ORGANIC ELECTROLUMINESCENT DEVICE

Abstract

The present invention relates to organic electroluminescent devices which comprise mixtures of at least one phosphorescent material and at least two electron-transporting materials.

Claims

1-12. (canceled)

13. An organic electroluminescent device comprising a cathode, an anode and an emitting layer comprising the following compounds: (A) at least one electron-transporting compound which has a LUMO≦−2.4 eV; and (B) at least one further electron-transporting compound which is different from the first electron-transporting compound and has a LUMO≦−2.4 eV; and (C) at least one phosphorescent iridium compound which comprises at least one at least bidentate ligand bonded to the iridium via one carbon atom and one nitrogen atom or via two carbon atoms and which comprises at least one unit of one of formulae (1) to (7): ##STR00386## wherein the two carbon atoms explicitly drawn in are atoms which are part of the ligand and the dashed bonds indicate the linking of the two carbon atoms in the ligand; A.sup.1 and A.sup.3 are, identically or differently on each occurrence, C(R.sup.3).sub.2, O, S, NR.sup.3, or C(═O); A.sup.2 is C(R.sup.1).sub.2, O, S, NR.sup.3, or C(═O); with the proviso that no two heteroatoms in the groups of formulae (1) to (7) are bonded directly to one another and no two groups C═O are bonded directly to one another; G is an alkylene group having 1, 2, or 3 C atoms, which is optionally substituted by one or more radicals R.sup.2, —CR.sup.2═CR.sup.2—, or an ortho-linked arylene or heteroarylene group having 5 to 14 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2; R.sup.1 is on each occurrence, identically or differently, H, D, F, Cl, Br, I, N(R.sup.2).sub.2, CN, Si(R.sup.2).sub.3, B(OR.sup.2).sub.2, C(═O)R.sup.2, a straight-chain alkyl, alkoxy, or thioalkoxy group having 1 to 20 C atoms or a straight-chain alkenyl, or alkynyl group having 2 to 20 C atoms or a branched or cyclic alkyl, alkenyl, alkynyl, alkoxy, or thioalkoxy group having 3 to 20 C atoms, each of which are optionally substituted by one or more radicals R.sup.2, wherein one or more non-adjacent CH.sub.2 groups are optionally replaced by R.sup.2C═CR.sup.2, Si(R.sup.2).sub.2, C═O, NR.sup.2, O, 5, or CONR.sup.2 and wherein one or more H atoms are optionally replaced by D, F, or CN, an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2, an aryloxy or heteroaryloxy group having 5 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2, or a diarylamino group, diheteroarylamino group, or arylheteroarylamino group having 10 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2; and wherein two or more adjacent radicals R.sup.1 optionally define an aliphatic ring system with one another; R.sup.2 is on each occurrence, identically or differently, H, D, F, or an aliphatic, aromatic, and/or heteroaromatic organic radical having 1 to 20 C atoms, wherein one or more H atoms are optionally replaced by D or F; and wherein two or more substituents R.sup.2 optionally define an aliphatic or aromatic ring system with one another; R.sup.3 is, identically or differently on each occurrence, F, a straight-chain alkyl or alkoxy group having 1 to 10 C atoms or a branched or cyclic alkyl or alkoxy group having 3 to 10 C atoms, each of which is optionally substituted by one or more radicals R.sup.2, wherein one or more non-adjacent CH.sub.2 groups are optionally replaced by R.sup.2C═CR.sup.2, Si(R.sup.2).sub.2, C═O, NR.sup.2, O, S, or CONR.sup.2 and wherein one or more H atoms are optionally replaced by D or F, an aromatic or heteroaromatic ring system having 5 to 24 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2, an aryloxy or heteroaryloxy group having 5 to 24 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2, or an aralkyl or heteroaralkyl group having 5 to 24 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2; and wherein two radicals R.sup.3 which are bonded to the same carbon atom optionally define an aliphatic or aromatic ring system with one another to form a spiro system; and wherein R.sup.3 optionally defines an aliphatic ring system with an adjacent radical R.sup.1.

14. The organic electroluminescent device of claim 13, wherein the LUMO of each of the electron-transporting compounds is ≦−2.50 eV.

