WO2005061655A1

WO2005061655A1 - Use of gadolinium(iii) chelates as luminescent materials in organic light-emitting diodes (oleds)

Info

Publication number: WO2005061655A1
Application number: PCT/EP2004/014494
Authority: WO
Inventors: Arnd Vogler; Andreas Strasser
Original assignee: Basf Aktiengesellschaft
Priority date: 2003-12-19
Filing date: 2004-12-20
Publication date: 2005-07-07
Also published as: DE10360680A1

Abstract

The invention relates to the use of gadolinium(III) complexes of formulas (I) and (II) as emitter molecules in organic light-emitting diodes, wherein the radicals have the meaning defined in the claims and the description. The invention further relates to the use of said gadolinium(III) complexes as a light-emitting layer in OLEDs, a light-emitting layer containing at least one gadolinium(III) complex, an OLED containing said light-emitting layer, and devices comprising an inventive OLED.

Description

Use of Gadolinium (III) chelates as luminescent materials in organic light-emitting diodes (OLEDs)

description

The present invention relates to the use of gadolinium (III) complexes as emitter molecules in organic light-emitting diodes (OLEDs), the use of the gadolinium (III) complexes as light-emitting layer in OLEDs, a light-emitting layer containing at least one gadolinium (III). Complex, an OLED containing this light-emitting layer and devices that contain an OLED according to the invention.

In organic light-emitting diodes (OLEDs), the property of materials is used to emit light when they are excited by electrical current. OLEDs are particularly interesting as an alternative to cathode ray tubes and liquid crystal displays for the production of flat screens. Due to the very compact design and the intrinsically lower power consumption, devices containing OLEDs are particularly suitable for mobile applications, for example for applications in cell phones, laptops, etc.

Numerous materials have been proposed that emit light when excited by electrical current.

JP 01-256584 relates to an electroluminescent thin film element which contains a rare earth metal complex as a luminescent material. Complexes of the following formulas are mentioned as suitable complexes

EP-A 0 556 005 relates to compounds which are obtained by reacting an imido reagent such as diphenylphosphonimido-triphenylphosphorane with a chelate of a transition metal, a lanthanide or an actinide, for example tris (dibenzoylmethide) europium (III). The compounds fluoresce when irradiated with UV light. Suitable chelates have one or more diketonato ligands. Prefers are selected as metals lanthanide metal ions from Sm ³⁺ , Eu ³⁺ , Tb ³⁺ , Dy ³⁺ , Yb ³⁺ , Lu ³⁺ , Gd ²⁺ and Eu ²⁺ and actinide metal ions selected from U ³⁺ and U0 ₂ ³⁺ used.

US 5,757,026 relates to a multicolor display containing a plurality of multicolor OLEDs. Each LED contains a light-emitting layer that has an organic material, which can be a metal-acetylacetonate complex. These are preferably used to generate an emission in the blue region of visible light and preferably contain Al ³⁺ , Ga ³⁺ and In ³⁺ as metals. Concrete metal acetylacetonate complexes are not mentioned in US 5,757,026.

JP 11-260552 relates to organic light-emitting diodes which contain rare earth metal acetylacetonate complexes as light-emitting material and which have two perfluoroalkyl, perfluoroalkenyl, perfluoroaryl or perfluoroaralkyl groups. Examples are Eu complexes of the formulas Eu (CF ₃ COCHCOCF ₃ ) ₃ , Eu (C ₂ F ₅ COCHCOC ₂ F ₅ ) ₃ , Eu (C ₆ F ₅ COCHCOC ₆ F ₅ ) ₃ and Eu (CF ₃ COCHCOC ₆ F5 ) Called ₃ .

US Pat. No. 6,524,727 relates to electroluminescent materials and organic light-emitting diodes which contain rare earth, actinide or transition metal complexes which have a diphenylphosphonimide-trisphenylphosphine ligand. The complexes preferably contain diketonato groups as chelating groups. Preferred metals are Sm (III), Eu (III), Tb (III), Dy (III), Yb (III), Lu (III), Gd (III), Eu (II), U (III), UO ₂ (IV) and Th (III). Specific examples are disclosed for Tb (III), Eu (III), Dy (III) and UO ₂ (IV).

