EP1714332A2

EP1714332A2 - Phosphorescent electroluminescent element

Info

Publication number: EP1714332A2
Application number: EP05707296A
Authority: EP
Inventors: Esther Breuning; Anja Gerhard; Horst Vestweber; Philipp STÖSSEL
Original assignee: Merck Patent GmbH
Current assignee: Merck Patent GmbH
Priority date: 2004-02-10
Filing date: 2005-02-10
Publication date: 2006-10-25
Also published as: WO2005078818A3; KR20070004621A; WO2005078818A2; US20070122653A1; CN1918723B; DE102004006622A1; CN1918723A; JP2007522661A

Abstract

The invention relates to electroluminescent elements containing cathodes and anodes and at least one emission layer, said layer containing at least one matrix material A, which contains certain elements and at least one emitter material B, which emits light in the triplet state.

Description

description

Phosphorescent electroluminescent element

In a number of different applications, which can be broadly attributed to the electronics industry, the use of organic semiconductors as functional materials has been a reality for some time or is expected in the near future. The use of semiconducting organic compounds that are capable of emitting light in the visible spectral range is just at the beginning of the market launch, for example in organic electroluminescent devices (OLEDs). The OLEDs have already been launched on the market for simpler devices, as demonstrated by the car radios from Pioneer or a digital camera from Kodak with an "organic display". Nevertheless, there is still a great need for technical improvement.

A more recent development is the use of organometallic complexes which show phosphorescence (= triplet emission) instead of fluorescence (= singlet emission) (M.A. Baldo et al., Appl. Phys. Lett. 1999, 75, 4-6). For quantum mechanical reasons, up to four times the quantum, energy and power efficiency is possible using such emitters. To do this, however, appropriate device compositions must be found that can also implement these advantages in OLEDs. The essential conditions for practical application are, in particular, efficient energy transfer to the triplet emitter and thus efficient emission, a long operational life and a low operating and operating voltage.

The general structure of organic electroluminescent devices is described, for example, in US 4539507, US 5151629 and EP 01202358. The emission layer in phosphorescent devices usually consists of phosphorescent dyes, e.g. B. Tris (phenylpyridyl) iridium (lr (PPy) ₃ ), which are doped in matrix materials. This matrix material has a special role: it must enable or improve the charge transport and / or the charge carrier recombination of holes and / or electrons and, if necessary, transfer the energy generated during the recombination to the emitter. So far, this task has mainly been performed by matrix materials based on carbazole, such as 4,4'-bis (carbazol-9-yl) biphenyl (CBP). In addition, there are recently ketones and imines (WO 04/093207) and phosphine oxides, sulfoxides, sulfones, etc. (Not disclosed application DE 10330761.3) have been described as matrix materials.

In practice, matrix materials based on carbazole have some disadvantages. These can be seen, among other things, in the often short lifespan of the devices and the often high operating voltages that lead to low power efficiencies. Furthermore, it has been shown that CBP is unsuitable for blue-emitting electroluminescent devices, which results in poor efficiencies. In addition, the construction of the devices with CBP is very complex since a hole blocking layer and an electron transport layer must also be used. If these additional layers are not used, e.g. B. by Adachi et al. (Organic Electronics 2001, 2, 37), one can observe good efficiencies, but only at extremely low brightness levels, while the efficiency at higher brightness levels, as is necessary for the application, is more than an order of magnitude lower. High voltages are required for high brightness levels, so that the power efficiency is very low, especially in passive matrix applications.

WO 00/057676 mentions matrix materials from the group of the metal complexes of quinoxolates, oxadiazoles and triazoles, no advantages of these matrix materials compared to other materials being mentioned and Alq ₃ (tris (hydroxyquinolinato) aluminum) being mentioned as the only example. WO 04/095598 describes tetraaryl compounds of the elements carbon, silicon, germanium, tin, lead, selenium, titanium, zirconium and hafnium as matrix materials for triplet emitters.

There are still significant problems with OLEDs that need urgent improvement:

1. So v. a. the operational lifespan of OLEDs is still short, so that only simple applications have so far been commercially possible.

