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Definitions

• the present invention relates to the use of Pt and Pd bis- and tetracarbene complexes, with bridged carbene ligands in organic light-emitting diodes, organic light-emitting diodes, containing at least one above-mentioned Pt or Pd carbene complex, organic light-emitting diodes, wherein the at least one Sprintgangsme- a carbene complex of the general formula I and / or II in the light-emitting layer, a block layer for electrons, a block layer for excitons and / or a block layer for holes, a light-emitting layer containing at least one aforementioned Pt or Pd-carbene complex, organic light-emitting diodes, containing at least one light-emitting layer according to the invention and devices which contain at least one organic light-emitting diode according to the invention.
• OLEDs organic light emitting diodes
• the property of materials is used to emit light when excited by electric current.
• OLEDs are of particular interest as an alternative to cathode ray tubes and liquid crystal displays for the production of flat panel displays. Due to the very compact design and the intrinsically low power consumption, the devices containing OLEDs are particularly suitable for mobile applications, eg. For applications such as cell phones, laptops, etc.
• WO 2005/019373 discloses for the first time the use of neutral transition metal complexes which contain at least one carbene ligand in OLEDs. These transition metal complexes can be used according to WO 2005/019373 in each layer of an OLED, wherein the ligand skeleton or central metal can be varied to adapt to desired properties of the transition metal complexes. For example, the use of the transition metal complexes in a block layer for Electrons, a block layer for excitons, a block layer for holes or the light-emitting layer of the OLED possible, wherein the transition metal complexes are preferably used as emitter molecules in OLEDs.
• WO 2005/113704 relates to luminescent compounds which carry carbene ligands. According to WO 2005/1 13704, numerous transition metal complexes with different carbene ligands are mentioned, the transition metal complexes preferably being used as phosphorescent light-emitting material, particularly preferably as doping substance.
• Both the transition metal carbene complexes disclosed in WO 2005/019373 and in WO 2005/1 13704 have carbene ligands which are bonded to the transition metal atom by cyclometalation.
• the linking of the carbene ligand (s) with the transition metal occurs on the one hand via the carbene carbon atom and further via another carbon or heteroatom.
• the object of the present invention over the aforementioned prior art is to provide further transition metal carbene complexes for use in OLEDs which exhibit a balanced property spectrum, e.g. Good stability, good efficiencies and / or improved durability.
• transition metal complexes selected from transition metal carbene complexes of the general formulas (I) and (II) in organic light-emitting diodes are used.
• R 1 , R 1 are each independently hydrogen, alkyl, cycloalkyl, aryl, heteroaryl, aralkyl;
• R 2 , R 3 , R 2 , R 3 independently of one another are hydrogen, alkyl, aryl or R 2 and R 3 or R 2 and R 3 in each case together form a bridge of 3, 4 or 5, preferably 4, carbon atoms which are saturated or may be mono- or di-unsaturated and may be optionally substituted with one or more C 1 to C 6 alkyl radicals, preferably an unsubstituted diunsaturated bridge of 4 carbon atoms having the structure:
• X, X ' are independently alkylene
• transition metal carbene complexes of the general formulas I and II used according to the invention have no cyclometalation of the carbene ligands via a further carbon atom or heteroatom. It has surprisingly been found that sufficiently stable transition metal carbene complexes suitable for use in OLEDs can be provided without requiring cyclometalation of the carbene ligand (s) via another carbon or heteroatom.
• the present invention comprises both the individual isomers of the transition metal carbene complexes of the formula I and mixtures of different isomers in any mixing ratio.
• various isomers of the metal complexes of the formulas I and II can be prepared by methods known to those skilled in the art, e.g. Example, by chromatography, sublimation or crystallization, are separated.
• the transition metal carbene complexes of the formulas I and II can be used in any layer of an OLED, wherein the ligand skeleton or central metal can be varied to match desired properties of the metal complex.
• the transition metal carbene complexes of the formulas I and II in a block layer for electrons, a block layer for excitons, a block layer for holes or the light-emitting layer of the OLED.
• the compounds of the formulas I and II are preferably used as emitter molecules in OLEDs.
• a monodentate ligand is to be understood as meaning a ligand which coordinates at one point of the ligand with the transition metal atom M 1 .
• Transition metal carbene complexes which exclusively have a linkage of the carbene ligand (s) with the transition metal atom via carbene carbon atoms are known in the art.