Although compounds are already known which show electroluminescence in the blue, red and green region of the electromagnetic spectrum, the provision of further compounds which can also be used in substance as a light-emitting layer and which luminesce at room temperature is desirable. Electroluminescence is understood to mean both electrofluorescence and electrophosphorescence.

The object of the present application is therefore to provide compounds which are suitable for electroluminescence in the blue, red and green regions of the electromagnetic spectrum, which enables the production of full-color displays. Furthermore, it is an object of the present application to provide compounds which can be used in substance, without host substances, as a light-emitting layer in OLEDs.

This task is accomplished by using

Gadolinium (III) complexes selected from the group consisting of Gadolinium (III) diketonato complexes of the formula (I)

and

Gadolinium (III) oxinate complexes of the formula (II)

where the symbols have the following meanings:

R ³ , R ⁴ , R ⁵ independently of one another are a substituted or unsubstituted aryl, alkyl, heteroaryl or alkenyl group, R ¹ and R ³ are preferably, independently of one another, C to C ₄ alkyl, phenyl, pyridyl, imidazolyl, furyl , Thienyl, CF ₃ , C ₂ F ₅ . or C ₆ F ₅ ; preferably methyl, ethyl, thienyl or CF ₃ , particularly preferably thienyl or CF ₃ ; and R ⁴ and R ^{5 are} independently C to C ₄ alkyl, phenyl, 1-naphthyl, 2-naphthyl;

R ² H, a substituted or unsubstituted aryl, alkyl, heteroaryl or alkenyl group, preferably H, C to C ₄ alkyl, CF ₃ , phenyl; neutral ^' ligand, preferably selected from the group consisting of water, ^' pyridine, preferably 4-NN-

Dimethylaminopyridine, 3-cyanopyridine, 4-cyanopyridine, 4-methoxypyridine, 4-phenylpyridine and their N-oxides, bipyridyls, preferably 2,2'-bipyridyl, N-methylimidazole, phenanthroline, preferably 1, 10-diphenylphenanthroline, bathophenanthroline, bathocuproin Phosphine oxide, preferably triphenylphosphine oxide, Phosphonimido ligand, preferably diphenylphosphonimide trisphenylphosphorane, and sulfoxide; n, m independently of one another 0 to 3, preferably 0 or 1, particularly preferably 0; p 0 to 2, preferably 0 or 1, particularly preferably 0; as emitter molecules in organic light-emitting diodes.

It has been found that the gadolinium (III) complexes of the formulas I and II according to the present application are suitable as light-emitting substances in OLEDs for the production of full-color displays.

Gadolinium (III) complexes of the formulas I and II are preferably used, in which the

Symbols have the following meanings:

R ¹ , R ³ independently of one another are C to C ₄ alkyl, phenyl, pyridyl, imidazolyl, furyl, thienyl, CF ₃ , C ₂ F ₅ or C ₆ F ₅ ; preferably methyl, ethyl, thienyl or CF ₃ , particularly preferably thienyl or CF ₃ ; R ⁴ , R ⁵ independently of one another are C to C ₄ -alkyl, phenyl, 1-naphthyl, 2-naphthyl;

R ² H, C _r to C ₄ alkyl, CF ₃ , phenyl; n, m 0 or 1, preferably 0.