2. The efficiencies of OLEDs are acceptable, but improvements are still desired here, especially for mobile applications.

3. The required operating voltage is high, especially in the case of efficient phosphorescent OLEDs, and must therefore be reduced in order to improve the power efficiency. This is particularly important for mobile applications.

4. Due to the variety of layers, the structure of the OLEDs is complex and technologically very complex. This applies in particular to phosphorescent OLEDs, in which a hole blocking layer must be used in addition to the other layers. So it would be very beneficial To be able to realize OLEDs with a simpler structure with fewer layers, but still good or improved properties. These reasons make improvements in the production of OLEDs necessary.

It has now surprisingly been found that the use of certain matrix materials in combination with triplet emitters leads to significant improvements over the prior art, in particular in terms of efficiency, in combination with a greatly increased service life and reduced operating voltage. In addition, a significantly simplified layer structure of the OLED is possible with these matrix materials, since neither a separate hole blocking layer nor a separate electron transport and / or electron injection layer need be used. Depending on the material, a separate hole transport layer can also be dispensed with, which is also a clear technological advantage. The presence of at least one element with an atomic number> 15 is necessary for an efficient energy transfer.

The invention relates to organic electroluminescent devices containing cathode and anode and at least one emission layer, characterized in that the emission layer

• Contains at least one matrix material A, which contains at least one element with an atomic number> 15, with the proviso that the matrix material does not contain any of the elements Si, Ge, Sn, Pb, Al, Ga, In or TI, and is not a noble gas compound with the proviso that matrix materials A with the substructure L = X are excluded, where L stands for a substituted C, P, As, Sb, Bi, S, Se or Te and X has at least one non-binding electron pair, with the proviso that tetraaryl compounds of the elements Se, Ti, Zr and Hf are excluded, and with the proviso that metal complexes of the quinoxolates, oxadiazoles and triazoles are excluded as matrix material; and

• contains at least one emission material B, which emits light, preferably in the visible range, from the triplet state with suitable excitation and contains at least one element of atomic number greater than 20.

The symbol used above, = "stands for a double bond in the Lewis notation. X can represent substituted O, S, Se or N, for example. The lowest triplet energy of the matrix materials is preferably between 2 and 4 eV. The lowest triplet energy is defined as the energy difference between the singlet ground state and the lowest triplet state of the molecule. The triplet energy can be determined by various spectroscopic methods or by quantum chemical calculation. This triplet position has proven to be advantageous since the energy transfer of the matrix material to the triplet emitter then proceeds very efficiently and thus leads to high efficiency of the emission from the triplet emitter. A triplet energy of <2 eV is generally not sufficient for efficient energy transfer, even for red-emitting triplet emitters. Preferred are matrix materials A whose triplet energy is greater than the triplet energy of the triplet emitter B used. The triplet energy of the matrix material A is preferably at least 0.1 eV greater than that of the triplet emitter B, in particular by at least 0.5 eV greater than that of the triplet emitter B.

In order to ensure a high thermal stability of the display, amorphous matrix materials A are preferred whose glass transition temperature T _g (measured as pure substance) is greater than 90 ° C., particularly preferably greater than 110 ° C., in particular greater than 130 ° C.

So that the materials are stable during the vapor deposition process, they should preferably have a high thermal stability, preferably greater than 200 ° C., particularly preferably greater than 300 ° C.

The matrix material A is preferably an uncharged compound. These are preferred over salts because they are generally easier to evaporate or at a lower temperature than charged compounds which form ionic crystal lattices. In addition, salts tend to crystallize, which prevents the formation of glass-like phases. Furthermore, the matrix material A is preferably defined molecular compounds.

