Optoelectronic component and method for its manufacture

Abstract

Including an optoelectronic component: - a substrate (1); - an anode (2) and a cathode (10) - at least one active layer arranged between the anode and the cathode (6), wherein - an amorphous dielectric layer (3) containing or consisting of a metal oxide, a metal nitride or a metal oxynitride is arranged directly on the cathode-side surface of the anode (2), wherein the metal contained in the metal oxide, metal nitride or metal oxynitride is selected from one or more of the metals of the group consisting of aluminium, gallium, titanium, zirconium, hafnium, tantalum, lanthanum and zinc, wherein a hole injection layer (4) having a thickness of less than or equal to 20 nm is arranged directly on the amorphous dielectric layer (3).

Description

[0001] The invention relates to an optoelectronic component, in particular an organic optoelectronic component, in which an amorphous dielectric layer is arranged on the anode.

[0002] The efficiency and lifespan of optoelectronic components, such as light-emitting diodes, infrared-emitting diodes, organic light-emitting diodes (OLEDs), organic solar cells or organic photodetectors with functional layers, can be greatly reduced by the occurrence of a short circuit.

[0003] Publication WO 2005 / 106987 A1 describes a layer arrangement for an organic light-emitting diode.

[0004] The publication JP 2002-208479 A describes a substrate with an intermediate resistor for an organic LED element.

[0005] Publication WO 2007 / 112038 A2 describes a composite electrode for a light-emitting device.

[0006] The publication WO 2005 / 101540 A2 describes an OLED component.

[0007] Publication WO 2008 / 140644 A1 describes an electroluminescence device.

[0008] Publication US 2008 / 0136320 A1 describes an organic electroluminescent element.

[0009] The publication Lehmbacher, Dissertation, 2004, Technical University of Munich describes metal alkoxides as precursors for metal oxides.

[0010] Document US 2008 / 100202A1 describes a method for producing a conductive protective layer for OLEDs.

[0011] The publication WO 2009 / 095006 describes a component comprising an encapsulation unit.

[0012] One object of the invention is to provide an optical component in which the susceptibility to short circuits can be reduced.

[0013] This problem is solved by an optoelectronic component and a method for its fabrication according to the independent claims. Further embodiments and developments of the optoelectronic component or the method for its fabrication are the subject of dependent claims and are further described in the following description and drawings.

[0014] An optoelectronic device according to the present invention comprises a substrate, an anode, and a cathode, and at least one active layer, e.g., an emitter layer, arranged between the anode and the cathode. Furthermore, an amorphous dielectric layer is arranged directly on the cathode-side surface of the anode. This layer contains or consists of a metal oxide, a metal nitride, and / or a metal oxynitride; the metal contained in the metal oxide, metal nitride, or metal oxynitride is selected from one or more of the metals in the group consisting of aluminum, gallium, titanium, zirconium, hafnium, tantalum, lanthanum, and zinc.

[0015] Here and in the following, a layer or element that is arranged "on" another layer or element means that the layer or element is in direct mechanical and / or electrical contact (i.e., directly) with the other layer or element. It can also mean that the layer or element is arranged indirectly on the other layer or element. In this case, further layers and / or elements may be arranged between the layer and the element.

[0016] The fact that a layer or element is arranged "between" two other layers or elements can mean, here and in the following, that the layer or element is in direct mechanical and / or electrical contact, or in indirect contact with one of the other two layers or elements, and in direct mechanical and / or electrical contact with the other layer or element. In the case of indirect contact, further layers and / or elements may be arranged between the layer and at least one of the other two layers, or between the layer and at least one of the other two elements.

[0017] An "amorphous" layer is understood to be a layer in which no sharp Bragg reflections (or signals) are obtained by X-ray diffraction (XRD). In particular, in the short-order regions of this amorphous layer, there are a maximum of four, and usually a maximum of three, parallel lattice planes. Therefore, an amorphous layer is specifically understood to be a layer in which the "crystallites" have a maximum diameter of 2.5 nm. Furthermore, an amorphous material within the meaning of the present invention is usually also characterized by the fact that the density of this amorphous material is at least ten percent, frequently at least 15 percent, and often more than 20 percent lower than that of the corresponding fully crystalline naturally occurring material (in the case of several modifications of the naturally occurring modification with the highest density). For example, corundum has a density of 3.99 g / cm³. 3and amorphous aluminium oxide according to the present inventions has a density of about 2.8 to 3.4 g / cm³ 3 , often 2.8 to 3 g / cm³ 3 The density of the amorphous layer can be determined using X-ray reflectometry (XRR).

[0018] According to the invention, an amorphous dielectric layer can also be understood to be a layer in which only the surface on one or both main sides of the layer (namely, the side of the dielectric layer facing the anode or the emitter layer) is fully amorphous in the sense of the present invention. This can be demonstrated using angle-dependent X-ray photoelectron spectroscopy (XPS) (here, too, no sharp signals are present for the near-surface regions).