For the purposes of the present application, the terms aryl radical or group, heteroaryl radical or group, alkyl radical or group, alkenyl radical or group, arylene radical or group and heteroarylene radical or group have the following meanings:

An aryl radical (or group) is to be understood as a radical with a backbone of 6 to 30 carbon atoms, preferably 6 to 18 carbon atoms, which is composed of an aromatic ring or several fused aromatic rings. Suitable basic structures are, for example, phenyl, naphthyl, anthracenyl or phenanthrenyl. This backbone can be unsubstituted (ie that all carbon atoms that can be substituted carry hydrogen atoms) or can be substituted at one, more or all substitutable positions of the backbone. Suitable substituents are, for example, alkyl residues, preferably alkyl residues with 1 to 8 carbon atoms, particularly preferably methyl, ethyl, i-propyl or t-butyl, aryl residues, preferably C ₆ aryl residues, which in turn can be substituted or unsubstituted, heteroaryl residues, preferably heteroaryl residues, which contain at least one nitrogen atom, particularly preferably pyridyl radicals, alkenyl radicals, preferably alkenyl radicals which carry a double bond, particularly preferably alkenyl radicals with a double bond and 1 to 8 carbon atoms, or groups with donor or acceptor action. Groups with a donor effect are to be understood as groups which have a + 1 and / or + M effect and groups with an acceptor effect To understand groups that have an -I and / or -M effect. Suitable groups with donor or acceptor action are halogen residues, preferably F, Cl, Br, particularly preferably F. alkoxy residues, carbonyl residues, ester residues, amine residues, amide residues, CH ₂ F groups, CHF ₂ groups, CF ₃ groups, CN groups Groups, thio groups or SCN groups. The aryl radicals very particularly preferably carry substituents selected from the group consisting of methyl, F, Cl and alkoxy, or the aryl radicals are unsubstituted. The aryl radical or the aryl group is preferably a C ₆ aryl radical or a naphthyl radical which is optionally substituted by at least one of the abovementioned substituents. The C ₆ aryl radical particularly preferably has none, one or two of the abovementioned substituents, the one substituent preferably being arranged in the para position to the further linking point of the aryl radical and - in the case of two substituents - each in the meta position further linkage point of the aryl radical are arranged or all H atoms of the C ₆ aryl radical are substituted by F, that is to say C ₆ F ₅ . The C ₆ aryl radical is very particularly preferably an unsubstituted phenyl radical or C ₆ F ₅ . The naphthyl radical is preferably 1-naphthyl or 2-naphthyl.

A heteroaryl radical or a heteroaryl group is understood to mean radicals which differ from the aryl radicals mentioned above in that at least one carbon atom in the basic structure of the aryl radicals is replaced by a hetero atom. Preferred heteroatoms are N, O and S. Very particularly preferably one or two carbon atoms of the basic structure of the aryl radicals are replaced by heteroatoms. The basic structure is particularly preferably selected from systems such as pyridyl, imidazolyl, cyclic esters, cyclic amides and five-membered heteroaromatics such as thienyl, pyrryl, furyl. The basic structure can be substituted at one, more or all substitutable positions of the basic structure. Suitable substituents are the same as those already mentioned for the aryl groups. Thienyl is particularly preferred.

An alkyl radical or an alkyl group is a radical with 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, particularly preferably 1 to 8 carbon atoms, very particularly preferably 1 to 4 carbon atoms. This alkyl radical can be branched or unbranched and optionally interrupted by one or more heteroatoms, preferably N, O or S. Furthermore, the alkyl radical or the alkyl group can be a C ₃ to C ₈ cycloalkyl radical, preferably a C ₅ or C ₆ cycloalkyl radical, which can optionally be interrupted by one or more heteroatoms, preferably N, O or S, for example cyclopentyl and cyclohexyl. Furthermore, this alkyl radical can be substituted with one or more of the substituents mentioned in relation to the aryl groups, in particular halogen radicals, preferably F, Cl, Br, particularly preferably F. It is also possible for the alkyl radical to carry one or more aryl groups. Are all of the aryl groups listed above are suitable. The alkyl radicals are particularly preferably selected from the group consisting of methyl, ethyl, i-propyl, n-propyl, i-butyl; n-butyl, t-butyl, sec-butyl, i-pentyl, n-pentyl, sec-pentyl, neo-pentyl, n-hexyl, i-hexyl, sec-hexyl, cyclopentyl, cyclohexyl, CF ₃ and C ₂ F ₅ . Methyl, ethyl, i-propyl, n-hexyl, CF ₃ and C ₂ F ₅ are very particularly preferred.

