, the base electrode, the layer system, and / or the cover electrode are laser-structured. In a preferred embodiment of the invention, the layer system is electrically connected to the base electrode and / or the cover electrode by means of laser structuring. In a preferred embodiment of the invention, the base electrode forms a cathode and the cover electrode an anode, with the base electrode and the cover electrode making electrical contact with the layer system.

[0011] In a preferred embodiment of the invention, the electrically conductive particles are incorporated into the planarization layer, wherein the electrically conductive particles electrically bridge the planarization layer through the at least one barrier layer. As a result, in particular, the cover electrode and the current collecting bar of the optoelectronic component are electrically conductively connected to one another by means of the planarization layer comprising the electrically conductive particles.

[0012] A planarization layer is understood to mean, in particular, a layer for leveling unevenness, in particular for reducing roughness, of at least one other layer of the optoelectronic component, in particular a layer of a base electrode and / or a layer of a cover electrode.

[0013] An optoelectronic component is understood, in particular, to be a component that emits electromagnetic radiation or a component that absorbs electromagnetic radiation. An electromagnetic radiation-absorbing component is preferably an organic photovoltaic element (OPV) or an organic photocell. An electromagnetic radiation-emitting component is preferably an OLED (organic light-emitting diode) or a transistor.

[0014] A photovoltaic element is understood to mean, in particular, a photovoltaic cell, in particular a solar cell. The photovoltaic element is preferably composed of several photovoltaic cells, which can be connected in series or in parallel. The several photovoltaic cells can be arranged and / or connected in different ways within the photovoltaic element.

[0015] A busbar is understood in particular to be an arrangement that, for electrical contact, serves as a central distributor of electrical energy to incoming and outgoing lines, preferably with at least one base electrode and / or at least one cover electrode. The busbar is particularly planar in design, as a strip, plate, or metal layer.

[0016] In a preferred embodiment of the invention, the at least one busbar has a layer thickness of 10 µm to 500 µm, preferably of 100 µm to 500 µm, preferably of 10 µm to 200 µm, preferably of 10 µm to 100 µm, preferably of 10 µm to 50 µm, preferably of 20 µm to 80 µm, preferably of 20 µm to 40 µm, or preferably of 30 µm to 50 µm.

[0017] In a preferred embodiment of the invention, the at least one busbar is arranged on the barrier layer directly or by means of an adhesive layer arranged between the barrier layer and the at least one busbar. In a preferred embodiment of the invention, the busbar has an adhesive layer, wherein the busbar is arranged on the at least one barrier layer by means of the adhesive layer. In a preferred embodiment of the invention, the busbar and / or the busbar with an adhesive layer arranged thereon has a layer thickness of 10 µm to 100 µm, preferably from 10 µm to 80 µm, preferably from 20 µm to 80 µm, preferably from 30 µm to 100 µm, preferably from 30 µm to 80 µm, or preferably from 30 µm to 60 µm.

[0018] In a preferred embodiment of the invention, the base electrode and / or the cover electrode are electrically conductively connected to the adhesive layer and / or the at least one current collecting bar by means of the electrically conductive particles through the at least one barrier layer.

[0019] A possible structure of the layer system of a photovoltaic element is described in WO2004083958A2, WO2011013219A1, WO2011138021A2, and WO2011161108A1. The applications cited herein preferably use layer systems in which the photoactive layers comprise absorber materials that are vaporizable and are applied or have been applied by vapor deposition. Materials belonging to the group of "small molecules" are used for this purpose, as described, inter alia, in WO2006092134A1, WO2010133208A1, WO2014206860A1, WO2014128278A1, WO2017114937A1, and WO2017114938A1. The photoactive layers form acceptor-donor systems and can consist of multiple individual layers or mixed layers, as planar heterojunctions, and preferably as bulk heterojunctions. Layer systems that are applied entirely by evaporation are preferred.

[0020] The layer system can be designed as a single, tandem, or multi-cell; the designation is determined by the number of subcells, with each subcell containing at least one photoactive layer, which is preferably separated by transport layers and optional recombination layers, and can itself consist of several layers. The p- or n-layer systems, also referred to as just p- or n-layer, can consist of several layers, with at least one of the layers of the p- or n-layer system being p-doped or n-doped, preferably as a p- or n-doped widegap layer. The i-layer system, also referred to as i-layer, is undoped or less doped than the p- or n-layers in the subcell, i.e. more weakly doped, and is designed as a photoactive layer. Each of these n-, p-, or i-layers can consist of further layers, with the n- or p-layer consisting of at least one doped n- orp-layer, which, through its doping, contributes to an increase in charge carriers. This means that the layer system of the optoelectronic component consists of a sensible combination of p-, n-, and i-layer systems, i.e., each subcell comprises an i-layer system and at least one p- or n-layer system.

