Organic light-emitting device

Abstract

Organic light-emitting device comprising: (i) an anode; (ii) a cathode; (iii) at least one light-emitting layer arranged between the anode and the cathode; (iv) a first hole-injecting layer comprising a first hole-injecting compound, wherein the first hole-injecting layer is arranged between the anode and the light-emitting layer and the hole-injecting layer is adjacent to the anode; (v) a first hole-transporting layer comprising a first hole-transporting matrix compound, wherein the first hole-transporting layer is arranged between the first hole-injecting layer and the light-emitting layer and adjacent to the first hole-injecting layer;(vi) a second hole injection layer arranged between the first hole transport layer and the light emission layer, wherein the second hole injection layer is adjacent to the first hole transport layer and wherein the second hole injection layer comprises a second hole-injecting compound; wherein the second hole-injecting compound is a halogenated fullerene of the formula CxFy, where x is an even integer from 60 to 120 and y is from x / 2 to 4x / 5; wherein the first hole injection layer comprises a second hole-transporting matrix compound;wherein the organic light-emitting device further comprises a second hole transport layer arranged between the second hole injection layer and the light emission layer, wherein the second hole transport layer is adjacent to the second hole injection layer and wherein the second hole transport layer comprises a fourth hole-transporting matrix compound, wherein the second hole-transporting matrix compound and the fourth hole-transporting matrix compound each have a redox potential of the HTL matrix / HTL matrix cation residue redox couple, measured by cyclic voltammetry against a ferrocene / ferrocenium redox couple as a reference, of 0.0 to 1.0 V.

Description

[0001] The present invention relates to an organic light-emitting device which is optimized with respect to the electronic properties of its layer structure. TECHNICAL BACKGROUND

[0002] Organic light-emitting diodes (OLEDs), which are self-emitting devices, have a wide viewing angle, excellent contrast, fast response time, high brightness, outstanding operating voltage characteristics, and color rendering. A typical OLED comprises an anode, a high-hole transport layer (HTL), an emissive layer (EML), an electron transport layer (ETL), and a cathode, which are stacked sequentially on a substrate. In this context, the HTL, EML, and ETL are thin films made of organic and / or organometallic compounds.

[0003] When a voltage is applied to the anode and cathode, holes injected from the anode electrode move through the high-temperature transducer (HTL) into the electron microlead (EML), and electrons injected from the cathode electrode move into the EML via the electron microlead (ETL). The holes and electrons recombine in the EML to generate excitons. When the excitons decay from an excited state to a ground state, light is emitted. The injection and flux of holes and electrons must be balanced so that an OLED with the structure described above exhibits excellent efficiency.

[0004] Organic light-emitting devices can include hole-injection layers and / or p-doped hole-transport layers, which utilize compounds with (on an absolute energy scale that conventionally sets the vacuum energy level to zero) the energy level of their lowest unoccupied molecular orbital (LUMO) approximately 3 eV below the vacuum level or lower. Known compounds in this context are low-molecular-weight organic compounds comprising one or (preferably) several nitrile functional groups. These materials are represented, for example, by hexacyanohexaazatriphenylene (CNHAT) or by the following compounds, which have become a kind of industrial standard.

[0005] As shown in application US 2014 / 001444 A1, it may be advantageous that instead of and / or in addition to a first hole injection layer, which is usually arranged adjacent to the anode, the electroluminescent device comprises a second hole injection layer which is arranged between the anode and the emission layer, wherein the second hole injection layer is not adjacent to the anode.

[0006] However, there remains a need to improve the performance of organic light-emitting devices with the aim of keeping the operating voltage as low as possible while maximizing the efficiency of the device.

[0007] It is therefore the object of the present invention to provide an organic light-emitting device which overcomes the disadvantages of the prior art, in particular an organic light-emitting device which has an improved operating voltage and / or efficiency. SUMMARY OF THE INVENTION

[0008] The above problem is solved by an organic light-emitting device comprising: (i) an anode; (ii) a cathode; (iii) at least one light-emitting layer arranged between the anode and the cathode; (iv) optionally a first hole-injecting layer comprising a first hole-injecting compound, wherein the first hole-injecting layer is arranged between the anode and the light-emitting layer and is adjacent to the anode; (v) a first hole-transporting layer comprising a first hole-transporting matrix compound, wherein the first hole-transporting layer is arranged a) between the first hole-injecting layer and the light-emitting layer and adjacent to the first hole-injecting layer; or b) between the anode and the light-emitting layer and adjacent to the anode;(vi) a second hole injection layer arranged between the first hole transport layer and the light emission layer, wherein the second hole injection layer is adjacent to the first hole transport layer and wherein the second hole injection layer comprises a second hole-injecting compound; wherein the second hole-injecting compound is a fullerene, a partially or fully halogenated metal complex or a mixture thereof.

[0009] Surprisingly, the inventors discovered that an organic light-emitting device according to the invention, comprising halogenated fullerenes and / or partially or fully halogenated metal complexes in its second hole-injection layer (as defined herein), exhibits improved properties, in particular a lower operating voltage or higher efficiency. Furthermore, the inventors found that the aforementioned compounds provide greater design freedom in the manufacture of organic light-emitting devices.

[0010] A fullerene is an allotrope of carbon in the form of a hollow sphere, ellipsoid, tube, and many other shapes. Fullerenes are structurally similar to graphite. Unless they are cylindrical, they must also contain pentagonal (or sometimes heptagonal) rings. According to the present invention, a halogenated fullerene is a fullerene derivative obtained by adding an odd number of halogen atoms to a fullerene, e.g., a compound with the general formula C x X y , where x is an integer equal to or greater than 60, y is an integer less than x, and each X is independently selected from F, Cl, Br, and I.

[0011] According to the present invention, the "metal complex" can be an organometallic complex, e.g., a complex comprising at least one organic ligand, e.g., a group capable of forming a dative bond and further comprising at least one hydrocarbyl group, wherein the atom capable of forming a dative bond provides the dative bond (= coordinate covalent bond or coordinate bond) to the at least one metal ion included in the metal complex. The metal complex according to the invention may consist of a central atom or ion, which is the so-called coordination center. The coordination center is surrounded by bound molecules or ions (preferably organic molecules or ions), which in turn are known as ligands or complexing agents.According to the present invention, a partially halogenated metal complex can be a metal complex comprising such organic ligands, wherein at least one, but not all, of the hydrogen atoms included therein are substituted by halogen atoms. Likewise, a fully halogenated metal complex can be a metal complex comprising such hydrocabyl-containing ligands, wherein all hydrogen atoms in the ligands are replaced by halogen atoms.

[0012] In the light-emitting device according to the invention, the first hole-injection layer can further comprise a second hole-transporting matrix compound. In this way, further advantages can be achieved with regard to the operating voltage and / or efficiency of the device.

[0013] In the organic light-emitting device according to the invention, the second hole-injection layer can further comprise a third hole-transporting matrix compound. In this way, further advantages can be achieved with regard to the operating voltage and / or efficiency of the device.

[0014] The organic light-emitting device can further comprise a second hole transport layer arranged between the second hole injection layer and the light emission layer, wherein the second hole transport layer is adjacent to the second hole injection layer and wherein the second hole transport layer comprises a fourth hole-transporting matrix compound. In this way, further advantages with respect to the operating voltage and / or efficiency of the device can be achieved.

[0015] According to the present invention, a halogenated compound can be a fluorinated compound; for example, a partially halogenated compound can be a partially fluorinated compound, and a fully halogenated compound can be a fully fluorinated compound. This means that the halogenated fullerene can be a fluorinated fullerene, the partially halogenated metal complex can be a partially fluorinated metal complex, and the fully halogenated metal complex can be a fully fluorinated metal complex. In this way, further advantages can be achieved with regard to the operating voltage and / or efficiency of the device.

[0016] In the organic light-emitting device, the halogenated fullerene can have the formula C x F yhave, where x is an even integer from 60 to 120 and y is an even integer from x / 2 to 4x / 5. In this way, further advantages can be achieved with regard to the operating voltage and / or efficiency of the device.