[0019] The optoelectronic component with a dielectric layer according to the invention is characterized by a significantly lower frequency of short circuits and increased current efficiency due to the dielectric layer. The use of an amorphous dielectric layer has the advantage over a non-amorphous dielectric layer that grain boundaries cannot form in the layer in the vertical direction; according to the invention, it has been found that this further significantly reduces the frequency of short circuits.

[0020] If the optoelectronic component according to the invention is an organic light-emitting diode (OLED), the reduced number of short circuits can also be recognized by the appearance of the OLED. Compared to an OLED with an identical structure but lacking a dielectric amorphous layer, the OLED according to the invention has a significantly more homogeneous light pattern; the number of "black spots" is also significantly reduced compared to the reference OLEDs and is mostly zero. "Black spots" are defined here as areas visible to the naked eye (i.e., where the maximum diameter is greater than or equal to 50 µm).

[0021] The material of the amorphous dielectric layer is a metal oxide, a metal nitride, or a metal oxynitride, where the metal can be aluminum, gallium, titanium, zirconium, hafnium, tantalum, lanthanum, and / or zinc. These compounds typically have the formula M m E nwhere M is the metal, E stands for oxygen and / or nitrogen, and m and n are integers. The metal is present in oxidation states II (zinc), III (aluminum, gallium, lanthanum), IV (titanium, zirconium, hafnium), or V (tantalum); the (formal) proportion of the metal in other oxidation states is a maximum of 2 atomic percent and is usually less than 0.5 atomic percent, and often zero. The specific indices m and n are therefore derived from the oxidation state of 2 for oxygen and 3 for nitrogen; this results in (in the order of the oxidation states described above for oxides, for example, the formulas MO, M₂O₃, MO₂, and M₂O₅).The aforementioned compounds may also exhibit a certain degree of non-stoichiometry; however, (corresponding to the metal atoms in oxidation states other than those specified) the deviation from the integer index is usually a maximum of 2 percent (in the case of a compound of the type M2O5, the non-stoichiometry should therefore not be greater than that of compound M). 1,96 O5). Preferably, however, the aforementioned compounds should not exhibit any non-stoichiometry, since the dielectric constant of non-stoichiometric compounds increases compared to the corresponding stoichiometric compounds, and this increase is proportional to the degree of non-stoichiometry. Materials with higher dielectric constants are less suitable for preventing short circuits.

[0022] In one embodiment, the optoelectronic component according to the invention has a hole injection layer that is arranged directly on the dielectric layer (specifically on the side facing away from the anode) and has a thickness of, in particular, less than or equal to 5 nm. Typically, the thickness of the hole injection layer is at least 1 nm; often, the thickness of this layer is 1 to 2 nm.

[0023] Compared to identical components according to the prior art that do not have a dielectric layer, the thickness of the hole injection layer can therefore be significantly reduced. According to the invention, it has been found that the current efficiency remains essentially the same, as does the homogeneity of the luminescent pattern. According to the prior art, hole injection layers with a thickness of 400 nm or greater are frequently used to avoid short circuits. The thickness of the hole injection layer used according to the invention is therefore typically reduced by at least 90 percent, often by at least 95 percent, and frequently even by at least 97.5 percent compared to a hole injection layer in a comparable optoelectronic component according to the prior art. Thus, an enormous material saving can be achieved with such an embodiment. In addition, the overall thickness of the optoelectronic component can also be significantly reduced.

[0024] In another embodiment, the dielectric layer contained in the optoelectronic component has a thickness of 0.1 to 3 nm. A thickness of 0.1 to 1 nm, for example 0.5 to 1 nm, is usually more suitable.

[0025] A particularly thin dielectric layer generally results in better current efficiency than a thick dielectric layer, since the tunneling probability for the formed holes is then significantly higher. The luminance is also greater for very thin layers than for thick layers. Typically, the luminance of an optoelectronic device according to the invention, designed as an OLED, is at least 1000 cd / m². 2 usually even more than 3000 cd / m² 2 The luminance efficiency is [value] at a current density of 10 to 200 mA / cm². 2 Typically about 5 to 10 cd / A.

[0026] The thickness of the dielectric layer is also significantly influenced by the homogeneity of the layer thickness achievable with the application method. To ensure effective protection against short circuits, the layer should ideally cover the entire surface of the anode without gaps. Therefore, the homogeneity of the layer depends not only on the application method but also on the surface quality of the underlying anode. If this surface has pores or undercuts, a method is preferable in which the pore surface is completely covered with the dielectric layer, or the pores are filled, and no gaps occur in the dielectric layer, even in the case of undercuts.

[0027] To achieve this, layer thicknesses of 5 to 15 nm or even greater layer thicknesses may be required, depending on the method used.

[0028] In one embodiment, the dielectric layer of the optoelectronic component consists of or contains aluminium oxide.

[0029] Such a layer is particularly easy to apply, and the starting materials used are inexpensive. Furthermore, aluminum oxide has a particularly low dielectric constant.