In order to avoid electron transfer between the matrix material and the triplet emitter in the ground state, it is preferred if the LUMO (lowest vacant molecular orbital) of the matrix material A is higher than the HOMO (highest occupied molecular orbital) of the triplet emitter B. For the same reason, it is preferred if the LUMO of triplet emitter B is higher than the HOMO of matrix material A. The connection of the emission layer with the higher (less negative) HOMO is mainly responsible for the hole current. It is preferred if the HOMO of this compound, regardless of whether it is the matrix material A or the triplet emitter B, is in the range of ± 0.5 eV compared to the HOMO of the hole transport layer or the hole injection layer or the anode (depending on which of these layers is directly adjacent to the emission layer). The connection in the emission layer with the lower (more negative) LUMO is mainly responsible for the electron current. It is preferred if the LUMO of this compound, regardless of whether it is the matrix material A or the triplet emitter B, is in the range of ± 0.5 eV compared to the LUMO of the hole blocking layer or the electron transport layer or the cathode (depending on which of these layers is directly adjacent to the emission layer).

The charge carrier mobility of the emission layer is preferably between 10 ^"8 and 10 ^{" 1} cm ² / Vs below the field strengths given in the OLED.

The position of the HOMO or LUMO can be determined by different methods, for example by solution electrochemistry, e.g. B. cyclic voltammetry, or by UV photoelectron spectroscopy. In addition, the position of the LUMO can be calculated from the electrochemically determined HOMO and the bandgap determined optically by absorption spectroscopy.

Also preferred are materials which are predominantly stable during electron transfer (oxidation and / or reduction), i. H. show predominantly reversible reduction or oxidation. For example, electron-conducting materials should remain stable, especially when reduced, and hole-conducting materials during oxidation. “Stable” or “reversible” means that the materials show little or no decomposition or chemical changes, such as rearrangement, upon reduction or oxidation.

The HOMO or LUMO position of the matrix materials can be adapted over a wide range to the respective conditions in the device and thus optimized. So they can be shifted by chemical modification. This is possible, for example, by varying the central atom while maintaining the ligand system or the substituents or by introducing other, in particular electron-donating or electron-withdrawing, substituents on the ligands. For any triplet emission material, the person skilled in the art is able to adjust the properties of the matrix in such a way that optimal emission properties are obtained overall. Furthermore, matrix materials A which have a dipole moment other than zero have proven particularly favorable. In the case of materials that contain several identical molecular fragments, however, the total dipole moment can also be canceled. Therefore, in this case, the total dipole moment should not be considered in this case for the determination of preferred matrix materials, but rather the dipole moment of the molecular fragment (i.e. the part of the molecule) around the element with the atomic number> 15. A dipole moment of the matrix materials A (or of the molecular fragment around the element with the atomic number> 15) of> 1 D, particularly preferably of> 1.5 D. The dipole moment can be determined by quantum chemical calculation.

The matrix material A can be both organic and inorganic. It can also be organometallic compounds or coordination compounds, the metals being both main group and transition metals or lanthanides and the compounds being both mononuclear and multinuclear. An organometallic compound in the sense of this application is a compound which has at least one direct metal-carbon bond. A coordination compound in the sense of this application is a metal complex in which there is no direct metal-carbon bond, and the ligands can be organic but also purely inorganic ligands.

As stated above, suitable matrix materials A are compounds which have at least one element with an atomic number> 15, but none of the elements Si, Ge, Sn, Pb, Al, Ga, In or TI, and which have no tetraaryl compound of the elements Se , Ti, Zr or Hf. For practical reasons, noble gas compounds (unstable or low-melting compounds) are also excluded. Compounds of radioactive elements are not preferred as matrix material for health reasons. Suitable materials can be compounds of the main group elements and compounds of the subgroup elements. Suitable matrix materials of the main group elements can therefore be compounds of the alkali metals potassium, rubidium or cesium, furthermore compounds of the alkaline earth metals calcium, strontium or barium, compounds of the heavier elements of the 5th main group (group 15 according to IUPAC), that is phosphorus, arsenic, antimony or bismuth, Connections of the heavier elements of the 6th main group (group 16 according to IUPAC), i.e. sulfur, selenium or tellurium, or compounds of the halogens chlorine, bromine or iodine. The compounds of the 5th and 6th main group are particularly suitable for organic molecular compounds. Likewise there are compounds of the subgroup elements, i.e. transition metal compounds (compounds of the elements Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd or Hg) and lanthanoid compounds (compounds of the elements La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu) in question. It may also be preferred if the matrix material contains two or more of the above-mentioned elements, which may be the same or different. In principle, compounds come into question here, as in Houben-Weyl, Methods of Organic Chemistry (4th edition, Georg Thieme Verlag, Stuttgart, 1964) in volumes 9 (S, Se, Te), 12/1 and 12/2 ( P), 13/1 (Li, Na, K, Rb, Cs, Cu, Ag, Au), 13 / 2a (Be, Mg, Ca, Sr, Ba, Zn, Cd), 13 / 2b (Hg), 13/7 (Pb, Ti, Zr, Hf, Nb, Ta, Cr, Mo, W), 13/8 (As, Sb, Bi), 13 / 9a (Mn, Re, Fe, Ru, Os, Pt) , 13 / 9b (Co, Rh, Ir, Ni, Pd), as well as in the supplementary volumes E1 and E2 (P) and E12, b (Te) from 1982.

