WO2007039383A1

WO2007039383A1 - Phosphorescent mixtures

Info

Publication number: WO2007039383A1
Application number: PCT/EP2006/066054
Authority: WO
Inventors: Gerhard Beer; Christoph Briehn
Original assignee: Wacker Chemie Ag
Priority date: 2005-10-04
Filing date: 2006-09-06
Publication date: 2007-04-12
Also published as: DE102005047397A1

Abstract

The invention concerns a phosphorescent mixture, containing: A) at least one organopolysilane, characterized by a repetition unit of general formula (I), in which R1 and R2, independent of one another, represent a hydrogen atom, an optionally substituted, completely or partially unsaturated or heteroatom-containing hydrocarbon radical with 1 to 20 C atoms, an optionally substituted completely or partially unsaturated or heteroatom-containing cyclic hydrocarbon radical with 1 to 20 C atoms, an optionally substituted heteroatom-containing aryl radical, and n represents an integer from 2 to 2000, with the provision that the repetition units, independent of one another, can exist as a sequence of different combinations of general formula (1) and can be distributed in any manner, for example, as a block or statistically in the organopolysilane molecule; B) at least one triplet emitter, and; C) optionally at least one additional compound from the group containing electron-conductive, hole-conductive, electron-blocking or hole blocking semiconducting organic materials having a polymeric, oligomeric, dendrimeric or low-molecular structure.

Description

Phosphorescent mixtures

The present invention relates to phosphorescent mixtures containing at least one organopolysilane and at least one triplet emitter, their preparation and their use as light-emitting or -empfangende polymer layer in photoactive devices.

Polymers and oligomers whose backbone is composed of linked Si atoms are called polysilanes or, alternatively, polysilylenes. The Si-Si linkage allows σ-conjugation along the polymer backbone and provides a unique electronic and photophysical property profile that differs greatly from structurally analogous polymers with sp ³ -hybridized C atoms in the polymer backbone and opens up a variety of technological applications. Application examples are described, for example, in Miller et al. , Chem. Rev. 1989, 89, 1359-1410.

The use of polysilanes as a hole-conducting material for the production of polymer-based organic light-emitting diodes, so-called polymer OLEDs, proved to be particularly interesting. Kepler et al. , Phys. Rev. B 1987, 35, 2818 determined for polymethylphenylsilane a

Charge mobility for positive charges in the range 10 ^"4 cm ² V- ¹ S ^{" 1} .

The structure and mode of operation of OLEDs are described, for example, in J. Shinar (Editor), Organic Light-Emitting Devices,

Springer-Verlag, New York, 2004. An OLED consists of one or more organic semiconducting layers, which are located between two electrodes. By creating An external voltage, typically between 2 and 20 volts, injects holes from the anode and electrons from the cathode into the semiconductive organic layers. If the charge carriers meet, an electron-hole pair is formed, a so-called exciton, whose decay can occur under the emission of light. The process described is called electroluminescence. The wavelength of the emitted light is determined by an organic, organometallic or inorganic emission material used in OLED production, which may be present in the form of an emission layer or as a dopant in other organic functional materials.

The layer structuring of OLEDs can be achieved by deposition of the organic materials from the gas phase

Vacuum conditions take place. A layer may contain one or more organic materials. Alternatively, the OLED fabrication can be done by applying the material layers from solution. For example, spin, dip, spraycoat processes and printing processes such as inkjet, flexo,

Offset or screen printing application. A prerequisite for the production of efficient OLEDs is a good solubility of the organic materials in solvents and a good film-forming property of the organic materials. Polysilanes have a good substitution pattern with a suitable

Solubility in organic solvents and show good film-forming properties. Likewise, the processing ability of polysilanes by evaporation processes in vacuum is known and for example by Hattori et al. , Jpn. J. Appl. Phys. 1996 (35), L1509-L1511. Xu et al. teach in Chem. Lett. 1998, 299-300 that polysilanes offer the potential for the production of UV-emitting OLEDs. First solution-produced, at room temperature in the near UV emitting polymer OLEDs contain linear, high molecular weight (M _w > 5 * 10 ⁵ g / mol) polymethylphenylsilane as a hole conductor material and emitter. The emission maximum of the electroluminescence was 360 nm.

Other applications of polysilanes for the production of OLEDs with electroluminescence in the visible wavelength range, based on the concept, polysilanes exclusively as

Hole manager to use and low molecular weight

Fluorescent dyes that are doped in the polysilane matrix to use as an emission source.

Kido et al. describe in J. Alloys. Compd. 1993, 192, 30-33 a red electroluminescent device with

Polymethylphenylsilan as a hole-conducting matrix substance and the

Lanthanoid complex tris (thienyltrifluoroacetylacetonato) - europium (III) as a molecularly doped, red emitter.

Seoul et al. describe in polym. Prepr. 2003, 44 (2), 435-436 discloses an OLED having a perylene-doped polymethylphenylsilane having electroluminescence maxima at 470 nm and 490 nm.

N. Kamata et al. describe in Appl. Phys. Lett. 2002, 81 (23), 4350-4352 the production of electroluminescent devices based on molecularly doped m- (hexoxyphenyl) phenylpolysilane. The fluorescent dyes used were perylene (blue), coumarin 6 (green), 4-dicyanomethylene-2-methyl-6- (p-diaminostyryl) -4H-pyran (orange) and zinc tetraphenylporphyrin (red). The polysilane serves in these cases as a hole-conducting matrix substance. The production of OLEDs whose electroluminescence is based on phosphorescence instead of fluorescence is a current approach to increasing the efficiency of OLEDs. Phosphorescent OLEDs described, for example, by Baldo et al. in Nature 1998, 395, 151-154, use phosphorescent rather than fluorescent emitters. Phosphorescent emitters can increase the power efficiency of OLEDs by a factor of four compared to fluorescent emitters for spinstatic reasons. Phosphorescent emitters are also referred to as triplet emitters.