[0017] In this context, it may be stipulated that x is 60, e.g., that the halogenated fullerene is a halogenated C 60 Fullerene (a fullerene with 60 carbon atoms) is used. This allows for further advantages regarding the operating voltage and / or efficiency of the device.

[0018] The halogenated fullerene can also be given the formula C 60 F 48 have. In this way, further advantages can be achieved with regard to the operating voltage and / or efficiency of the device.

[0019] The partially or fully halogenated metal complex can have the formula (I) where Mx is an x-valent cation of a metal selected from alkali metals, alkaline earth metals, rare earth metals and Al, Ga, In, Sn, Pb, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Zn and Cd; x 1 is for M selected from alkali metals; 2 for M selected from alkaline earth metals, Pb, Mn, Fe, Co, Ni, Zn and Cd; 2 or 3 for M selected from rare earth metals; 3 for Al, Ga, In; 2, 3 or 4 for Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W; and 2 or 4 for Sn; B1 and B2 are each independently selected from partially or fully halogenated C3- to C 20 -Alkyl, C3- to C 20 -Cycloalkyl or C3- to C 20 -Arylalkyl. In this way, further advantages can be achieved with regard to the operating voltage and / or efficiency of the device.

[0020] In this context, M can be selected from Mg, Mn, and Zn, and x can be 2. This allows for further advantages regarding the operating voltage and / or efficiency of the device.

[0021] In this context, it may be provided that the compound according to formula (I), e.g. the partially or fully halogenated metal complex, may be selected from compounds (II) and (III).

[0022] In this way, further advantages can be achieved with regard to the operating voltage and / or efficiency of the device.

[0023] Further examples of partially or fully halogenated metal complexes suitable for the present invention can be found in the most recently published applications WO 2018 / 150048 A1, WO 2018 / 150049 A1, WO 2018 / 150050 A1 and WO 2018 / 150051 A1.

[0024] The light emission layer in the organic light-emitting device according to the present invention can comprise a phosphorescent emitter, or alternatively a green phosphorescent emitter.

[0025] The organic light-emitting device may further comprise at least one additional layer selected from the group consisting of an electron transport layer, a hole-blocking layer and an electron injection layer.

[0026] The anode of the organic light-emitting device according to the present invention can be a transparent conductive oxide (TCO) anode.

[0027] In this context, the transparent conductive oxide can be indium tin oxide (ITO), indium zinc oxide (IZO), aluminum zinc oxide (ALZO), or a mixture of two or more of these.

[0028] The cathode of the organic light-emitting device according to the present invention can be a reflective cathode and / or a semi-transparent cathode.

[0029] In this context, the cathode can comprise an elemental metal. The elemental metal that can be included in the cathode of the light-emitting device according to the present invention can be selected from the group consisting of aluminum (Al), silver (Ag), magnesium (Mg), and a mixture of two or more thereof.

[0030] In the organic light-emitting device according to the present invention, the electron transport layer and / or the electron injection layer can comprise an n-doped molecule.

[0031] The n-doping agent, which may be included in the electron transport layer and / or the electron-injecting layer of the light-emitting device according to the present invention, may be selected from the group consisting of metal salts, metal complexes, elemental metal, and reducing organic groups. Exemplary suitable compounds are listed below. FURTHER LAYERS

[0032] The organic light-emitting device according to the invention comprises a plurality of different layers which are stacked together to form the essential functional part of the organic light-emitting device. Further details regarding the respective layers and areas of the organic light-emitting device according to the present invention are provided below. electron transport region

[0033] An electron transport region of the stack of organic layers that form the organic light-emitting device can be arranged on the emission layer.

[0034] The electron transport region of the stack of organic layers contains at least the first electron transport layer and optionally a second electron transport layer. The electron transport region of the stack of organic layers may also contain an electron injection layer.

[0035] For example, the electron transport region of the stack of organic layers can have a first electron transport layer / electron injection layer structure, or alternatively, a first electron transport layer / second electron transport layer / electron injection layer, but is not limited to this. For example, an organic light-emitting diode according to one embodiment of the present invention contains at least one electron transport layer, and in this case, the electron transport layer comprising the electrical p-doper and the at least one first electron-transporting matrix compound is defined as the first electron transport layer.In another embodiment, the organic light-emitting diode can comprise at least two electron transport layers in the electron transport region of the stack of organic layers, and in this case, the electron transport layer that contacts the emission layer is defined as the second electron transport layer.

[0036] The electron transport layer can contain one, two, or more different electron-transporting matrix compounds.

[0037] The thickness of the first electron transport layer can range from approximately 2 nm to approximately 100 nm, for example, from approximately 3 nm to approximately 30 nm. If the thickness of the first electron transport layer is within this range, the first electron transport layer can exhibit improved auxiliary electron transport properties without a substantial increase in the operating voltage.

[0038] The thickness of the optional second electron transport layer can be approximately 10 nm to approximately 100 nm, for example, approximately 15 nm to approximately 50 nm. If the thickness of the electron transport layer is within this range, the electron transport layer can have satisfactory electron-transporting properties without a substantial increase in the operating voltage. First electron-transporting matrix compound

[0039] The first electron-transporting matrix is ​​not particularly restricted. Similar to other materials which are enclosed outside the emission layer in the device according to the invention, the electron-transporting matrix can be non-light-emitting.

[0040] According to one embodiment, the first electron-transporting matrix can be an organic compound, an organometallic compound, or a metal complex.

[0041] According to one embodiment, the first electron-transporting matrix can be a covalent compound comprising a conjugated system of at least six delocalized electrons. A covalent material, in the broadest possible sense, can be understood as a material in which at least 50% of all chemical bonds are covalent bonds, with coordination bonds also being considered covalent bonds. In the present application, the term in its broadest sense encompasses all common electron-transporting matrices, predominantly selected from organic compounds, but also, for example, from compounds comprising structural units that do not include carbon, such as substituted 2,4,6-tribor-1,3,5-triazines, or from metal complexes, such as aluminum tris(8-hydroxyquinolinolate).

[0042] The molecular covalent materials can comprise low molecular weight compounds, which are preferably stable enough to be processed by thermal vacuum evaporation (VTE). Alternatively, covalent materials can comprise polymeric covalent compounds, preferably compounds that are soluble in a solvent and thus processable in solution. It should be noted that a polymeric, essentially covalent material can be crosslinked to form an infinite, irregular network; however, it is assumed that such a crosslinked polymeric, essentially covalent matrix compound comprises both skeletal and peripheral atoms. Skeletal atoms of the covalent compound are covalently bonded to at least two neighboring atoms. Other atoms of the covalent compound are peripheral atoms, which are covalently bonded to a single neighboring atom.Inorganic infinite crystals or fully cross-linked networks with partial covalent bonding but essentially no peripheral atoms, such as silicon, germanium, gallium arsenide, indium phosphide, zinc sulfide, silicate glass, etc., are not considered covalent matrices for the purposes of this application, since such fully cross-linked covalent materials only contain peripheral atoms on the surface of the phase formed by that material. A compound comprising cations and anions is still considered covalent if at least the cation or at least the anion contains at least ten covalently bonded atoms.

[0043] Preferred examples of covalent first electron-transporting matrix compounds are organic compounds consisting mainly of covalently bonded C, H, O, N, S, which optionally also include covalently bonded B, P, As, Se, In. In one embodiment, the first electron-transporting matrix compound lacks metal atoms, and the majority of its framework atoms are selected from C, O, S, N.

[0044] In another embodiment, the first electron-transporting matrix compound comprises a conjugated system of at least six, preferably at least ten, more preferably at least fourteen delocalized electrons.

[0045] Examples of conjugated systems of delocalized electrons are systems of alternating pi and sigma bonds. Optionally, one or more diatomic structural units, which have the pi bond between their atoms, can be replaced by an atom carrying at least one lone pair of electrons, usually a divalent atom selected from O, S, Se, Te, or a trivalent atom selected from N, P, As, Sb, Bi. Preferably, the conjugated system of delocalized electrons comprises at least one aromatic or heteroaromatic ring that satisfies Hückel's rule. The first electron-transporting matrix compound also preferably comprises at least two aromatic or heteroaromatic rings, which are either covalently bonded or condensed.

[0046] In one particular embodiment, the first electron-transporting matrix compound comprises a ring consisting of covalently bonded atoms and at least one atom in the ring is phosphorus.