• M. Albrecht et al., Inorganica Chimica Acta 359 (2006) 1929-1938 relates to the synthesis and structural analysis of palladium-biscarbene complexes bearing bisimidazolium ligands.
• M. Albrecht et al. mechanistic investigations of the metallation of the bisimidazolium ligand.
• Ch.-M. Che et al., Organometallics 1998, 17, 1622-1630, relates to an investigation of the spectroscopic properties of luminescent rhenium (I) -N-heterocyclic carbene complexes bearing aromatic photoactive diimine ligands.
• the investigation of the spectroscopic properties of the complexes serves to better understand the electronic conditions in these complexes.
• An application of the N-heterocyclic rhenium (I) carbene complexes as well as possible electroluminescent properties are described in Ch.-M. Che not specified.
• DE-A 10 2005 058 206 discloses N-heterocyclic biscarbene complexes of platinum and palladium, their preparation and their use as catalyst, in particular as catalyst for the partial oxidation of hydrocarbons or hydrocarbon-containing feeds.
• DE-A 10 2005 058 206 contains no information regarding the luminescence properties of the disclosed complexes.
• transition metal carbene complexes of the formulas I and II according to the present invention for use in OLEDs is not in any of the above-mentioned mentioned documents mentioned. It has thus been found that the transition metal carbene complexes of the formulas I and II according to the present application are suitable for use in OLEDs.
• Suitable monoanionic ligands L which are monodentate are the ligands commonly used as monodentate monoanionic ligands.
• Suitable ligands L are halides, especially Cl “ , Br “ , I “ , pseudohalides, in particular CN “ , and alkoxy and OAc “ and CF 3 COO " , preferred ligands L are Br “ , I “ and OAc “ and CF 3 COO " .
• Suitable monoanionic counterions W “ are, for example, halides, in particular Cl “ , Br “ , I “ , pseudohalides, in particular CN “ , alkoxy, OAc “ , BF 4 “ , PF 6 “ , SbF 6 “ , AsF 6 “ , SCN “ , OCN “ and CIO 4 " , preferred monoanionic counterions are Br “ and I “ .
• aryl radical or group alkyl radical or group, cycloalkyl radical or group, aralkyl radical or group, alkoxy radical or group have the following meanings:
• an aryl radical is meant a radical having a backbone of 6 to 18 carbon atoms, which is composed of one or more fused aromatic rings.
• Suitable backbones are, for example, phenyl, naphthyl, anthracenyl or phenanthrenyl. This backbone may be unsubstituted (ie, all carbon atoms which are substitutable bear hydrogen atoms) or substituted at one, several or all substitutable positions of the backbone.
• Suitable substituents are, for example, alkyl radicals, preferably alkyl radicals having 1 to 8 carbon atoms, more preferably methyl, ethyl or i-propyl.
• the aryl radical is preferably a C 6 -aryl radical which is substituted by at least one of the abovementioned substituents.
• the C 6 -aryl radical particularly preferably has one, two or three alkyl radicals, one substituent being arranged in the ortho, meta or para position relative to the further linking site of the aryl radical, and - in the case of two substituents - these may each be be arranged in the meta position or ortho position to the further point of attachment of the aryl radical or a radical is arranged in the ortho position and a radical in the meta position or a radical is arranged in ortho or meta position and the remainder is in para Position arranged.
• alkyl radical or an alkyl group is to be understood as meaning a radical having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms.
• This alkyl radical may be branched or unbranched.
• the alkyl radicals are particularly preferably selected from the group consisting of methyl, ethyl, isopropyl, n-propyl, n-butyl, isobutyl and tert-butyl, very particularly preferred are methyl, isopropyl and n-butyl.
• An alkoxy radical or an alkoxy radical is an O-alkyl radical. Suitable alkyl radicals are mentioned above.
• a cycloalkyl radical or a cycloalkyl radical is to be understood as meaning a radical having 3 to 8 carbon atoms.
• This backbone may be unsubstituted (i.e., all carbon atoms that are substitutable bear hydrogen atoms) or substituted at one, several, or all substitutable positions of the backbone.
• Suitable substituents are the groups already mentioned above with respect to the aryl radicals. Particularly preferred is cyclohexyl.
• an aralkyl radical is meant a radical having a skeleton of 6 to 18 carbon atoms, which may be unsubstituted or substituted by the radicals mentioned relative to the aryl groups.