15. The organic electroluminescent device of claim 13, wherein the emitting layer consists only of the two electron-transporting compounds and the phosphorescent iridium compound or the emitting layer, apart from the two electron-transporting compounds and the phosphorescent iridium compound, further comprises at least one luminescent iridium compound.

16. The organic electroluminescent device of claim 13, wherein the following applies to each of the two electron-transporting compounds: T.sub.1(matrix)≧T.sub.1(emitter), wherein T.sub.1(matrix) is the lowest triplet energy of the respective electron-transporting compound and T.sub.1(emitter) is the lowest triplet energy of the phosphorescent iridium compound.

17. The organic electroluminescent device of claim 13, wherein the electron-transporting compounds are selected from the group consisting of the classes of the triazines; the pyrimidines; the pyrazines; the pyridazines; the pyridines; the lactams; the metal complexes; the aromatic ketones; the aromatic phosphine oxides; the azaphospholes; the azaboroles; which are substituted by at least one electron-transporting substituent; and the quinoxalines.

18. The organic electroluminescent device of claim 13, wherein one of the electron-transporting compounds is a triazine or pyrimidine compound and the other of the electron-transporting compounds is a lactam compound.

19. The organic electroluminescent device of claim 13, wherein at least one electron-transporting compound is selected from the compounds of the formulae (8) and (9): ##STR00387## wherein R is selected on each occurrence, identically or differently, from the group consisting of H, D, F, Cl, Br, I, CN, NO.sub.2, N(R.sup.1).sub.2, C(═O)R.sup.1, P(═O)R.sup.1, a straight-chain alkyl, alkoxy, or thioalkyl group having 1 to 20 C atoms or a branched or cyclic alkyl, alkoxy, or thioalkyl group having 3 to 20 C atoms or an alkenyl or alkynyl group having 2 to 20 C atoms, each of which is optionally substituted by one or more radicals R.sup.1, wherein one or more non-adjacent CH.sub.2 groups are optionally replaced by R.sup.1C═CR.sup.1, C≡C, Si(R.sup.1).sub.2, C═O, C═S, C═NR.sup.1, P(═O)(R.sup.1), SO, SO.sub.2, NR.sup.1, O, S, or CONR.sup.1 and wherein one or more H atoms are optionally replaced by D, F, Cl, Br, I, CN, or NO.sub.2, an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.1, an aryloxy or heteroaryloxy group having 5 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.1, or an aralkyl or heteroaralkyl group having 5 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.1, and wherein two or more adjacent substituents R optionally define a monocyclic or polycyclic, aliphatic, aromatic or heteroaromatic ring system, which is optionally substituted by one or more radicals R.sup.1; with the proviso that at least one of the substituents R is an aromatic or heteroaromatic ring system.

20. The organic electroluminescent device of claim 19, wherein at least one electron-transporting compound is selected from the group consisting of compounds of formulae (8a) and (9a) through (9d): ##STR00388## wherein R is, identically or differently, for an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.1.