[0030] In another embodiment, the anode comprises a transparent conductive oxide, in particular indium tin oxide. Transparent conductive oxides (TCOs) are transparent, conductive materials, usually metal oxides such as zinc oxide, tin oxide, cadmium oxide, titanium oxide, indium oxide, or indium tin oxide (ITO). Besides binary metal-oxygen compounds, such as ZnO, SnO₂, or In₂O₃, ternary metal-oxygen compounds, such as Zn₂SnO₄, CdSnO₃, ZnSnO₃, MgIn₂O₄, GaInO₃, Zn₂In₂O₅, or In₄Sn₃O₄, are also included. 12or mixtures of different transparent conductive oxides belong to the group of TCOs. Furthermore, TCOs do not necessarily have a stoichiometric composition and can also be p- or n-doped. If a TCO is used as an anode material, the dielectric layer can be applied particularly easily. In addition, if the radiation emission occurs on the anode side, a particularly high transparency of the optoelectronic component can be achieved. Alternatively, the anode can also comprise a metal, in particular a metal layer, or consist of one. The material of such an electrode can then be selected from one or more of the metals in the group consisting of aluminum, barium, indium, silver, gold, magnesium, calcium, and lithium, as well as compounds, in particular alloys, thereof.

[0031] In a further embodiment, the homogeneity of the layer thickness is independent of the surface structure of the layers directly adjacent to the dielectric layer, in particular the layer onto which the dielectric layer is applied, and especially independent of the surface structure of the anode of the optoelectronic device. The dielectric layer can therefore be designed such that it can at least partially or approximately follow the surface structure of the anode, which in particular means that the cathode-side surface of the dielectric layer partially or approximately follows the topographic structure of the interface between the dielectric layer and the anode (and the surface of the dielectric layer essentially maps the surface of the anode).

[0032] According to the invention, the fact that the cathode-side surface of the dielectric layer at least partially follows the interface between the anode and the dielectric layer, and thus the surface structure of the anode, means in particular that the cathode-side surface of the dielectric layer also has a topographic surface structure. The topographic surface structure of the cathode-side surface of the dielectric layer can, in particular, be identical or similar to the topographic surface structure of the surface of the anode facing the cathode. "Identical" or "similar" here means that the respective topographic surface structures of the sides of the anode facing the cathode and of the dielectric layer have identical or similar height profiles with corresponding structures such as elevations and depressions.For example, these topographic surface features can each exhibit laterally arranged elevations and depressions in a specific characteristic sequence, which, apart from the relative height differences of the elevations and depressions, are identical for the aforementioned topographic surface features. In other words, a surface that at least partially follows the topographic surface feature of another surface can have an elevation arranged above a elevation or a depression arranged above a depression of the topographic surface feature of the surface of the adjacent layer.The relative height difference between adjacent elevations and depressions of one surface can also differ from the relative height difference of the corresponding elevations and depressions of the topographic surface structure of the other area - but often this relative height difference is also approximately the same.

[0033] If the surface structure of the anode has pores and / or undercuts, "same" or "similar" means that the side of the dielectric layer facing the cathode need not (but may) replicate these pores and / or undercuts. As explained above, for the purposes of the present invention, it is sufficient if it is ensured that no "gaps" are formed in the dielectric layer in such structural elements and that a layer completely covering the anode is obtained.

[0034] In other words, "partially or approximately following" can mean, in particular, that the upper surface of the dielectric layer and the interface between the dielectric layer and the anode are parallel or at least approximately parallel. The dielectric layer can therefore, in particular, have a thickness that is independent or approximately independent of the surface structure of the anode.

[0035] The thickness of the dielectric layer can therefore exhibit a thickness variation of a maximum of 10 percent, often less than or equal to 5 percent, measured against the total thickness of the dielectric layer. Such a dielectric layer formation with such a small thickness variation can also be described as a so-called "conformal coating".

[0036] However, the thickness variation of the dielectric layer can naturally be greater in very thin films (especially when the layer is only up to 10 atomic layers thick, or up to 1 nm thick). For such thin films, the thickness variation is then ± 2 atomic layers (typically even ± 1 atomic layer).

[0037] Furthermore, the dielectric layer can have a thickness smaller than the dimensions of at least some structures, and in particular macroscopic structures, of the anode's surface. Macroscopic structures are defined here as surface features resolvable by visible light (and can include slopes, protrusions, angles, edges, corners, depressions, grooves, furrows, pores, and the like). Specifically, this means that structures referred to as macroscopic here have dimensions greater than or equal to approximately 400 nm. Smaller structures are referred to as microscopic structures. In particular, the dielectric layer can follow the microscopic structures of the anode's surface, the dimensions of which are larger than the thickness of the dielectric layer.

[0038] The thickness of the dielectric layer can also be independent of pores in the anode's surface facing the cathode. In particular, if the pore diameter (or, in the case of bottle-shaped pores, the smallest pore diameter) is greater than twice the dielectric layer thickness, the pore surface can be uniform and, in the above sense, at least nearly uniform in thickness, as the dielectric layer follows the surface structure of the anode. If the dielectric layer thickness is greater than half the diameter of these pores, the dielectric layer will cover the pores without following their surface structure, yet still exhibit a thickness that remains at least nearly uniform in the above sense. The average roughness R a The diameter of TCO anodes, especially ITO anodes, is typically less than or equal to 1.5 nm and is usually less than 2.5 nm.