Preferred compounds are discrete molecular or coordinative compounds which also form discrete structures in the solid. Salts, coordination polymers, etc. are therefore not very suitable, since these can generally be evaporated poorly or not at all. Salts are also less suitable because of their tendency to crystallize. For processing from solution, the compounds must be soluble in solvents in which the triplet emitter is also soluble.

Compounds of the transition metals and compounds of the elements of the 5th, 6th and 7th main group are preferred; Compounds of the transition metals and compounds of the elements of the 5th and 6th main group are particularly preferred.

Organic phosphorus compounds and the corresponding arsenic, antimony and bismuth compounds are preferred as compounds of the elements of main group 5 (phosphorus, arsenic, antimony, bismuth). Aromatic or aliphatic phosphines or phosphites and the corresponding As, Sb and Bi compounds are particularly suitable here. Organic phosphorus halides or hydroxides (and the corresponding As, Sb and Bi compounds) are also possible, the alkyl compounds in particular being partially pyrophoric and therefore not preferred. Compounds with multiple element-element bonds, phospha- and arsa-aromatic compounds (e.g. phospha- and arsabenzene derivatives) and unsaturated five-membered rings (e.g. phosphol and arsol) are also suitable. Phosphoranes (pentavalent Phosphorus compounds) and pentavalent organoarsen compounds and corresponding pentavalent organoarsen halides or hydroxides (and the corresponding Sb and Bi compounds), the thermal stability decreasing with increasing halogen content and these compounds are therefore less preferred.

Also preferred are phosphorus sulfides that do not contain a phosphorus-sulfur double bond, such as P ₄ S ₃ , PS ₄ or PS ₅ .

Organic sulfur compounds (and the corresponding selenium and tellurium compounds) such as aromatic or aliphatic thiols (or corresponding selenium and tellurium compounds), organosulfur halides (or corresponding selenium) are particularly suitable as compounds of the elements of main group 6 (sulfur, selenium, tellurium) - And tellurium compounds), aromatic or aliphatic thioethers (or seleno or telluroethers) or aromatic or aliphatic disulfides (or diselenides or ditellurides). Also preferred are sulfur-containing aromatic compounds, such as derivatives of thiophene, benzothiophene or dibenzothiophene (and the corresponding selenium and tellurium compounds, such as derivatives of selenophene, tellurophen, etc.).

Suitable compounds of the halogens are, for example, organic halogen compounds, but also compounds in which chlorine, bromine or iodine on the above-mentioned elements, for. B. is bound to S, Se, Te, P, As, Sb or Bi, which are not preferred because of the high sensitivity to hydrolysis.

Particularly preferred matrix materials are compounds containing at least one element of the 5th or 6th main group which is substituted by at least one substituted or unsubstituted, aromatic or heteroaromatic ring system having 3 to 60 C atoms, in particular those in which all substituents on the element the 5th or 6th main group are aromatic or heteroaromatic ring systems with 3 to 60 C atoms, according to formula (A) or formula (B),

X (Ar) ₃ Y (Ar) ₂ Formula (A) Formula (B)

the following applies to the symbols used:

X is P, As, Sb or Bi, preferably P or As, particularly preferably P at each occurrence; Y is S, Se or Te, preferably S or Se, particularly preferably S; Ar is the same or different in each occurrence, an aromatic or heteroaromatic ring system with 3 to 60 C atoms, which can be substituted with F or organic radicals with 1 to 40 C atoms, preferably an aromatic ring system with 6 to 40 C atoms.