An alkenyl radical or an alkenyl group is understood to mean a radical which corresponds to the above-mentioned alkyl radicals having at least two carbon atoms, with the difference that at least one C-C single bond of the alkyl radical is replaced by a C-C double bond. The alkenyl radical preferably has one or two double bonds.

Preferred gadolinium (IH) complexes of the formula I are those in which R ¹ and R ³ independently of one another are C to C ₄ -alkyl, phenyl, pyridyl, imidazolyl, furyl, thienyl, CF ₃ , C ₂ F ₅ or C ₆ F ₅ , particularly preferably methyl, ethyl, thienyl or CF ₃ , very particularly preferably thienyl or CF ₃ and R ² , H, C _r C ₄ alkyl, phenyl, preferably H means, p preferably means in the gadolinium (III) - Complexes of the formula I 0 or 1, particularly preferably 0.

Preferred gadolinium (III) complexes of the formula II are those in which R ⁵ and R ⁶ independently of one another are C to C ₄ -alkyl and phenyl and m and n are 0 or 1, preferably 0, where if m and n = 0 mean, the oxinate group is unsubstituted and, when m and n are 1, the oxinate group is substituted with the substituents already mentioned. p in the gadolinium (H]) complexes of the formula II preferably denotes 0 or 1, particularly preferably 0.

Very particularly preferred compounds of the formulas I and II are the formulas listed below

Gd (hfac) ₃

Gd (qu) ₃

Where:

hfac hexafluoroacetylacetonate tta thienyl trifluoroacetonate qu 8-quinolinolate (oxinate)

The transition metal complexes mentioned above are outstandingly suitable as emitter molecules in organic light-emitting diodes (OLEDs). Simple variations of the ligands make it possible to provide transition metal complexes which show electroluminescence in the red, green and in particular in the blue region of the electromagnetic spectrum. The neutral transition metal complexes used according to the invention are therefore suitable for use in technically usable full-color displays.

The GadoIinium (III) complexes are prepared by methods known to those skilled in the art. -

Typical methods are, for example, deprotonation of the ligand precursors corresponding to the ligands of the compounds of the formulas I and II and subsequent, generally in situ, reaction with suitable metal complexes containing Gd. Furthermore, the preparation of the gadolinium (III) complexes of the formulas I and II is possible by direct reaction of the neutral ligand precursors corresponding to the ligands of the gadolinium (III) complexes with the suitable gadolinium (III) complexes, which is preferred.

Suitable ligand precursors which lead to the ligands of the godinium (III) complexes of the formulas I and II are known to the person skilled in the art.

If the ligands are deprotonated, this can be done by basic metal salts, basic anions such as acetates, acetylacetonates, carbonates or alkoxylates or external bases such as KO'Bu, NaO'Bu, LiO ^l Bu, NaH, silylamides and phosphazene bases.

Suitable gadolinium complexes which can be used as the starting compound are known to the person skilled in the art. GdCl ₃ x 2H ₂ 0 is particularly preferably used.

The reaction is preferably carried out in a solvent. Suitable solvents are known to the person skilled in the art and are preferably selected from water and alcohols such as ethanol and mixtures thereof.

The molar ratio of gadolinium complex used to ligand precursor used is preferably 0.7: 3.0 to 1.5: 3.0, particularly preferably 0.9: 3.0 to 1.1, very particularly preferably 1: 3.

The gadolinium (III) complexes of the formulas I and II are preferably obtained by directly reacting the corresponding ligand precursor with a gadolinium complex. This reaction is particularly preferably carried out in water or an alcohol or mixtures thereof in the molar ratios of gadolinium complexes and ligand precursors already mentioned above.

The reaction is generally carried out at temperatures from 0 to the reflux temperature of the solvent, preferably 10 to 50 ° C., particularly preferably at room temperature.