[0039] One method that makes it possible to apply dielectric layers that obey the above-mentioned conditions is atomic layer deposition (ALD).

[0040] With this method, individual atomic layers are deposited successively, so that the thickness of the resulting layer remains essentially constant, since the deposited atomic layers (especially with a suitable choice of precursor – particularly one that is not sterically demanding) essentially completely cover the underlying atomic layer or the surface to be coated. The layers produced by ALD have the advantage that they also completely cover undercuts and pore surfaces, since layer formation is independent of the deposition direction (that is, the deposited material – or the precursor – does not impinge on the surface to be coated from a preferred direction or spatial segment – ​​as is the case, for example, with sputtering).In general, methods for applying the dielectric layer according to the invention are therefore preferred in which the layer formation in pores and undercuts is independent of the application method.

[0041] In a further embodiment, atomic layer deposition is carried out without plasma. This results in a particularly homogeneous layer thickness of the formed dielectric layer. While a reaction of the precursor with the plasma cannot be ruled out in plasma-enhanced atomic layer deposition (which can lead to a reaction in the gas phase and therefore to the formation of not completely uniform monolayers), this is not the case with plasma-free ALD. Especially at very thin layer thicknesses of 0.1 to 0.5 nm, plasma-free ALD therefore usually yields better results; as a rule, only plasma-free ALD can achieve complete coverage of the anode surface and a reasonably uniform layer thickness at such layer thicknesses.

[0042] A dielectric layer produced by atomic layer deposition (ALD) is characterized, in particular, by the fact that it is typically free or substantially free of gas inclusions. Specifically, no gas inclusions are present that can be attributed to a carrier gas used in the deposition process. Such inclusions (for example, inclusions of argon as a carrier gas) are always found in sputtering processes for layer deposition. Gas inclusions originating from the precursor material used (for example, methane) are conceivable. However, due to the successive deposition of the atomic layers, such inclusions are generally not found in plasma-free ALD. Only in plasma-assisted ALD is there a certain tendency for the formation of gas inclusions (which, however, depends on the specific deposition conditions).

[0043] Atomic layer deposition is carried out in particular as follows: A substrate with an electrode layer to be coated is first fed into a reactor in which ALD is performed. The substrate or the reactor is then subjected to an absorption pulse (process step B1). During this step, either a precursor or an oxidizing agent (or, alternatively, a reducing agent instead of an oxidizing agent) is added to the reactor.An oxidizing agent is required when oxidation of the precursor or a component of the precursor is necessary to obtain a layer of the desired composition (for example, in the production of metal oxide layers); a reducing agent is required when reduction of the precursor or a component of the precursor is necessary to obtain the layer to be formed, or when the layer to be formed contains a component "transferred to the precursor metal" (for example, a nitride component) through the reaction with the reducing agent (for example, in the formation of metal nitrides with, for example, ammonia as the precursor). The precursor or the oxidizing or reducing agent is usually supplied to the reactor in gaseous form. During the absorption pulse, the precursor or the oxidizing or reducing agent can then adsorb onto the surface to be coated.As a rule, the surface is completely or at least almost completely covered by this gaseous compound. If a precursor with particularly bulky substituents is used (for example, a metal-alkyl compound with alkyl groups of three or more carbon atoms each), complete surface coverage (which then leads to a complete atomic layer after completion of the respective ALD cycle) is not always guaranteed. It is therefore usually advantageous to use precursors with less bulky substituents, as this results in a "denser packing" in the absorbed atomic layer. The above statements regarding the precursor also apply if the precursor is added in a subsequently described reaction pulse.

[0044] Following the absorption pulse, a purging and / or evacuation step (process step B2) takes place in the reactor. This essentially removes any molecules not absorbed onto the surface to be coated from the reactor. An inert gas (for example, argon) can be used as the purging gas. The purging and / or evacuation step is typically carried out by maintaining a constant flow of purge gas through the reactor, gradually restoring the pressure conditions that existed before the adsorption pulse.

[0045] Subsequently, a reaction pulse (process step B3) is carried out in which the substrate with the absorbed precursor is exposed to an oxidizing agent (or a reducing agent), or—if the precursor is not absorbed on the substrate but rather the oxidizing agent (or the reducing agent) is exposed to a precursor. The addition of the second reaction component in the reaction pulse allows a reaction between the precursor and the oxidizing agent or the precursor and the reducing agent to occur, thereby forming a monolayer of the metal oxide, metal nitride, or metal oxynitride (the dielectric layer of the present invention). Optionally, the surface to be coated or the reactor can be heated to thermally assist the reaction of the precursor and the oxidizing or reducing agent.

[0046] After the reaction pulse has been completed, a further rinsing and / or evacuation step (process step B4) is usually carried out to remove excess molecules of the component supplied during the reaction pulse from the reactor.

[0047] To achieve the desired layer produced by ALD, the absorption pulse, rinsing / evacuation step, reaction pulse and second rinsing / evacuation step are repeated in the specified order until the desired number of atomic layers has been deposited (or the desired layer thickness has been reached).