[0047] In a preferred embodiment, the phosphorus-containing ring consisting of covalently bonded atoms is a phosphepin ring.

[0048] In another preferred embodiment, the first electron-transporting compound comprises a phosphine oxide group. Also preferably, the first electron-transporting matrix compound comprises a heterocyclic ring comprising at least one nitrogen atom. Examples of nitrogen-containing heterocyclic compounds, which are particularly advantageous as first electron-transporting matrix compounds for the device according to the invention, are matrices comprising, individually or in combination, pyridine structural units, diazine structural units, triazine structural units, quinoline structural units, benzoquinoline structural units, quinazoline structural units, acridine structural units, benzacridine structural units, dibenzacridine structural units, diazole structural units, and benzodiazole structural units.

[0049] The first electron-transporting matrix compound can have a molecular weight (Mw) of ≥400 to ≤ 850 g / mol, preferably ≥450 to ≤ 830 g / mol. If the molecular weight is selected within this range, particularly reproducible evaporation and coating in a vacuum can be achieved at temperatures for which good long-term stability is observed.

[0050] Preferably, the first electron-transporting matrix compound can be essentially non-emitting.

[0051] In another embodiment, the first electron-transporting matrix compound can have a dipole moment greater than 2.3 Debye, calculated by using the hybrid-functional B3LYP with a Gaussian 6-31G* basis, as implemented in the TURBOMOLE V6.5 program package for the low-energy conformer found using the TURBOMOLE V6.5 program package with the hybrid-functional B3LYP and a Gaussian 6-31G* basis. This can be a preferred embodiment in conjunction with redox dopants selected from elemental metals.

[0052] According to another aspect of the invention, the reduction potential of the first electron-transporting matrix compound, when measured under the same conditions by cyclic voltammetry against Fc / Fc+ in tetrahydrofuran, can have a value that is less negative than the value obtained for triphenylphosphine oxide and more negative than the value obtained for tetrakis(quinoxalin-5-yloxy)zirconium.

[0053] Under these conditions, the redox potential of triphenylphosphine oxide is approximately -3.06 V and the reduction potential of tetrakis(quinoxalin-5-yloxy)zirconium is approximately -1.78 V.

[0054] According to a further aspect of the invention, the redox potential of the first electron-transporting matrix compound, when measured under the same conditions by cyclic voltammetry against Fc / Fc+ in tetrahydrofuran, can have a value that is less negative than the corresponding value obtained for triphenylphosphine oxide, preferably less negative than the corresponding value for bis(4-(9-H-carbazol-9-yl)phenyl)-(phenyl)phosphine oxide, more preferably less negative than the corresponding value for 3-([1,1'-Biphenyl]-4-yl)-5-(4-(tertbutly)phenyl)-4-phenyl-4H-1,2,4-triazole, even more preferably less negative than the corresponding value for pyrene, most preferably less negative than the corresponding value for 2,7-dipyrenyl-9,9-spirobifluorene, also preferably less negative than the corresponding value for 2,4,7,9-tetraphenyl-1,10-phenanthroline, and also preferably less negative than the corresponding value for 7-([1,1'-Biphenyl]-4-yl)dibenzo[c,h]acridine,preferably less negative than the value for 2,4,6-triphenyltriazine, and even more preferably less negative than the corresponding value for 2,4,6-tri(biphenyl-4-yl)-1,3,5-triazine.

[0055] According to a further aspect of the invention, the redox potential of the first electron-transporting matrix compound, when measured under the same conditions by cyclic voltammetry against Fc / Fc+ in tetrahydrofuran, can have a value that is more negative than the corresponding value obtained for tetrakis(quinoxalin-5-yloxy)zirconium, preferably more negative than the corresponding value for 4,4'-Bis(4,6-diphenyl-1,3,5-triazine-2-yl)-1,1'-biphenyl, and most preferably more negative than the corresponding value for 2,4,6-Tri(biphenyl-4-yl)-1,3,5-triazine.

[0056] The redox potential can be determined at room temperature using the following standard procedures with cyclic voltammetry using the Metrohm PGSTAT30 potentiostatic device and AutolabGPES software. The redox potentials given for specific compounds were measured in an argon-vented, dry 0.1 M THF solution of the tested substance, with 0.1 M tetrabutylated ammonium hexafluorophosphate conducting salt, between platinum working electrodes and with an Ag / AgCl pseudostandard electrode (Metrohm silver rod electrode), consisting of a silver wire coated with silver chloride and immersed directly in the measured solution at a feed rate of 100 mV / s. The first run was performed in the broadest range of the potential set on the working electrodes, and the range was subsequently adjusted accordingly in the following runs.The last three runs were performed with the addition of ferrocene (0.1 M concentration) as a standard. The mean values ​​of the potentials corresponding to the cathodic and anodic peaks of the investigated compound, after subtracting the mean values ​​of the cathodic and anodic potentials observed for the standard Fc / Fc+ redox couple, ultimately yielded the values ​​given above. All investigated compounds and the given comparison examples showed well-defined, reversible electrochemical behavior.

[0057] Examples of electron transport layers and suitable electron-transporting matrix compounds can be found, for example, in the most recently published application WO 2018 / 138373 A1.

[0058] According to various embodiments of the electroluminescent device, the first electron transport layer comprises approximately ≤ 100 wt.% to approximately ≥ wt.% 30, preferably ≤ 95 wt.% to approximately ≥ 40 wt.%, of a matrix compound, based on the total weight of the first electron transport layer.

[0059] Preferably, the first electron-transporting matrix compound can be essentially non-emitting. Second electron transport matrix

[0060] The second electron-transporting compound is not particularly restricted. Similar to other materials which are enclosed outside the emission layer in the device according to the invention, the second electron-transporting matrix cannot be light-emitting.

[0061] According to one embodiment, the second electron-transporting matrix compound can be an organic compound, an organometallic compound, or a metal complex.

[0062] Compounds listed as examples of the first electron-transporting matrix compound can also be used as the second electron-transporting matrix compound.

[0063] According to one embodiment, the device additionally comprises a second electron transport layer, which includes at least one electron-transporting matrix compound selected from covalent compounds, comprising a conjugated system of at least 6 delocalized electrons, preferably from organic compounds comprising at least one aromatic ring, more preferably from organic compounds comprising at least two aromatic rings, more preferably from organic compounds comprising at least three aromatic rings, and most preferably from organic compounds comprising at least four aromatic rings;The second electron transport layer is arranged between the first electron transport layer and the light emission layer; preferably, the second hole transport layer is formed from the second electron-transporting matrix compound, and furthermore, the second electron transport layer is arranged adjacent to the first electron transport layer and / or the light emission layer.

[0064] According to one embodiment, the second electron-transporting matrix compound can be a polyvalent compound comprising a conjugated system of at least 6 delocalized electrons.

[0065] In one embodiment, the dipole moment of the second electron-transporting matrix compound is selected from ≥ 0.5 Debye and ≤ 4.5 Debye, preferably ≥ 1.0 Debye and ≤ 4.0 Debye, more preferably ≥ 1.5 Debye and ≤ 3.5 Debye.

[0066] According to another aspect of the invention, the redox potential of the second electron-transporting matrix compound can be selected to be less negative than -2.35 V and more negative than -2.14 V, preferably less negative than -2.3 V and more negative than -2.16 V, more preferably less negative than -2.25 V and more negative than -2.16 V, measured against Fc / Fc+ in tetrahydrofuran. Redox n-Dotan

[0067] A redox n-dot is a compound which, when embedded in an electron-transporting matrix, increases the concentration of free electrons compared to the pure matrix under the same physical conditions, as measured by cyclic voltammetry against a ferrocene / ferrocenium reference redox couple.

[0068] Under the operating conditions of an electroluminescent device, such as an OLED, the redox n-doped compound may not emit light. In one embodiment, the redox n-doped compound is selected from an elemental metal, an electrically neutral metal complex, and / or an electrically neutral organic radical.

[0069] The best practical measure of the strength of an n-doped molecule is the value of its redox potential. There are no particular restrictions on how negative the value of the redox potential can be.