[0021] Individual layers of the optoelectronic component are deposited on a substrate to manufacture the optoelectronic component. To ensure defect-free deposition and / or defect-free bonding of a subsequent layer, it is necessary to planarize the surface of the underlying layers, in particular to reduce surface unevenness.

[0022] In a preferred embodiment of the invention, the base electrode is arranged on a substrate, in particular a film. In a preferred embodiment of the invention, the optoelectronic component comprises a substrate, wherein the substrate is in particular a carrier. In a preferred embodiment, the substrate is a film, preferably a film formed from a plastic; in particular, the film is at least partially transparent.

[0023] A barrier layer is understood, in particular, to be a protective layer that forms a barrier against chemical contaminants, moisture, and / or oxygen. The barrier layer is, in particular, a protective layer for preventing the permeability of external influences, in particular atmospheric oxygen and / or moisture, a protective layer for increasing mechanical resistance, in particular scratch resistance, and / or a filter layer, preferably a layer with a UV filter.

[0024] In a preferred embodiment, the optoelectronic component comprises at least one cell with at least one photoactive layer, in particular a CIS, CIGS, GaAs, or Si cell, a perovskite cell, or an organic photovoltaic element (OPV), a so-called organic solar cell. An organic photovoltaic element is understood to mean, in particular, a photovoltaic element with at least one organic photoactive layer, in particular a polymeric organic photovoltaic element or an organic photovoltaic element based on small molecules. While polymers are characterized by the fact that they are not evaporable and can therefore only be applied from solutions, small molecules are usually evaporable and can be applied either as a solution like polymers, but also using evaporation technology, in particular by evaporation from a vacuum.

[0025] In a preferred embodiment of the invention, the at least one photoactive layer of the layer system comprises small molecules that are evaporable in a vacuum. In a preferred embodiment of the invention, at least one photoactive layer of the layer system is vacuum-deposited.

[0026] Small molecules are defined, in particular, as non-polymeric organic molecules with monodisperse molar masses between 100 and 2000 g / mol that exist in the solid phase under normal pressure (the atmospheric pressure of our surroundings) and at room temperature. Small molecules are particularly photoactive, meaning that the molecules change their charge state and / or polarization state upon exposure to light. Advantages of these small-molecule-based absorber materials include their evaporability in a vacuum.

[0027] In a preferred embodiment of the invention, the at least one busbar is formed as a metal layer made of at least one metal or an alloy thereof, preferably of aluminum or an alloy thereof.

[0028] In a preferred embodiment of the invention, the planarization layer is not electrically conductive.

[0029] In a preferred embodiment of the invention, the cover electrode is made of silver or a silver alloy, aluminum or an aluminum alloy, gold or a gold alloy, or a combination of these materials, preferably as a silver alloy of Ag:Mg or Ag:Ca.

[0030] In a preferred embodiment of the invention, the base electrode comprises ITO (indium tin oxide).

[0031] In a preferred embodiment of the invention, the photovoltaic element comprises a layer system with at least two photoactive layers, wherein the photovoltaic element is a tandem cell, preferably with at least three photoactive layers, wherein the photovoltaic element is a triple cell.

[0032] In a preferred embodiment of the invention, the layer system additionally comprises at least one charge carrier transport layer, wherein the at least one charge carrier transport layer is arranged between the base electrode or the cover electrode and a photoactive layer, preferably the layer system comprises at least a first charge carrier transport layer and a second charge carrier transport layer, wherein the first charge carrier transport layer is arranged between the base electrode and the at least one photoactive layer, and wherein the second charge carrier transport layer is arranged between the at least one photoactive layer and the cover electrode.

[0033] In a preferred embodiment of the invention, the planarization layer is formed over the entire layer system of the optoelectronic component.

