ORGANIC LIGHT EMISSING BUILDING ELEMENT

Abstract

Organic light-emitting component (100), comprising a translucent substrate (1) on which an optical output coupling layer (2) is applied, a translucent electrode (3) on the output coupling layer (2), an organic functional layer stack with organic functional layers, comprising an organic hole-conducting layer (4) on the translucent electrode (3), at least one organic light-emitting layer (5) on the hole-conducting layer (4) and an organic electron-conducting layer (6), and a reflective electrode (7), including at least one organic light-emitting layer (5) has a distance of greater than or equal to 150 nm to the reflecting electrode (7), where the organic functional layer stack at least an organic functional layer that is thicker than 5 nm and has an absorption coefficient k of less than or equal to 0.005 for wavelengths greater than 450 nm and is doped as an electron-conducting layer (6) arranged between the reflecting electrode (7) and the at least one light-emitting layer (5), where the translucent electrode (3) for wavelengths larger as 450 nm has an absorption coefficient k of less than or equal to 0.005 and a total transmission in the visible spectral range of greater than or equal to 80%, wherein the reflecting electrode (7) at least one comprising an optical matching layer, wherein the at least one optical matching layer is conductive and comprises one or more TCO layers arranged one above the other in a Bragg mirror-like arrangement, and wherein an encapsulation arrangement over the electrodes (3,7) and the organic layers (4,5) wherein the encapsulation arrangement comprises a layer sequence with a plurality of thin layers, each having a thickness between including one atomic layer and including 10 nm, wherein the thin layers are applied by means of an atomic layer deposition (ALD) process.

Description

[0001] An organic light-emitting component is specified.

[0002] In organic light-emitting diodes (OLEDs), only a portion of the generated light is directly extracted. The remaining light produced in the active region is distributed across various loss channels, including light guided by waveguiding effects in the substrate, a transparent electrode, and organic layers, as well as surface plasmons that can be generated in a metallic electrode. These waveguiding effects arise primarily from the differences in refractive index at the interfaces between the individual layers and regions of an OLED.Typically, in known OLEDs, only about a quarter of the light generated in the active region is coupled out into the surroundings, such as air, while approximately 25% of the generated light is lost to waveguides in the substrate, about 20% to waveguides in a transparent electrode and the organic layers, and about 30% to the generation of surface plasmons in a metallic electrode. The light trapped in these loss channels cannot be extracted from an OLED without additional technical measures.

[0003] To increase light extraction and thus the emitted light output, methods are known to convert the light guided in a substrate into emitted light. For this purpose, films with scattering particles or films with surface structures such as microlenses are used on the substrate's outer surface. It is also known to directly structure the substrate's outer surface or to incorporate scattering particles into the substrate itself. Some of these approaches, such as the use of scattering films, are already commercially available and can be scaled up, particularly for OLEDs used as lighting modules, with respect to the emitting area.However, these approaches to light extraction have the significant disadvantages that the extraction efficiency is limited to about 60-70% of the light guided in the substrate and that the appearance of the OLED is significantly affected, as the applied layers or films create a milky, diffusely reflective surface.

[0004] There are also known approaches for extracting light guided in organic layers or a transparent electrode. However, these approaches have not yet achieved commercial success in OLED products. For example, the publication by Y. Sun, SR Forrest, Nature Photonics 2, 483 (2008), proposes the formation of so-called "low-index grids," in which structured areas with a low-refractive-index material are deposited onto a transparent electrode. Furthermore, it is also known to deposit highly refractive scattering areas under a transparent electrode in a polymer matrix, as described, for example, in publication US 2007 / 0257608. In this case, the polymer matrix typically has a refractive index in the range of n=1.5 and is deposited using wet chemical processes.Furthermore, so-called Bragg gratings or photonic crystals with periodic scattering structures with structure sizes in the wavelength range of light are also known, as described, for example, in the publications Ziebarth et al., Adv. Funct. Mat. 14, 451 (2004) and Do et al., Adv. Mat. 15, 1214 (2003).

[0005] However, such measures cannot influence or even decouple the proportion of light generated in the active area of ​​an OLED that is converted into plasmons.

[0006] Publication WO 2006 / 129265 A2 discloses an organic electroluminescent light source.

[0007] Publication WO 2011 / 132773 A1 discloses an organic electroluminescent element and a lighting device.

[0008] Publication US 2007 / 0063628 A1 discloses an OLED component with improved light output.

[0009] Document DE 10 2010 054 893 A1 discloses a radiation-emitting organic electronic device and a method for its manufacture.

[0010] The publication Brütting et al., Europhysicsnews, 2011, 42, 4, 20-24 reveals organic light-emitting diodes.

[0011] Publication DE 10 2009 037 185 A1 discloses an organic light-emitting diode.

[0012] Document DE 10 2008 022 830 A1 discloses a radiation-emitting component.

[0013] At least one objective of certain embodiments is to provide an organic light-emitting component that exhibits improved efficiency and light extraction.

[0014] This problem is solved by the objects according to the independent claims. Advantageous embodiments and further developments of the objects are characterized in the dependent claims and are further described in the following description and drawings.

[0015] An organic light-emitting device has a translucent electrode and a reflective electrode on a substrate, between which an organic functional layer stack is arranged.

[0016] The term "translucent" here and in the following refers to a layer that is permeable to visible light. This translucent layer can be transparent, i.e., clearly see-through, or at least partially scattering and / or partially absorbing light, so that the translucent layer can also be, for example, diffusely or milkily translucent. A layer described here as translucent is particularly preferred if it is as transparent as possible, so that, in particular, the absorption of light is as low as possible.

[0017] The organic functional layer stack comprises at least one organic light-emitting layer positioned between a hole-conducting layer and an electron-conducting layer. For example, the organic hole-conducting layer can be located on the translucent electrode, above which is the at least one organic light-emitting layer, and above this, the organic electron-conducting layer. Alternatively, the organic functional layer stack can also have an inverted structure, meaning that in this case, the organic electron-conducting layer is located on the translucent electrode, followed by the at least one organic light-emitting layer, and above this, the organic hole-conducting layer.