• the aralkyl group preferably denotes benzyl.
• alkylene in the context of the present application, has the meanings mentioned with regard to the alkyl radicals, with the difference that the alkylene group has two bond sites to the nitrogen atoms of the biscarbene ligands in the transition metal carbene complexes of the formulas I and II.
• Preferred alkylene groups are (CR 4 2 ) n , where R 4 is H or alkyl, preferably H, methyl or ethyl, particularly preferably H and n is 1 to 3, preferably 1 or 2, particularly preferably 1. Most preferably, the alkylene group is CH 2 .
• radicals with the same numbering occur several times in the compounds according to the present application, these radicals can each independently have the meanings mentioned.
• R 1 , R 1 independently of one another, are hydrogen, alkyl, cycloalkyl, aryl, aralkyl, preferably C 1 -C 4 -alkyl, cyclohexyl, 2,4,6-trimethylphenyl or benzyl, more preferably methyl, iso-propyl, n- butyl;
• R 2 , R 3 , R 2 , R 3 independently of one another are hydrogen or alkyl, preferably hydrogen, or R 2 and R 3 or R 2 and R 3 in each case together form a bridge of 3, 4 or 5, preferably 4, carbon atoms, which are saturated or may be mono- or diunsaturated and may optionally be substituted by one or more C 1 to C 6 alkyl radicals, preferably an unsubstituted diunsaturated bridge of 4 carbon atoms, having the structure:
• R 4 is H, alkyl, preferably H, methyl or ethyl, particularly preferably H and n is 1 to 3, preferably 1 or 2, particularly preferably
• W monoanionic counterion, preferably halide, pseudohalide or OAc " , more preferably Cl “ , Br “ , I “ , CN “ , OAc “ , most preferably Br “ or I “ .
• the present application relates to the use of Pt and Pd biscarbene complexes of the general formula (I)
• R 1 independently of one another are C 1 -C 4 -alkyl, cyclohexyl, 2,4,6-trimethylphenyl or benzyl, preferably methyl, isopropyl, n-butyl, cyclohexyl, 2,4,6-trimethylphenyl or benzyl;
• R 2 , R 3 are independently hydrogen or alkyl, preferably hydrogen, or R 2 and R 3 together form a bridge of 3, 4 or 5, preferably 4 carbon atoms, which may be saturated or mono- or diunsaturated and optionally with one or more C 1 to C 6 alkyl radicals may be substituted, preferably an unsubstituted diunsaturated bridge of 4 carbon atoms atoms having the structure:
• L are independently selected from halides, pseudohalides and OAc “ and CF 3 COO “ , preferably Cl “ , Br “ , I “ , CN “ or OAc “ and CF 3 COO “ , more preferably Br “ , I “ or OAc “ and CF 3 COO " .
• R 1 , R 2 and R 3 in the biscarbene complex of the formula I each have the same meanings, so that the biscarbene ligand is symmetrical.
• the present invention relates to tetracarbene complexes bearing two biscarbene ligands.
• the tetracarbene complexes may be homoleptic tetracarbene complexes, that is, the two biscarbene complexes ligands in the homoleptic tetracarbene complexes are identical. However, they can also be heteroleptic tetracarbene complexes, ie the two biscarbene ligands in the heteroleptic tetracarbene complexes are not identical.