[0034] The optoelectronic component according to the invention has advantages over the prior art. Advantageously, a closed planar topology of an electrode layer is obtained. Advantageously, simple and reliable electrically conductive contacting of the optoelectronic component is enabled, in particular within the optoelectronic component between an electrode and a busbar. Advantageously, the planarization layer is electrically conductively bridged by the electrically conductive particles. Advantageously, damage to the layer system and / or the electrodes during contacting is avoided. Advantageously, no or hardly any losses of electrical conductivity are observed with such an electrically conductive contact. Advantageously, contacting is enabled in a cost-effective and simple manner.Advantageously, such electrically conductive contacting increases the service life of optoelectronic components. The planarization layer with the electrically conductive particles advantageously enables a reduction in the unevenness of the underlying layer, particularly the surface of the underlying layer, while simultaneously establishing an electrically conductive contact. Advantageously, the electrically conductive particles are particularly easy to integrate into the planarization layer. The process can advantageously be integrated into a roll-to-roll process.

[0035] According to a further development of the invention, it is provided that the planarization layer has a layer thickness of 5 µm to 100 µm, preferably of 10 µm to 50 µm, and / or the at least one barrier layer has a layer thickness of 100 nm to 2000 nm, preferably of 100 nm to 1000 nm, preferably of 150 nm to 1000 nm, preferably of 200 nm to 800 nm, or preferably of 300 nm to 600 nm.

[0036] In a preferred embodiment, the planarization layer has a layer thickness of less than 200 µm, preferably less than 100 µm, preferably less than 70 µm, preferably less than 50 µm, preferably less than 30 µm, preferably from 10 µm to 200 µm, preferably from 10 µm to 100 µm, preferably from 10 µm to 70 µm, preferably from 10 µm to 50 µm, or preferably from 10 µm to 30 µm.

[0037] In a further preferred embodiment, the barrier layer has a layer thickness of less than 10 µm, preferably less than 5 µm, preferably less than 3 µm, or preferably less than 1 µm.

[0038] According to a further development of the invention, it is provided that the electrically conductive particles have an average diameter of 1 µm to 100 µm, preferably of 1 µm to 50 µm, and / or the average diameter of the electrically conductive particles is greater than the layer thickness of the planarization layer, preferably up to 100% greater than the layer thickness of the planarization layer, or preferably up to 10% greater.

[0039] In the context of the present invention, a diameter is understood to mean, in particular, an equivalent diameter, preferably a geometric equivalent diameter, which also includes, in particular, the diameter of irregularly shaped particles. The geometric equivalent diameter is obtained by determining the diameter of a sphere or a circle with the same geometric property.

[0040] In a preferred embodiment of the invention, the electrically conductive particles have an average diameter of 1 µm to 100 µm, preferably from 1 µm to 70 µm, preferably from 1 µm to 50 µm, or preferably from 1 µm to 30 µm. In a preferred embodiment of the invention, the electrically conductive particles have an average diameter that is greater than the layer thickness of the planarization layer. In a preferred embodiment of the invention, the electrically conductive particles have a specific size distribution, wherein the specific size distribution of the electrically conductive particles preferably has the smallest possible standard deviation.

[0041] In a preferred embodiment of the invention, an average diameter of the electrically conductive particles is greater than the layer thickness of the planarization layer, preferably up to 200% greater than the layer thickness of the planarization layer, preferably up to 150%, preferably up to 100%, preferably up to 80%, preferably up to 60%, preferably up to 50%, preferably up to 40%, preferably up to 30%, preferably up to 20%, preferably up to 10%, preferably up to 5%, preferably up to 2%, or preferably up to 1%, or preferably at least 1% greater than the layer thickness of the planarization layer, preferably at least 2%, preferably at least 5%, preferably at least 10%, preferably at least 20%, preferably at least 30%, or preferably at least 50%.

[0042] In an alternatively preferred embodiment of the invention, the average diameter of the electrically conductive particles is smaller than the layer thickness of the planarization layer, wherein a plurality of the electrically conductive particles are in electrically conductive contact within the planarization layer, so that the electrically conductive contact is ensured through the planarization layer.

[0043] According to a further development of the invention, it is provided that the shape of the electrically conductive particles is spherical, angular, needle-shaped, and / or crystalline, preferably the shape of the electrically conductive particles is different from one another, and / or the electrically conductive particles are regularly or irregularly shaped, preferably as splinters, crystals or granules.

[0044] In a preferred embodiment of the invention, the electrically conductive particles have a certain surface energy that is readily wettable with a planarization material.