21. The organic electroluminescent device of claim 13, wherein at least one electron-transporting compound is a lactam which is selected from the group consisting of compounds of formulae (53) and (54): ##STR00389## wherein R is selected on each occurrence, identically or differently, from the group consisting of H, D, F, Cl, Br, I, CN, NO.sub.2, N(R.sup.1).sub.2, C(═O)R.sup.1, P(═O)R.sup.1, a straight-chain alkyl, alkoxy, or thioalkyl group having 1 to 20 C atoms or a branched or cyclic alkyl, alkoxy, or thioalkyl group having 3 to 20 C atoms or an alkenyl or alkynyl group having 2 to 20 C atoms, each of which is optionally substituted by one or more radicals R.sup.1, wherein one or more non-adjacent CH.sub.2 groups are optionally replaced by R.sup.1C═CR.sup.1, C≡C, Si(R.sup.1).sub.2, C═O, C═S, C═NR.sup.1, P(═O)(R.sup.1), SO, SO.sub.2, NR.sup.1, O, S, or CONR.sup.1 and wherein one or more H atoms are optionally replaced by D, F, Cl, Br, I, CN, or NO.sub.2, an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.1, an aryloxy or heteroaryloxy group having 5 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.1, or an aralkyl or heteroaralkyl group having 5 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.1, and wherein two or more adjacent substituents R optionally define a monocyclic or polycyclic, aliphatic, aromatic or heteroaromatic ring system, which is optionally substituted by one or more radicals R′; with the proviso that at least one of the substituents R is an aromatic or heteroaromatic ring system; R.sup.1 is on each occurrence, identically or differently, H, D, F, Cl, Br, I, N(R.sup.2).sub.2, CN, Si(R.sup.2).sub.3, B(OR.sup.2).sub.2, C(═O)R.sup.2, a straight-chain alkyl, alkoxy, or thioalkoxy group having 1 to 20 C atoms or a straight-chain alkenyl, or alkynyl group having 2 to 20 C atoms or a branched or cyclic alkyl, alkenyl, alkynyl, alkoxy, or thioalkoxy group having 3 to 20 C atoms, each of which are optionally substituted by one or more radicals R.sup.2, wherein one or more non-adjacent CH.sub.2 groups are optionally replaced by R.sup.2C═CR.sup.2, Si(R.sup.2).sub.2, C═O, NR.sup.2, O, S, or CONR.sup.2 and wherein one or more H atoms are optionally replaced by D, F, or CN, an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2, an aryloxy or heteroaryloxy group having 5 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2, or a diarylamino group, diheteroarylamino group, or arylheteroarylamino group having 10 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2; and wherein two or more adjacent radicals R.sup.1 optionally define an aliphatic ring system with one another; R.sup.2 is on each occurrence, identically or differently, H, D, F, or an aliphatic, aromatic, and/or heteroaromatic organic radical having 1 to 20 C atoms, wherein one or more H atoms are optionally replaced by D or F; and wherein two or more substituents R.sup.2 optionally define an aliphatic or aromatic ring system with one another; E is, identically or differently on each occurrence, a single bond, NR, CR.sub.2, O or S; Ar.sup.1 is, together with the carbon atoms explicitly depicted, an aromatic or heteroaromatic ring system having 5 to 18 aromatic ring atoms, which may be substituted by one or more radicals R; Ar.sup.2 and Ar.sup.3 are, identically or differently on each occurrence, together with the carbon atoms explicitly depicted, an aromatic or heteroaromatic ring system having 5 to 18 aromatic ring atoms, which is optionally substituted by one or more radicals R; L is for m=2 a single bond or a divalent group, or for m=3 a trivalent group or for m=4 a tetravalent group, which is in each case bonded to Ar.sup.1, Ar.sup.2, or Ar.sup.3 at any desired position or is bonded to E in place of a radical R; m is 2, 3 or 4.

22. The organic electroluminescent device of claim 13, wherein the structures of the formulae (1) to (7) are selected from the structures of the formulae (1-A) through (1-F), (2-A) through (2-F), (3-A) through (3-E), (4-A) through (4-C), (5-A), (6-A), and (7-A), ##STR00390## ##STR00391## ##STR00392## wherein A.sup.1, A.sup.2 and A.sup.3 are, identically or differently on each occurrence, for O or NR.sup.3.

23. The organic electroluminescent device of claim 13, wherein the phosphorescent iridium compound is a compound of formula (75):
Ir(L.sup.1).sub.p(L.sup.2).sub.q  75) wherein L.sup.1 is a bidentate monoanionic ligand comprising at least one aryl or heteroaryl group bonded to the iridium via a carbon or nitrogen atom and which comprises a group of formulae (1) to (7); L.sup.2 is, identically or differently on each occurrence, a monoanionic bidentate ligand; p is 1, 2, or 3; q is (3−p).

24. A process for producing an organic electroluminescent according to claim 13, comprising producing one or more layers by means of (1) a sublimation process and/or (2) an organic vapour phase deposition process or with the aid of carrier-gas sublimation and/or (3) from solution.