[0048] In one embodiment, the ALD process is carried out such that the layer deposition (process step B) or the multiple repetitions of process steps B1, B2, B3, and B4 are performed at a temperature of at least 60 °C and / or a pressure of no more than 50 mbar. By selecting the process parameters in this way, it is ensured, on the one hand, that the absorption occurring in process step B2 (absorption pulse) actually results in a monolayer, and on the other hand, that a complete reaction takes place in process step B3 (reaction pulse). Furthermore, the low pressure (and optionally also the elevated temperature) ensures that the precursors or oxidizing or reducing agents used are in gaseous form.

[0049] In one embodiment, the temperature in process step B) is 80 to 260 °C. Within such a reaction range, it is ensured that no damage occurs to a more sensitive surface to be coated. If an organic layer (for example, a perforated injection layer) is used as the surface to be coated, the reaction temperature should not exceed 100 °C and is preferably 80 to 100 °C to prevent damage to this layer.

[0050] Process step B is preferably carried out at a pressure of no more than 5 mbar, usually more than 0.1 mbar. This also ensures that a particularly densely packed monolayer can be formed in the absorption pulse.

[0051] Suitable oxidizing agents include water and ozone (but also oxygen or hydrogen peroxide). These oxidizing agents can also be present in mixtures (for example, an O₂ / O₃ mixture). When using water as the oxidizing agent, the ALD process is often carried out such that water is absorbed onto the surface to be coated during the absorption pulse; the precursor (for example, trimethylaluminum) is then introduced during the reaction pulse. When using other oxidizing agents, the precursor is often adsorbed during the adsorption pulse.

[0052] In the case of water as the oxidizing agent supplied in the absorption pulse, it has been found according to the invention that a monolayer of water can also be applied directly to the surface to be coated without damaging the component or the surface itself. A prerequisite for this is that the time the water can remain on the surface to be coated before the second compound is supplied in the reaction pulse must be shorter than the diffusion time required for the water to diffuse into the layer to be coated. This can often be achieved by ensuring that process steps B1 and B2 do not last longer than 5 s (for example, not longer than 100 s). The short overall times, typically around 10–20 s for an ALD cycle, allow for a short process time and thus very high economic efficiency of the method described here.

[0053] The aforementioned oxidizing agents are used in particular for the production of metal oxides.

[0054] Ammonia is used as the reducing agent in the process according to the invention. In the absorption pulse, the precursor (for example, a metal amide) is often absorbed on the surface and reacts with the ammonia in the reaction pulse, forming a metal nitride.

[0055] In another embodiment, a metal alkyl, a metal alkoxide, a metal dialkylamide, and / or a metal halide compound is used as a precursor for the ALD process. Typically, the precursors used will only bear one type of substituent (i.e., alkyl, alkoxide, dialkylamide, or halide); however, mixed systems (which, for example, bear a halide and an alkoxide group) can also be used.

[0056] For the deposition of aluminum oxide layers, aluminum alkyl compounds (e.g., trimethylaluminium) or aluminum alkoxide compounds (e.g., aluminum ethoxide) are frequently used. For gallium oxide, gallium alkyl compounds (e.g., trimethylgallium) or gallium halides (e.g., gallium chloride) are frequently used. For titanium oxides, zirconium oxides, and hafnium oxides, metal halides (e.g., TiCl₄, ZrCl₄, or HfCl₄) or metal alkoxide compounds (e.g., Ti(OR)₄, Zr(OR)₄, or Hf(OR)₄) are frequently used. For the production of tantalum oxide, tantalum halides (e.g., tantalum chloride) are frequently used, and for lanthanum oxides, the corresponding alkoxy or halide compounds. Finally, for the production of zinc oxide layers, zinc alkyl compounds (e.g., dimethylzinc) or zinc halides (e.g., zinc chloride) are frequently used; however, zinc can also be used in elemental form.Metal nitrides are typically produced using the metal dialkylamide compounds of the corresponding elements (for example, M. k (N(CH3)2)1 - where k and 1 are integers) is used.

[0057] The deposition of an oxynitride layer can be achieved, for example, by alternately depositing nitride and oxide layers.

[0058] The substrate of the component is particularly suitable as a support element for electronic components, especially optoelectronic components. For example, the substrate can contain or consist of glass, quartz, and / or a semiconductor material. Furthermore, the substrate can contain or consist of a plastic film or a laminate with one or more plastic films. The plastic can comprise one or more polyolefins such as high-density and low-density polyethylene (PE) and polypropylene (PP). The plastic can also comprise polyvinyl chloride (PVC), polystyrene (PS), polyester, and / or preferably polycarbonate (PC), polyethylene terephthalate (PET), polyethersulfone (PES), and / or polyethylene naphthalate (PEN).

[0059] Furthermore, the substrate may contain metal, in particular a metal foil. A substrate comprising or designed as a metal foil may, for example, consist of aluminum foil, copper foil, stainless steel foil, or a combination or stack of these materials.

[0060] The substrate can consist of one or more of the above-mentioned materials and can be transparent, partially transparent, or opaque.