In a preferred embodiment of the invention, Ar is phenyl, biphenyl, terphenyl, naphthyl, anthryl, phenanthrenyl, pyryl, fluorenyl, spirobifluorenyl, dihydrophenanthrenyl, tetrahydropyrenyl or a combination of 2 or 3 of these systems. At least one of the radicals Ar is particularly preferably fluorenyl or spirobifluorenyl, very particularly preferably all radicals Ar are fluorenyl or spirobifluorenyl.

In principle, three substance classes are possible for the compounds of the transition metal elements, as well as for the compounds of the lanthanides, the alkali and alkaline earth metals: organometallic compounds, organic coordination compounds and purely inorganic metal complexes. In the case of the metal compounds, preference is given to compounds of the transition metal elements. These can each contain one or more metal atoms, right down to metal clusters. In multinuclear metal complexes, the metals can be connected by bridging ligands and / or by a direct metal-metal bond. At this point, it should be expressly pointed out that compounds which can also be used as a triplet emitter in a different context can also be considered and may be preferred. For example, a green-emitting triplet emitter, such as tris (phenylpyridyl) iridium (III) (IrPPy), can also be a good matrix material for a red-emitting triplet emitter and, in this combination, can lead to highly efficient red emission.

An overview of organometallic compounds can be found, for example, in Comprehensive Organometallic Chemistry: The Synthesis, Reactions and Structures of Organometallic Compounds, Volumes 1-9, Wilkinson Ed., Pergamon Press, Oxford, 1982, in Comprehensive Organometallic Chemistry-II, Volumes 1-14, Abel Ed., Pergamon Press, Oxford, 1995 and in Elschenbroich, Salzer, Organometallchemie, Teubner Study Books, Stuttgart, 1993. An overview of non-organometallic metal complexes can be found, for example, in Hollemann, Wiberg, Textbook of Inorganic Chemistry, Walter de Gruyter, Berlin, 1985, in Huheey, Keiter, Keiter, Inorganic Chemistry, Harper Collins, New York, 1993 and in Comprehensive Coordination Chemistry.

Compounds may also be preferred which may contain two or more atomic numbers> 15, which may be the same or different, such as halogenated main group element compounds, polynuclear metal complexes, metal complexes with phosphine or halogen ligands, etc. Furthermore, it is also preferred To use mixtures of two or more matrix materials A which meet the above conditions.

In order to be used as functional material, the matrix materials A are emitted together with the emitters B according to generally known methods known to the person skilled in the art, such as vacuum evaporation, evaporation in a carrier gas stream or also from solution by spin coating or with various printing processes (e.g. inkjet printing, off-line printing). Set printing, LITI printing, etc.) applied in the form of a film to a substrate.

Depending on the processing, further requirements are placed on matrix materials A and triplet emitters B. If the layer is to be created by vacuum evaporation, it is necessary that the materials can be evaporated in a vacuum without decomposition. This requires sufficient volatility and high thermal stability of the materials. If the layer is to be produced from solution, for example by printing techniques, it is necessary that the materials have a sufficiently high solubility, preferably> 0.5%, in a suitable solvent or solvent mixture.

The matrix materials A described above are used in combination with phosphorescence emitters B. The organic electroluminescent device shown in this way contains as emitter B at least one compound which, when suitably excited, emits light, preferably in the visible range and also contains at least one atom of atomic number greater than 20, preferably greater than 38 and less than 84, particularly preferably greater than 56 and less than 80 ,

Compounds which contain molybdenum, tungsten, rhenium, ruthenium, osmium, rhodium, iridium, palladium, platinum, silver, gold or europium, in particular iridium or platinum, are preferably used as the phosphorescence emitter B.