[0070] Since the redox potentials of common electron transport matrices used in organic light-emitting diodes, when measured by cyclic voltammetry against a ferrocene / ferrocenium reference redox couple, are approximately in the range of -1.8 V to -3.1 V, the practically applicable range of redox potentials for n-doped matrices that can effectively n-dope such matrices is in a slightly broader range, approximately -1.7 V to -3.3 V.

[0071] The measurement of the redox potentials is practically carried out for a corresponding redox couple, which consists of the reduced and the oxidized form of the same compound.

[0072] In the event that the redox n-doping agent is an electrically neutral metal complex and / or an electrically neutral organic residue, the measurement of its redox potential is actually carried out for the redox couple formed by (i) the electrically neutral metal complex and its cation residue formed by abstraction of an electron from the electrically neutral metal complex, or (ii) the electrically neutral organic residue and its cation, formed by abstraction of an electron from the electrically neutral organic radical.

[0073] Preferably, the redox potential of the electrically neutral metal complex and / or the electrically neutral organic radical can have a value that is more negative than -1.7 V, preferably more negative than -1.9 V, more preferably more negative than -2.1 V, even more preferably more negative than -2.3 V, and best of all more negative than -2.5 V, as measured by cyclic voltammetry against a ferrocene / ferrocenium reference redox couple for a corresponding redox couple consisting of (i) the electrically neutral metal complex and its cation residue formed by abstraction of an electron from the electrically neutral metal complex, or (ii) the electrically neutral organic radical and its cation, formed by abstraction of an electron from the electrically neutral organic radical.

[0074] In a preferred embodiment, the redox potential of the n-doping agent is between the value which is about 0.5 V more positive and the value which is about 0.5 V more negative than the value of the reduction potential for the selected electron-transporting matrix.

[0075] Electrically neutral metal complexes suitable as redox n-dotandes can be, for example, strongly reducing complexes of some transition metals in low oxidation states. In particular, strong redox n-dotandes can be selected, for example, from Cr(II), Mo(II) and / or W(II) guanidinate complexes such as W2(hpp)4, as described in more detail in WO2005 / 086251.

[0076] Electrically neutral organic residues suitable as redox n-doping agents can be, for example, organic residues formed from their stable dimers, oligomers, or polymers by the addition of energy, as described in more detail in EP 1 837 926 B1, WO2007 / 107306, or WO2007 / 107356. Specific examples of such suitable residues include diazolyl, oxazolyl, and / or thiazolyl residues.

[0077] An elemental metal is understood to be a metal in a state of pure metal, a metal alloy, or in a state of free metal atoms or metal clusters. It is understood that metals deposited by thermal vacuum evaporation evaporate from a metallic phase, for example, from a pure, solid metal, in their elemental form. Furthermore, it is understood that if the evaporated elemental metal is deposited with a covalent matrix, the metal atoms and / or clusters are embedded in the covalent matrix. In other words, it is understood that a metal-doped covalent material produced by thermal vacuum evaporation contains the metal, at least partially, in its elemental form.

[0078] For use in consumer electronics, only metals with stable radionuclides or nuclides with very long half-lives of radioactive decay are suitable. The nuclear stability of natural potassium can be considered an acceptable measure of this stability.

[0079] In one embodiment, the n-doping agent is selected from electropositive metals, specifically alkali metals, alkaline earth metals, and less frequently, earth metals and metals of the first transition period, namely Ti, V, Cr, and Mn. Preferably, the n-doping agent is selected from Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Sm, Eu, Tm, and Yb; more preferably from Li, Na, K, Rb, Cs, Mg, and Yb; even more preferably from Li, Na, Cs, and Yb; and most preferably from Li, Na, and Yb.

[0080] The redox dopant can be essentially non-emitting. Hole injection layer

[0081] The organic light-emitting device according to the invention can comprise one or more hole-injection layers. In the case that the hole-injection layer is arranged between the first hole-transport layer and the light-emission layer, this hole-transport layer is the "second hole-injection layer" within the meaning of the present invention and comprises the second hole-injecting compound, e.g., a halogenated fullerene, a partially or fully halogenated metal complex, or a mixture thereof, as defined herein.

[0082] The organic light-emitting device according to the invention can comprise one or more further hole injection layers in addition to the second hole injection layer, for example a first hole injection layer as defined herein, which is adjacent to the anode. Unless otherwise stated (particularly with regard to the second hole injection layer), the hole injection layer can have the properties listed below and can comprise the materials listed below to form it.

[0083] The hole injection layer can improve the interfacial properties between the anode and an organic material used for hole transport. Applied to a non-planarized anode, it planarizes the anode surface. For example, the hole injection layer can contain a material that sets a median energy level for its highest occupied molecular orbital (HOMO) between the work function of the anode material and the energy level of the HOMO in the hole transport layer, thus achieving a difference between the anode's work function and the HOMO's energy level.

[0084] If the hole-transporting area contains a hole injection layer 36, the hole injection layer on the anode can be formed by a variety of processes, for example vacuum deposition, spin coating, casting, Langmuir-Blodgett (LB) process or the like.

[0085] When the hole injection layer is formed using vacuum deposition, the vacuum deposition conditions can vary depending on the material used to form the hole injection layer and the desired structure and thermal properties of the hole injection layer to be formed. For example, vacuum deposition can be carried out at a temperature of about 100 °C to about 500 °C, a pressure of about 10-6 Pa to about 10-1 Pa, and a deposition rate of about 0.1 to about 10 nm / sec, but the deposition conditions are not limited to these.

[0086] When the injection layer is formed using spin coating, the spin coating conditions can vary depending on the material used to form the injection layer and the desired structure and thermal properties of the resulting layer. For example, the coating rate can range from approximately 2000 rpm to approximately 5000 rpm, and the temperature at which heat treatment is performed to remove a solvent after coating can range from approximately 80 °C to approximately 200 °C, but the coating conditions are not limited to these.

[0087] Examples of hole-transporting matrix materials suitable for the present invention can be found, for example, in WO 2013 / 135237 A1, WO 2014 / 060526 A1 or WO 2015 / 158886 A1 and in documents cited therein, or in the most recently published applications WO2018 / 150006 A1, WO 2018 / 150048 A1, WO 2018 / 150049 A1, WO 2018 / 150050 A1 and WO 2018 / 150051 A1. Hole transport layer

[0088] Conditions for the formation of the hole transport layer and the electron blocking layer can be defined based on the formation conditions for the hole injection layer described above.

[0089] The thickness of the hole-transporting portion of the charge-transporting region can range from approximately 10 nm to approximately 1000 nm, for example, approximately 10 nm to approximately 100 nm. If the hole-transporting portion of the charge-transporting region includes the hole injection layer and the hole transport layer, the thickness of the hole injection layer can range from approximately 10 nm to approximately 1000 nm, for example, approximately 10 nm to approximately 100 nm, and the thickness of the hole transport layer can range from approximately 5 nm to approximately 200 nm, for example, approximately 10 nm to approximately 150 nm. If the thicknesses of the hole-transporting portion of the charge-transporting region, the HIL, and the HTL are within these ranges, satisfactory hole-transporting properties can be achieved without a significant increase in the operating voltage.

[0090] The hole-transporting matrix materials used in the hole-transporting region are not particularly limited. Covalent compounds comprising a conjugated system of at least six delocalized electrons are preferred; organic compounds comprising at least one aromatic ring are preferred; organic compounds comprising at least two aromatic rings are preferred; organic compounds comprising at least three aromatic rings are preferred; and organic compounds comprising at least four aromatic rings are preferred. Typical examples of hole-transporting matrix materials widely used in hole-transport layers are polycyclic aromatic hydrocarbons, triarylamine compounds, and heterocyclic aromatic compounds.Suitable ranges of the frontier orbital energy levels of hole-transporting matrices, which are useful in different layers of the hole-transporting region, are known. With respect to the redox potential of the redox couple HTL matrix / cation residue of the HTL matrix, the preferred values ​​(measured by cyclic voltammetry against a ferrocene / ferrocenium redox couple as a reference) can be in the range of 0.0–1.0 V, preferably in the range of 0.2–0.7 V, and even more preferably in the range of 0.3–0.5 V.