Phosphorescent emitters are often used as a dopant in a matrix. The prerequisites which a matrix has to fulfill in order to ensure an effective triplet emission of the doped emitters are known to the person skilled in the art and are described, for example, by van Dijken et al. , J. Am. Chem. Soc. 2004, 126, 7718-7729 for polymeric materials.

A widely used matrix polymer is called polyvinylcarbazole in the following PVK. The use of PVK as a matrix polymer for green-emitting triplet emitters is described, for example, in P.I. Djurovic et al. , Polymer Preprints 2000, 41 (1), 770. A disadvantage of PVK is that it as

Matrix substance is not suitable for blue triplet emitters due to too low a triplet energy level.

It is therefore desirable to develop polymers as a matrix substance for blue triplet emitters.

Within the class of polysilanes, a polymer composition appears to be developable, which is also the use as Matrix substance for blue triplet emitters. WO 2003/092334 describes the use of polysilanes as a component for the production of phosphorescent copolymers by combining polysilane repeating units and phosphorescent repeating units, and the like

Use as luminescent substance in phoshoretic OLEDs. In particular, WO 2003/092334 describes transition metal-derivatized polymethylphenylsilanes which are used in the form of a mixture with electron-conducting substances for producing an emission layer in polymer OLEDs. Derivatives of iridium were used as electrophosphorescent transition metal complexes. The generation of blue, green and red electroluminescence could be shown. These phosphorescent polysilane copolymer structures known from the prior art are based on polymer emission after occupation of the excited states due to charge recombination in an OLED device. The implementation of the concept, however, requires elaborate, cost-intensive synthesis processes for the preparation of the copolymers for the generation of a desired emission color. Furthermore, the

Processability of the materials for the production of OLEDs limited to solution-based methods.

The object of this invention was therefore to produce polysilanes with optimized optoelectronic properties and to provide by combination with triplet emitters a light-emitting or -empfangendes material, which by an easy to perform and easy to be optimized variation of the mixture components for the widest possible range of the visible Light is suitable.

This object has been achieved by the inventive phosphorescent mixture containing A) at least one organopolysilane, characterized by a repeating unit of the general formula (1)

in which

Rl and R2 independently, one

Hydrogen atom, an optionally substituted, fully or partially unsaturated or heteroatoms containing

Hydrocarbon radical having 1 to 20 C atoms, an optionally substituted, fully or partially unsaturated or heteroatom-containing cyclic hydrocarbon radical having 1 to 20 C atoms

Atoms, an optionally substituted or heteroatom-containing aryl radical, n is an integer from 2 to 2,000, with the proviso that the repeating units can also be present independently of one another as a sequence of different combinations of the general formula (1) and in any desired manner, for example as a block or statistically, may be distributed in the organopolysilane molecule,

B) at least one triplet emitter,

C) and optionally at least one further compound from the group comprising electron-conductive, hole-conductive, electron-blocking or hole-blocking, semiconductive, organic materials polymeric, oligomeric, dendrimeric or low molecular weight structure.

The essential advantage of the polymer matrix according to the invention from A) and optionally C) is shown by an efficient charge transfer and / or energy transfer to a doped triplet emitter B).

Another advantage is that the inventive polymer matrices from A) and optionally C) have energetically high singlet and triplet states in order to avoid radiationless deactivation channels for the occupied triplet state of the doped triplet emitter by energy transfer to the polymer matrix. The property of high energetic triplet states is accompanied by the property of a large energy gap of polymers. Energy gap is the distance between the energetic ground state and the first excited state with singlet character.

Examples of optionally substituted, fully or partially unsaturated or heteroatom-containing hydrocarbon radicals R 1 or R 2 are methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, isopropyl, isobutyl, tert-butyl, 1 Phenylethyl, 1-phenylethenyl, ethenyl, butadienyl, 1-butenyl or 1-hexenyl radicals.

Examples of optionally substituted, fully or partially unsaturated or heteroatom-containing cyclic hydrocarbon radicals R 1 or R 2 are cyclobutyl,

Cyclopentyl, cyclohexyl, 2-methylpyrrolidonyl, oxethanyl, cyclooctatetraenyl, cyclohexadienyl, cyclohexenyl, tetrahydrothiophenyl or tetrahydrofuranyl radicals. Examples of optionally substituted or heteroatom-containing aryl radicals R 1 and R 2 are phenyl, biphenyl, terphenyl, methylphenyl, ethylphenyl, methoxyphenyl, propoylphenyl, butylphenyl, methylbiphenyl,

Methylterphenyl radicals, condensed aromatics such as naphthyl, methylnaphthyl, tert-butyl-perylenyl, anthryl, pentacenyl, furyl, phenylfuryl, thienyl, phenylthienyl, pyrrolyl, phenylpyrrolyl, pyridinyl, phenylpyridinyl, phenylacrydyl, Pyrimidyl, phenylpyrimidyl, imidazoyl, phenylimidazoyl, pyridyl, phenylpyridyl, porphyrinyl, oxadiazolyl, phenyloxadiazolyl, 1, 3, 4-triazolyl, phenyl-1,3,3,4-triazolyl, benzimidazolyl, phenylbenzimidazoyl , Oxazolyl or phenyloxazolyl radicals.

Examples of heteroatoms are silicon, oxygen, sulfur and nitrogen.

Examples of substituents are halogen atoms, silyl groups, alkyl groups, alkoxy groups, alkylthio groups,

Alkylamino groups, alkylsilyl groups, aryl groups, aryloxy groups, arylthio groups, arylamino groups, arylsilyl groups, arylalkyl groups, arylalkoxy groups, arylalkylthio groups, arylalkylamino groups, arylalkylsilyl groups, acyl groups, acyloxy groups, imino groups, amide groups, arylalkenyl groups, arylalkynyl groups, cyano groups, nitrile groups, isonitrile groups, nitro groups or nitroso groups.