[0045] According to a further development of the invention, it is provided that the electrically conductive particles are formed from conductively coated glass, preferably coated with silver, from conductive metal, preferably from nickel or an alloy thereof, or from crystallites.

[0046] According to a further development of the invention, it is provided that a proportion of the volume of the electrically conductive particles in the planarization layer is 10 to 50%, preferably 20 to 40%, preferably 10 to 30%, preferably 10 to 20%, preferably 5 to 30%, or preferably 5 to 20%, in each case based on the total volume of the planarization layer, and / or a proportion of the surface of the electrically conductive particles on a side of the planarization layer facing the barrier layer is 10 to 50%, preferably 10 to 30%, preferably 10 to 20%, preferably 5 to 50%, preferably 5 to 30%, preferably 5 to 20%, or preferably 5 to 10%, in each case based on the surface of the planarization layer, and / or the electrically conductive particles in the planarization layer are arranged at least largely in the region of the at least one busbar.

[0047] In a preferred embodiment of the invention, the electrically conductive particles in the planarization layer are arranged at least largely in the region of the at least one downstream busbar. In a preferred embodiment of the invention, the electrically conductive particles in the planarization layer are arranged at least largely beneath the at least one busbar.

[0048] In a preferred embodiment of the invention, the optoelectronic component is a flexible optoelectronic component, preferably a flexible photovoltaic element, particularly preferably a flexible organic photovoltaic element.

[0049] According to a further development of the invention, it is provided that the optoelectronic component is an organic photovoltaic element, preferably a flexible organic photovoltaic element, wherein preferably at least one photoactive layer of the organic photovoltaic element comprises small molecules as absorber material.

[0050] A flexible optoelectronic component is understood in particular to be an optoelectronic component that is bendable and / or stretchable in a certain area.

[0051] In a preferred embodiment of the invention, the optoelectronic component is encapsulated by at least one additional barrier layer, with the at least one busbar extending from the at least one additional barrier layer. The encapsulation is preferably a thin-film encapsulation.

[0052] In a preferred embodiment of the invention, the optoelectronic component has an encapsulation consisting of at least one barrier layer that surrounds, i.e., seals, the optoelectronic component in a diffusion-tight manner. In a preferred embodiment, the encapsulation is a polymer encapsulation.

[0053] In a preferred embodiment of the invention, the optoelectronic component comprises at least a first photovoltaic cell and a second photovoltaic cell, wherein the first photovoltaic cell and the second photovoltaic cell are connected in series, and wherein preferably the cover electrode of the first photovoltaic cell is electrically conductively connected to the base electrode of the second photovoltaic cell.

[0054] The object of the present invention is also achieved by providing a method for contacting an optoelectronic component, in particular a flexible optoelectronic component, in particular according to one of the previously described embodiments. The method for contacting the optoelectronic component offers, in particular, the advantages already described in connection with the optoelectronic component. The method comprises the following steps: a) Providing a substrate having a base electrode arranged thereon, a layer system having at least one photoactive layer, and a cover electrode, wherein the layer system is arranged between the base electrode and the cover electrode, b) Applying a planarization material to the base electrode and / or the cover electrode, c) Introducing electrically conductive particles into and / or onto the planarization material, d) Curing the planarization material, preferably by UV radiation and / or thermal treatment, whereby a planarization layer comprising the electrically conductive particles is formed, e) Applying at least one barrier layer to the planarization layer, wherein preferably the at least one barrier layer is at least partially penetrated by the electrically conductive particles, and f) Applying at least one current collecting bar to the at least one barrier layer,so that the base electrode and / or the cover electrode are electrically contacted with the at least one current collecting bar via the electrically conductive particles.

[0055] In a preferred embodiment of the invention, step b) and step c) are carried out simultaneously, in particular the electrically conductive particles are at least partially already contained in the planarization material.

[0056] A planarization material is understood in particular to be a material which, after being applied to a surface, forms a planarization layer by curing, in particular crosslinking.

[0057] In a preferred embodiment of the invention, the planarization material is applied directly to the layer to be planarized, in particular the base electrode and / or the cover electrode.

[0058] In a preferred embodiment of the invention, the planarization material is a planarization lacquer. In a preferred embodiment of the invention, the planarization material is applied in liquid form.

[0059] In a preferred embodiment, the electrically conductive particles are introduced into the planarization layer in step c) by means of an inkjet printing process, an offset printing process, a plexographic printing process, a gravure printing process, a screen printing process or a doctor blade process.