Particularly preferred mixtures contain as emitter B at least one compound of the formula (1) to (4), Formula (1) Formula (2)

Formula (3) Formula (4) where the following applies to the symbols and indices used:

DCy is the same or different at each occurrence a cyclic group which contains at least one donor atom, preferably nitrogen or phosphorus, via which the cyclic group is bonded to the metal and which in turn can carry one or more substituents R ¹ ; the groups DCy and CCy are connected to one another via at least one covalent bond;

CCy is the same or different at each occurrence a cyclic group which contains a carbon atom via which the cyclic group is bonded to the metal and which in turn can carry one or more substituents R ¹ ;

Each occurrence R ¹ is the same or different H, F, Cl, Br, I, NO ₂ , CN, a straight-chain, branched or cyclic alkyl or alkoxy group with 1 to 40 C atoms, one or more non-adjacent CH ₂ -Groups can be replaced by -O-, -S-, -NR ² - or -CONR ² - and where one or more H atoms can be replaced by F, or an aryl or heteroaryl group with 4 to 14 C atoms , which can be substituted by one or more non-aromatic radicals R ¹ ; a plurality of substituents R ¹ , both on the same ring and on the two different rings, can in turn span another mono- or polycyclic, aromatic or aliphatic ring system;

A is the same or different in each occurrence a bidentate, chelating ligand, preferably a diketonate ligand,

Each occurrence of R ² is the same or different and is H or an aliphatic or aromatic hydrocarbon radical having 1 to 20 C atoms; several of the ligands can also have one or more substituents

R ^{1 can} be linked as a bridging unit to form a larger polypodal ligand. Examples of the emitters described above can be found in the applications

WO 00/70655, WO 01/41512, WO 02/02714, WO 02/15645, EP 1191613,

EP 1191612, EP 1191614, WO 04/081017 and the unpublished application

DE 10345572.8 are taken.

It may also be preferred if the emission layer contains two or more triplet emitters B.

It may also be preferred if the emission layer contains one or more further compounds in addition to the at least one matrix material A and the at least one emitter B.

The emission layer of the organic electroluminescent device contains between 99 to 1% by weight, preferably 97 to 5% by weight, particularly preferably 95 to 50% by weight, in particular 93 to 80% by weight, of matrix compounds A, based on the overall composition of the emission layer.

The emission layer further contains between 1 to 99% by weight, preferably 3 to 95% by weight, particularly preferably 5 to 50% by weight, in particular 7 to 20% by weight, based on the total composition of the emission layer.

The organic electroluminescent device may contain other layers besides the cathode, the anode and the emission layer, such as e.g. B. hole injection layer, hole transport layer, hole blocking layer, electron transport layer and / or electron injection layer. Each of these layers, but in particular charge injection and transport layers, can also be doped. However, it should be pointed out at this point that each of these layers does not necessarily have to be present. It has been shown, for example, that an OLED that neither contains a separate hole blocking layer nor a separate electron transport layer can continue to show very good results in electroluminescence, in particular a significantly higher power efficiency. This is particularly surprising since a corresponding OLED with a carbazole-containing matrix material without a hole blocking and electron transport layer shows only very low performance efficiencies (cf. Adachi et; al., Organic Electronics 2001, 2, 37). It has also been shown that an OLED that does not contain a separate hole transport and / or hole injection layer continues to have very good results in the Can show electroluminescence. This is particularly the case when using hole-conducting matrix materials A.

Another object of the invention is therefore an organic electroluminescent device according to the invention, in which the emission layer directly adjoins the electron transport layer without using a hole blocking layer or directly adjoins the electron injection layer or the cathode without using a hole blocking layer and an electron transport layer. Yet another object of the invention is an organic electroluminescent device according to the invention, in which the emission layer borders directly on the hole injection layer without using a hole transport layer or borders directly on the anode without using a hole transport layer and a hole injection layer.

Another possible device structure contains an emission layer according to the invention, containing matrix material A and triplet emitter B, characterized in that the doping zone of emitter B in matrix A extends perpendicularly to the layer only over part of the matrix layer. This has already been described for other matrix materials in the unpublished application DE 10355381.9. With this device structure, the use of a separate hole blocking layer is not necessary, and a separate electron transport layer also does not necessarily have to be used.