The preparation of the organopolysilane A) is carried out by

Polymerization of one or more monomer units.

The preparation methods are known to the person skilled in the art and are described, for example, in Jones et al. (Eds.), "Silicon Containing Polymers ", Section 3, Kluwer Academic Publishers, 2003, the disclosure of which is also to be the subject of this application.

Examples of the preparation methods are the

Dehydropolymerization of hydrosilanes using transition metal catalysts, a ring-opening polymerization starting from cyclic silanes, a condensation of lithiosilanes with halosilanes, the electrochemical polymerization of dihalosilanes, the condensation of

Halosilanes with reducing agents such as sodium naphthalide and the condensation of halosilanes with alkali metals, the so-called Kippingmethode.

In particular, the implementation of the Kippingmethode to form organopolysilanes from monomer has preserved. The synthesis takes place starting from dihalosilanes in a reductive polymerization by reaction with alkali metals in high-boiling, inert solvents such as toluene or xylene under reflux conditions in an inert gas atmosphere.

Alternatively, the reaction can be carried out at room temperature and use of ultrasonic conditions in an inert gas atmosphere.

Possible monomer components for implementation by the

Kipping method are known in the art and, for example, Miller et al. , Chem. Rev. 1989, 89, 1359-1410, the disclosure of which should also be the subject of this application. As monomer building blocks, for example, dimethydichlorosilane, diphenyldichlorosilane,

Methylphenyldichlorosilane, propoxyphenyldichlorosilane are used. The dihalosilanes used as monomer can, for example, by reaction of trichlorosilane or Tetrachlorosilane be prepared with Grignard reagents or an organolithium compound of an organic compound. Furthermore, dihalosilanes can be prepared, for example, by hydrosilylation of a hydrodichlorosilane with an olefinic or acetylene-derivatized organic compound.

Organopolysilanes A) according to the invention can also be prepared by polymer-analogous reactions. An example is the metal-catalyzed derivatization of a polyphenylsilane with styrene in a hydrosilylation reaction.

In the context of the invention, organopolysilanes A) preferably have a number-average molecular weight Mn of between 300 g / mol and 500,000 g / mol. More preferably, the number average molecular weight Mn is between 400 g / mol and 100,000 g / mol. Most preferably, Mn is 500 g / mol to 50,000 g / mol.

The structure of the organopolysilanes A) according to the invention is preferably linear, branched, dendritic or cyclic.

Organopolysilanes A) present as copolymer may have a random, alternating or block-like structure.

The radicals R 1 and R 2 are preferably a substituted or unsubstituted phenyl or benzyl radical or a linear alkyl radical, in particular having 1 to 10, especially 1 to 6, carbon atoms. Particularly preferred radicals R 1 and R 2 are methyl, ethyl, n-propyl, phenyl, 4-alkoxyphenyl and 4-alkoxybenzyl.

For organopolysilanes A) of the formula (1), n is preferably an integer from 2 to 2,000. Particularly preferably an integer from 2 to 1000. Most preferably an integer from 2 to 500.

The triplet emitters B) in the context of the invention are compounds which emit light from the triplet state, ie exhibit phosphorescence instead of fluorescence, preferably organic or organometallic triplet emitters which may be low molecular weight, oligomeric, dendrimeric or polymeric compounds. Triplet emitters B) known to the person skilled in the art are transition-metal complexes which are composed of at least one central atom from the 3rd to 12th group of the Periodic Table and organic or organometallic chelating ligands which coordinate at the central atom.

Examples of central atoms are yttrium, rhenium, ruthenium, rhodium, osmium, iridium, palladium, platinum or gold, as well as metals from the group of lanthanides.

The structure of triplet emitters is described, for example, in US 6,303,238, US 6,310,360, WO 01/41512, WO 01/39234, WO 03/079736, WO 03/084972 and in Lamansky et al. , Inorg. Chem. 2001, 40, 1704 or Lamansky et al. , J. Am. Chem. Soc. 2001, 123, 4304, the disclosure of which is also intended to be the subject of this application.

Preferred common commercial examples of blue, green and red emitting triplet emitters B) are bis (3,5-difluoro-2 (2-pyridyl) phenyl- (2-carboxypyridyl) iridium (III) [FIrpic] of the formula ( 2), iridium (III) tris (2- (4-tolyl) pyridinato-N, C ² ) [Ir (mppy) ₃ ] of the formula (3), tris (1-phenylisoquinoline) iridium (III) [Ir (piq) ₃ ] of the formula (4) and Bis- (1- (4 '- tert -butyl-phenyl) -isoquinoline) -1,3-pentanedionate-iridium (III) [Ir (piq-t) 2 (acac)] of the formula (5).

FIrpic

Ir (mppy)

Ir (piq) 3

Ir (piq-t) ₂ (acac; Organic compounds C) with electron transport properties are known to the person skilled in the art and are described, for example, by Kulkarni et al. in Chem. Mater. 2004, 16, 4556-4573, the disclosure of which should also be the subject of this application.

Polymers, oligomeric, dendrimeric or low molecular weight electron-conducting organic compounds C) include, for example, oxadiazole structures, triazole structures, metal chelates of 8-hydroxyquinoline, for example with Al, Ga, In or metal chelates of thiazole units, for example with Zn, imidazole, benzimidazole, oxazole, benzoxazole -, thiadiazole, benzthiadiazole, imidazole, benzimidazole, triazine, thiodiazole, pyridine, quinoline, quinoxaline, anthrazoline, phenantroline, silol, anthraquinone or Anthrachinondimethanstrukturen, fluorenone and derivatives, and cyanosubstituted semiconducting organic materials or perfluorinated semiconducting organic materials.