Description

EXAMPLES

[0201] Determination of HOMO, LUMO, Singlet and Triplet Level

[0202] The HOMO and LUMO energy levels and the energy of the lowest triplet state T.sub.1 or of the lowest excited singlet state S.sub.1 of the materials are determined via quantum-chemical calculations. To this end, the “Gaussian09W” software package (Gaussian Inc.) is used. In order to calculate organic substances without metals, firstly a geometry optimisation is carried out using the “Ground State/Semi-empirical/Default Spin/AM1/Charge 0/Spin Singlet” method. This is followed by an energy calculation on the basis of the optimised geometry. The “TD-SFC/DFT/Default Spin/B3PW91” method with the “6-31G(d)” base set is used here (Charge 0, Spin Singlet). For metal-containing compounds, the geometry is optimised via the “Ground State/Hartree-Fock/Default Spin/LanL2 MB/Charge 0/Spin Singlet” method. The energy calculation is carried out analogously to the organic substances as described above, with the difference that the “LanL2DZ” base set is used for the metal atom and the “6-31G(d)” base set is used for the ligands. The energy calculation gives the HOMO energy level HEh or LUMO energy level LEh in hartree units. The HOMO and LUMO energy levels calibrated with reference to cyclic voltammetry measurements are determined therefrom in electron volts as follows:

HOMO(eV)=((HEh*27.212)−0.9899)/1.1206

LUMO(eV)=((LEh*27.212)−2.0041)/1.385

[0203] These values are to be regarded in the sense of this application as HOMO and LUMO energy levels of the materials.

[0204] The lowest triplet state T.sub.1 is defined as the energy of the triplet state having the lowest energy which arises from the quantum-chemical calculation described.

[0205] The lowest excited singlet state S.sub.1 is defined as the energy of the excited singlet state having the lowest energy which arises from the quantum-chemical calculation described.

[0206] Table 4 below shows the HOMO and LUMO energy levels and S.sub.1 and T.sub.1 of the various materials.

Synthesis Examples

[0207] The following syntheses are carried out, unless indicated otherwise, in dried solvents under a protective-gas atmosphere. The metal complexes are additionally handled with exclusion of light or under yellow light. The solvents and reagents can be purchased, for example, from SigmaALDRICH or ABCR. The respective numbers in square brackets or the numbers indicated for individual compounds relate to the CAS numbers of the compounds which are known from the literature.

[0208] A: Synthesis of the Synthones S:

Example S1: Dispiro[cyclopentane-1,1′-[1H]indene-3′(2′H),1″-cyclopentane]-5-boronic acid pinacol ester

[0209] ##STR00362##

a) Dispiro[cyclopentane-1,1′-[1H]inden-3′(2′H),1″-2-onecyclopentane], [1620682-15-6]

[0210] ##STR00363##

[0211] A solution of 66.1 g (500 mmol) of indan-2-one [615-13-4] and 340.9 g (1100 mmol) of 1,4-diiodobutane [628-21-7] in 500 ml of THF is added dropwise over the course of 2 h to a vigorously stirred mixture of 40.0 g (1 mol) of NaOH, 40 ml of water, 18.5 g (50 mmol) of tetrabutylammonium iodide [311-28-4] and 1500 ml of THF. When the addition is complete, the mixture is stirred at room temperature for a further 14 h, the aqueous phase is separated off, and the organic phase is evaporated to dryness. The residue is taken up in 1000 ml of n-heptane, washed five times with 300 ml of water each time and dried over magnesium sulfate. The crude product obtained after removal of the n-heptane is subjected to fractional distillation in an oil-pump vacuum (about 0.2 mbar, T about 135° C.). Yield: 83.0 g (345 mmol), 69%. Purity about 95% according to .sup.1H-NMR.

b) Dispiro[cyclopentane-1,1′-[1H]indene-3′(2′H),1″-cyclopentane]

[0212] ##STR00364##

[0213] A mixture of 83 g (345 mmol) of dispiro[cyclopentane-1,1′-[1H]inden-3′(2′H),1″-2-onecyclopentane] from a), 100.1 g (2.0 mol) of hydrazine hydrate, 112.2 g (2.5 mol) of potassium hydroxide and 500 ml of triethylene glycol is stirred at 180° C. with vigorous stirring for 16 h. The temperature is then increased stepwise until 250° C. has been reached, during which distillate formed is removed via a water separator and discarded, and the mixture is stirred further until the evolution of nitrogen peters out. After cooling, the reaction mixture is diluted with 500 ml of water and extracted three times with 300 ml of n-heptane each time. The combined n-heptane phases are washed five times with 200 ml of water each time and dried over magnesium sulfate. The crude product obtained after removal of the n-heptane is subjected to fractional distillation in an oil-pump vacuum (about 0.2 mbar, T about 105° C.). Yield: 57.7 g (255 mmol), 74%. Purity about 95% according to .sup.1H-NMR.