[0091] Examples of hole-transporting matrix materials suitable for the present invention can be found, for example, in WO 2013 / 135237 A1, WO 2014 / 060526 A1 or WO 2015 / 158886 A1 and in documents cited therein or in the most recently published applications WO 2018 / 150006 A1, WO 2018 / 150048 A1, WO 2018 / 150049 A1, WO 2018 / 150050 A1 and WO 2018 / 150051 A1.

[0092] The hole-transporting region of the stack of organic layers should further include an electronic p-doping agent to improve conductivity and / or hole injection from the anode, in addition to the materials as described above. Electrical p-dot

[0093] The charge-generating material can be distributed homogeneously or inhomogeneously in the first hole transport layer.

[0094] The electronic p-doper can be, but is not limited to, a compound containing a quinone derivative, a radial compound, a metal oxide, and a cyanogroup. Non-restrictive examples of the p-doper include quinone derivatives such as tetracyanoquinonimethane (TCNQ), 2,3,5,6-tetrafluorotetracyano-1,4-benzoquinonimethane (F4-TCNQ); radial compounds such as PD-2 and the like; metal oxides such as tungsten oxide, molybdenum oxide, and the like; and cyano-containing compounds such as the compound HT-D1 below. Buffer layer

[0095] The hole-transporting part of the load-transporting area may also contain a buffer layer.

[0096] Buffer layers that can be used appropriately are disclosed in US 6140763, US 6614176 and in US2016 / 248022.

[0097] The buffer layer can compensate for an optical resonance distance of the light corresponding to a wavelength of the light emitted from the EML and can thus increase efficiency. Emission layer

[0098] The emission layer (EML) can be formed on the hole-transporting region by vacuum deposition, spin coating, casting, LB processes, or similar methods. When the emission layer is formed by vacuum deposition or spin coating, the deposition and coating conditions can be similar to those used for the formation of the hole injection layer, although the specific conditions may vary depending on the material used to form the emission layer. The emission layer can contain an emitter host (EML host) and an emitter dot (hereinafter referred to as the emitter).

[0099] The emitter can be a red, green, or blue emitter.

[0100] In one embodiment, the emitter host material is a polar emitter host compound. Preferably, the emitter host material can be a polar emitter host compound exhibiting a gas-phase dipole moment in the range of approximately ≥ 0.2 Debye to approximately ≤ 2.0 Debye, calculated using the B3LYP hybrid functionality with a Gaussian 6-31G* base set, as implemented in the TURBOMOLE V6.5 program package for the lowest-energy conformer of the TURBOMOLE V6.5 program package using the B3LYP hybrid functionality with a Gaussian 6-31G* base set.

[0101] In one embodiment, the emitter host material is a polar emitter host compound which has at least 3 aromatic rings, each of which is independently selected from carbocyclic rings and heterocyclic rings.

[0102] In a preferred embodiment, the emitter host material can be a polar emitter host compound with at least 3 aromatic rings, each independently selected from carbocyclic and heterocyclic rings, exhibiting a gas-phase dipole moment in the range of approximately ≥ 0.2 Debye to approximately ≤ 2.0 Debye, calculated using the B3LYP hybrid functionality with a Gaussian 6-31G* base set, as implemented in the TURBOMOLE V6.5 program package for the lowest-energy conformer of the TURBOMOLE V6.5 program package using the B3LYP hybrid functionality with a Gaussian 6-31G* base set.

[0103] In one embodiment, the emitter host material is a polar emitter host compound, represented by the chemical formula 1: where A1 is selected from the group consisting of a substituted or unsubstituted C6- to C6o-aryl or a C6- to C6o-heteroaryl; A2 is selected from the group consisting of a substituted or unsubstituted C1 to C10 alkyl group or a substituted or unsubstituted C6 to C60 aryl or C6 to C60 heteroaryl; A3 is selected from the group consisting of a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C6 to C6o aryl or C6 to C6o heteroaryl; A4 selected from the group consists of a substituted or unsubstituted C6- to C6o-aryl or C6- to C6o-heteroaryl, preferably a C6- to C6o-heteroaryl. Emitterwirt

[0104] The polar emitter host compound has at least 3 aromatic rings, each of which is independently selected from carbocyclic and heterocyclic rings.

[0105] The polar emitter host compound can exhibit a gas-phase dipole moment in the range of approximately ≥ 0.2 Debye to approximately ≤ 2.0 Debye, calculated using the hybrid functionality B3LYP with a Gaussian 6-31G* base set, as implemented in the TURBOMOLE V6.5 program package for the lowest energy conformer of the TURBOMOLE V6.5 program package using the hybrid functionality B3LYP with a Gaussian 6-31G* base set.

[0106] According to one embodiment of the electroluminescent device, the polar emitter host compound has at least three aromatic rings, each independently selected from carbocyclic and heterocyclic rings, and can exhibit a gas-phase dipole moment in the range of approximately ≥ 0.2 Debye to approximately ≤ 2.0 Debye, calculated using the B3LYP hybrid functionality with a Gaussian 6-31G* base set, as implemented in the TURBOMOLE V6.5 program package for the lowest-energy conformer of the TURBOMOLE V6.5 program package using the B3LYP hybrid functionality with a Gaussian 6-31G* base set.

[0107] According to another embodiment, the emitter-host compound can have a gas-phase dipole moment in the range of approximately ≥ 0.3 Debye to approximately ≤ 1.8 Debye, preferably in the range of approximately ≥ 0.5 Debye to approximately ≤ 1.6 Debye, more preferably in the range of approximately ≥ 0.6 Debye to approximately ≤ 1.4 Debye, and most preferably in the range of approximately ≥ 0.7 Debye to approximately ≤ 1.3 Debye, calculated using the B3LYP hybrid functionality with a Gaussian 6-31G* base set, as implemented in the TURBOMOLE V6.5 program package for the lowest-energy conformer of the TURBOMOLE V6.5 program package using the B3LYP hybrid functionality with a Gaussian 6-31G* base set.

[0108] The dipole moment |µ → The number of atoms in a molecule containing N atoms is given by: μ → = ∑ i N q i r → l | μ → | = μ x 2 + μ y 2 + μ z 2 <?page 15=""?> where q i and d r → l The partial charge and position of atom i in the molecule are.

[0109] The partial charges and atomic positions are calculated for the lowest-energy conformation of the ground state of a molecule in a gas phase using a standardized procedure, employing the B3LYP hybrid functionality with a Gaussian 6-31G* basis set, as implemented in the TURBOMOLE V6.5 software package. If more than one conformation is allowed, the energies of the possible conformations are first calculated using the B3LYP hybrid functionality with a Gaussian 6-31G* basis set, as implemented in the TURBOMOLE V6.5 software package, and the conformation with the lowest total energy is selected to determine the dipole moment.

[0110] The dipole moments and redox potentials of compounds that may be suitable as second electron transport matrix compounds can be found in the recently published application WO 2018 / 138373 A1.According to a further aspect of the invention, the emitter host has a redox potential which, measured under the same conditions by cyclic voltammetry against Fc / Fc+ in tetrahydrofuran, is more negative than the respective value for 7-([1,1'-Biphenyl]-4-yl)dibenzo[c,h]acridine, preferably more negative than the respective value for 9,9',10,10'-tetraphenyl-2,2'-bianthracene, more preferably more negative than the respective value for 2,9-Di([1,1'-Biphenyl]-4-yl)-4,7-Diphenyl-1,10-phenanthroline, even more preferably more negative than the respective value for 2,4,7,9-tetraphenyl-1,10-phenanthroline, even more preferably more negative than the respective value for 9,10-Di(naphthalene-2-yl)-2-phenylanthracene, even more preferably more negative than the respective Value for 2,9-bis(2-methoxyphenyl)-4,7-diphenyl-1,10-phenanthroline, preferably more negative than the respective value for 9,9'-spirobi[fluorene]-2,7-diylbis(diphenylphosphine oxide).

[0111] The emitter is mixed in a small quantity to cause light emission. The emitter can be, for example, an inorganic, organic, or organometallic compound, and one or more types of these can be used.