[0060] In a preferred embodiment of the invention, the at least one barrier layer is at least partially pierced by the electrically conductive particles in step e) and / or in step f).

[0061] In a preferred embodiment of the invention, the layers are applied by means of a printing process, preferably an inkjet process, a screen printing process, and / or a flexographic printing process, and / or by evaporation of the materials to be applied. These processes are known to those skilled in the art and are therefore not explained in detail here.

[0062] According to a further development of the invention, it is provided that the planarization material is applied in step b) by means of a wet coating, and / or the electrically conductive particles are introduced in step c) into certain regions of the planarization material, preferably into regions of the planarization material with the subsequent application of the at least one busbar in step f).

[0063] According to a further development of the invention, it is provided that the electrically conductive particles are introduced into the planarization material in step c) by means of pressure, preferably by means of a pressure roller or, in the case of magnetic particles, by means of a magnet arranged under the optoelectronic component to be contacted.

[0064] In a preferred embodiment of the invention, the process is used in a roll-to-roll process.

[0065] In a preferred embodiment of the invention, the electrically conductive particles are applied to the barrier layer using a transfer belt. After crosslinking of the planarization layer, the introduced particles adhere better to the planarization layer than to the transfer belt, so that the transfer belt can be removed from the planarization layer. Preferably, the transfer belt for applying the electrically conductive particles is at least partially transparent to UV radiation, so that the barrier layer can be cured with the conveyor belt in place.

[0066] In a preferred embodiment of the invention, the at least one busbar is embossed onto the barrier layer, wherein a specific topology is formed on the busbar, which preferably has a size of 10 to 100% of the layer thickness of the planarization layer, preferably 10 to 70%, preferably 10 to 50%, or preferably 10 to 30%. In a preferred embodiment of the invention, the at least one busbar is placed and / or pressed into the planarization lacquer after the planarization lacquer has been applied.

[0067] The invention is explained in more detail below with reference to the drawings. In the drawings: Fig. 1 a schematic representation of a structure of a layer system with electrodes of an optoelectronic component; Fig. 2a schematic representation of an embodiment of an optoelectronic component with a planarization layer with electrically conductive particles in a side view. Examples of implementation

[0068] Fig. 1 shows a schematic representation of a structure of a layer system 4 with electrodes 2,3 of an optoelectronic component 1.

[0069] Optoelectronic components 1, in particular organic photovoltaic elements, consist of a sequence of thin layers with at least one photoactive layer, which are preferably vacuum-deposited or processed from a solution. The electrical connection, i.e. contacting, can be achieved by metal layers, transparent conductive oxides and / or transparent conductive polymers. Vacuum deposition of the organic layers is particularly advantageous in the production of multilayer solar cells, in particular tandem or triple cells. A layer system 4 of such an optoelectronic component 1 is shown in one embodiment in Fig. 1 shown.

[0070] In this exemplary embodiment, the optoelectronic component 1 has a base electrode 2, in particular a transparent base electrode made of ITO, arranged on a substrate 11, in particular made of glass. The layer system 4 is formed thereon, comprising an n-layer 12 with fullerene C60 as the charge carrier layer, a photoactive layer 13 with at least one absorber material and fullerene C60, and a p-layer 14 as a hole-transport layer made of Di-NPB and NDP9. A cover electrode 3, in particular made of gold, is arranged thereon. The layer system 4 and / or the electrodes 2, 3 are usually laser-structured. The layer system 4 can have further hole-injection layers, hole-transport layers, photoactive layers, electron-transport layers, and / or electron-injection layers.

[0071] The topography of a laser-structured optoelectronic component 1 typically has protrusions (not shown) that need to be planarized by a subsequent layer, in particular a barrier layer 6, in particular by means of a planarization layer 5. The barrier layer 6 can be arranged above the cover electrode 3, in particular after a previously applied planarization layer 5. The barrier layer 6 can, in particular, be a thin-film encapsulation.

[0072] Fig. 2 shows a schematic representation of an embodiment of an optoelectronic component 1 with a planarization layer 5 with electrically conductive particles 9, 10 in a side view. Identical and functionally identical elements are provided with the same reference numerals, so reference is made to the preceding description. The proportions of the layers of the layer system 4 are not shown to scale.