The reaction time depends on the desired gadolinium (III) complex and is generally from 10 minutes to 50 hours, preferably from 20 minutes to 24 hours, particularly preferably from 0.5 hours to 12 hours.

The gadolinium complex of the formulas I and II obtained is worked up by methods known to the person skilled in the art. For example, the product is precipitated by adding water and the precipitated product is filtered, washed, for example with water, and then dried.

The gadolinium (III) complexes of the formulas I or II used according to the invention are outstandingly suitable as emitter substances, since they have luminescence (electroluminescence) in the visible range of the electromagnetic spectrum. With the aid of the gadolinium (III) complexes used as emitter substances according to the invention, it is possible to provide compounds which have electroluminescence in the red, green and blue regions of the electromagnetic spectrum. So it is possible with the help of To provide gadolinium (III) complexes used according to the invention as emitter substances for full-color displays which can be used technically.

A special property of the gadolinium (III) complexes of the formulas I and II is that they show luminescence in the solid state, particularly preferably electroluminescence, in the visible range of the electromagnetic spectrum. These complexes which are luminescent in the solid state can be used in bulk, that is to say without any further additives, as emitter substances in OLEDs. As a result, an OLED can be produced with a light-emitting layer, with no complex cover evaporation of a matrix material with the emitter substance being necessary.

Another subject of the present application is therefore the use of gadolinium (III) complexes of the formulas I and II as a light-emitting layer in OLEDs.

Organic light-emitting diodes are basically made up of several layers:

1. Anode

2. Hole-transporting layer 3. Light-emitting layer

4. Electron transporting layer

5. Cathode

The gadolinium (III) complexes of the formulas I and II are preferably used in the light-emitting layer as emitter molecules. Another object of the present application is therefore a light-emitting layer containing at least one gadolinium (III) complex of the formulas I and II as an emitter molecule. Preferred gadolinium (III) complexes of the formulas I and II have already been mentioned above.

The gadolinium (III) complexes of the formulas I and II used according to the invention can be present in substance - without further additives - in the light-emitting layer. However, it is also possible that in addition to the gadolinium (III) complexes of the formulas I or II used according to the invention, further compounds are present in the light-emitting layer. For example, a fluorescent dye can be present in order to change the emission color of the gadolinium (III) complex used as the emitter molecule. A dilution material can also be used. This dilution material can be a polymer, for example Poly (N-vinyl carbazole) or polysilane. However, the diluent can also be a small molecule, for example 4,4'-N, N'-dicarbazole biphenyl (CDP) or tertiary aromatic amines. If a dilution material is used, the proportion of the gadolinium (III) complexes used according to the invention in the light-emitting layer is generally less than 20% by weight, preferably 3 to 10% by weight. The Gadoliήium (III) complexes of the formulas I and II are preferably used in substance, as a result of which costly cover evaporation of the Gadolinium (III) complexes with a matrix material (diluent material or fluorescent dye) is avoided. It is essential for this that the gadolinium (III) complexes luminesce in the solid. The gadolinium (III) complexes of the formulas I and II show luminescence in the solid state. Thus, the light-emitting layer preferably contains at least one gadolinium (III) complex of the formula I or II and no matrix material selected from the dilution material and fluorescent dye.

Another object of the present application is, in a preferred embodiment, a light-emitting layer consisting of at least one gadolinium (III) complex of the formulas I and / or II as an emitter molecule. Preferred complexes of the formulas I and II have already been mentioned above.

^• Each of the aforementioned layers of the OLED can be constructed again of 2 or more layers. For example, the hole-transporting layer can be constructed from a layer into which holes are injected from the electrode and a layer which transports the holes away from the hole-injecting layer into the light-emitting layer. The electron-transporting layer can 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-injecting layer and transports them into the light-emitting layer. These layers are selected according to factors such as energy level, temperature resistance and charge mobility, as well as the energy difference of the 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 gadolinium (III) complexes used as emitter substances according to the invention.

In order to obtain particularly efficient OLEDs, the HOMO (highest occupied molecular orbital) of the hole-transporting layer should match the work function of the anode and the LUMO (lowest unoccupied molecular orbital) electron transporting layer should match the work function of the cathode.