[0112] The emitter can be a fluorescent emitter; e.g., ter-fluorine, 4,4'-bis(4-diphenylaminostyryl)biphenyl (DPAVBi), 2,5,8,11-tetra-tert-butylperylene (TBPe) and compound 4 below are examples of fluorescent blue emitters. Connection 4

[0113] The thickness of the emission layer can range from approximately 10 nm to approximately 100 nm, for example, from approximately 20 nm to approximately 60 nm. If the thickness of the emission layer is within this range, the emission layer can exhibit improved emissive properties without a substantial increase in operating voltage. Electron-injecting layer

[0114] According to another aspect of the invention, the organic electroluminescent device may further comprise an electron injection layer between the first electron transport layer and the cathode.

[0115] The electron injection layer (EIL) can enable the injection of electrons from the cathode.

[0116] According to another aspect of the invention, the electron injection layer comprises: (i) an electropositive metal selected from alkali metals, alkaline earth metals and rare earth metals in substantially elemental form, preferably selected from Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Eu and Yb, more preferably from Li, Na, Mg, Ca, Sr and Yb, even more preferably from Li and Yb, most preferably Yb; ​​and / or (ii) an alkali metal complex and / or alkali metal salt, preferably the lithium complex and / or salt, more preferably a lithium quinolinolate, more preferably a lithium 8-hydroxyquinolinolate, most preferably the alkali metal salt and / or complex being identical to the alkali metal salt and / or complex of the injection layer.

[0117] The electron injection layer can contain at least one selected from LiF, NaCl, CsF, Li20 and BaO.

[0118] The thickness of the electron injection layer (EIL) can range from approximately 0.1 nm to approximately 10 nm or approximately 0.3 nm to approximately 9 nm. If the thickness of the EIL is within this range, the EIL can exhibit satisfactory electron-injecting properties without a substantial increase in the operating voltage. cathode

[0119] A cathode material can be a metal, an alloy, or an electrically conductive compound with a low work function, or a combination thereof. Specific examples of cathode materials include lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium indium (Mg-In), magnesium silver (Mg-Ag), and so on. To create a peak emission light-emitting device that has a reflective anode deposited on a substrate, the cathode can be a transparent electrode form, such as indium tin oxide (ITO) or indium zinc oxide (IZO).

[0120] In devices comprising a transparent metal oxide cathode or a reflective metal cathode, the cathode can have a thickness of about 50 nm to about 100 nm, with semi-transparent metal cathodes being about 5 nm to about 15 nm thin. anode

[0121] The anode material can be a metal or a metal oxide, or an organic material, preferably a material with a work function above about 4.8 eV, more preferably above about 5.1 eV, and most preferably above about 5.3 eV. Preferred metals are noble metals such as Pt, Au, or Ag; preferred metal oxides are transparent metal oxides such as ITO or IZO, which can be advantageously used in bottom-emitting OLEDs with a reflective cathode.

[0122] In devices comprising a transparent metal oxide anode or a reflective metal anode, the anode may have a thickness of about 50 nm to about 100 nm, while semi-transparent metal anodes may be thin, from about 5 nm to about 15 nm. Organic light-emitting diode (OLED)

[0123] According to one aspect of the present invention, an organic light-emitting diode (OLED) is provided, comprising: a substrate, an anode electrode formed on the substrate, optionally a first hole injection layer, a hole transport layer, a second hole injection layer, an emission layer and a cathode electrode.

[0124] According to another aspect of the present invention, an OLED is provided which comprises: a substrate; an anode electrode formed on the substrate, optionally a first hole injection layer, a hole transport layer, a second hole injection layer, an electron blocking layer, an emission layer, a hole blocking layer, an electron transport layer and a cathode electrode.

[0125] According to another aspect of the present invention, an OLED is provided which comprises: a substrate; an anode electrode formed on the substrate, optionally a first hole injection layer, a hole transport layer, a second hole injection layer, an electron blocking layer, an emission layer, an electron transport layer, an electron injection layer and a cathode electrode.

[0126] According to another aspect of the present invention, an OLED is provided comprising a substrate; an anode electrode formed on the substrate; optionally a first hole injection layer, a hole transport layer, a second hole injection layer, an electron-blocking layer, a hole-blocking layer, an emission layer, a hole-blocking layer, an electron transport layer, and a cathode electrode.

[0127] According to different embodiments of the present invention, OLEDs can be provided which comprise layers arranged between the layers described above, on the substrate or on the top electrode.

[0128] According to one aspect, the OLED can comprise a layered substrate structure, which is arranged adjacent to an anode electrode, the anode electrode is arranged adjacent to an (optional) first hole injection layer, the first hole injection layer is arranged adjacent to a first hole transport layer, the first hole transport layer is arranged adjacent to a second hole injection layer, the second hole injection layer is arranged adjacent to a first electron blocking layer, the first electron blocking layer is arranged adjacent to a first emission layer, the first emission layer is arranged adjacent to a first electron transport layer, the first electron transport layer is arranged adjacent to an n-charge generating layer, the n-charge generating layer is arranged adjacent to a hole generating layer, the hole generating layer is arranged adjacent to a second hole transport layer.the second hole transport layer is arranged adjacent to a second electron-blocking layer, the second electron-blocking layer is arranged adjacent to a second emission layer, and an optional electron transport layer and / or an optional third injecting layer are arranged between the second emission layer and the cathode electrode.

[0129] For example, OLED ( 100 ) according to Fig. 2 are formed by a process in which an anode ( 110 ), a first hole injection layer ( 120 ), a hole transport layer ( 130 ), a second hole injection layer ( 140 ), an electron-blocking layer ( 145 ), an emission layer ( 150 ), a hole-blocking layer ( 155 ), an electron transport layer ( 160 ), an electron injection layer ( 180 ) and the cathode electrode ( 190) are formed successively on a substrate (not shown). Details and definitions of the invention

[0130] In the organic light-emitting device according to the invention, the second hole-injecting layer comprises a second hole-injecting compound. In this context, it is possible for the second hole-injecting layer to consist of the second hole-injecting compound. It is also possible for the second hole-injecting compound to be embedded in a matrix material, i.e., for the matrix material to be the predominant material in such a layer.

[0131] The term ‘hydrocarbyl group’ used herein encompasses any organic group with carbon atoms, in particular organic groups such as alkyl, aryl, heteroaryl, heteroalkyl, especially those groups which are common substituents in organic electronics.

[0132] The term "alkyl" as used here encompasses linear, branched, and cyclic alkyl. For example, C3 alkyl can be selected from n-propyl and isopropyl. Similarly, C4 alkyl includes n-butyl, sec-butyl, and t-butyl. Likewise, C6 alkyl includes n-hexyl and cyclo-hexyl.

[0133] The subscript n in C n refers to the total number of carbon atoms in the respective alkyl, arylene, heteroarylene or aryl group.

[0134] The term "aryl" as used herein encompasses phenyl (C6-aryl), condensed aromatics such as naphthalene, anthracene, phenanthrene, tetracene, etc. It also includes biphenyl and oligo- or polyphenyls such as terphenyl, etc. Furthermore, it includes all other aromatic hydrocarbon substituents such as fluorenyl, etc. Arylene or heteroarylene refers to groups to which two other units are bonded.

[0135] The term “heteroaryl” used here refers to aryl groups in which at least one carbon atom is substituted by a heteroatom, preferably selected from N, O, S, B or Si.

[0136] The term "halogenated" refers to an organic compound in which one hydrogen atom has been replaced by a halogen atom. The term "perhalogenated" refers to an organic compound in which all hydrogen atoms have been replaced by halogen atoms. The meaning of the terms "fluorinated" and "perfluorinated" is analogous.

[0137] The subscript n in C n -Heteroaryl refers only to the number of carbon atoms, without considering the number of heteroatoms. In this context, it is clear that a C3 heteroaryl group is an aromatic compound comprising three carbon atoms, such as pyrazole, imidazole, oxazole, thiazole, and the like.

[0138] For the purposes of the invention, the term "between" in relation to a layer located between two other layers does not preclude the presence of further layers that may be arranged between that layer and either of the other two layers. For the purposes of the invention, the term "in direct contact" in relation to two layers that are in direct contact with each other means that no further layer is arranged between these two layers. A layer deposited on the top surface of another layer is considered to be in direct contact with that layer.