[0018] According to a further particularly preferred embodiment, the substrate is translucent, and the translucent electrode is arranged between the translucent substrate and the organic functional stack, such that light generated in the at least one organic light-emitting layer can be emitted through the translucent electrode and the translucent substrate. Such an organic light-emitting component can also be referred to as a "bottom emitter." For example, the substrate can comprise one or more materials in the form of a layer, a plate, a film, or a laminate, selected from glass, quartz, plastic, metal, or silicon wafers. Particularly preferably, the substrate comprises or is made of glass, for example, in the form of a glass layer, glass film, or glass plate.

[0019] An optical output coupling layer is applied to the substrate, on which the translucent electrode is arranged. The optical output coupling layer can be particularly suitable and designed for so-called internal coupling, i.e., for reducing that portion of the radiant power or light generated in the light-emitting layer that is guided in organic layers and / or in the translucent electrode. The optical output coupling layer is particularly preferably made of a material with a refractive index greater than or equal to 1.6. It is particularly advantageous if the refractive index of the optical output coupling layer is greater than or equal to 1.8, and especially preferably greater than or equal to 1.85.It is particularly advantageous if the optical output coupling layer has a refractive index that is greater than or equal to a layer-thickness-weighted average refractive index of the organic functional layers and the translucent electrode.

[0020] The optical output coupling layer can, for example, comprise a so-called high-refractive-index glass, i.e., a glass with a refractive index greater than or equal to 1.8 and particularly preferably greater than or equal to 1.85, for example with a refractive index of 1.9.

[0021] Furthermore, it is also possible for the optical output layer to comprise an organic material, in particular a polymer-based material, which can be applied to the substrate using wet chemical processes, for example. For instance, the optical output layer can comprise one or more of the following materials: polycarbonate (PC), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyurethane (PU), polyacrylate, for example polymethyl methacrylate (PMMA), or epoxy.

[0022] According to another embodiment, the optical output coupling layer is light-scattering. For this purpose, the optical output coupling layer has, for example, scattering centers that are distributed throughout one of the aforementioned materials. The aforementioned materials form a matrix material in which the scattering centers are embedded. The scattering centers can be formed by regions and / or particles with a higher or lower refractive index than the matrix material. For example, the scattering centers can be formed by particles such as SiO2, TiO2, ZrO2, or Al2O3, or by pores, which can, for example, be air-filled.

[0023] The at least one organic light-emitting layer is located at a distance of 150 nm or greater than or equal to the reflecting electrode. This can particularly mean that the organic functional layers of the organic functional layer stack arranged between the at least one organic light-emitting layer and the reflecting electrode have a total thickness of 150 nm or greater. Particularly preferably, the charge carrier-conducting layer arranged between the at least one organic light-emitting layer and the reflecting electrode—that is, the electron-conducting layer or the hole-conducting layer, depending on the arrangement described above—has such a thickness.

[0024] In a particularly preferred embodiment, the organic light-emitting device comprises a translucent substrate on which an optical output coupling layer is applied, and above this, a translucent electrode and above that, an organic functional layer stack comprising an organic hole-conducting layer on the translucent electrode, at least one organic light-emitting layer on the hole-conducting layer, and above that, an organic electron-conducting layer. A reflecting electrode is arranged above this, wherein the at least one organic light-emitting layer is located at a distance of greater than or equal to 150 nm from the reflecting electrode.

[0025] In a further particularly preferred embodiment, the organic light-emitting device comprises a translucent substrate on which an optical output coupling layer is applied, and above this, a translucent electrode and above that, an organic functional layer stack comprising an organic electron-conducting layer on the translucent electrode, at least one organic light-emitting layer on the electron-conducting layer, and above that, an organic hole-conducting layer. A reflecting electrode is arranged above this, wherein the at least one organic light-emitting layer is located at a distance of greater than or equal to 150 nm from the reflecting electrode.

[0026] According to a further embodiment, no further organic light-emitting layer is arranged between the at least one organic light-emitting layer located at a distance of 150 nm or greater than or equal to the reflecting electrode and the reflecting electrode. In other words, only non-radiating organic functional layers are located between the reflecting electrode and the at least one organic light-emitting layer, specifically, depending on the arrangement described above, the hole-conducting layer or the electron-conducting layer, so that the at least one organic light-emitting layer located at a distance of 150 nm or greater than or equal to the reflecting electrode is the light-emitting layer of the organic functional layer stack closest to the reflecting electrode.The reflective electrode can also be located directly adjacent to the hole-conducting layer or the electron-conducting layer.

[0027] According to a further embodiment, the optical length between the at least one light-emitting layer and the reflecting electrode, for a wavelength of, for example, 600 nm, is greater than or equal to 1.6 times 150 nm and less than or equal to 1.8 times 225 nm. The values ​​1.6 and 1.8 correspond to a range of preferred refractive index values.

[0028] Particularly preferably, the distance between the layer emitting at least one organic light and the reflecting electrode can be greater than or equal to 180 nm and less than or equal to 225 nm.

[0029] The inventors have found that the distance described here between the at least one organic light-emitting layer and the reflecting electrode particularly advantageously reduces the relative proportion of the radiant power or light generated in the light-emitting layer that is coupled into the reflecting electrode in the form of plasmons. In particular, the inventors have found that the distance between the at least one organic light-emitting layer and the reflecting electrode can be selected such that the relative proportion of the radiant power generated in the at least one organic light-emitting layer that is coupled into the reflecting electrode in the form of plasmons, especially surface plasmons, is less than or equal to 10%.Accordingly, at such a distance, the proportion of the generated radiant power or light that is guided through the organic layers and / or the translucent electrode by waveguiding effects is increased. In contrast to plasmons, this proportion can be at least partially coupled out of the organic light-emitting device using the optical output coupling layer, so that, in the organic light-emitting device described here, it is possible to increase the light power emitted by the substrate compared to known OLEDs with a typically much smaller distance between the at least one organic light-emitting layer and the reflecting electrode.