c) Dispiro[cyclopentane-1,1′-[1H]indene-3′(2′H),1″-cyclopentane]-5-boronic acid pinacol ester

[0214] 14.0 g (55 mmol) of bispinacolatodiborane [73183-34-3] are added with stirring to a mixture of 1.7 g (2.5 mmol) of methoxy(cyclooctadiene)iridium(I) dimer [12148-71-9], 1.4 g (5 mmol) of 4,4′-di-tert-butyl-2,2-bipyridinyl [72914-19-3] and 500 ml of n-heptane, and the mixture is stirred at room temperature for 15 min. A further 50.8 g (200 mmol) of bispinacolatodiborane and then 57.7 g (255 mmol) of dispiro[cyclopentane-1,1′-[1H]indene-3′(2′H),1″-cyclopentane] from b) are then added, and the reaction mixture is heated at 80° C. for 16 h. After cooling, the n-heptane is removed in vacuo, and the residue is washed by stirring twice with 400 ml of methanol each time. Yield: 70.1 g (199 mmol), 78%. Purity about 98% according to .sup.1H-NMR.

[0215] B. Synthesis of the Ligands L

Example L1: 2-(Dispiro[cyclopentane-1,1′-[1H]inden-3′(2′H),1″-5-yl-cyclopentane]pyridine

[0216] ##STR00365##

[0217] 841 mg (3 mmol) of tricyclohexylphosphine [2622-14-2] and then 449 mg (2 mmol) of palladium(II) acetate are added to a vigorously stirred mixture of 70.1 g (199 mmol) of dispiro[cyclopentane-1,1′-[1H]indene-3′(2′H),1″-cyclopentane]-5-boronic acid pinacol ester S1, 39.5 g (250 mmol) of 2-bromopyridine [109-04-6], 115.1 g (500 mmol) of tripotassium phosphate monohydrate, 600 ml of toluene, 600 ml of dioxane and 600 ml of water, and the mixture is then heated under reflux for 40 h. After cooling, the organic phase is separated off, washed three times with 200 ml of water each time and once with 200 ml of saturated sodium chloride solution and dried over magnesium sulfate. The desiccant is filtered off via a Celite bed, the solvent and excess 2-bromopyridine are stripped off, and the oil which remains is subjected to fractional bulb-tube distillation twice in vacuo (p about 10.sup.−4 mbar, T about 220° C.). Yield: 40.7 g (134 mmol), 67%. Purity about 99% according to .sup.1H-NMR.