• R 1 , R 1 independently of one another are hydrogen, alkyl, cycloalkyl, aryl, aralkyl, preferably hydrogen, C 1 -C 4 -alkyl, cyclohexyl, 2,4,6-trimethylphenyl or benzyl, particularly preferably methyl, isopropyl, n-butyl, cyclohexyl Benzyl, 2,4,6-trimethylphenyl; R 2 , R 3 , R 2 , R 3
• Hydrogen or alkyl preferably hydrogen, or R 2 and R 3 or R 2 and R 3 in each case together form a bridge of 3, 4 or 5, preferably 4 carbon atoms, which may be saturated or mono- or diunsaturated and optionally with one or more C 1 to C 6 alkyl radicals may be substituted, preferably an unsubstituted, diunsaturated bridge of 4 carbon atoms, which has the following structure:
• X, X ' are each CH 2 ;
• R 1 , R 1 are each CH 3 , iso-propyl, n-butyl or cyclohexyl;
• R 2 , R 3 , R 2 , R 3 are each hydrogen, or R 2 and R 3 or R 2 and R 3 together form a bridge an unsubstituted diunsaturated bridge of 4 carbon atoms, which are the following comprising:;
• X, X are each CH 2 ;
• R 1 , R 1 are independently CH 3 , iso-propyl, n-butyl, cyclohexyl, benzyl or 2,4,6-trimethylphenyl, wherein R 1 and R 1 have different meanings;
• R 2 , R 3 , R 2 , R 3 are each hydrogen, or R 2 and R 3 or R 2 and R 3 each form an unsubstituted diunsaturated bridge of 4 carbon atoms, having the structure:
• transition metal carbene complexes of the formulas I and II used according to the invention can in principle be prepared according to processes known to the person skilled in the art or analogously to processes known to the person skilled in the art. Suitable general methods for the preparation of carbene complexes are, for. See, for example, in the review articles W.A. Hermann et al., Advances in Organometallic Chemistry, 2001, Vol. 48, 1-69, W.A. Hermann et al., Angew. Chem. 1997, 109, 2256-2282 and G. Bertrand et al., Chem. Rev. 2000, 100, 39-91 and the literature cited therein. Other manufacturing processes are z. In Ch.-M.
• transition metal carbene complexes of formulas I and II are prepared from precursors corresponding to the carbene ligands and suitable metal complexes containing the desired metal.
• Suitable ligand precursors of the carbene ligands of the transition metal carbene complexes used according to the invention are bisimidazolium salts of the general formula III
• Q " is a monoanionic counterion, preferably halides, in particular Cl “ , Br “ , I “ , pseudohalides, in particular CN “ , alkoxy, OAc “ , BF 4 “ , PF 6 “ , SbF 6 “ , AsF 6 “ , SCN “ , OCN “ and CIO 4 " , preferred monoanionic counterions are Br “ and I “ .
• the bisimidazolium salts of the formula III can be prepared by processes known to the person skilled in the art or by processes analogous to those known to the person skilled in the art. Suitable methods are described, for example, in M. Albrecht et al., Organometallics 2002, 21, (17), 3596-3604, G. Maletz et al., "Palladium or Platinum Carbene Complexes as Catalyst for Partial Oxidation of Alkanes", 2001 10151660, 10151660, 20011019., 2003 and M. Muehlhofer et al., Journal of Organometallic Chemistry 2002, 660, (2), 121 to 126, as well as in DE-A 10 2005 058 206 mentioned.
• the bisimidazolium salts of the formula III can be obtained by reacting the correspondingly substituted imidazoles with CH 2 Z 2 , where Z may denote Cl, Br or I.
• the correspondingly substituted imidazoles can be prepared according to processes known to the person skilled in the art or are commercially available.
• the suitable metal complexes containing the desired metal are generally Pt (II) or Pd (II) metal complexes.
• Suitable metal complexes are known to the person skilled in the art. Examples of suitable metal complexes are Pt (acac) 2 , wherein acac is acetylacetonate, PtCl 2 , Pt (OAc) 2 , Pd (acac) 2 , PdCl 2 , Pd (OAc) 2 , Pt (cod) Cl 2 , wherein cod is cyclooctadiene means.
• the desired transition metal carbene complex is a biscarbene complex of the general formula I
• the desired transition metal carbene complex is a homoleptic transition metal carbene complex of the formula II
• a ligand precursor of the general formula III it is possible, on the one hand, for a ligand precursor of the general formula III to be present with a suitable metal complex in a molar ratio of generally 3: 1 to 2: 1, preferably 2.5: 1 to 2: 1, more preferably 2: 1 is reacted, wherein the desired homoleptic tetracarbene complex of the formula II is obtained directly.
• a biscarbene complex by reacting a ligand precursor of the formula III with a corresponding metal complex in the aforementioned stoichiometric ratios which are suitable for the preparation of biscarbene complexes, and to obtain this biscarbene complex, preferably in situ, without further workup, with further ligand precursor of the formula IM to implement, wherein the molar ratio of the preferred in situ obtained biscarbene complex to the further ligand precursor is generally 0.75: 1 to 1: 0.75, preferably 0.9 : 1 to 1: 0.9, more preferably 1: 1.
• the preparation of a biscarbene complex is generally carried out initially, the ligand precursor of the formula III used and the metal complex being used in the stoichiometric ratios mentioned above for the preparation of biscarbene complexes become.