Another object of the present application is an OLED containing at least one light-emitting layer according to the invention. The further layers in the OLED can be constructed from any material that is usually used in such layers and is known to the person skilled in the art.

The anode (1) is an electrode that provides positive charge carriers. For example, it can be constructed from materials that contain a metal, a mixture of different metals, a metal alloy, a metal oxide or a mixture of different metal oxides. Alternatively, the anode can be a conductive polymer. Suitable metals include the metals of Groups Ib, IVa, Va and Via of the Periodic Table of the Elements and the transition metals of Group VIII. If the anode is to be translucent, mixed metal oxides of Groups Mb, Illb and IVb of the Periodic Table of the Elements are generally used , for example indium tin oxide (ITO). It is also possible that 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 couple out 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 Technologie, 4th edition, vol. 18, pages 837 to 860, 1996. Both hole transporting molecules and polymers can be used as hole transport material. Holes used to transport holes are selected from the group consisting of 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (α-NPD), N, N'-diphenyl-N, N '-bis (3-methylphenyl) - [, 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), α-phenyl-4-N, N-diphenylaminostyrene (TPS), p- (diethylamino) -benza! dehyddiphenyIhydrazone ^' (DEH), triphenylamine (TPA), bis [4- (N, N-diethylamino) -2-methylphenyl) (4-methy) -phenyl) methane (MPMP), 1-phenyl-3- [p- ( diethylamino) styryl] -5- [p- (diethylamino) phenyl] pyrazoline (PPR or DEASP), 1, 2-trans-bis (9H-carbazol-9-yl) cyclobutane (DCZB), N, N, N ', N'-tetrakis (4-methylphenyl) - (1, 1'-biphenyl) -4,4'-diamine (TTB) and porphyrin compounds such as copper phthalocyanines. Commonly used hole transporting polymers are selected from the group consisting of polyvinyl carbazoles, (phenylmethyl) polysilanes and polyanilines. It is also possible to obtain hole transporting polymers by doping hole transporting molecules in polymers such as polystyrene and polycarbonate. Suitable molecules which transport holes are the molecules already mentioned above.

Suitable electron-transporting materials for the layer (4) of the OLEDs according to the invention include metals chelated with oxinoid compounds such as tris (8-quinolinato) aluminum (AIq ₃ ), compounds based on phenanthroline such as 2,9-dimethyl, 4,7-diphenyl-1, 10-phenanthroline (DDPA) or 4,7-diphenyl-1, 10-phenanthroline (DPA) and azole compounds such as 2- (4-biphenylyl) -5- (4-t-butylphenyl) - 1, 3,4-oxadiazole ( PBD) and 3- (4-biphenylyI) -4-phenyl-5- (4-t-butylphenyl) -1, 2,4-triazole

(TAZ). The layer (4) can serve both to facilitate 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. ^■ Preferably, the layer (4) improves the mobility of electrons and reduces quenching of the exciton.

The cathode (5) is an electrode that is used to introduce electrons or negative charge carriers. The cathode can be any metal or non-metal that has a lower work function than the anode. Suitable materials for the cathode are selected from the group consisting of alkali metals of group 1, for example Li, Cs, alkaline earth metals of group 2, metals of group 12 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 as well as combinations thereof can also be used. Furthermore, lithium-containing organometallic compounds or LiF can be applied between the organic layer and the cathode in order to reduce the operating voltage.

The OLED according to the present invention can additionally contain further layers which are known to the person skilled in the art. For example, 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 adjusts the band gap of the layers to one another. Alternatively, this additional layer can serve as a protective layer. Analogously, additional layers can be present between the light-emitting layer (3) and the layer (4) in order to facilitate the transport of the negative charge and / or to match the band gap between the layers. Alternatively, this layer can serve as a protective layer. In a preferred embodiment, the OLED according to the invention contains, in addition to the layers (1) to (5), at least one of the further layers mentioned below: a hole injection layer between the anode (1) and the hole-transporting layer (2); - A block layer for electrons between the hole-transporting layer (2) and the light-emitting layer (3); a block layer for holes between the light-emitting layer (3) and the electron-transporting layer (4); an electron injection layer between the electron transporting layer (4) and the cathode (5). The person skilled in the art knows how to select suitable materials (for example on the basis of electrochemical tests). Suitable materials for the individual layers are known to the person skilled in the art and are disclosed, for example, in WO 00/70655.