[0030] An encapsulation arrangement is further arranged over the electrodes and the organic layers. The encapsulation arrangement can, for example, be in the form of a glass lid or, preferably, in the form of a thin-film encapsulation.

[0031] A glass lid, for example in the form of a glass substrate with a cavity, can be glued to the substrate using an adhesive layer. A moisture-absorbing material (getter), such as zeolite, can then be glued into the cavity to bind any moisture or oxygen that might penetrate the adhesive.

[0032] In this context, an encapsulation arrangement designed as a thin-film encapsulation is understood to be a device suitable for forming a barrier against atmospheric substances, in particular against moisture and oxygen, and / or against other harmful substances such as corrosive gases, for example, hydrogen sulfide. In other words, the thin-film encapsulation is designed in such a way that it can be penetrated by atmospheric substances only to a very small extent.

[0033] In thin-film encapsulation, this barrier effect is primarily achieved through thin barrier layers and / or passivation layers that are part of the encapsulation assembly. The layers of the encapsulation assembly typically have a thickness of less than or equal to a few hundred nanometers.

[0034] In particular, the thin-film encapsulation can have or consist of thin layers that are responsible for the barrier effect of the encapsulation arrangement. The thin layers are applied using an atomic layer deposition (ALD) process. Suitable materials for the layers of the encapsulation arrangement include, for example, aluminum oxide, zinc oxide, zirconium oxide, titanium oxide, hafnium oxide, lanthanum oxide, and tantalum oxide. The encapsulation arrangement has a layer sequence with a plurality of the thin layers, each with a thickness between one atomic layer and 10 nm, including the boundaries.

[0035] Alternatively or additionally to thin films produced by ALD, the encapsulation arrangement can comprise at least one or more further layers, in particular barrier layers and / or passivation layers, which are deposited by thermal evaporation or by a plasma-enhanced process, such as sputtering or plasma-enhanced chemical vapor deposition (PECVD). Suitable materials for this purpose can be the aforementioned materials as well as silicon nitride, silicon oxide, silicon oxynitride, indium tin oxide, indium zinc oxide, aluminum-doped zinc oxide, aluminum oxide, and mixtures and alloys of the aforementioned materials. The one or more further layers can, for example, each have a thickness between 1 nm and 5 µm, and preferably between 1 nm and 400 nm, including the limits of this range.

[0036] Furthermore, particularly in the case of an optical output coupling layer formed from a polymer, it is possible that an encapsulation arrangement designed as a thin-film encapsulation is formed on this layer beneath the translucent electrode. Especially in the case of a non-hermetically sealed optical output coupling layer, the organic light-emitting device can thus be sealed and encapsulated from below, i.e., beneath the translucent electrode.

[0037] The inventors have determined that the further embodiments and features described below can have a particularly advantageous effect on the efficiency and light output of the organic light-emitting component described here, in conjunction with the previously described embodiments and features, and in particular the distance described above between the at least one organic light-emitting layer and the reflecting electrode, thus increasing efficiency and light output. Therefore, the embodiments and features described here can also be understood as design rules for a particularly efficient layer architecture for the organic light-emitting component, which are particularly distinguished by their advantageous interaction.

[0038] According to a further embodiment, the translucent electrode has a refractive index that is adapted to the refractive index of the organic layers and preferably corresponds to the layer-thickness-weighted average of the refractive indices of the organic layers. The translucent electrode can, in particular, have a refractive index greater than or equal to 1.6 and, more preferably, greater than or equal to 1.7. A refractive index for the translucent electrode in the range of greater than or equal to 1.7 and less than or equal to 2.1 has also proven to be particularly advantageous.

[0039] According to a further embodiment, the translucent electrode exhibits low absorption, particularly in a spectral range above 450 nm, for example, in the visible spectral range between 450 nm and 640 nm. Particularly preferably, the translucent electrode has an absorption coefficient k of less than or equal to 0.005 in such a spectral range. In particular, the total transmission of the translucent electrode in the visible spectral range should not fall below 80% and should therefore be greater than or equal to 80%.

[0040] According to another embodiment, the translucent electrode is configured as the anode and can thus serve as the hole-injecting material. The reflective electrode is then configured as the cathode. Alternatively, the translucent electrode can also be configured as the cathode and thus serve as the electron-injecting material. The reflective electrode is then configured as the anode. The configuration of the translucent electrode and the reflective electrode as anode or cathode depends in particular on the structure of the organic functional layer stack described above.

[0041] The translucent electrode can, for example, have a transparent conductive oxide or consist of a transparent conductive 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. 12 or 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.

[0042] According to a further preferred embodiment, the translucent electrode comprises or is made of ITO. In particular, the translucent electrode can have a thickness greater than or equal to 50 nm and less than or equal to 200 nm. In such a thickness range, the transmission in the visible spectral range of the translucent electrode is greater than or equal to 80%, and the resistivity ρ is in the range of approximately 150 to 500 µΩ·cm.

[0043] According to a further embodiment, the reflective electrode comprises a metal that may be selected from aluminum, barium, indium, silver, gold, magnesium, calcium, and lithium, as well as compounds, combinations, and alloys. In particular, the reflective electrode may comprise Ag, Al, or alloys containing these, for example, Ag:Mg, Ag:Ca, Mg:Al. Alternatively or additionally, the reflective electrode may also comprise one of the aforementioned TCO materials.

[0044] Furthermore, it is also possible for the reflective electrode to have at least two or more layers and to be designed as a so-called bi-layer or multi-layer electrode. For example, the reflective electrode can have an Ag layer with a thickness of 30 nm or greater and 50 nm or less than or equal to that, facing the organic layers, on which an aluminum layer is deposited. Alternatively to metal-metal layer combinations or metal-multi-layer combinations, the reflective electrode can also have one or more TCO layers in combination with at least one metal layer. For example, the reflective electrode can have a combination of a TCO and a silver layer. It is also possible for a metal layer to be positioned between two TCO layers.In such designs, one or more of the layers can also be configured as nucleation layers.