Organic compounds C) with hole-blocking properties are known to the person skilled in the art and are distinguished by a high ionization potential. Examples of low molecular weight, hole-blocking organic compounds C) are 3-phenyl-4 (1'-naphthyl) 5-phenyl-l, 2, 4-triazole and 2, 9-dimethyl-4, 7-diphenyl-1, 10-phenanthrol in .

Organic compounds (C) with hole transport properties are known to the person skilled in the art and are described, for example, in EP 0766498, EP 0838976 or PM Borsenberger et al. in Organic Photoreceptors for Xerography, Marcel Dekker, New York 1998, the disclosure of which is also to be the subject of this application. Polymers, oligomers, dendrimers or low molecular weight hole-conducting organic compounds C) contain, for example, triarylamine, benzidine, pyrazoline, phthalocyanine, carbazolyl, thiophenyl, fluorenyl or phenylenevinylene structures.

Semiconductive organic matrix materials according to the invention from A) and optionally C) for triplet emitter B) are preferably distinguished by a high optical band gap. In this case, the energy gap between the energetic ground state (HOMO) and the energetically first excited state (LUMO) of the organic material is referred to as the optical band gap.

To determine the optical band gap of organic matrix materials from A) and optionally C), various methods are available to the person skilled in the art. A common method is the use of absorption spectroscopic data. In this case, approximately the energy of the optical band gap of the energy of the long-wave edge of the absorption band of the organic material can be equated. Organopolysilanes A) having an optical band gap of at least 2.5 eV, more preferably at least 3.0 eV, are preferably used for the phosphorescent mixture according to the invention.

The phosphorescent mixture preferably contains at least 0.5% of the triplet emitter B).

The phosphorescent mixture preferably contains at most 99.5% by weight of the organopolysilane A).

In a preferred embodiment, the phosphorescent mixture contains at least 30 Gewi of Organopolysilane A).

In a further preferred embodiment, the phosphorescent mixture contains at least 40% by weight of the organopolysilane A).

In a particularly preferred embodiment, the phosphorescent mixture contains at least 40% by weight of the organopolysilane A), at least 0.5% by weight of the triplet emitter B) and at least 10% by weight of a further compound C).

In a further particularly preferred embodiment, the phosphorescent mixture contains at least 40% by weight of the organopolysilane A), at least 0.5% by weight of the triplet emitter B) and at least 20% by weight of a further compound C).

In a further preferred embodiment, the phosphorescent mixture contains at least 35% by weight of the organopolysilane A), at least 0.5% by weight of the triplet emitter B), at least 20% by weight of an electron-conducting compound C) and at least 5% by weight of a hole-conducting compound C).

In a further particularly preferred embodiment, the phosphorescent mixture contains at least 35% by weight of the organopolysilane A), at least 0.5% by weight of the triplet emitter B), at least 20% by weight of an electron-conducting compound C) and at least 10% by weight of a hole-conducting compound C).

Furthermore, preferably used matrix materials of A) and optionally C) are characterized by an energetically high triplet state. The methods for determining the triplet energy of an organic material are known to those skilled in the art. A common procedure is the determination of Triplet energy states by low-temperature emission spectroscopy. An energetically high triplet state of the matrix material from A) and optionally C) enables the effective triplet emission of a triplet emitter B) doped into the matrix material by preventing an energy back transfer from the excited triplet state of the triplet emitter B) onto the matrix. The location of the triplet energy state of an organic material correlates with the amount of optical band gap of the material in the mold such that a high triplet energy is expected for high optical band gap materials.

Organopolysilanes A) whose triplet energy is greater by 0.1 eV than the triplet energy of a triplet emitter B) are preferably used for the phosphorescent mixture according to the invention. Particularly preferably, the triplet energy of an organopolysilane A) according to the invention is at least 0.2 eV larger than the triplet energy of a triplet emitter B).

In a further preferred embodiment, in addition to A) and B), the phosphorescent mixture also contains at least one further compound C) from the group comprising electron-conductive, hole-conducting, electron-blocking or hole-blocking organic semiconducting materials having a polymeric, oligomeric, dendrimeric or low molecular weight structure.

A preferred method for producing the phosphorescent mixture is characterized in that the components are applied after dissolving or suspending in a solvent on a substrate and the solvent is then evaporated off. Preferred solvents are organic solvents such as acetone, tetrahydrofuran, dioxane, dichloromethane, chloroform, toluene, 1, 2-dichloroethane, chlorobenzene, dichlorobenzene or xylene, and mixtures of these.

The application of the solution can be carried out by coating processes known to those skilled in the art, such as spin coating, dip coating, knife coating, spraying, printing processes such as inkjet printing, gravure printing, screen printing and flexographic printing.

Preference is given to organopolysilanes A) which show good solubility in organic solvents and good film-forming properties.

Another advantage of the invention is that in addition to the method described above, other methods for preparing the mixture of A), B) and optionally C) according to the invention are suitable.

A further preferred production form is characterized in that the mixture components are thermally evaporated separately and collectively deposited on a substrate.

In a further preferred form, the mixtures according to the invention are prepared by deposition of the mixture components from the gas phase, the so-called Organic Vapor Phase Deposition method.

In another manufacturing method, the individual

Components of solution or suspension applied in separate steps and subsequent diffusion of the components leads to the mixture according to the invention. In detail, it turns this process is as follows: The mixture according to the invention is prepared by first producing a film containing at least one organopolysilane A) by processing from solution or suspension or by evaporation. In the cited film initially no triplet emitter B) is included. A second film containing at least one triplet emitter B) is applied to said film. The mixture according to the invention is produced by diffusion of the triplet emitter B) into the said film containing organopolysilane A).