[0073] The optoelectronic component 1, in particular a photovoltaic element, has a base electrode 2, a cover electrode 3, a layer system 4 with at least one photoactive layer, wherein the layer system 4 is arranged between the base electrode 2 and the cover electrode 3, a planarization layer 5 arranged on the side of the base electrode 2 and / or the cover electrode 3 facing away from the layer system 4, at least one barrier layer 6 arranged on the planarization layer 5, and at least one current collecting bar 7, wherein the at least one current collecting bar 7 is arranged on the at least one barrier layer 6.The planarization layer 5 has electrically conductive particles 9, 10, wherein the electrically conductive particles 9, 10 are at least largely incorporated into the planarization layer 5, and wherein the electrically conductive particles 9, 10 electrically conductively bridge the planarization layer 5 through the at least one barrier layer 6, so that the base electrode 2 and / or the cover electrode 3 are electrically conductively contacted with the at least one current collecting rail 7.

[0074] This ensures simple and secure electrically conductive contacting of the optoelectronic component 1, particularly within the optoelectronic component 1 between an electrode 2, 3 and a busbar 7. In particular, the planarization layer 5 is electrically conductively bridged by the electrically conductive particles 9, 10. No or hardly any loss of electrical conductivity is observed with such electrically conductive contacting. The electrically conductive particles 9, 10 are particularly easy to integrate into the planarization layer 5.

[0075] In one embodiment of the invention, the planarization layer 5 has a layer thickness of 5 µm to 100 µm, preferably of 10 µm to 50 µm, and / or the at least one barrier layer 6 has a layer thickness of 100 nm to 2000 nm, or preferably of 200 nm to 800 nm.

[0076] In a further embodiment of the invention, the electrically conductive particles 9, 10 have an average diameter of 1 µm to 100 µm, preferably of 1 µm to 50 µm, and / or the average diameter of the electrically conductive particles 9, 10 is greater than the layer thickness of the planarization layer 5, preferably up to 100% greater than the layer thickness of the planarization layer 5, or preferably up to 10% greater.

[0077] In a further embodiment of the invention, the shape of the electrically conductive particles 9, 10 is spherical, angular, needle-shaped, and / or crystalline, preferably the shape of the electrically conductive particles 9, 10 is different from one another, and / or the electrically conductive particles 9, 10 are regularly or irregularly shaped, preferably as splinters, crystals or granules.

[0078] In a further embodiment of the invention, the electrically conductive particles 9, 10 are formed from conductively coated glass, preferably coated with silver, from conductive metal, preferably from nickel or an alloy thereof, or from crystallites.

[0079] In a further embodiment of the invention, a proportion of the volume of the electrically conductive particles 9, 10 in the planarization layer 5 is 10 to 30%, based on the total volume of the planarization layer 5, and / or a proportion of the surface of the electrically conductive particles 9, 10 on a side of the planarization layer 5 facing the barrier layer 6 is 10 to 50%, preferably 10 to 30%, based on the surface of the planarization layer 5, and / or the electrically conductive particles 9, 10 in the planarization layer 5 are arranged at least largely in the region of the at least one busbar 7.

[0080] In a further embodiment of the invention, the optoelectronic component 1 is an organic photovoltaic element, preferably a flexible organic photovoltaic element, wherein preferably at least one photoactive layer of the organic photovoltaic element comprises small molecules as absorber material.

[0081] The method for contacting the optoelectronic component 1, in particular a flexible optoelectronic component 1, comprises the following steps: a) Providing a substrate having a base electrode 2 arranged thereon, a layer system 4 with at least one photoactive layer, and a cover electrode 3, wherein the layer system 4 is arranged between the base electrode 2 and the cover electrode 3, b) Applying a planarization material to the base electrode 2 and / or the cover electrode 3, c) Introducing electrically conductive particles 9, 10 into and / or onto the planarization material, d) Curing the planarization material, preferably by UV radiation and / or thermal treatment, whereby a planarization layer 5 with the electrically conductive particles 9, 10 is formed, e) Applying at least one barrier layer 6 to the planarization layer 5, wherein preferably the at least one barrier layer 6 is at least partially penetrated by the electrically conductive particles 9, 10, and f) Applying at least one current collecting bar 7 to the at least one barrier layer 6,so that the base electrode 2 and / or the cover electrode 3 are electrically conductively contacted with the at least one current collecting bar 7. ,

[0082] In a further embodiment of the invention, the planarization material is applied in step b) by means of a wet coating, and / or the electrically conductive particles 9, 10 are introduced into specific regions of the planarization material in step c), preferably into regions of the planarization material with the subsequent application of the at least one busbar 7 in step f).