[0061] The optoelectronic component according to the invention can in particular comprise an organic light-emitting diode (OLED), an organic photodiode (OPD), an organic solar cell (OSC), an organic thin-film transistor (OTFT) or an integrated circuit (IC) or a plurality or combination of the aforementioned elements, or consist of only one of these elements.

[0062] The component can further comprise a functional layer sequence with at least one organic functional layer. This layer sequence is, in particular, arranged between the two electrodes.

[0063] If the device features, for example, an OLED, an OPD, and / or an OSC, the functional layer sequence can include an active region (for example, an emitter layer) that is capable of generating or detecting electromagnetic radiation during operation. Furthermore, the device often has a transparent substrate.

[0064] Furthermore, the first electrode and / or the second electrode can be transparent and, for example, contain or consist of a TCO. An electrode with such a material can, in particular, be designed as an anode, i.e., as a hole-injecting material.

[0065] Furthermore, the first and / or second electrode can comprise a metal that can serve, for example, as a cathode material, i.e., as an electron-injecting material. Aluminum, barium, indium, silver, gold, magnesium, calcium, or lithium, as well as compounds, combinations, and alloys thereof, can prove particularly advantageous as cathode materials. Alternatively or additionally, one or both electrodes can also comprise combinations, especially layer sequences of TCOs and / or metals.

[0066] The at least one functional layer can comprise an organic layer or a sequence of several organic functional layers. For example, these layers can contain organic polymers, organic oligomers, or small organic non-polymeric (monomeric) molecules ("small molecules") or combinations of these classes of compounds, or the layers can consist of these classes of compounds or mixtures thereof.

[0067] In particular, it can be advantageous if a component designed as an organic electronic device has a functional layer designed as a hole transport layer, for example in the case of an OLED to enable effective hole injection into an electroluminescent layer or electroluminescent area.

[0068] Furthermore, the active layer can be designed as an electroluminescent layer. Suitable materials for this purpose are those that exhibit radiation emission due to fluorescence or phosphorescence, whereby the layer can consist of these materials or contain the emitter materials in a matrix. Depending on the materials in this emitter layer, the generated radiation can have wavelength ranges from the ultraviolet to the red spectral range.

[0069] A component comprising one or more OLEDs can be configured, in particular, as a lighting device or as a display and have a large active luminous area. "Large area" can mean that the component has an area greater than or equal to several square millimeters, preferably greater than or equal to one square centimeter, and especially preferably greater than or equal to one square decimeter.

[0070] With such large illuminated surfaces, displays can be created that exhibit less than one black spot per square centimeter even after an operating time of 500 hours.

[0071] The aforementioned list of embodiments of the component is not to be understood as limiting. Rather, the component may include further electronic elements and / or functional layer sequences that are known to those skilled in the art and are therefore not listed here.

[0072] Further advantages and advantageous embodiments and developments of the invention will become apparent from the embodiments described below in conjunction with the figures. The Fig. 1 and Fig. Figures 2 each show schematic overviews of an embodiment of an optoelectronic component according to the present invention. Fig. 3 and the Fig. Figures 4A - 4C show schematic representations of sections of dielectric layers on an anode layer.

[0073] The Fig. Figure 1 shows the schematic structure of an organic radiation-emitting component. From bottom to top, the following layer structure is realized: At the bottom is the substrate 1, which can be transparent, for example, made of glass. On top of this is an anode layer 2, which can be, for example, a transparent conductive oxide such as indium tin oxide (ITO). Above this anode layer 2 is a dielectric layer 3, for example, made of aluminum oxide. Above this is a hole transport layer 4, which consists of, or contains, a material that can be, for example, selected from tertiary amines, carbazole derivatives, polyaniline, or polyethylene dioxythiophene. Examples include NPB (N,N'-bis(naphth-1-yl)-N,N'-bis(phenyl)benzidine) and TAPC (di-[4-(N,N-ditolyl-amino)phenyl]cyclohexane).The hole transport layer is followed by the active layer—in the case of an OLED, for example, an organic emitter layer. Such an organic emitter layer can contain or consist of an organic or organometallic compound as the emitting material. Derivatives of polyfluorene, polythiophene, and polyphenylene (e.g.,2- or 2,5-substituted poly-p-phenylenevinylene) and metal complexes, for example iridium complexes such as blue phosphorescent FIrPic (Bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)-iridium III), green phosphorescent Ir(ppy)3 (Tris(2-phenylpyridine)iridium(III)), red phosphorescent Ru(dtb-bpy)3*2(PF6) (Tris[4,4'-di-tert-butyl-(2,2')-bipyridine]ruthenium(III) complex) and blue fluorescent DPAVBi (4,4-Bis[4-(di-p-tolylamino)styryl]biphenyl), green fluorescent TTPA (9,10-Bis[N,N-di-(p-tolyl)-amino]anthracene) and red fluorescent DCM2 (4-(dicyanomethylene)-2-methyl-6-julolidyl-9-enyl-4H-pyran) as non-polymeric emitters. A cathode, for example a metal cathode or a cathode also made of a transparent conductive oxide (resulting in a top / bottom emitter), is then placed on the emitter layer.The thickness of the dielectric layer 3 can be, for example, 1.5 nm, and that of the hole injection layer 4, for example, 15 nm.