The phosphorescent mixtures of the present invention are used as a light emitting or receiving polymer layer in photoactive devices. The photoactive devices are, for example, OLEDs. When used as a light-emitting material, for example as a polymer layer in an OLED, light is emitted due to a current flow induced by an electric field.

The structure of OLEDs is known to the person skilled in the art and described, for example, in J. Shinar (Editor), Organic Light-Emitting Devices, Springer-Verlag, New York, 2004.

A typical structure of a solution-produced polymer OLED for the execution of the examples described below is characterized by the layer sequence anode / hole injection layer / polymer layer / cathode, but is not limited to this layer structure.

Suitable anode materials are transparent and sufficiently conductive to provide effective hole transport to the organic polymer layer. Anode materials preferably have a work function of greater than 4 eV. preferred Materials are metals or metal oxides such as gold, platinum, selenium, tin oxide, indium tin oxide or copper iodide or conductive organic materials such as the conjugated polymers polyaniline and derivatives, polypyrrole and derivatives, polythiophene and derivatives, polyphenylenevinylene and derivatives, polyquinoline and derivatives, polyquinoxaline and derivatives, polymers containing aromatic amine structures in the main chain or side chain or metal phthalocyanines.

The function of the hole injection layer is analogous to the function of the anode materials. A hole injection layer must be sufficiently conductive to ensure effective hole transport from the anode to the organic polymer layer. Typically, the hole injection layer additionally serves to smooth the surface structure of the anode. Suitable materials for a hole injection layer are conductive organic materials such as the conjugated polymers polyaniline and derivatives, polypyrrole and derivatives, polythiophene and derivatives, polyphenylenevinylene and derivatives, polyquinoline and derivatives, polyquinoxaline and derivatives, polymers containing aromatic amine structures in the main chain or side chain or metal phthalocyanines. A particularly suitable material is polystyrenesulfonic acid doped polyethylenedioxothiophene, referred to as PEDOT.

Suitable cathode materials are sufficiently conductive to ensure effective electron transport to the organic polymer layer. The preferred cathode material is materials having a working function of less than 4 eV. Typical cathode materials are metals, metal alloys, doped metals, and metal salts such as for example, barium, magnesium, aluminum, calcium, silver, lithium, sodium fluoride, lithium fluoride, cesium fluoride and alloys of these metals. The cathode may be constructed of one or more layers.

The electroluminescence occurs in polymer OLEDs in a polymer film embedded between the electrodes or between the charge carrier injection layers. Polymer film in the sense used means that at least one component of the film is present as a polymer.

Furthermore, polymer film in the sense used means that no

Restriction to a single layer is present, but may be present several adjacent polymer layers.

In a preferred form, the polymer layer contains the phosphorescent mixture according to the invention. The thickness of the

Polymer layer containing the phosphorescent mixture according to the invention is preferably 10 nm to 250 nm, more preferably 40 nm to 150 nm.

As part of the inventive phosphorescent mixture in the polymer layer of the OLED organopolysilanes A) are used with an ionization potential, which allows an effective charge injection from the anode or the hole injection layer.

This is the case when the energy difference between the working functions of the anode or the hole injection layer and the ionization potential of the organopolysilane A) is minimized, if the

Ionization potential of the organopolysilane A) is greater than the working function of the anode or the Hole injection layer.

An effective charge injection is also made possible if the ionization potential of the organopolysilane A) is smaller than the working function of the anode or of the hole injection layer.

The determination of the amount of ionization potential of organic materials is known to the person skilled in the art. For hole-conductive organic materials, the determination of the ionization potential can be carried out by ultraviolet photoelectron spectroscopy or by electrochemical measurements in solution. A common method is the determination of the oxidation potential of organic materials by

Cyclic voltammetry. By knowing the relative position of the peak potentials of the oxidation waves of the organic materials against ferrocene as an internal standard, the determination of the ionization potential of the polymer systems against vacuum is possible. The calculation is based on the assumption that the energy level of ferrocene against vacuum is -4.8 eV, as described by J. Pommerehne et al. in Adv. Mater. 1995, 7, 551 was published, whose disclosure in this respect should also be the subject of this application.

Depending on the substitution pattern, the organopolysilanes A) have ionization potentials between 6.0 eV and 5.0 eV, determined by cyclic voltammetry in solution.

The phosphorescent mixture preferably contains

Organopolysilane A) having an ionization potential of at most 6.5 eV. Particularly preferably, the phosphorescent mixture contains organopolysilane A) having an ionization potential of at most 6.0 eV.

Examples

The following examples describe the basic practicability of the present invention without, however, limiting it to the contents disclosed therein.

Cyclic voltammetric experiments

The cyclovoltammetric measurements were carried out in anhydrous

Methylene chloride was carried out with a potentiostat M273 from EG & G Princeton Applied Research, Princeton, N.J., USA.

The concentration of the solutions studied was about

10 ^{~ 3} mol / 1. As conductive salt was

Tetrabutylammonium hexafluorophosphate in a concentration of

0.1 mol / 1 added. The measurement was carried out in a three-electrode arrangement with a Pt disk (diameter 1 mm) as a working electrode, a Pt wire counter electrode and a

Silver / silver chloride pseudo reference electrode (internal calibration against ferrocene / ferrocenium). The feed rate was

100 mV / s.

The following abbreviations are used in the text below:

ITO: indium tin oxide.

PEDOT: poly (3,4-ethylenedioxythiophene) / poly (styrenesulfonic acid).

PTFE: polytetrafluoroethylene. PVDF: polyvinylidene fluoride.

PBD: 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1, 3, 4-oxadiazole.