The organic electroluminescent devices show higher efficiency, significantly longer life and, in particular without using a hole blocking and electron transport layer, significantly lower operating voltages and higher power efficiencies than OLEDs according to the prior art, which use CBP as the matrix material. Furthermore, the structure of the OLED is significantly simplified if no separate hole blocking and / or electron transport layer or no separate hole transport and / or hole injection layer is used, which represents a considerable technological advantage.

In the present application text, only organic light-emitting diodes and the corresponding displays are targeted. Despite this limitation of the description, it is possible for the person skilled in the art without further inventive step to use corresponding mixtures of matrix material A and triplet emitter B for other applications, in particular in OLED-related or related applications, such as organic solar cells (O-SCs), organic laser diodes (O-laser), organic field-effect transistors (O-FETs), organic thin-film transistors (O-TFTs) and others.

Examples:

Example 1: Determination of Suitable Compounds by Quantum Chemical Calculation The electronic properties of some compounds were determined by quantum chemical calculation. The geometries were optimized using the Hartree-Fock calculation (6-31 g (d)). The HOMO and LUMO values as well as the dipole moment were determined by DFT (density functional theory) calculation (B3PW91 / 6-31g (d)). Triplet levels were determined by RPA (random phase approximation) (B3LYP / 6-31 + g (d)). All calculations were carried out with the Gaussian 98 program package. Some compounds whose quantum chemical properties (although not necessarily the further properties, such as glass transition temperature etc.) are suitable for triplet matrix materials are listed in Table 1.

Table 1: Calculated physical properties of some materials that (due to these properties) are suitable as triplet matrix materials

Claims

claims:

1. Organic electroluminescent device containing cathode and anode and at least one emission layer, characterized in that the emission layer contains • at least one matrix material A, which contains at least one element with the atomic number> 15, with the proviso that the matrix material does not contain any of the elements Si, Contains Ge, Sn, Pb, Al, Ga, In or TI, is not a noble gas compound, further with the proviso that matrix materials A with the substructure L = X are excluded, where L represents a substituted C, P, As, Sb, Bi , S, Se or Te and X has at least one non-binding pair of electrons, with the proviso that tetraaryl compounds of the elements Se, Ti, Zr and Hf are excluded, and with the proviso that metal complexes of the quinoxolates, oxadiazoles and triazoles as matrix material excluded are; and • contains at least one emission material B capable of emission, which emits light from the triplet state with suitable excitation and contains at least one element with an atomic number greater than 20.

2. Organic electroluminescent device according to claim 1, characterized in that the matrix material A contains a main group element.

3. Organic electroluminescent device according to claim 2, characterized in that the matrix material A contains phosphorus, arsenic, antimony and / or bismuth.

4. Organic electroluminescent device according to claim 2, characterized in that the matrix material A contains sulfur, selenium and / or tellurium.

5. Organic electroluminescent element according to claim 3 and / or 4, characterized in that the element with the atomic number> 15 is substituted with at least one substituted or unsubstituted, aromatic or heteroaromatic ring system with 3 to 60 carbon atoms.

6. Organic electroluminescent element according to claim 5, containing as matrix material A at least one compound according to formula (A) or formula (B),

X (Ar) ₃ Y (Ar) ₂ Formula (A) Formula (B) where the following applies to the symbols used: X is P, As, Sb or Bi, preferably P or As at each occurrence; Y is S, Se or Te, preferably S or Se; Ar is the same or different in each occurrence, an aromatic or heteroaromatic ring system with 3 to 60 C atoms, which can be substituted with F or organic radicals with 1 to 40 C atoms, preferably an aromatic ring system with 6 to 40 C atoms.

7. Organic electroluminescent element according to claim 6, characterized in that the aromatic ring system is selected from the group consisting of phenyl, biphenyl, terphenyl, naphthyl, anthryl, phenanthrenyl, pyryl, fluorenyl, spirobifluorenyl, dihydrophenanthrenyl, tetrahydropyrenyl or a combination of 2 or 3 of these systems.

8. Organic electroluminescent device according to claim 1, characterized in that the matrix material A contains at least one transition metal element and / or a lanthanoid element.

9. Organic electroluminescent device according to one or more of claims 2 to 8, characterized in that the emission layer contains a mixture of at least two of these matrix materials.