[0074] When a voltage is applied between the anode and cathode, current flows through the device, and photons are released in the organically active layer. These photons exit the device as light via the transparent anode and the substrate, or, in the case of a top / bottom emitter, also via the transparent cathode. In one embodiment, the OLED emits white light; in this case, the emitter layer contains either several emitter materials emitting different colors (for example, blue and yellow or blue, green, and red); alternatively, the emitter layer can also be composed of several sublayers, each emitting one of the aforementioned colors, with the emission of light appearing white resulting from the mixing of the different colors.Alternatively, a converter material can be arranged in the beam path of the primary emission generated by these layers, which at least partially absorbs the primary radiation and emits secondary radiation of a different wavelength, so that a white color impression results from a (not yet white) primary radiation through the combination of primary and secondary radiation.

[0075] The in Fig. The component shown in 1 can be manufactured, in particular, by first sputtering the anode onto the substrate and then applying the dielectric layer using ALD. Subsequently, the hole injection layer 4, the active layer (emitter layer) 6, and the cathode are applied.

[0076] Fig. Figure 2 shows an OLED designed as a top emitter; if the cathode 10 is transparent, it is a top / bottom emitter.

[0077] Here, a cathode 10 (which is made of a metal, for example, or—especially if a transparent electrode is desired—of a TCO) is arranged on a substrate 1 (for example, a glass substrate). An electron injection layer 9 is arranged on the cathode, and on this is an electron transport layer 8. On the electron transport layer 8 is a hole-blocking layer 7, on which the active layer (an organic emitter layer) 6 is then arranged. This emitter layer can be arranged as follows: Fig. 1 described as being trained.

[0078] On the emitter layer is a hole transport layer 5, which can, for example, comprise TPBi (2,2',2''-(1,3,5-benz-triyl)-tris(1-phenyl-1-H-benzimidazole)). On top of the hole transport layer is a thin hole injection layer 4, for example, with a thickness of 15 nm. Above the hole injection layer 4 is the dielectric layer 3 (for example, made of aluminum oxide), on which the anode (for example, formed from a TCO) is arranged.

[0079] An OLED according to Fig. For example, layer 2 can be fabricated by applying the organic layers 4 to 9 using a wet process (e.g., spin coating); this is particularly advantageous if the layers to be applied contain a polymer. Alternatively, the organic layers can also be applied by vapor deposition. For this purpose, the substrate to be coated, along with an electrode or an electrode and a dielectric layer, is placed in a receiver containing the various organic materials in different sources. To produce the individual functional layers, the organic substances are then vaporized from the respective sources and deposited onto the coated surface. Furthermore, several sources are provided for supplying one or more different matrix materials. For example, to form a hole injection layer, one source with matrix material and one source with a p-doped molecule are used.Accordingly, the emitter material and matrix material, or different emitter materials and matrix materials, are deposited together for emitter layer 6. The subsequent organic layers can then be deposited in the same way. Finally, a mixed deposition process is also possible, in which the first organic layers are applied by spin coating and the subsequent organic layers are applied by evaporation.

[0080] For the production of the component according to Fig. 2. An ITO layer can first be deposited on a substrate as a cathode (in the case of a top / bottom emitter) using RF sputtering, or an aluminum layer can be deposited using CVD (chemical vapor deposition). This aluminum layer has the advantage of being reflective, meaning that radiation emitted from the active layer, which is directed towards the substrate, is reflected by this reflective electrode and deflected towards the transparent electrode. The organic layers 9 to 4 (starting with the electron injection layer 9 and ending with the hole injection layer 4) are then deposited onto this cathode. A dielectric layer 3 (for example, made of aluminum oxide) is subsequently deposited onto the hole injection layer using ALD. To avoid damaging the already deposited organic layers, the ALD process is therefore carried out at a temperature of approximately 90 to 100 °C.Finally, the transparent anode (for example made of ITO) is applied to this dielectric layer 3 by means of sputtering.

[0081] In Fig. Figure 3 shows a section of an optoelectronic component, illustrating the situation after the dielectric layer 3 has been applied to the anode 2. As shown from Fig. As can be seen in Figure 3, the surface 21 of the anode layer 2, on which the dielectric layer 3 is applied, exhibits a surface structure in the form of roughness, which is caused, for example, by the application method used to deposit the anode layer 2. Furthermore, impurities on the surface 11 of the substrate 1 during the application of the anode layer can also cause the surface 21 of the anode layer 2 to exhibit roughness.

[0082] The dielectric layer 3 has a thickness which, purely by way of example, is indicated at two points by the reference numeral 31. As shown from Fig. As can be seen from Figure 3, the dielectric layer 3 follows the surface structure of the surface 21 of the anode layer 2 in the manner described in the general section, such that the thickness 31 of the dielectric layer 3 is almost independent of the surface structure of the anode layer 2. The thickness variation of the thickness 31 is less than 10 percent. As in Fig. As shown in Figure 3, the dielectric layer 3 is designed such that it can at least almost closely follow the microscopic structures of the surface structure 21 of the anode layer. In the Fig. Figures 4A to 4C show further sections of the surface structure of the anode layer 2 and the dielectric layer 3 of the optoelectronic device according to the invention. Various macroscopic structures are shown here as purely exemplary examples.