[0045] Furthermore, it is also possible for the reflecting electrode to have additional optical matching layers for adjusting the reflectivity or the reflected spectral range. Such optical matching layers can be particularly advantageous for monochromatic organic light-emitting layers or components. An optical matching layer is conductive and comprises one or more TCO layers arranged one above the other in a Bragg mirror-like configuration.

[0046] Preferably, the reflecting electrode has a reflectivity of greater than or equal to 80% in the visible spectral range.

[0047] The reflective electrode can be produced, for example, by means of a physical vapor deposition (PVD) process, by electron beam evaporation and / or by sputtering.

[0048] The organic functional layers between the translucent electrode and the reflecting electrode, i.e., at least the hole-conducting layer, the at least one organic light-emitting layer, and the electron-conducting layer, can consist of organic polymers, organic oligomers, organic monomers, organic small non-polymeric molecules or low-molecular-weight compounds ("small molecules") or combinations thereof.

[0049] According to a further embodiment, the charge carrier-conducting layer between the at least one organic light-emitting layer and the reflecting electrode—that is, depending on the configuration of the organic functional layer stack according to the embodiments above, the electron-conducting layer or the hole-conducting layer—includes a dopant. In particular, the charge carrier-conducting layer has a thickness corresponding to the aforementioned distance. Due to the large thickness of such a charge carrier-conducting layer, the dopant advantageously increases the conductivity in order to keep the operating voltage of the organic light-emitting device low.

[0050] According to another embodiment, the hole-conducting layer comprises at least one hole injection layer, one hole transport layer, or a combination thereof. In particular, both doped layers of molecular compounds and electrically conductive polymers are suitable as hole transport and hole injection layers. For example, tertiary amines, carbazole derivatives, conductive polyaniline, or polyethylene dioxythiophene can prove advantageous as materials, especially for a hole transport layer. Furthermore, the following materials, for example, may be suitable: N,N'-Bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine (NPB), N,N'-Bis(naphthalen-2-yl)-N,N'-bis(phenyl)-benzidine (β-NPB), N,N'-Bis(3-methylphenyl)-N,N'-bis(phenyl)benzidine (TPD), N,N'-Bis(3-methylphenyl)-N,N'-bis(phenyl)-9,9-spirobifluorene (Spiro-TPD), N,N'-Bis(naphthalen-1-yl)-N,N'-bis(phenyl)-9,9-spirobifluorene (Spiro-NPB), N,N'-Bis(3-methylphenyl)-N,N'-bis(phenyl)-9,9-dimethylfluorene (DMFL-TPD), N,N'-Bis(naphthalen-1-yl)-N,N'-bis(phenyl)-9,9-dimethyl-fluorene (DMFL-NPB), N,N'-Bis-(3-methylphenyl)-N,N'-bis(phenyl)-9,9-diphenyl-fluorene (DPFL-TPD), N,N'-Bis(naphthalen-1-yl)-N,N'-bis(phenyl)-9,9-diphenyl-fluorene (DPFL-NPB), 2,2',7,7'-Tetrakis(N,N-diphenylamino)-9,9'-spirobifluorene (Spiro-TAD), 9,9-Bis[4-(N,N-bis-biphenyl-4-yl-amino)phenyl]-9H-fluorene (BPAPF), 9,9-Bis[4-(N,N-bis-naphthalen-2-yl-amino)phenyl]-9H-fluorene (NPAPF), 9,9-Bis[4-(N,N'-bis-naphthalen-2-yl-N,N'-bis-phenyl-amino)-phenyl]-9H-fluorene (NPBAPF), 2,2',7,7'-Tetrakis[N-naphthalenyl(phenyl)-amino]-9,9-spirobifluorene (Spiro-2NPB), N,N'-Bis(phenanthren-9-yl)-N,N'-bis(phenyl)-benzidine (PAPB), 2,7-Bis[N,N-bis(9,9-spiro-bifluorene-2-yl)-amino]-9,9-spirobifluorene (Spiro-S), 2,2'-Bis[N,N-bis(biphenyl-4-vl)amino] -9,9-spirobifluorene (2,2'-Spiro-DBP), 2,2'-Bis(N,N-di-phenyl-amino)-9,9-spirobifluorene (Spiro-BPA).

[0051] The dopant can be, for example, a metal oxide, a metal-organic compound, an organic material or a mixture thereof, such as WO3, MoO3, V2O5, Re2O7 and Re2O5, di-rhodium tetratrifluoroacetate (Rh2(TFA)4) or the isoelectronic ruthenium compound Ru2(TFA)2(CO)2 or an organic material that has aromatic functional groups or is an aromatic organic material, for example aromatic materials with a significant number of fluorine and / or cyanide (CN) substituents.

[0052] Low-molecular-weight compounds can be deposited, in particular, by vacuum thermal evaporation (VTE or physical vapor deposition, PVD) or from the liquid phase. Polymeric materials, for example, can be deposited from the liquid phase or formed by linking low-molecular-weight starting materials on the surface of the translucent electrode. A combination of both approaches is also possible, in which a thin layer of p-doped injection layer, 10 to 20 nm thick, is deposited onto a hole injection layer applied using a liquid process.

[0053] The perforating layer preferably has a refractive index greater than or equal to 1.6 and particularly preferably in a range greater than or equal to 1.6 and less than or equal to 1.9.

[0054] According to another embodiment, the light-emitting layer comprises an electroluminescent material and is particularly preferably designed as an electroluminescent layer or electroluminescent layer stack.Suitable materials for this purpose are those that exhibit radiation emission due to fluorescence or phosphorescence, for example, polyfluorene, polythiophene, or polyphenylene, or derivatives, compounds, mixtures, or copolymers thereof, such as 2- or 2,5-substituted polyp-phenylenevinylene, as well as 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).