TAZ: 3- (4-biphenylyl) -4-phenyl-5- (4-tert-butylphenyl) -1,2,4-triazole. Silane 1: anisylmethyldichlorosilane.

Silane 2: 4-Butoxyphenyl-methyldichlorosilane.

General regulation for the production of polymer OLEDs

The layer structure of the prepared OLEDs is ITO / PEDOT / semiconducting polymer mixture / Ca / Ag.

The production of OLEDs took place on cleaned ITO substrates of the company Präzisions Glas & Optik GmbH, Iserlohn, Germany (CEC020S), which started directly before the beginning of the manufacturing process 20

Minutes were treated with ozone (UV ozone cleaner UVOH 150 LAB the company FHR Anlagenbau, Ottendorf-Okrilla, Germany). On the ITO layer was formed by spin coating at speeds of 1500 rev / min to 2500 rev / min, a PEDOT polymer anode (Baytron P VP. AL 4083) nm with a layer thickness between 30 and deposited 60 nm and 10 min at 110 ⁰ C annealed. Baytron P was filtered before application (0.45 μm, PVDF). Subsequently, with exclusion of atmospheric moisture (content H2O <5 ppm) and oxygen (content O2 <5 ppm) in a glove box with Stickstoffinertgasatmosphäre by spin coating with speeds between 1000 and 5000 rev / min applied the polymer mixture with a layer thickness of 80 nm to 150 nm , The polymer was processed from a solution in 1, 2-dichlorobenzene with a solids content between 2% and 6%, filtered before the order (0.45 microns, PTFE) and after formation of the layer for 10 min at 8O ⁰ C in the glove box annealed , Finally, without interruption of the protective gas atmosphere, the vapor deposition with metal cathodes. For this purpose, calcium was applied in a high vacuum (<5 × 10 -6 mbar) with a layer thickness of 5 nm and provided with a silver protective layer of thickness 200 nm.

The various layer thicknesses were determined by a Profiler Dektak 6M from Veeco Europe SAS, Dourdan Cedex, France or by quartz oscillating during the vapor deposition. The current-voltage characteristic and current-luminance characteristic were carried out under exclusion of humidity and oxygen within a glovebox. The control of the measuring devices and the data acquisition took place with a Keithley KPCI-3104 measuring card and suitable pre-amplifiers. The detection of the photocurrent was carried out with a calibrated photodiode 74868 UG - 625 B / U S2281 the company Hamamatsu Photonics Germany GmbH, Herrsching, Germany and corresponding self-made preamplifiers (current-voltage converters).

The threshold voltage is the voltage threshold above which a photocurrent distinguishable from the background noise is detected.

Chemicals:

PBD was developed by Sigma-Aldrich-Chemie GmbH, Taufkirchen,

Germany related. The transition metal complex (2) F (Ir) pic was purchased from HW Sands, Indianatown, USA. The transition metal complex (5) Ir (piq-t) 2 (acac) was purchased from Sensient Imaging Technologies GmbH, Bitterfeld-Wolfen, Germany. Ir (mppy) ₃ (3) and Ir (piq) ₃ (4) were purchased from American Dye Source Inc., Quebec, Canada. Baytron P VP. Al 4083 (PEDOT) was purchased from HC Starck, Leverkusen, Germany. Calcium and silver were purchased from Sigma-Aldrich-Chemie GmbH, Taufkirchen, Germany. All substances were used without further purification. The anhydrous solvent was purchased from Sigma-Aldrich-Chemie GmbH, Taufkirchen, Germany.

Spectroscopy: The detection of the electroluminescence spectra and photoluminescence spectra was carried out using the device LS55 from Perkin Elmer, Rodgau-Jugesheim, Germany. To determine the photoluminescence spectra, dichloromethane of the quality grade UVASOL.RTM. From VWR International GmbH, Ismaning, Germany was used as the solvent. As the excitation wavelength for the triplet emitters of the formulas (2) to (5), the wavelength of the longest wavelength absorption was used.

Synthesis examples:

Example A:

Synthesis of 4-alkoxyphenyl-methyl-dichlorosilanes (silane 1, silane 2)

A solution of a Grignard reagent prepared from 4-bromoanisole or l-bromo-4-butoxybenzene (0.26 mol) in 90 ml diethyl ether was added at 0 ⁰ C to a solution of trichloromethylsilane (0.26 mol) was dropped in 250 ml of diethyl ether and then heated to reflux for 1 h. After distilling off the solvent, the product was distilled in vacuo. Silane 1 or silane 2 was obtained as colorless oils in 19% or 29% yield.

Example B:

General procedure for the synthesis of polysilanes (polysilane 1-5)

To a dispersion of 1.67 g of sodium in 50 ml of toluene at 110 ⁰ C within 30 min, a solution of one or more dichlorosilanes such as silane 1, silane 2, dimethyl-dichlorosilane, phenyl-methyl-dichlorosilane and / or methyl-propyl dichlorosilane and optionally methyltrichlorosilane in 20 ml of toluene and the reaction mixture heated for 2 h to reflux. After cooling the mixture, 20 ml of methanol and 70 ml of water were added dropwise, the organic phase was separated and washed with 2 x 70 ml of water. The product was precipitated as a colorless solid by dropwise addition of the organic phase in methanol, isolated by filtration and dried in vacuo. Polysilanes 1-5 were obtained as colorless solids.

Polysilane 1: Following the general procedure, a solution of 0.25 g (1.94 mmol) of dimethyldichlorosilane and 6.43 g (29.06 mmol) of silane 1 was added dropwise to the sodium dispersion. 2.19 g of polysilane 1. Cyclic voltammetric measurements gave an irreversible oxidation at 235 mV against ferrocene / ferrocenium.