[0139] In the context of this description, the term "essentially non-emitting" or "non-emitting" means that the contribution of the compound or layer to the visible emission spectrum of the device is less than 10%, preferably less than 5%, based on the visible emission spectrum. The visible emission spectrum is an emission spectrum with a wavelength of approximately ≥ 380 nm to approximately ≤ 780 nm.

[0140] Preferably, the layer comprising the second hole-injecting compound is substantially non-emitting or non-emitting.

[0141] With regard to the organic light-emitting device according to the invention, the compounds mentioned in the experimental section are most preferred.

[0142] According to a further aspect, the organic electroluminescent device according to the present invention can comprise more than one emission layer, preferably two or three emission layers. An OLED comprising more than one emission layer is also referred to as a tandem OLED or stacked OLED.

[0143] The organic electroluminescent device (OLED) can be a device that emits light from the bottom or the top.

[0144] Another aspect focuses on a device comprising at least one organic electroluminescent device (OLED). A device comprising organic light-emitting diodes is, for example, a display or a lighting panel.

[0145] In the present invention, these definitions of the following defined terms shall apply unless a different definition is given in the claims or elsewhere in this description.

[0146] In the context of this description, the term “different” or “distinguishes” in relation to the matrix material means that the matrix material differs in its structural formula.

[0147] The energy levels of the most occupied molecular orbital, also called HOMO, and the lowest unoccupied molecular orbital, also called LUMO, are measured in electron volts (eV).

[0148] The terms "OLED" and "organic light-emitting diode" are used interchangeably and have the same meaning. The term "organic electroluminescent device" used here can encompass both organic light-emitting diodes and organic light-emitting transistors (OLETs).

[0149] As used herein, “weight percent”, “wt%”, wt%, “weight percent”, “weight percent”, “weight percent”, and variations thereof refer to a composition, component, substance, or agent as the weight of that component, substance, or agent of the respective electron transport layer divided by the total weight of that component, substance, or agent of the respective electron transport layer and multiplied by 100. It is understood that the total weight percentage of all components, substances, and agents of the respective electron transport layer and electron injection layer is chosen such that it does not exceed 100 wt%.

[0150] As used herein, “volumetric percent”, “volumetric percent”, “volumetric percent”, “volumetric percent”, “volumetric percent”, and variations thereof refer to a composition, component, substance, or agent as the volume of that component, substance, or agent of the respective electron transport layer divided by the total volume of that electron transport layer thereof, multiplied by 100. It is understood that the total percentage volume fraction of all components, substances, and agents of the cathode layer is chosen such that it does not exceed 100 vol%.

[0151] All numerical values ​​herein are deemed to be modified by the term "approximately," whether explicitly stated or not. As used herein, the term "approximately" refers to the variation in numerical magnitude that may occur. Regardless of whether the claims are modified by the term "approximately" or not, they include equivalents of the quantities.

[0152] It should be noted that, as used in this description and the attached claims, the singular forms “ein”, “eine” and “der / die / das” include multiple references unless the content clearly specifies otherwise.

[0153] The terms "free from", "do not contain", and "do not include" do not exclude impurities. Impurities have no technical effect on the object achieved by the present invention. List of characters

[0154] These and / or other aspects and advantages of the present invention will be evident and easier to recognize from the following description of the exemplary embodiments, which are taken in conjunction with the accompanying drawings: Fig. Figure 1 is a schematic sectional view of an organic light-emitting diode (OLED) according to an exemplary embodiment of the present invention; Fig. Figure 2 is a schematic sectional view of an OLED according to an exemplary embodiment of the present invention. Fig. Figure 3 is a schematic sectional view of a tandem OLED with a charge generation layer according to an exemplary embodiment of the present invention. FORM OF EXECUTION OF THE DEVICE ACCORDING TO THE INVENTION

[0155] Detailed reference is now made to the exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings, where identical reference numerals consistently refer to the same elements. The exemplary embodiments are described below in order to explain the aspects of the present invention with reference to the figures.

[0156] In this context, when a first element is described as formed or placed "on" a second element, the first element can be placed directly on top of the second element, or one or more other elements can be placed between them. When a first element is described as formed or placed "directly" on top of a second element, no other elements are placed between them.

[0157] Fig. Figure 1 is a schematic cross-sectional view of an organic light-emitting diode (OLED) 100 according to an exemplary embodiment of the present invention. The OLED 100 includes an anode 110 , a first hole injection layer ( HIL ) 120 , a first hole transport layer (HTL) 130 , a second hole injection layer 140 , an emission layer (EML) 150 and an electron transport layer (ETL) 160. The electron transport layer (ETL) 160directly on the EML 150 formed. On the electron transport layer (ETL) 160 is an electron injection layer ( EIL ) 180 arranged. The cathode 190 is directly on the electron injection layer ( EIL ) 180 arranged.

[0158] Instead of a single electron transport layer 160 Optionally, an electron transport layer stack (ETL) can be used.

[0159] Fig. 2 is a schematic cross-sectional view of an OLED 100 , according to a further exemplary embodiment of the present invention. Fig. 2 differs from Fig. 1 because the OLED 100 from Fig. 2 a second hole transport layer 145 and a hole-blocking layer ( HBL ) 155 includes.

[0160] With reference to Fig. 2 includes the OLED 100 an anode110 , a first hole injection layer ( HIL ) 120 , a first hole transport layer (HTL) 130 , a second hole injection layer 140 , a second hole transport layer 145 , an emission layer (EML) 150 , a hole-blocking layer ( HBL ) 155 , an electron transport layer (ETL) 160 , an electron injection layer( EIL ) 180 and a cathode electrode 190 .

[0161] Fig. Figure 3 is a schematic sectional view of a tandem OLED. 200 , according to a further exemplary embodiment of the present invention. Fig. 3 differs from Fig. 2 because the OLED 100 from Fig. 3 further comprises a charge-generating layer and a second emission layer.

[0162] With reference to Fig. 3, includes the OLED 200 an anode 110, a first hole injection layer ( HIL ) 120 , a first hole transport layer (HTL) 130 , a second hole injection layer 140 , a second hole transport layer 145 , a first emission layer (EML) 150 , a first hole-blocking layer ( HBL ) 155 , a first electron transport layer (ETL) 160 , an n-charge generating layer (n-type CGL) 185 , a hole-generating layer (p-type charge-generating layer); p-type GCL) 135 , a third hole transport layer (HTL) 141 , a fourth hole transport layer 146 , a second emission layer (EML) 151 , a second hole-blocking layer ( EBL ) 156 , a second electron transport layer (ETL) 161 , a second electron injection layer( EIL ) 181 and a cathode 190 .

[0163] Although in Fig. 1, Fig. 2 and Fig. 3 not shown, can be found on the cathode electrodes 190 a sealing layer is formed to protect the OLEDs 100 and 200 to seal. Likewise, although not in Fig. 1, Fig. 2 and Fig. As shown in Figure 3, the layers can be formed on a substrate adjacent to the anode, starting with the anode. Furthermore, various other modifications are possible.

[0164] One or more exemplary embodiments of the present invention are described in detail below with reference to the following examples. However, these examples are not intended to limit the purpose and scope of the one or more exemplary embodiments of the present invention. EXPERIMENTAL PART

[0165] Auxiliary materials for apparatus testing F1 is N-([1,1'-biphenyl]-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amine, CAS 1242056-42-3; F2 is 9-([1,1'-biphenyl]-3-yl)-9'-([1,1'-biphenyl]-4-yl)-9H,9'H-3,3'-bicarbazole, CAS 1643479-47-3; F3 is 8-(4-(4,6-di(naphthalen-2-yl)-1,3,5-triazin-2-yl)phenyl)quinoline, CAS 1312928-44-1; F4 is (2-(4-phenylpyridin-2-yl)phenyl)bis(2-(pyridin-2-yl)phenyl)iridium, CAS 1215281-24-5; F5 is 2,4-diphenyl-6-(3'-(triphenylen-2-yl)-[1,1'-biphenyl]-3-yl)-1,3,5-triazine, CAS 1638271-85-8; F6 is 3-phenyl-3H-benzo[b]dinaphtho[2,1-d:1',2'-f]phosphepine-3-oxide, CAS 597578-38-6; GHM020S is an emitter host, EL-GD0108S is a green phosphorescent emitter dot, both of which are commercially available from SDI (Korea).