[0055] Materials exhibiting both fluorescence and phosphorescence are also possible. Furthermore, the materials of the light-emitting layer can utilize singlet or triplet harvesting, a phenomenon known to those skilled in the art. Depending on the materials of the at least one organic light-emitting layer, it can produce monochromatic, bichromatic, or polychromatic light, such as white light.

[0056] According to another embodiment, the electron-conducting layer has at least one electron injection layer, one electron transport layer or a combination thereof.

[0057] The following materials, for example, may be suitable for the electron-conducting layer: 8-Hydroxyquinolinolato-lithium (Liq), 2,2',2''-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi), 2-(4-Biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), 2,9-Dimethyl-4,7-diphenyl-1,10-phenanthrolin (BCP), 4,7-Diphenyl-1,10-phenanthrolin (BPhen), Bis-(2-methyl-8-quinolinolat)-4-(phenylphenolato)aluminium (BAlq), 1,3-Bis[2-(2,2'-bipyridin-6-yl)-1,3,4-oxadiazo-5-yl]benzen (Bpy-OXD), 6,6'-Bis[5-(biphenyl-4-yl)-1,3,4-oxadiazo-2-yl]-2,2'-bipyridyl (BP-OXD-Bpy), 3-(4-Biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazol (TAZ), 4-(Naphthalen-1-yl)-3,5-diphenyl-4H-1,2,4-triazol (NTAZ), 2,9-Bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthrolin (NBphen), 2,7,-Bis[2-(2,2'-bipyridin-6-yl)-1,3,4-oxadiazo-5-yl]-9,9-dimethylfluoren (Bby-FOXD), 1,3-Bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazo-5-yl]benzen (OXD-7).

[0058] The dopant can be, for example, an alkali metal, an alkali metal salt, an alkaline earth metal salt, an organometallic compound, a molecular dopant, or a mixture thereof, such as Li, Cs3Po4, Cs2CO3, a metallocene (i.e., an organometallic compound with a metal M and two cyclopentadienyl groups (Cp) in the form M(Cp)2), or a metal-hydropyrimidopyrimidine complex. The metal can, for example, include or be tungsten, molybdenum, and / or chromium.

[0059] For example, the electron-conducting layer can include an electron transport layer comprising, for example, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) or 4,7-diphenyl-1,10-phenanthroline (BPhen). This material can preferably include a dopant selected from Li, Cs₂CO₃, Cs₃Po₄, or a molecular dopant.

[0060] In addition to the organic hole-conducting layer, the at least one organic light-emitting layer, and the organic electron-conducting layer, one or more further organic layers may be present in the organic functional layer stack. In particular, for example, a hole-blocking layer may be arranged between the electron-conducting layer and the light-emitting layer. It is also possible for an electron-blocking layer to be arranged between the hole-conducting layer and the light-emitting layer.

[0061] The inventors have found that it is particularly advantageous if the organic layers of the organic functional layer stack, especially those with a thickness of 5 nm or greater, have an absorption coefficient k of less than or equal to 0.005 in the visible spectral range, i.e., for wavelengths greater than 450 nm. This also applies in particular to the hole-conducting layer, which may, for example, have a hole transport layer with a thickness of up to 350 nm.

[0062] According to a further embodiment, a plurality of light-emitting layers are arranged between the hole-conducting layer and the electron-conducting layer, with at least one organic light-emitting layer being the primary component. The plurality of light-emitting layers can form a layer stack. Furthermore, it is also possible that an electron-conducting layer and a hole-conducting layer are arranged between adjacent light-emitting layers. In particular, the organic light-emitting device can have at least two or more functional layer stack units between the translucent electrode and the reflecting electrode, each of which comprises at least one organic electron-conducting layer and one organic hole-conducting layer with an organic light-emitting layer arranged between them.The functional layer stack units can be connected in series such that an electron-conducting layer of one stack unit borders a hole-conducting layer of an adjacent stack unit, or vice versa. Such a combination of adjacent electron- and hole-conducting layers, between which an undoped layer acting as a charge-generating zone may also be arranged, can also be referred to as a "charge generation layer" (CGL).

[0063] The at least one organic light-emitting layer, in the form of a single layer or multiple layers, can particularly preferably emit visible light in a narrow or broad wavelength range, i.e., monochromatic or multicolored, or, for example, white light. The at least one organic light-emitting layer can, in the form of a single layer or multiple layers, comprise one or more organic light-emitting materials. Multicolored or white light can be generated by combining different organic light-emitting materials within the at least one light-emitting layer.

[0064] In the case of multiple organic light-emitting layers, particularly in stacked layer units, the organic light-emitting layers can preferably be arranged in one of the following combinations: - One of the light-emitting layers emits red and green light, another light-emitting layer emits blue light. - There are at least two or three light-emitting layers present, all of which emit white light. - There are at least three light-emitting layers, one of which emits red, one yellow and one blue light. - At least three light-emitting layers are present, one of which emits red and green light, and two of which emit blue light. The blue-emitting layers, as well as the red and green-emitting layers, can be, for example, the lowest or uppermost light-emitting layers when viewed from the substrate.

[0065] The organic layers of the organic light-emitting device described here can have a total thickness of at least 250 nm according to the embodiments described above. In the case of multiple light-emitting layers, particularly in the case of several stacked functional layer units, the total thickness of the organic layers can be up to 1 µm.

[0066] In the organic light-emitting device described here, an effective suppression of the plasmon loss channel described above can be achieved by maintaining a distance of 150 nm or greater between the at least one organic light-emitting layer and the reflecting electrode. This, in particular in conjunction with the optical output coupling layer between the translucent substrate and the translucent electrode, allows for an increase in efficiency compared to known OLEDs. It is especially advantageous if the optical output coupling layer and the translucent electrode have the refractive indices mentioned above.

[0067] Further advantages, advantageous embodiments and further developments result from the exemplary embodiments described below in conjunction with the figures.