Polysilane 2: Following the general procedure, a solution of 0.29 g (2.28 mmol) of dimethyldichlorosilane and 9.00 g (34.0 mmol) of silane 2 was added dropwise to the sodium dispersion. 1.60 g of polysilane 2 were obtained.

Cyclic voltammetric measurements revealed an irreversible oxidation at 220 mV against ferrocene / ferrocenium.

Polysilane 3: Following the general procedure, a solution of 0.25 g (1.97 mmol) of dimethyldichlorosilane and 5.66 g (29.6 mmol) of phenylmethyldichlorosilane was added dropwise to the sodium dispersion. Cyclic voltammetric measurements revealed an irreversible oxidation at 510 mV against ferrocene / ferrocenium.

Polysilane 4: According to the general procedure, a solution of 4.95 g (32.0 mmol) of methyl-propyldichlorosilane was added dropwise to the sodium dispersion. 1.59 g of polysilane 4 were obtained. Cyclic voltammetric measurements revealed irreversible oxidation at 720 mV against ferrocene / ferrocenium.

Polysilane 5: Following the general procedure, a solution of 7.0 g (37.0 mmol) of phenylmethyldichlorosilane, 0.28 g (2.0 mmol) of dimethyldichlorosilane and 0.64 g (4.0 mmol) of trichloromethylsilane in the Sodium dispersion is added dropwise. 5.98 g of polysilane were obtained. 5. Cyclic voltammetric measurements gave an irreversible oxidation at 510 mV against ferrocene / ferrocenium.

Table 1 shows the maxima of the photoluminescence spectra of the triplet emitter used of the formulas (2) to (5).

Table 1:

In the examples and in the comparative example, the layer thickness in (nm) is given in brackets.

Comparative example for non-inventive blue emitting OLEDs

Comparative Example 1: PVK, F (Ir) pic of the formula (2), PBD Using the general procedure, a device with the layer structure ITO / PEDOT (57 nm) / polyvinylcarbazole (69% by weight), PBD (30% by weight), F ( Ir) pic of formula (2) (1 wt) (91 nm) / Ca (5 nm) / Ag (200 nm). The device showed a threshold voltage of 6.5 V and blue electroluminescence with a maximum at 410 nm observed emission is a matrix emission of polyvinylcarbazole.

The desired phosphorescence of the doped emitter F (Ir) pic of the formula (2) with a maximum of the emission wavelength in the range 465 nm could not be observed.

Examples of inventive blue-emitting OLEDs

Example 1: Polysilane 1, PBD, F (Ir) pic of the formula (2)

Using the general procedure, a device with the layer structure ITO / PEDOT (41 nm) / polysilane 1 (69% by weight), PBD (30% by weight), F (Ir) pic of the formula (2) (1% by weight) (96 nm) / Ca (5 nm) / Ag (200 nm). The device showed a threshold voltage of 6.3 V and blue electroluminescence of the doped emitter with a maximum at 469 nm.

Example 2: Polysilane 3, PBD, F (Ir) pic of the formula (2)

Using the general procedure, a device with the layer structure ITO / PEDOT (41 nm) / polysilane 3

(69% by weight), PBD (26% by weight), F (Ir) pic of formula (2) (5% by weight) (99 nm) / Ca (5 nm) / Ag (200 nm). The device showed a threshold voltage of 12.7 V and blue electroluminescence of the doped emitter with a maximum at 473 nm.

Example 3: Polysilane 5, PBD, F (Ir) pic of the formula (2)

Using the general working procedure was a

Device with the layer structure ITO / PEDOT (55 nm) / polysilane 5

(65 wt.), PBD (30 wt.), F (Ir) pic of formula (2) (5 wt.) (113 nm) / Ca (5 nm) / Ag (200 nm). The device showed a threshold voltage of 18.5 V and blue electroluminescence of the doped emitter with a maximum at 471 nm. In all the examples according to the invention, it was possible to show the desired phosphorescence of the doped emitter F (Ir) pic of the formula (2) with a maximum of the emission wavelength in the region of 465 nm.

Examples of green emitting OLEDs according to the invention

Example 4: Polysilane 1, PBD, Ir (mppy) _{3 of} the formula (3) Using the general procedure, a device with the layer structure ITO / PEDOT (34 nm) / polysilane 1 (49% by weight), PBD (50% by weight) was prepared. , Ir (mppy) ₃ of formula (3) (1 wt%) (97 nm) / Ca (5 nm) / Ag (200 nm). The device showed a threshold voltage of 5.5 V and green electroluminescence of the doped emitter with a maximum at 510 nm.

Example 5: Polysilane 3, Ir (mppy) ₃ of formula (3) Using the general procedure, a device with the layer structure ITO / PEDOT (33 nm) / polysilane 3 (97% by weight), Ir (mppy) _{3 of} the formula (3) (3 wt%) (117 nm) / Ca (5 nm) / Ag (200 nm). The device showed a threshold voltage of 21 V and green electroluminescence of the doped emitter with a maximum at 514 nm.

Example 6: Polysilane 3, TAZ, Ir (mppy) _{3 of} the formula (3) Using the general procedure, a

Device with the layer structure ITO / PEDOT (38 nm) / polysilane 3 (69% by weight), TAZ (30% by weight), Ir (mppy) _{3 of} the formula (3) (1% by weight) (119 nm) / Ca (5 nm ) / Ag (200 nm). The device showed a threshold voltage of 18 V and green electroluminescence of the doped emitter with a maximum at 508 nm.

Example 7: Polysilane 3, PBD, Ir (mppy) _{3 of} the formula (3) Using the general procedure, a device with the layer structure ITO / PEDOT (39 nm) / polysilane 3 (69% by weight), PBD (25% by weight), Ir (mppy) _{3 of} the formula (3) (6% by weight) (124 nm) / Ca (5 nm) / Ag (200 nm). The device showed a threshold voltage of 8 V and green electroluminescence of the doped emitter with a maximum at 515 nm.