• the biscarbene complex obtained is then, preferably in situ, without further work-up, with a second ligand precursor of formula IM (wherein R 1 , R 2 , R 3 and X in the second ligand precursor of the formula IM by R 1 , R 2 , R 3 and X ') other than the first ligand precursor of the formula IM.
• the molar ratio between the biscarbene complex and the second ligand precursor of the formula III is generally 0.75: 1 to 1: 0.75, preferably 0.9: 1 to 1: 0.9, particularly preferably 1: 1.
• the resulting transition metal carbene complex of the formulas I or II is worked up by methods known to the person skilled in the art and optionally purified. Usually, work-up and purification are carried out by extraction, column chromatography and / or recrystallization according to methods known to the person skilled in the art.
• the transition metal carbene complexes of the formulas I and II are used in organic light-emitting diodes (OLEDs).
• OLEDs organic light-emitting diodes
• the present application relates to the uses of transition metal carbene complexes of the formula II.
• the transition metal carbene complexes of the formulas I and II are suitable as emitter substances since they have an emission (electroluminescence) in the visible region of the electromagnetic spectrum.
• the transition metal carbene complexes of the formulas I and II used as emitter substances according to the invention it is possible to provide compounds which exhibit electroluminescence in the entire range of the electromagnetic spectrum with good efficiency. It is the High quantum yield and the stability of the inventively used transition metal carbene complexes of the formulas I and II in the device high.
• transition metal carbene complexes of the formulas I and II used according to the invention are suitable as electron, exciton or hole blockers or hole conductors, electron conductors, hole injection layer or matrix material in OLEDs, depending on the ligands used and the central metal used.
• OLEDs Organic light-emitting diodes
• the OLED does not have all of the layers mentioned, for example an OLED with the layers (1) (anode), (3) (light-emitting layer) and (5) (cathode) is also suitable. wherein the functions of the layers (2) (hole-transporting layer) and (4) (electron-transporting layer) are taken over by the adjacent layers. OLEDs comprising layers (1), (2), (3) and (5) or layers (1), (3), (4) and (5) are also suitable.
• the transition metal carbene complexes of formulas I and II can be used in different layers of an OLED.
• Another object of the present invention is therefore an OLED containing at least one transition metal carbene complex of the formulas I and / or II.
• the at least one transition metal carbene complex of the general formula I and / or II is in the light-emitting layer, a block layer for Electrons, a block layer for excitons and / or a block layer for holes.
• the transition metal carbene complexes of the formulas I and II are preferably used in the light-emitting layer, particularly preferably as emitter molecules.
• Another object of the present invention is therefore a light-emitting layer containing at least one transition metal carbene complex of the formulas I and II, preferably as an emitter molecule.
• Preferred transition metal carbene complexes of the formulas I and II are mentioned above.
• the transition metal carbene complexes of the formulas I and II used according to the invention can be present in bulk-without further additives-in the light-emitting layer or another layer of the OLED, preferably in the light-emitting layer.
• a fluorescent dye may be present in the light-emitting layer in order to change the emission color of the transition metal carbene complex of the formula I or II used as emitter molecule.
• a diluent material can be used.
• This diluent material may be a polymer, for example poly (N-vinylcarbazole) or polysilane.
• the individual of the abovementioned layers of the OLED can in turn be composed of 2 or more layers.
• the hole-transporting layer may be composed of a layer into which holes are injected from the electrode and a layer that transports the holes away from the hole-injecting layer into the light-emitting layer.
• the electron-transporting layer may also consist of several layers, for example a layer in which electrons are injected through the electrode and a layer which receives electrons from the electron-injection layer and transports them into the light-emitting layer. These layers are selected in each case according to factors such as energy level, temperature resistance and charge carrier mobility, as well as the energy difference of said layers with the organic layers or the metal electrodes.
• the person skilled in the art is able to choose the structure of the OLEDs in such a way that it is optimally adapted to the transition metal carbene complexes of the formulas I and II used according to the invention, preferably as emitter substances.
• the HOMO (highest occupied molecular orbital) of the hole-transporting layer should be aligned with the work function of the anode and the LUMO (lowest unoccupied molecular orbital) of the electron-transporting layer should be aligned with the work function of the cathode.
• a further subject of the present application is an OLED containing at least one light-emitting layer according to the invention.