[0083] In a further embodiment of the invention, the electrically conductive particles 9, 10 are introduced into the planarization material in step c) by means of pressure, preferably by means of a pressure roller or, in the case of magnetic particles, by means of a magnet arranged below the optoelectronic component 1 to be contacted.

[0084] Before and / or during the application of the at least one busbar 7 to the barrier layer 6, the at least one barrier layer 6 is pierced for contacting, i.e., the barrier layer 6 is opened at the location of the electrically conductive particles 9, 10. The barrier layer 6 itself is non-conductive and covers the electrically conductive particles 9, 10 protruding from the planarization layer 5.

[0085] The process can be integrated in particular into a roll-to-roll process.

[0086] In a further embodiment of the invention, the layer system 4 has at least two photoactive layers, wherein the photovoltaic cell is a tandem cell, preferably at least three photoactive layers, wherein the photovoltaic cell is a triple cell, and / or the layer system 4 additionally has at least one charge carrier transport layer, wherein the at least one charge carrier transport layer is arranged between the base electrode 2 or the cover electrode 3 and a photoactive layer, preferably at least a first charge carrier transport layer and a second charge carrier transport layer, wherein the first charge carrier transport layer is arranged between the base electrode 2 and the at least one photoactive layer, and wherein the second charge carrier transport layer is arranged between the at least one photoactive layer and the cover electrode 3.

[0087] The schematic layer sequence of a contact structure of an optoelectronic component 1 in an embodiment ( Fig. 2) is designed as follows: On the layer system 4, which is arranged on the base electrode 2, there is a cover electrode 3. The planarization layer 5, which has electrically conductive particles 9, 10, is arranged on the cover electrode 3, wherein the planarization layer 5 has a layer thickness of 50 µm and an average diameter of the electrically conductive particles 9, 10 is greater than the layer thickness of the planarization layer 5, in this embodiment greater than 50 µm. The electrically conductive particles 9, 10 can be regularly shaped 9 or irregularly shaped 10. The electrically conductive particles 9, 10 are formed, for example, from glass particles coated with conductive silver or from conductive metal particles, in particular from nickel or an alloy thereof.The barrier layer 6, which has a layer thickness of less than 1 µm, is arranged on the planarization layer 5 with the electrically conductive particles 9, 10. The barrier layer 6 is deposited over the planarization layer 5 with the embedded electrically conductive particles 9, 10. In the present exemplary embodiment, the barrier layer 6 has a layer thickness of less than 1 µm. The barrier layer 6 is at least partially pierced by the electrically conductive particles 9, 10, so that an electrically conductive connection is formed through the barrier layer 6. A current collecting bar 7 and an adhesive layer 8 arranged thereon are arranged on the barrier layer 6. The electrically conductive contact between the cover electrode 3 and the at least one current collecting bar 7 is thus formed in particular by means of the electrically conductive particles 9, 10.In the present embodiment, the current collecting bar 7 with the adhesive layer 8 arranged thereon has a layer thickness of 35 µm.

[0088] The substrate 11 provided in step a) with the base electrode 2, the layer system 4 arranged on the base electrode 2, and the cover electrode 3 can be obtained in one embodiment as follows: After the substrate 11 has been provided, the base electrode 2 of the photovoltaic element is applied thereto and structured. The layer system 4 is then applied to the base electrode 2. The layer system 4 can be applied as a single, tandem, or multiple cell, preferably by evaporating small molecules. The layer system 4 is then structured, followed by the application of the cover electrode 3 and the final structuring.The application of the layers to a region of the base contact 3 to form the layer system 4 can be carried out at least partially by a printing process, preferably by an injector, screen printing, gravure printing, or flexographic printing process, or by evaporation of the materials to be applied. The structuring of the individual layers can be carried out, for example, by laser ablation, electron or ion beam ablation, or shadow masks.