[0068] They show: Fig. 1A a schematic representation of an organic light-emitting component according to an exemplary embodiment, Fig. 1B a schematic representation of an organic light-emitting component according to a further embodiment, Fig. 2 a schematic representation of the relative proportions of output and loss channels of the radiant power generated in the active layer of a conventional OLED and Fig. 3 a schematic representation of an organic light-emitting component according to a further embodiment.

[0069] In the exemplary embodiments and figures, identical, similar, or similarly functioning elements may be designated with the same reference numerals. The depicted elements and their relative sizes are not to be considered to scale; rather, individual elements, such as layers, components, building elements, and areas, may be exaggerated for clarity and / or better understanding.

[0070] In Fig. Figure 1 shows an embodiment of an organic light-emitting device 100. This device has a substrate 1 on which an optical output coupling layer 2 is applied. A translucent electrode 3 and a reflective layer 7 are applied above the optical output coupling layer 2, and an organic functional layer stack is arranged between them, comprising organic functional layers with an organic hole-conducting layer 4, at least one organic light-emitting layer 5, and an organic electron-conducting layer 6.

[0071] The organic light-emitting component is designed as a so-called "bottom emitter" and features a translucent glass substrate. Alternatively, the substrate 1 can also be made of another translucent material, such as a plastic or a glass-plastic laminate.

[0072] For effective light extraction, the optical output coupling layer 2 has a refractive index that is greater than or equal to the layer-thickness-weighted average refractive index of the organic functional layers and the translucent electrode 3. In the illustrated embodiment, the optical output coupling layer 2 also comprises a glass, in particular a high-refractive-index glass with a refractive index of approximately 1.9. Alternatively, the optical output coupling layer 2 can also be based on a polymer material, as described above in the general section.

[0073] Furthermore, the output coupling layer 2 has scattering centers distributed throughout the glass material in the form of particles or pores that have a higher or lower refractive index than the glass material. In the case of pores, these can be air-filled, for example, while particles such as SiO2, TiO2, ZrO2, and / or Al2O3 can be used. The optical output coupling layer 2 enables at least a portion of the waveguided light from the organic light-emitting device 100 to be coupled out through the substrate 1, as described above in the general section. This occurs in the translucent electrode 3 or in the organic layers, particularly in the hole-conducting layer 4.

[0074] An encapsulation arrangement, not shown for clarity, can also be arranged over the electrodes 3, 7 and the organic layers 4, 5, 6. The encapsulation arrangement can, for example, be in the form of a glass lid or, preferably, in the form of a thin-film encapsulation, as described above in the general section.

[0075] Furthermore, particularly in the case of an optical output coupling layer 2 comprising a polymer, it may be necessary to form an encapsulation arrangement on this layer under the translucent electrode 3, designed as a thin-film encapsulation, as described above in the general section.

[0076] The translucent electrode 3 has a refractive index greater than or equal to 1.6, and preferably greater than or equal to 1.7 and less than or equal to 2.1. Furthermore, the thickness and material of the translucent electrode 3 are selected such that the absorption coefficient in a visible spectral range from 450 nm to 640 nm is less than or equal to 0.005. In particular, the transmission of the translucent electrode 3 in the visible spectral range is greater than or equal to 80%.

[0077] In the illustrated embodiment, the translucent electrode is made of indium tin oxide (ITO) with a thickness greater than or equal to 50 nm and less than or equal to 200 nm. This also ensures that the specific resistance of the translucent electrode 3 lies in the range of greater than or equal to 150 and less than or equal to 500 µΩ·cm, thereby guaranteeing a sufficiently high conductivity of the translucent electrode 3.

[0078] The hole-conducting layer 4 has at least one hole transport layer, which can have a thickness of up to 350 nm. Furthermore, the hole-conducting layer 4 can have a hole injection layer between the hole transport layer and the translucent electrode 3, which can have a thickness in the range of several tens of nanometers. Both the hole transport and the hole injection layers can be made of the materials described above in the general section, for example, small molecules or polymers.

[0079] The at least one organic light-emitting layer 5 comprises at least one organic material which, during the operation of the organic light-emitting device 100, as indicated by the schematically represented interconnection of electrodes 3 and 7, emits light in a visible wavelength range. The organic light-emitting layer 5 may comprise one or more of the materials mentioned above in the general section.

[0080] In the illustrated embodiment, the electron-conducting layer 6 is arranged directly adjacent to the reflecting electrode 7 and has a thickness of ≥ 150 nm, and preferably ≥ 180 nm. This results in a distance of ≥ 150 nm, and preferably ≥ 180 nm, between the at least one organic light-emitting layer 5 and the reflecting electrode 7. Considering the refractive indices typical of organic functional layer stacks, the optical length between the at least one light-emitting layer 5 and the reflecting electrode at a wavelength of 600 nm is preferably ≥ 1.6 × 150 nm and ≥ 1.8 × 225 nm. In particular, a distance range between 150 nm and 225 nm, and preferably between 180 nm and 220 nm, including the boundaries between these ranges, has proven to be particularly advantageous.

[0081] To ensure sufficiently high conductivity of the electron-conducting layer 6 at the aforementioned thickness, it is conductively doped. In the illustrated embodiment, the electron-conducting layer has an electron transport layer whose matrix material is BCP or BPhen, doped with Li, Cs₂CO₃, Cs₃Po₄, or via molecular doping.

[0082] Furthermore, the electron-conducting layer 6 can have an electron injection layer between the electron transport layer and the reflecting electrode 7. The aforementioned thickness of the electron-conducting layer 6 refers to the combined thickness of the electron injection layer and the electron transport layer. Additionally, at least one further organic layer, such as a hole-blocking layer, can be arranged between the organic light-emitting layer 5 and the electron-conducting layer 6. The combined thickness of all organic functional layers arranged between the organic light-emitting layer 5 and the reflecting electrode is chosen such that the distance described above between the organic light-emitting layer 5 and the reflecting electrode 7 is achieved.