10. Organic electroluminescent device according to one or more of claims 1 to 9, characterized in that the triplet energy of the matrix material A is between 2 and 4 eV.

11. Organic electroluminescent device according to one or more of claims 1 to 10, characterized in that the triplet energy of the matrix material A is greater than the triplet energy of the triplet emitter B used.

12. Organic electroluminescent device according to one or more of claims 1 to 11, characterized in that the matrix material A is amorphous.

13. Organic electroluminescent device according to claim 12, characterized in that the matrix material A has a glass transition temperature T _g greater than 90 ° C.

14. Organic electroluminescent device according to one or more of claims 1 to 13, characterized in that the matrix material A is uncharged compounds.

15. Organic electroluminescent device according to one or more of claims 1 to 14, characterized in that the LUMO of the matrix material A is higher than the HOMO of the triplet emitter B and that the LUMO of the triplet emitter B is higher than the HOMO of the matrix material A

16. Organic electroluminescent device according to one or more of claims 1 to 15, characterized in that the HOMO of the connection with the less negative HOMO in the emission layer in the range of ± 0.5 eV compared to the HOMO of the layer to which the emission layer borders on the anode side, lies.

17. Organic electroluminescent device according to one or more of claims 1 to 16, characterized in that the LUMO of the connection with the more negative LUMO in the emission layer is in the range of ± 0.5 eV compared to the LUMO of the layer to which the emission layer is adjacent on the cathode side ,

18. Organic electroluminescent device according to one or more of claims 1 to 17, characterized in that the dipole moment of the molecular fragment around the element with the atomic number> 15 is not equal to zero.

19. Organic electroluminescent device according to one or more of claims 1 to 18, characterized in that the matrix materials A are discrete molecular or coordinative compounds which also form discrete structures in the solid.

20. Organic electroluminescent device according to one or more of claims 1 to 19, characterized in that a compound is used as matrix material A which itself can also emit light from the triplet state.

21. Organic electroluminescent device according to one or more of claims 1 to 20, characterized in that the layers of matrix material A and triplet emitter B are applied to a substrate by vacuum evaporation, evaporation in the carrier gas stream or from solution by spin coating or by printing processes.

22. Organic electroluminescent device according to one or more of claims 1 to 21, characterized in that the triplet emitter B contains at least one atom of atomic number greater than 38 and less than 84.

23. Organic electroluminescent device according to claim 22, characterized in that the triplet emitter contains at least one of the elements molybdenum, tungsten, rhenium, ruthenium, osmium, rhodium, iridium, palladium, platinum, silver, gold or europium.

24. Organic electroluminescent device according to claim 22 and / or 23, characterized in that a mixture of at least two triplet emitters B is used.

25. Organic electroluminescent device according to one or more of claims 1 to 24, characterized in that the emission layer between 1 to 99% by weight of one or more matrix compounds A and between 99 and 1% by weight of one or more emitters B based on the total composition of the Emission layer.

26. Organic electroluminescent device according to claim 25, characterized in that the emission layer contains between 80 to 93% by weight of one or more matrix compounds A and between 20 and 7% by weight of one or more emitters B based on the total composition of the emission layer.

27. Organic electroluminescent device according to one or more of claims 1 to 26, characterized in that in addition to the cathode, the anode and the emitter layer, further layers are contained.

28. Organic electroluminescent device according to claim 27, characterized in that at least one hole injection layer, which can also be doped, and / or at least one hole transport layer, which can also be doped, and or at least one hole blocking layer and / or at least one electron transport layer, which is also doped can be, and / or at least one electron injection layer, which can also be doped, is present.

29. Organic electroluminescent device according to one or more of claims 1 to 28, characterized in that the emission layer directly adjoins the electron transport layer without using a hole blocking layer or that it directly adjoins the electron injection layer or the cathode without using a hole blocking layer and an electron transport layer.

30. Organic electroluminescent device according to one or more of claims 1 to 29, characterized in that the emission layer directly adjoins the hole injection layer without using a hole transport layer or that it borders directly on the anode without using a hole transport layer and a hole injection layer.