Claims

1. Optoelectronic component (1), in particular photovoltaic element, comprising a base electrode (2), a top electrode (3) and a layer system (4) having at least one photoactive layer, the layer system (4) being disposed between the base electrode (2) and the top electrode (3), a planarization layer (5) arranged on the side of the base electrode (2) and / or top electrode (3) facing away from the layer system (4), at least one barrier layer (6) arranged on the planarization layer (5), wherein the barrier layer is not electrically conductive and formed over the entire layer system of the optoelectronic component, and at least one busbar (7), wherein the at least one busbar (7) is arranged on the at least one barrier layer (6), wherein the planarization layer (5) has electrically conductive particles (9, 10), wherein the electrically conductive particles (9, 10) being introduced into the planarization layer (5), and wherein the electrically conductive particles (9, 10) are electrically conductively bridging the planarization layer (5) through the at least one barrier layer (6) such that the base electrode (2) and / or the top electrode (3) are electrically conductively contacted with the at least one busbar (7).

2. Optoelectronic component (1) according to Claim 1, wherein the planarization layer (5) has a layer thickness from 5 µm to 100 µm, preferably from 10 µm to 50 µm, and / or the at least one barrier layer (6) has a layer thickness from 100 nm to 2000 nm, preferably from 200 nm to 800 nm.

3. Optoelectronic component (1) according to Claim 1 or 2, wherein the electrically conductive particles (9, 10) have a mean diameter from 1 µm to 100 µm, preferably from 1 µm to 50 µm, and / or the mean diameter of the electrically conductive particles (9, 10) is greater than the layer thickness of the planarization layer (5), preferably up to 100% greater than the layer thickness of the planarization layer (5), or preferably up to 10% greater.

4. Optoelectronic component (1) according to any of the preceding claims, wherein the shape of the electrically conductive particles (9, 10) is spherical, angular, acicular and / or crystalline, preferably the electrically conductive particles (9, 10) have different shapes, and / or the electrically conductive particles (9, 10) are shaped regularly or irregularly, preferably as splinters, crystals or granulate.

5. Optoelectronic component (1) according to any of the preceding claims, wherein the electrically conductive particles (9, 10) are formed from conductively coated glass, preferably silver-coated glass, from conductive metal, preferably from nickel or an alloy thereof, or from crystallites.

6. Optoelectronic component (1) according to any of the preceding claims, wherein a proportion of the volume of the electrically conductive particles (9, 10) in the planarization layer (5) is 10 to 30%, in relation to the overall volume of the planarization layer (5), and / or a proportion of the surface of the electrically conductive particles (9, 10) on a side of the planarization layer (5) facing the barrier layer (6) is 10 to 50%, preferably 10 to 30%, in relation to the surface of the planarization layer (5), and / or the electrically conductive particles (9, 10) in the planarization layer (5) are disposed in the region of the at least one busbar (7).

7. Optoelectronic component (1) according to any of the preceding claims, wherein the optoelectronic component (1) is an organic photovoltaic element, preferably a flexible organic photovoltaic element, preferably with at least one photoactive layer of the organic photovoltaic element having small molecules as absorber material.

8. Method for contacting an optoelectronic component (1) according to any of Claims 1 to 7, in particular a flexible optoelectronic component (1), comprising the following steps: a) providing a substrate with a base electrode (2) arranged thereon, a layer system (4) having at least one photoactive layer, and a top electrode (3), wherein the layer system (4) being disposed between the base electrode (2) and the top electrode (3), b) applying a planarization material on the base electrode (2) and / or the top electrode (3), c) introducing electrically conductive particles (9, 10) into and / or onto the planarization material, d) curing the planarization material, preferably by way of UV radiation and / or a thermal treatment, wherein a planarization layer (5) with the electrically conductive particles (9, 10) is formed, e) applying at least one not electrically conductive barrier layer (6) on the planarization layer (5) over the entire layer system of the optoelectronic component, wherein preferably the at least one barrier layer (6) being at least partly penetrated by the electrically conductive particles (9, 10), and f) applying at least one busbar (7) on the at least one barrier layer (6) such that the base electrode (2) and / or the top electrode (3) are electrically conductively contacted with the at least one busbar (7) by way of the electrically conductive particles (9, 10).

9. Method for contacting an optoelectronic component (1) according to Claim 8, wherein the planarization material in step b) is applied by means of a wet coating, and / or the electrically conductive particles (9, 10) are introduced into certain regions of the planarization material in step c), preferably in regions of the planarization material with a subsequent application of the at least one busbar (7) in step f).

10. Method for contacting an optoelectronic component (1) according to Claim 8 or 9, wherein the electrically conductive particles (9, 10) are introduced into the planarization material by means of pressure in step c), preferably by means of a pressure roller or, in the case of magnetic particles, by means of a magnet disposed under the optoelectronic component (1) to be contacted.