[0083] In Fig. In section 4A, the surface 21 of the dielectric layer 2 exhibits a depression that has a significantly greater depth compared to its diameter. The dielectric layer 3 follows the surface structure 21 of the anode layer 2 and therefore forms a continuous layer of constant thickness across the entire surface of the opening. The depth-to-diameter ratio of the depression changes accordingly.

[0084] In Fig. 4B the anode layer 2 has a surface 21 with a protruding partial area, while the anode layer 2 in Fig. 4C has a downwardly widening opening (similar to a bottle pore). Despite the negative angles for applying the dielectric layer 3 to such structures in the surface of the anode layer 2, the dielectric layer can be applied with a nearly constant thickness, as in Fig. 3 can be formed. Because the dielectric layer covers the anode evenly, homogeneously and completely, even undercuts such as in Fig. 4B or bottle-shaped pores as in Fig. 4C - ensures that electrons cannot "break through" to the anode, thereby significantly reducing the risk of short circuits.

Claims

[1] Including an optoelectronic component: - a substrate (1); - an anode (2) and a cathode (10) - at least one active layer arranged between the anode and the cathode (6), wherein - an amorphous dielectric layer (3) containing or consisting of a metal oxide, a metal nitride or a metal oxynitride is arranged directly on the cathode-side surface of the anode (2), wherein the metal contained in the metal oxide, metal nitride or metal oxynitride is selected from one or more of the metals of the group consisting of aluminium, gallium, titanium, zirconium, hafnium, tantalum, lanthanum and zinc, wherein a hole injection layer (4) having a thickness of less than or equal to 20 nm is arranged directly on the amorphous dielectric layer (3). [2] Optoelectronic device according to claim 1, wherein the amorphous dielectric layer (3) has a layer thickness between 0.1 nm and 3 nm. [3] Optoelectronic device according to one of the preceding claims, wherein the amorphous dielectric layer (3) consists of aluminium oxide. [4] Optoelectronic device according to any of the preceding claims, wherein the anode comprises a transparent conductive oxide (TCO), in particular indium tin oxide (ITO). [5] Optoelectronic device according to one of the preceding claims, wherein the homogeneity of the layer thickness of the amorphous dielectric layer (3) is independent of the surface structure of the layers directly adjacent to the dielectric layer, in particular independent of the surface structure of the anode (2). [6] Optoelectronic device according to the preceding claim, wherein the thickness variation of the amorphous dielectric layer (3) is a maximum of 10%. [7] Optoelectronic device according to one of the preceding claims, wherein the amorphous dielectric layer (3) can be produced by atomic layer deposition (ALD), in particular plasma-free atomic layer deposition. [8] Optoelectronic device according to any of the preceding claims, which is designed as an OLED. [9] A method for coating an anode of an optoelectronic device according to any of the preceding claims, wherein the optoelectronic device comprises a substrate (1), an anode (2), a cathode (10), at least one active layer (6) arranged between the anode and the cathode, and an amorphous dielectric layer (3) directly on the cathode-side surface of the anode (2), which contains or consists of a metal oxide, a metal nitride, or a metal oxynitride, wherein the metal contained in the metal oxide, metal nitride, or metal oxynitride is selected from one or more of the metals in the group consisting of aluminum, gallium, titanium, zirconium, hafnium, tantalum, lanthanum, and zinc, comprising the following steps: A) Provision of a substrate with an electrode layer arranged on it B) Deposition of the dielectric layer by means of atomic layer deposition (ALD) such that the electrode layer is completely covered with the dielectric layer, wherein a hole injection layer (4) with a thickness of less than or equal to 20 nm is arranged directly on the amorphous dielectric layer (3). [10] Method according to the preceding claim, wherein step B) is carried out by plasma-free atomic layer deposition (ALD). [11] Method according to one of the two preceding claims, wherein during step B) the following partial steps are repeated several times in succession in the specified order: B1) Adsorption pulse in which the substrate is exposed to a precursor or an oxidizing or reducing agent; B2) Flushing step or evacuation step; B3) Reaction pulse in which the substrate with the adsorbed precursor is exposed to an oxidizing agent or reducing agent, or the substrate with the adsorbed oxidizing agent or reducing agent is exposed to a precursor; B4) Flushing step or evacuation step. [12] Method according to one of the three preceding claims, wherein step B) is carried out at a temperature of at least 60 °C, in particular 80 °C to 260 °C, and a pressure of at most 50 mbar, in particular 0.1 mbar to 5 mbar. [13] A method according to any one of the four preceding claims, wherein the oxidizing agent is selected from the group consisting of water, ozone, oxygen, hydrogen peroxide and mixtures of the aforementioned substances. [14] Method according to any one of the five preceding claims, wherein the precursor is a metal alkyl, a metal alkoxide, a metal dialkylamide and / or a metal halide.

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