[0083] In the illustrated embodiment, the reflecting electrode is made of metal and, in particular, comprises Ag, Al, or alloys such as Ag:Mg, Ag:Ca, or Mg:Al. Alternatively, the reflecting electrode 7 may also have at least two or more metal layers or one or more TCO layers in combination with one or more metal layers. For example, the reflecting electrode 7 may also have optical matching layers, such as a TCO layer stack with a Bragg mirror-like configuration, to match the reflectivity of the reflecting electrode 7 to the emission spectrum of the light-emitting layer 5. The reflecting electrode 7 has a reflectivity of greater than or equal to 80% in the visible spectral range.

[0084] It is particularly advantageous if those organic layers of the organic functional layer stack, especially those with a thickness greater than or equal to 5 nm, have an absorption coefficient k of less than or equal to 0.005 in the visible spectral range, i.e. for wavelengths greater than 450 nm.

[0085] In addition to the in Fig. In addition to the layers shown in 1A, further organic layers may be present, for example an electron-blocking layer between the light-emitting layer and the hole-conducting layer 4.

[0086] In Fig. Figure 1B shows a further embodiment of an organic light-emitting component 101, in which, compared to the previous embodiment, the order of the organic light-emitting layer stack is reversed and which has an electron-conducting layer 6 on the translucent electrode 3, at least one organic light-emitting layer 5 above it and an organic hole-conducting layer 4 above it, so that in this embodiment the hole-conducting layer 4 is arranged between the at least one organic light-emitting layer 5 and the reflecting electrode 7.

[0087] The materials of the layers of component 101 can be designed as in the previous embodiment and as described in the general section. As in the embodiment of Fig. 1A features the organic light-emitting component 101 of the Fig. 1B between the at least light-emitting layer 5 and the reflecting electrode, there is also a distance of greater than or equal to 150 nm.

[0088] The particularly large distance of greater than or equal to 150 nm between the light-emitting layer 5 and the reflecting electrode 7 described here, in the illustrated embodiments, can, together with the optical output coupling layer 2, result in a significant increase in efficiency compared to known OLEDs. This is particularly evident in connection with Fig. Figure 2, based on a simulation of a conventional green-emitting OLED on a standard glass substrate without an optical output layer or other output coupling measures, shows the relative proportions L of the output and loss channels of the light generated in the light-emitting layer as a function of the thickness D of the layer(s) arranged between the light-emitting layer and the reflecting electrode, which corresponds to the distance between the reflecting electrode and the light-emitting layer. The relative proportions of the output and loss channels shown are not to be understood as limiting to the embodiments described here and can vary depending on the structure and material selection of the individual components.

[0089] Region 21 represents the relative proportion of light coupled out from the translucent substrate. Region 22 corresponds to the relative proportion of light guided by waveguides in the glass substrate. Region 23 represents the relative proportion of light lost through absorption in the organic layers, the translucent electrode, and the substrate. Region 24 represents the relative proportion of light lost in the translucent electrode and the organic layers, for example, in the case of a layer sequence as shown in Fig. 1A, particularly in the hole-conducting layer, is guided by waveguiding effects. Region 25 represents the portion lost through the coupling of surface plasmons into the reflecting electrode.

[0090] It can be seen that the relative proportion of light coupled out of the substrate (21) increases slightly from a D value of 150 nm, while, primarily, the loss channel caused by plasmon coupling (region 25) decreases considerably with increasing D value, thereby increasing the relative proportion of light guided in the organic layers and the translucent electrode. In particular, the proportion (25) of the plasmon loss channel is less than 10% for a D value greater than or equal to 150 nm.

[0091] The additional optical output layer 2 present in the organic light-emitting devices described here allows, in particular, the dominant component of the light guided in the translucent electrode 3 and the organic layers at a distance D of greater than or equal to 150 nm between the organic light-emitting layer 5 and the reflecting electrode 7, which is guided in the translucent electrode 3 and the organic layers, to be at least partially extracted. This enables a significant increase in efficiency for the organic light-emitting devices described here through increased light extraction.

[0092] In Fig. Figure 3 shows a further embodiment of an organic light-emitting component 102, which is a modification of the embodiment of the Fig. 1A represents and, in comparison to this, has a plurality of light-emitting layers, of which layers 51 and 5n are shown for illustrative purposes, between which further light-emitting layers may be located. Each of the light-emitting layers 51, ..., 5n is arranged between a hole-conducting layer and an electron-conducting layer, as for example in Fig. 3 Light-emitting layer 51 shown between the hole-conducting layer 4 and the electron-conducting layer 61.

[0093] The organic light-emitting device 102 thus has functional stack units arranged in series between the translucent electrode 3 and the reflective electrode 7, with conductive and electron-conducting layers between adjacent holes, such as those in Fig. Three recognizable electron-conducting layers 61 and the adjacent hole-conducting layer 41, a so-called "charge generation layer" (CGL) 8, are arranged, which serves as a charge carrier pair generation zone, thereby reducing the series voltage of the organic layer stack. For example, a CGL has a p-doped and an n-doped layer, between which an undoped intermediate layer, for example of a metal oxide, is arranged.

[0094] The uppermost electron-conducting layer 6 is as in the exemplary embodiment of the Fig. 1A is arranged directly adjacent to and adjacent to the reflecting electrode 7 and has a thickness as described in connection with the preceding embodiments, such that the distance between the in Fig. 3 shown uppermost and thus closest to the reflecting electrode 7 light-emitting layer 5n and the reflecting electrode 7 is greater than or equal to 150 nm in order to suppress plasmon excitation in the reflecting electrode 7 as much as possible.

[0095] The organic layers of the embodiments shown here have a thickness of at least 250 nm for the individual functional layer stacking units, so that the stacked structure in Fig. 3 can have a total thickness of up to 1 µm. The light-emitting layers 51, ..., 5n of the stacked structure of the organic light-emitting device 102 particularly preferably emit combinations of red, green, blue, and / or white light. Particularly preferred are a structure with two light-emitting layers that emit red / green and blue or that both emit white, or a structure with three light-emitting layers that all emit white, that emit red, green, and blue, or that emit red / green, blue, and blue.