• the further layers in the OLED may be constructed of any material commonly employed in such layers and known to those skilled in the art.
• the anode (1) is an electrode that provides positive charge carriers.
• it may be constructed of materials including a metal, a mixture of various metals, a metal alloy, a metal oxide, or a mixture of various metal oxides.
• the anode may be a conductive polymer. Suitable metals include the metals of Groups 11, 4, 5 and 6 of the Periodic Table of Elements and the transition metals of Groups 8 to 10.
• ITO indium tin oxide
• the anode (1) contains an organic material, for example polyaniline, as described for example in Nature, Vol. 357, pages 477 to 479 (June 11, 1992). At least either the anode or the cathode should be at least partially transparent in order to be able to decouple the light formed.
• Suitable hole transport materials for the layer (2) of the OLED according to the invention are disclosed, for example, in Kirk-Othmer Encyclopedia of Chemical Technology, 4th Edition, Vol. 18, pages 837 to 860, 1996. Both hole transporting molecules and polymers can be used as hole transport material.
• Commonly used hole transporting molecules are selected from the group consisting of 4,4'-bis [N- (1-naphthyl) -N-phenyl-amino] biphenyl ( ⁇ -NPD), N, N'-diphenyl-N , N'-Bis (3-methylphenyl) - [1,1'-biphenyl] -4,4'-diamine (TPD), 1,1-bis [(di-4-tolylamino) phenyl] cyclohexane (TAPC) , N, N'-bis (4-methylphenyl) -N, N'-bis (4-ethylphenyl) - [1, 1 '- (3,3'-dimethyl) biphenyl] -4,4'-diamine (ETPD ), Tetrakis (3-methylphenyl) -N, N, N ', N'-2,5-phenylenediamine (PDA), ⁇ -phenyl-4-N,
• hole transporting polymers are selected from the group consisting of polyvinylcarbazolen, (phenylmethyl) polysilanes, PEDOT (poly (3,4-ethylenedioxythiophene), preferably PEDOT doped with PSS (polystyrene sulfonate), and polyanilines. It is also if possible, to obtain hole transporting polymers by doping hole transporting molecules into polymers such as polystyrene and polycarbonate. Suitable hole-transporting molecules are the molecules already mentioned above.
• Suitable electron transport materials for layer (4) of the OLEDs according to the invention comprise chelated metals with oxinoid compounds, such as tris (8-hydroxyquinolato) aluminum (Alq 3 ), phenanthroline-based compounds, such as 2,9-dimethyl, 4,7-diphenyl-1, 10.
• oxinoid compounds such as tris (8-hydroxyquinolato) aluminum (Alq 3 )
• phenanthroline-based compounds such as 2,9-dimethyl, 4,7-diphenyl-1, 10.
• the layer (4) can serve both to facilitate the electron transport and as a buffer layer or as a barrier layer in order to avoid quenching of the exciton at the interfaces of the layers of the OLED.
• the layer (4) improves the mobility of the electrons and reduces quenching of the exciton.
• hole transporting materials and electron transporting materials some may fulfill several functions.
• some of the electron-conducting materials are simultaneously hole-blocking materials if they have a deep HOMO.
• the charge transport layers can also be electronically doped in order to improve the transport properties of the materials used, on the one hand to make the layer thicknesses more generous (avoidance of pinholes / short circuits) and on the other hand to minimize the operating voltage of the device.
• the hole transport materials can be doped with electron acceptors, for example phthalocyanines or arylamines such as TPD or TDTA can be doped with tetrafluorotetracyanoquinodimethane (F4-TCNQ).
• the electron transport materials may be doped with alkali metals, for example Alq 3 with lithium.
• the electronic doping is known to the person skilled in the art and described, for example, in W. Gao, A. Kahn, J. Appl.
• the cathode (5) is an electrode which serves to introduce electrons or negative charge carriers.
• the cathode may be any metal or non-metal that has a lower work function than the anode.
• Suitable materials for the catho- de are selected from the group consisting of Group 1 alkali metals, for example Li, Cs, Group 2 alkaline earth metals, Group 12 metals of the Periodic Table of the Elements comprising the rare earth metals and the lanthanides and actinides.
• metals such as aluminum, indium, calcium, barium, samarium and magnesium and combinations thereof can be used.
• lithium-containing organometallic compounds or LiF can be applied between the organic layer and the cathode to reduce the operating voltage (Operating Voltage).