Furthermore, each of the named layers of the OLED according to the invention can be made up of two or more layers. Furthermore, it is possible that some or all of the layers (1), (2), (3), (4) and (5) are surface-treated in order to increase the efficiency of the charge carrier transport. The choice of materials for each of the layers mentioned is preferably determined by obtaining an OLED with high efficiency.

The OLED according to the invention can be produced by methods known to the person skilled in the art. Generally, the OLED is replaced by successive ones

Vapor deposition of the individual layers to a suitable one

Substrate. Suitable substrates are, for example, glass or polymer films.

Conventional techniques such as thermal can be used for steam separation

Evaporation, Chemical Vapor Deposition and others. In an alternative method, the organic layers can be made from solutions or dispersions in suitable

Solvents are coated, known to those skilled in the art

Coating techniques are applied.

In general, the different layers have the following thicknesses: anode (2) 500 to 5000 Å, preferably 1000 to 2000 Å; Hole-transporting layer (3) 50 to 1000 Å, preferably 200 to 800 Å, light-emitting layer (4) 10 to 1000 Å, preferably 100 to 800 Å, electron-transporting layer (5) 50 to 1000 Å, preferably 200 to 800 Ä ^'cathode (6) 200 to 10,000 Å, preferably 300 to 5000 Å. The The position of the recombination zone of holes and electrons in the OLED according to the invention and thus the emission spectrum of the OLED can be influenced by the relative thickness of each layer. This means that the thickness of the electron transport layer should preferably be chosen so that the electron / hole recombination zone lies 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 any additional layers used are known to the person skilled in the art.

By using the gadolinium (III) complexes of the formulas I or II used as emitter molecules in the light-emitting layer of the OLEDs according to the invention, OLEDs can be obtained with high efficiency. The efficiency of the OLEDs according to the invention can also be improved by optimizing the other layers. For example, highly efficient cathodes such as Ca, Ba or LiF can be used. Shaped substrates and new hole-transporting materials which reduce the operating voltage or increase the quantum efficiency can also be used in the OLEDs according to the invention. Furthermore, additional layers can be present in the OLEDs in order to adjust the energy level of the different 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 as well as billboards, lighting and information boards. Mobile screens are e.g. Screens in cell phones, laptops, vehicles and destination displays on buses and trains.

Furthermore, the gadolinium (III) complexes of the formulas I or II used according to the invention can be used in OLEDs with an inverse structure. The gadolinium (HI) complexes in these inverse OLEDs are in turn used in the light-emitting layer, particularly preferably as a light-emitting layer without further additives. The structure of inverse OLEDs and the materials usually used therein are known to the person skilled in the art.

Examples 1. Production of gadolinium (III) complexes

General

All solvents used for spectrometric measurements have the appropriate quality suitable for spectrometric measurements. Hhfac (hexafluoroacetylacetone), Htta (thienyltrifluoroacetone), Hqu (8-quinolinol) and GdCI ₃ x H ₂ 0 are commercially available and are used without further purification.

a) Gd (qu) ₃ (Gadolinium tris oxinate)

The production of Gd (qu) ₃ is described in RG Charles et al. Spectrochim., Acta 8 (1956) 1.

b) Gd (hfac) ₃ x 3H ₂ 0 (gadolinium-t s-hexafluoroacetylacetonate)

A solution of 0.5 ml (3.52 mmol) of Hhfac in 15 ml of ethanol is added dropwise to a solution of GdCI ₃ × 2H ₂ O (300 mg _; 1.14 mmol) and sodium acetate (1 g) in 5 ml of water with stirring , After slowly adding water, a colorless precipitate is formed. The precipitate is collected by filtration, washed with water and dried over P ₂ 0 ₅ . 100 mg Gd (hfac) ₃ are obtained.