[0166] ITO is indium tin oxide. Standard procedure: Voltage stability

[0167] OLEDs are powered by constant current circuits. These circuits can supply a constant current over a specific voltage range. The larger the voltage range, the greater the power losses of such devices. Therefore, changes in the operating voltage must be minimized.

[0168] The operating voltage of an OLED is temperature-dependent. Therefore, the voltage stability must be assessed at thermal equilibrium. Thermal equilibrium is reached after one hour of operation.

[0169] Voltage stability is measured by measuring the difference between the operating voltage after 50 hours and after 1 hour of operation at a constant current density. A current density of 30 mA / cm² is used. 2 used. The measurements are taken at room temperature. dU [ V ] = U ( 50 h ,30 mA / cm 2 ) − U ( 1 h ,30 mA / cm 2 ) Examples

[0170] 1) Green phosphorescent OLED comprising the second hole-injecting layer doped with a fluorinated metal complex or with a fluorinated fullerene compound.

[0171] Table 1a schematically describes the model device. Table 1a Material c d [Vol.-%] [nm] ITO 100 90 F1: PD-2 92:8 10 F1 100 130 F2: p-Dotand (100-x) x 10 F2 100 20 GHMo2oS: EL-GDo108S 90:10 40 F3: LiQ 50:50 36 A1 100 100

[0172] The results are listed in Table 1b. Table 1b p-Dotand c U EQE CIE-y [Vol.-%] (10 mA / cm 2 ) [V] (10 mA / cm 2 ) [%] PD1 1 4,5 19,7 0,619 PD2 1 4,3 19,3 0,628 PD2 5 4,2 18,2 0,626 PD2 10 4,2 18,1 0,625 C 60 F 48 1 4,2 19,5 0,619 E1 5 4,2 19,2 0,627 E1 10 4,2 19,3 0,628 E1 20 4,3 19,5 0,628 E2 5 4,2 19,0 0,626 E2 10 4,2 19,1 0,626 E2 20 4,2 19,3 0,626

[0173] In comparison with the state-of-the-art nitrile compounds PD 1 and PD 2, the alternative dopants E1, E2 and C enable 60 F 48 comparable efficiency at lower operating voltage or higher efficiency at comparable operating voltage.

[0174] 2) Yellow phosphorescent OLED comprising the second hole-injecting layer doped with a fluorinated metal complex or with a fluorinated fullerene compound.

[0175] Table 2a schematically describes the model device Table 2a Material c d [Vol.-%] [nm] ITO 100 90 F1: PD2 92:8 10 F1 100 145 F2: p-Dotand (100-x) : x 10 F2 100 20 GHMo20S: F4 90:10 40 F5 100 25 F6: Yb 99:1 10 A1 100 100

[0176] The results are listed in Table 2b. Table 2b p-Dotand c U EQE CIE-y [Vol.-%] (10 mA / cm 2 ) [V] (10 mA / cm 2 ) [%] PD1 1 5,3 20,6 0,561 C 60 F 48 1 5,0 20,8 0,561

[0177] In comparison with the state-of-the-art nitrile compound PD1, the alternative Dotand C enables 60 F 48 comparable efficiency at lower operating voltage.

[0178] The properties disclosed in the preceding description, the claims and the associated drawings can, separately or in combination, be the subject of the realization of the invention in different forms thereof.

[0179] Key symbols and abbreviations used in the registration CV Cyclic voltammetry DSC Dynamic Differential Calorimetry EBL electron-blocking layer EIL electron injection layer EML emission layer eq. equivalent ETL electron transport layer ETM electron transport matrix FC Ferrocen FC + Ferrocenium HBL hole-blocking layer HIL (Hyper-Injection Layer) HOMO highest occupied molecular orbital HPLC High-performance liquid chromatography HTL perforated transport layer p-HTL p-doped hole transport layer HTM hole transport matrix ITO (Indium Tin Oxide) LUMO: lowest unoccupied molecular orbital mol% Mole percent NMR nuclear magnetic resonance OLED organic light-emitting diode OPV organic photovoltaics PTFE (Polytetrafluoroethylene) QE Quantum efficiency R f Retardation factor in TLC RGB red-green-blue TCO transparent conductive oxide TFT thin-film transistor T g Glass transition temperature TLC thin-layer chromatography VTE thermal vacuum evaporation wt% weight percent QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 2014 / 001444 A1

[0005] WO 2018 / 150048 A1 [0023, 0087, 0091] WO 2018 / 150049 A1 [0023, 0087, 0091] WO 2018 / 150050 A1 [0023, 0087, 0091] WO 2018 / 150051 A1 [0023, 0087, 0091] WO 2018 / 138373 A1 [0057, 0110] WO 2005 / 086251

[0075] EP 1837926 B1

[0076] WO 2007 / 107306

[0076] WO 2007 / 107356

[0076] WO 2013 / 135237 A1 [0087, 0091] WO 2014 / 060526 A1 [0087, 0091] WO 2015 / 158886 A1 [0087, 0091] WO 2018 / 150006 A1 [0087, 0091] US 6140763

[0096] US 6614176

[0096] US 2016248022

[0096]

Claims

[1] Organic light-emitting device comprising: (i) an anode; (ii) a cathode, (iii) at least one light-emitting layer arranged between the anode and the cathode; (iv) optionally a first hole injection layer comprising a first hole-injecting compound, wherein the first hole injection layer is arranged between the anode and the light-emitting layer and the hole injection layer is adjacent to the anode; (v) a first hole transport layer comprising a first hole-transporting matrix compound, wherein the first hole transport layer a) between the first hole injection layer and the light emission layer and adjacent to the first hole injection layer; or b) is located between the anode and the light emission layer and adjacent to the anode; (vi) a second hole injection layer arranged between the first hole transport layer and the light emission layer, wherein the second hole injection layer is adjacent to the first hole transport layer and wherein the second hole injection layer comprises a second hole-injecting compound; wherein the second hole-injecting compound is a halogenated fullerene, a partially or fully halogenated metal complex, or a mixture thereof. [2] Organic light-emitting device according to claim 1, wherein the first hole injection layer comprises a second hole-transporting matrix compound. [3] Organic light-emitting device according to claim 1 or 2, wherein the second hole injection layer further comprises a third hole-transporting matrix compound. [4] Organic light-emitting device according to one of the preceding claims, wherein the organic light-emitting device further comprises a second hole transport layer arranged between the second hole injection layer and the light emission layer, wherein the second hole transport layer is adjacent to the second hole injection layer and wherein the second hole transport layer comprises a fourth hole-transporting matrix compound. [5] Organic light-emitting device according to any of the preceding claims, wherein the halogenated fullerene is a fluorinated fullerene and / or the partially or fully halogenated metal complex is a partially or fully fluorinated metal complex. [6] Organic light-emitting device according to any one of the preceding claims, wherein the halogenated fullerene has the formula C x F y has, where x is an even integer from 60 to 120 and y is from x / 2 to 4x / 5. [7] Organic light-emitting device according to claim 6, wherein x is 60. [8] Device according to claim 6 or 7, wherein the halogenated fullerene has formula C 60 F 48 has. [9] Organic light-emitting diode according to any one of the preceding claims, wherein the halogenated metal complex has the following formula (I) wherein M x ⊕ an x-valent cation of a metal selected from alkali metals, alkaline earth metals, rare earth metals and Al, Ga, In, Sn, Pb, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Zn and Cd; x 1 is for M selected from alkali metals; 2 for M selected from alkaline earth metals, Pb, Mn, Fe, Co, Ni, Zn and Cd; 2 or 3 for M selected from rare earth metals; 3 for Al, Ga, In; 2, 3 or 4 for Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W; and 2 or 4 for Sn; B 1 and B 2is selected independently of each other from partially or fully halogenated C3 to C 20 -Alkyl, C3- to C 20 -Cycloalkyl or C3- to C 20 -Arylalkyl. [10] Organic light-emitting device according to any of the preceding claims, wherein the light-emitting layer comprises a phosphorescent emitter.

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