• the OLED according to the present invention may additionally contain further layers which are known to the person skilled in the art.
• a layer can be applied between the layer (2) and the light-emitting layer (3), which facilitates the transport of the positive charge and / or adapts the band gap of the layers to one another.
• this further layer can serve as a protective layer.
• additional layers may be present between the light-emitting layer (3) and the layer (4) to facilitate the transport of the negative charge and / or to match the band gap between the layers.
• this layer can serve as a protective layer.
• the OLED according to the invention contains at least one of the further layers mentioned below:
• the OLED does not have all of the mentioned layers (1) to (5), for example an OLED with the layers (1) (anode), (3) (light-emitting Layer) and (5) (cathode) are also suitable, the functions of the layers (2) (hole-transporting layer) and (4) (electron-transporting layer) being exceeded by the adjacent layers. be taken.
• OLEDs comprising layers (1), (2), (3) and (5) or layers (1), (3), (4) and (5) are also suitable.
• each of the mentioned layers of the OLED according to the invention can be composed of two or more layers. Further, it is possible that some or all of the layers (1), (2), (3), (4) and (5) are surface treated to increase the efficiency of charge carrier transport. The selection of materials for each of said layers is preferably determined by obtaining an OLED having a high efficiency.
• the preparation of the OLEDs according to the invention can be carried out by methods known to the person skilled in the art.
• the OLED is fabricated by sequential vapor deposition of the individual layers onto a suitable substrate.
• Suitable substrates are, for example, glass or polymer films.
• vapor deposition conventional techniques can be used such as thermal evaporation, chemical vapor deposition and others.
• the organic layers may be coated from solutions or dispersions in suitable solvents, using coating techniques known to those skilled in the art.
• compositions which, in addition to the at least one transition metal carbene complex of the formulas I and / or II, comprise a polymeric material in one of the layers of the OLED, preferably in the light-emitting layer, are generally applied as a layer by means of solution-processing methods.
• the various layers have the following thicknesses: anode (1) 500 to 5000 ⁇ , preferably 1000 to 2000 ⁇ ; Hole-transporting layer (2) 50 to 1000 ⁇ , preferably 200 to 800 ⁇ , light-emitting layer (3) 10 to 1000 ⁇ , preferably 100 to 800 ⁇ , Electron-transporting layer (4) 50 to 1000 ⁇ , preferably 200 to 800 ⁇ , cathode (5) 200 to 10,000 ⁇ , preferably 300 to 5000 ⁇ .
• the location of the recombination zone of holes and electrons in the inventive OLED and thus the emission spectrum of the OLED can be affected by the relative thickness of each layer.
• the thickness of the electron transport layer should preferably be selected so that the electron / holes recombination zone is in the light-emitting layer.
• the ratio of the layer thicknesses of the individual layers in the OLED depends on the materials used.
• the layer thicknesses of optionally used additional layers are known to the person skilled in the art.
• OLEDs can be obtained with high efficiency.
• the efficiency of the OLEDs according to the invention can be further improved by optimizing the other layers.
• highly efficient cathodes such as Ca, Ba or LiF can be used.
• Shaped substrates and new hole-transporting materials that bring about a reduction in the operating voltage or an increase in quantum efficiency are also usable in the OLEDs according to the invention.
• additional layers may be present in the OLEDs to adjust the energy levels of the various layers and to facilitate electroluminescence.
• the OLEDs according to the invention can be used in all devices in which electroluminescence is useful. Suitable devices are preferably selected from stationary and mobile screens. Stationary screens are e.g. Screens of computers, televisions, screens in printers, kitchen appliances and billboards, lights and signboards. Mobile screens are e.g. Screens in mobile phones, laptops, cameras, in particular digital cameras, vehicles and destination displays on buses and trains.
• Stationary screens are e.g. Screens of computers, televisions, screens in printers, kitchen appliances and billboards, lights and signboards.
• Mobile screens are e.g. Screens in mobile phones, laptops, cameras, in particular digital cameras, vehicles and destination displays on buses and trains.
• transition metal carbene complexes of the formulas I and II can be used in inverse-structure OLEDs.
• the transition metal carbene complexes of the general formulas I and II used according to the invention are preferably used in these inverse OLEDs in turn in the light-emitting layer.
• the construction of inverse OLEDs and the materials usually used therein are known to the person skilled in the art.