Elemental analysis (C1 _.5 H ₉ OgF1. ₈ Gd): C 21, 64%,

H 1.09%;

found: C 21.73%, H 1.04%.

c) Gd (tta) ₃ x 1.5 H ₂ 0 (gadolinium tris-thienyl trifluoroacetonate)

The procedure is analogous to the production of Gd (hfac) ₃ x 3H ₂ 0. Htta (760 mg, 3.42 mmol) in 8 ml of ethanol is added to a solution of GdCI ₃ × 2H ₂ O (300 mg, 1, 14 mmol) and 1 g of sodium acetate in 5 ml of H ₂ O. 520 mg Gd (tta) ₃ x 1.5 H ₂ 0 are obtained _* Elemental analysis: C: 34.00% H: 1.78%

found: C: 34.03% H: 1.75%.

Claims

claims

1. Use of gadolinium (III) complexes selected from the group consisting of gadolinium (III) ~ diketonato complexes of the formula (I)

and

Gadolinium (III) oxinate complexes of the formula (II)

where the symbols have the following meanings:

R ¹ , R ³ , R ⁴ , R ⁵ independently of one another are substituted or unsubstituted

Aryl, alkyl, heteroaryl or alkenyl group; R ² H, a substituted or unsubstituted aryl, alkyl,

Heteroaryl or alkenyl group; L neutral ligand; n, m independently of one another 0 to 3; p 0 to 2 as emitter molecules in organic light-emitting diodes.

Use according to claim 1, characterized in that the symbols have the following meanings:

R, R ³ independently of one another C to C ₄ alkyl, phenyl, pyridyl,

Imidazolyl, furyl, thienyl, CF ₃ , C ₂ F ₅ or C ₆ F ₅ ; prefers Methyl, ethyl, thienyl or CF, particularly preferably thienyl or CF ₃ ;

R 4 ⁴ , _D R5 independently of one another C to C ₄ alkyl, phenyl, 1-naphthyl,

2-naphthyl;

R ^ H, C _r to C ₄ alkyl, CF ₃ , phenyl; selected from the group consisting of water, pyridine, preferably 4-N, N-dimethylaminopyridine, 3-cyanopyridine, 4-

Cyanopyridine, 4-methoxypyridine, 4-phenylpyridine and their N-

Oxides, bipyridyls, preferably 2,2'-bipyridyl, N-methylimidazole,

Phenanthroline, preferably 1, 10-diphenylphenanthroline,

Bathophenanthroline, bathocuproin, phosphine oxide, preferred

Triphenylphosphine oxide, phosphonimido ligand, preferred

Diphenylphosphonimide-trisphenylphosphorane, and sulfoxide; n, m 0 or 1, preferably 0; P 0 or 1, preferably 0.

3. Use according to claim 1 or 2, characterized in that the gadolinium (III) diketonato complexes of the formula (I) are selected from the group consisting of gadolinium (III) diketonato complexes of the formula (Ia) and (Ib)

and the gadolinium (III) oxinate complex of the formula (II) has the formula (Ha)

4. Use of gadolinium (III) complexes according to one of claims 1 to 3 as a light-emitting layer in OLEDs.

5. Light-emitting layer containing at least one gadolinium (III) complex according to one of claims 1 to 3 as an emitter molecule.

6. Light-emitting layer consisting of at least one gadolinium (III) complex according to one of claims 1 to 3 as an emitter molecule.

7. OLED containing a light-emitting layer according to claim 5 or 6.

8.Device selected from the group consisting of stationary screens such as screens of computers, televisions, screens in printers, kitchen appliances as well as billboards, lighting, notice boards and mobile screens such as screens in cell phones, laptops, vehicles and destination displays on buses and trains containing an OLED according to Claim 7.