[0096] As an alternative to the layering sequence of the organic layers as described in Fig. As shown in 3, the structure of the organic layer stack of the exemplary embodiment of the Fig. 3 as in the exemplary embodiment of the Fig. 1B can also be inverted.

Claims

[1] Organic light-emitting device (100), comprising a translucent substrate (1) on which an optical output coupling layer (2) is applied, a translucent electrode (3) on the output coupling layer (2), an organic functional layer stack with organic functional layers, comprising an organic hole-conducting layer (4) on the translucent electrode (3), at least one organic light-emitting layer (5) on the hole-conducting layer (4) and an organic electron-conducting layer (6), and a reflective electrode (7), including at least one organic light-emitting layer (5) has a distance of greater than or equal to 150 nm to the reflecting electrode (7), where the organic functional layer stack at least an organic functional layer that is thicker than 5 nm and has an absorption coefficient k of less than or equal to 0.005 for wavelengths greater than 450 nm and is doped as an electron-conducting layer (6) arranged between the reflecting electrode (7) and the at least one light-emitting layer (5), where the translucent electrode (3) for wavelengths larger as 450 nm has an absorption coefficient k of less than or equal to 0.005 and a total transmission in the visible spectral range of greater than or equal to 80%, wherein the reflecting electrode (7) at least one comprising an optical matching layer, wherein the at least one optical matching layer is conductive and comprises one or more TCO layers arranged one above the other in a Bragg mirror-like arrangement, and wherein an encapsulation arrangement over the electrodes (3,7) and the organic layers (4,5) wherein the encapsulation arrangement comprises a layer sequence with a plurality of thin layers, each having a thickness between including one atomic layer and including 10 nm, wherein the thin layers are applied by means of an atomic layer deposition (ALD) process. [2] Organic light-emitting device (101) comprising a translucent substrate (1) on which an optical The coupling layer (2) is applied, a translucent electrode (3) on the output coupling layer (2), an organic functional layer stack with organic functional layers, comprising at least one organic electron-conducting layer (6) on the translucent electrode (3), at least one organic light-emitting layer (5) on the electron-conducting layer (6) and an organic hole-conducting layer (4) on the at least one organic light-emitting layer (5), and a reflective electrode (7) on the organic Holes conductive layer (4), including at least one organic light-emitting layer (5) has a distance of greater than or equal to 150 nm to the reflecting electrode (7), where the organic functional layer stack at least an organic functional layer that is thicker than 5 nm and has an absorption coefficient k of less than or equal to 0.005 for wavelengths greater than 450 nm and is doped with a hole-conducting layer (4) arranged between the reflecting electrode (7) and the at least one light-emitting layer (5), wherein the reflecting electrode (7) at least one comprising an optical matching layer, wherein the at least one optical matching layer is conductive and comprises one or more TCO layers arranged one above the other in a Bragg mirror-like arrangement, and wherein an encapsulation arrangement over the electrodes (3,7) and the organic layers (4,5) wherein the encapsulation arrangement comprises a layer sequence with a plurality of thin layers, each having a thickness between including one atomic layer and including 10 nm, wherein the thin layers are applied by means of an atomic layer deposition (ALD) process. [3] Component according to claim 1 or 2, wherein at a wavelength of 600 nm the optical length between the at least one light-emitting layer (5) and the reflecting electrode (7) is greater than or equal to 1.6·150 nm and less than or equal to 1.8·225 nm. [4] Component according to one of the preceding claims, wherein the distance between the at least one light-emitting layer (5) and the reflecting electrode (7) is greater than or equal to 180 nm and less than or equal to 225 nm. [5] Component according to one of the preceding claims, wherein the distance of the at least one light-emitting layer (5) to the reflecting electrode (7) is selected such that the relative proportion of the radiant power generated in the at least one light-emitting layer (5) which is coupled into the reflecting electrode (7) in the form of plasmons is less than or equal to 10%. [6] Component according to one of the preceding claims, wherein the at least one organic functional layer, which is thicker than 5 nm and which has an absorption coefficient k of less than or equal to 0.005 for wavelengths greater than 450 nm, is the hole-conducting layer (4) which has a hole transport layer with a thickness of up to 350 nm. [7] Component according to claim 2, wherein the translucent electrode (3) has an absorption coefficient k of less than or equal to 0.005 for wavelengths greater than 450 nm and a total transmission in the visible spectral range of greater than or equal to 80%. [8] Component according to any of the preceding claims, wherein the reflecting electrode (7) has a reflectivity of greater than or equal to 80% in the visible spectral range. [9] Component according to any of the preceding claims, wherein the optical output coupling layer (2) has a refractive index greater than or equal to a layer thickness-weighted mean refractive index of the organic functional layers and the translucent electrode (3). [10] Component according to one of the preceding claims, wherein the optical output coupling layer (2) is light scattering. [11] Component according to one of the preceding claims, wherein the optical output coupling layer (2) comprises a material with a refractive index greater than or equal to 1.8, in particular greater than or equal to 1.85, in which scattering centers are distributed. [12] Component according to one of the preceding claims, wherein the organic functional layer stack comprises at least one further organic layer selected from - a hole-blocking layer between the electron-conducting layer (6) and the at least one light-emitting layer (5), - an electron blocking layer between the hole-conducting layer (4) and the at least one light-emitting layer (5). [13] Component according to one of the preceding claims, wherein a plurality of light-emitting layers (51, 5n) are arranged between the hole-conducting layer (4) and the electron-conducting layer (6). [14] Component according to one of the preceding claims, wherein only non-radiating organic functional layers are located between the reflecting electrode (7) and the at least one organic light-emitting layer (5) and / or wherein the at least one organic light-emitting layer (5) is the light-emitting layer (5) of the organic functional layer stack closest to the reflecting electrode (7) at a distance of greater than or equal to 150 nm. [15] Component according to any of the preceding claims, wherein the translucent electrode (3) has a resistivity greater than or equal to 150 µΩ·cm and less than or equal to 500 µΩ·cm.

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