Example 8: Polysilane 4, PBD, Ir (mppy) _{3 of} the formula (3) Using the general procedure, a device with the layer structure ITO / PEDOT (60 nm) / polysilane 4 (69% by weight), PBD (30% by weight) was prepared. , Ir (mppy) ₃ of formula (3) (1 wt%) (90 nm) / Ca (5 nm) / Ag (200 nm). The device showed a threshold voltage of 9.0 V and green electroluminescence of the doped emitter with a maximum at 510 nm.

Example 9: Polysilane 5, PBD, Ir (mppy) _{3 of} the formula (3) Using the general procedure, a device with the layer structure ITO / PEDOT (35 nm) / polysilane 5 (60% by weight), PBD (30% by weight), Ir (mppy) ₃ of formula (3) (10 wt) (98 nm) / Ca (5 nm) / Ag (200 nm). The device showed a threshold voltage of 9.1 V and green electroluminescence of the doped emitter with a maximum at 514 nm.

In all examples of the invention, the desired phosphorescence of the doped emitter Ir (mppy) _{3 of} the formula

(3) with a maximum emission wavelength in the 515 nm range.

Examples of inventive red-emitting OLEDs

Example 10: Polysilane 1, PBD, Ir (piq-t) 2 (acac) of the formula (5) Using the general procedure, a device with the layer structure ITO / PEDOT (39 nm) / polysilane 1 (67% by weight), PBD (30% by weight), Ir (piq-t) ₂ (acac) of the formula (5) (3% by weight) (101 nm) / Ca (5 nm) / Ag (200 nm). The device showed a threshold voltage of 8.2 V and red

Electroluminescence of the doped emitter with a maximum at 618 nm.

EXAMPLE 11 Polysilane 2, PBD, Ir (piq) _{3 of} the Formula (4) Using the general procedure, a device with the layer structure ITO / PEDOT (35 nm) / polysilane 2 (69% by weight), PBD (30% by weight), Ir (piq) _{3 of} the formula (4) (1 wt) (150 nm) / Ca (5 nm) / Ag (200 nm). The device showed a threshold voltage of 11 V and red electroluminescence of the doped emitter with a maximum at 614 nm.

Example 12: Polysilane 3, PBD, Ir (piq-t) ₂ (acac) of formula (5) Using the general procedure, a device with the layer structure ITO / PEDOT (39 nm) / polysilane 3 (69 wt), PBD (30 wt.), Ir (piq-t) ₂ (acac) of the formula (5) (1 wt.) (101 nm) / Ca (5 nm) / Ag (200 nm). The device showed a threshold voltage of 8.8 V and red

Electroluminescence of the doped emitter with a maximum at 620 nm.

In all the examples according to the invention, the desired phosphorescence of the doped emitter Ir (piq-t) ₂ (acac) of the

Formula (5) or Ir (piq) _{3 of} the formula (4) are shown with a maximum of the emission wavelength in the range 620 nm or 615 nm.

Claims

claims

1. Phosphorescent mixture containing

A) at least one organopolysilane, characterized by a repeating unit of the general formula (1)

wherein R 1 and R 2 independently of one another

Hydrogen atom, an optionally substituted, fully or partially unsaturated or heteroatom-containing hydrocarbon radical having 1 to 20 C

Atoms, an optionally substituted, fully or partially unsaturated or heteroatom-containing cyclic hydrocarbon radical having 1 to 20 C

Atoms, an optionally substituted or heteroatom-containing aryl radical, n is an integer from 2 to 2,000, with the proviso that the repeating units can also be present independently of one another as a sequence of different combinations of the general formula (1) and in any desired manner, for example as a block or statistically, in the organopolysilane molecule can be distributed.

B) at least one triplet emitter

C) and optionally at least one further compound from the group comprising electron-conductive, hole-conductive, electron-blocking or hole-blocking, semiconductive, organic materials having a polymeric, oligomeric, dendrimeric or low molecular weight structure.

2. Phosphorescent mixture according to claim 1, characterized in that the organopolysilane A) has a number average molecular weight Mn between 300 g / mol and 500,000 g / mol.

3. Phosphorescent mixture according to claim 1 or 2, characterized in that the organopolysilane A) has an optical band gap of at least 2.5 eV.

4. Phosphorescent mixture according to one of claims 1 to 3, characterized in that the mixture contains at least 0.5 Gewi B).

5. Phosphorescent mixture according to one of claims 1 to 4, characterized in that it contains at least 30% by weight of A).

6. Phosphorescent mixture according to one of claims 1 to 5, characterized in that A) a

Ionization potential of at most 6.5 eV has.

7. A process for the preparation of the phosphorescent mixture according to any one of claims 1 to 6, characterized in that the components are applied after dissolving or suspending in a solvent or solvent mixture, on a substrate and the solvent is then evaporated.

8. A process for the preparation of the phosphorescent mixture according to any one of claims 1 to 6, characterized in that the mixture components are thermally evaporated separately and collectively deposited on a substrate.

9. A process for the preparation of the phosphorescent mixture according to any one of claims 1 to 6, characterized in that the mixture is prepared by deposition from the gas phase of the so-called Organic Vapor Phase Deposition method.

10. A process for the preparation of the phosphorescent mixture according to one of claims 1 to 6, characterized in that the individual components are applied from solution or suspension in separate steps and a subsequent diffusion of the components takes place.

11. Use of the mixture according to one of claims 1 to 6 as a light-emitting or -empfangende polymer layer in photoactive devices.

12. Use of the mixture according to claim 11, characterized in that the thickness of the polymer layer is 10 to 250 nm.

Use according to one of claims 11 or 12, characterized in that the photoactive devices are OLEDs.