• the following examples additionally illustrate the invention:
• the imidazoles shown here were synthesized in the mentioned literature (Arduengo, A.J., et al., IM Process for manufacture of imidazoles. 98-193700,
• 0.62 mol paraformaldehyde (18.600 g) is presented in 80 ml_ methanol. It is carefully added dropwise 0.6 mol terf butylamine (43.884 g, 63.32 ml_) in 80 ml of methanol with ice cooling. At a temperature of 0 ° C, add 0.3 mol of ammonium carbonate (28.820 g) and 0.6 mol of 40% glyoxal solution (87.040 g, 68.8 ml) in 160 ml of methanol. Thereafter, the reaction mixture is warmed to room temperature and stirred overnight, so that the resulting carbon dioxide can escape. Finally, the solvent must be removed and the product distilled under high vacuum through a column.
• 0.024 mol of methylimidazole (2.000 g, 1.94 ml) is added in an ACE pressure tube with 0.012 mol of dibromomethane (2.086 g, 0.84 ml) and 5 ml of tetrahydrofuran. The mixture is stirred for 24 hours at 130 ° C, the precipitated solid is filtered off and washed several times with a little tetrahydrofuran. The white solid 6 is obtained.
• 0.024 mol of methylimidazole (2.000 g, 1.94 ml) are carried in an ACE pressure tube 0.012 mol of diiodomethane (3.214 g, 0.97 ml) and 5 ml of tetrahydrofuran were added. The mixture is stirred for 20 hours at 110 ° C, the precipitated solid is filtered off and washed several times with a little tetrahydrofuran. The white solid 7 is obtained.
• 0.5 mmol of platinum (II) acetylacetonate (0.197 g) are introduced into 3 ml of dimethyl sulfoxide and heated to 100 ° C.
• a solution of 0.5 mmol of 1,1-dimethyl-3,3'-methylene-diimidazolium dibromide 6 (0.169 g) in 20 ml dimethyl sulfoxide is added over 13 hours with the aid of a syringe pump.
• the entire reaction mixture is stirred for a further 2 hours at 100.degree. Thereafter, the solvent is removed at 70 ° C in vacuo and the resulting solid washed twice with a little water and twice with a little tetrahydrofuran.
• the white solid 20 is still to dry.
• 0.55 mmol of platinum (II) acetylacetonate (0.216 g) and 0.55 mmol of 1,1'-di (2,4,6-trimethylphenyl) -3,3'-methylenediimidazolium dibromide 16 (0.300 g) are mixed with 5 ml of Dimethylsulfoxide in a Schlenk tube for 2 hours at 80 ° C, 2 hours at 100 ° C and a further 2 hours at 130 ° C stirred. The reaction mixture is cooled to 60.degree. There are 0.275 mmol of 1, 1 '-dimethyl-3,3'-methylene-diimidazolium-dibromide.
• 0.2 mol of benzimidazole (23.628 g) are dissolved in 55 ml of dimethyl sulfoxide. To this mixture is added 0.3 mol of powdered potassium hydroxide (16.832 g) and stirred for 30 minutes. Thereafter, 0.2 mol / so-propyl bromide (24.598 g, 18.8 mL) are added dropwise, while the mixture is cooled with a water bath. After stirring for 2 hours, the reaction mixture is quenched with water, extracted with dichloromethane, with Washed water and the organic phase dried over magnesium sulfate. Thereafter, the solvent is removed on a rotary evaporator. The result is a colorless liquid 54.
• transition metal carbene complexes In order to characterize the transition metal carbene complexes according to the invention further in the diluted solid, corresponding PVA films containing 2% by weight of the respective transition metal complex are prepared in PVA.
• PVA film In each case 2 mg transition metal carbene complex (37b, 42, 44, 45, 46) are dissolved per 1 ml 10% (mass percent) PVA solution (PVA in demineralized water (deionised water)) 60 ⁇ m squeegee a film on a microscope slide quartz glass). The film is then dried. The photoluminescence data of the corresponding transition metal carbene complexes are determined on the resulting films.
• Table 1 shows the photoluminescent quantum yields (QY) and the color coordinates (X RGB and Y RGB ) of selected transition metal carbene complexes of the general formula II (2% by weight of the respective transition metal complex in PVA (polyvinyl alcohol) films on quartz glass). summarized:

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