[0218] C. Synthesis of the Complexes

Example Ir(L1).SUB.3

[0219] ##STR00366##

[0220] A mixture of 30.3 g (100 mmol) of the ligand L1 and 12.2 g (25 mmol) of trisacetylacetonatoiridium(III) [15635-87-7] is initially introduced in a 250 ml two-necked round-bottomed flask with glass-clad magnetic bar. The flask is provided with a water separator and an air condenser with argon blanketing. The flask is placed in a metal heating bowl. The apparatus is flushed from above with argon via the argon blanketing for 15 min., during which the argon is allowed to flow out of the side neck of the two-necked flask. A glass-clad Pt-100 thermocouple is introduced into the two-necked flask via the side neck, and the end is positioned just above the magnetic stirrer bar. The apparatus is then thermally insulated using several loose wound layers of household aluminium foil, where the insulation is applied up to the centre of the rising tube of the water separator. The apparatus is then heated rapidly to 275° C., measured on the Pt-100 thermocouple which dips into the molten, stirred reaction mixture, using a laboratory heating stirrer. During the next 20 h, the reaction mixture is kept at 270-275° C., during which about 5 ml of acetylacetone distil off successively and collect in the water separator. After cooling, the melt cake is mechanically comminuted and then washed with 300 ml of boiling methanol. The beige suspension obtained in this way is filtered through a reverse frit, the beige solid is washed once with methanol and then dried in vacuo. Crude yield: quantitative. The crude product obtained in this way is subsequently chromatographed on silica gel (about 100 g per g of crude product) with toluene with exclusion of air and light, where the product (yellow band) elutes virtually with the eluent front and dark secondary components remain at the beginning. The core fraction of the yellow band is cut out, the toluene is removed in vacuo, and the yellow glass remaining is taken up in 200 ml of hot acetonitrile, during which crystallisation of the product commences. After stirring for a further one hour, the cooled suspension is filtered through a reverse frit with suction, and the yellow solid is washed once with 50 ml of acetonitrile. The further purification is carried out by continuous hot extraction with acetonitrile five times (amount of acetonitrile introduced about 300 ml, extraction thimble: standard cellulose Soxhlett thimble from Whatman) with careful exclusion of air and light. Finally, the product is subjected to fractional sublimation twice in vacuo (p about 10.sup.−5 mbar, T about 340° C.). Yield: 11.5 g, 42%. Purity: >99.9% according to HPLC.

Example: Production of the OLEDs

[0221] OLEDs according to the invention and OLEDs in accordance with the prior art are produced by a general process in accordance with WO 2004/058911, which is adapted to the circumstances described here (layerthickness variation, materials used).

[0222] The results of various OLEDs are presented in the following examples. Glass plates with structured ITO (50 nm, indium tin oxide) form the substrates to which the OLEDs are applied. The OLEDs have in principle the following layer structure: substrate/hole-transport layer 1 (HTL1) consisting of HTM doped with 3% of NDP-9 (commercially available from Novaled), 20 nm/hole-transport layer 2 (HTL2)/optional electron-blocking layer (EBL)/emission layer (EML)/optional hole-blocking layer (HBL)/electron-transport layer (ETL)/optional electron-injection layer (EIL) and finally a cathode. The cathode is formed by an aluminium layer with a thickness of 100 nm.

[0223] Firstly, vacuum-processed OLEDs are described. For this purpose, all materials are applied by thermal vapour deposition in a vacuum chamber. The emission layer here always consists of at least one matrix material (host material) and an emitting dopant (emitter), which is admixed with the matrix material or matrix materials in a certain proportion by volume by coevaporation. An expression such as M3:M2:Ir(LH1).sub.3 (55%:35%:10%) here means that material M3 is present in the layer in a proportion by volume of 55%, M2 is present in the layer in a proportion of 35% and Ir(LH1).sub.3 is present in the layer in a proportion of 10%. Analogously, the electron-transport layer may also consist of a mixture of two materials. The precise structure of the OLEDs is shown in Table 1. The materials used for the production of the OLEDs are shown in Table 3.

[0224] The OLEDs are characterised by standard methods. For this purpose, the electroluminescence spectra, the current efficiency (measured in cd/A) and the voltage (measured at 10 mA/cm.sup.2 in V) are determined from the current/voltage/luminance characteristic lines (IUL characteristic lines), are determined. The external quantum efficiency (EQE) and the CIE 1931 colour coordinates are derived therefrom. For selected experiments, the lifetime is determined. The lifetime is defined as the time after which the luminous density has dropped to a certain proportion from its initial luminous density at a defined, constant operating current (typically 50 mA/cm.sup.2). The term LT50 means that the said lifetime is the time by which the luminous density has dropped to 50% of the initial luminous density. The values for the lifetime can be converted to a value for other initial luminous densities with the aid of conversion formulae known to the person skilled in the art.

[0225] Table 1 below shows the layer structures and materials used (see Table 3) both for OLEDs according to the invention and also comparative examples. The associated results of the OLEDs are summarised in Table 2. The HTL1 used is basically HTM doped with 3% of NDP-9.

[0226] Examples 1-3 illustrate the crucial effect of this invention. The mixture according to the invention of two electron-transporting matrix materials with an emitter defined in accordance with the invention (see 1 a, 1 b, 1c) results in OLEDs which simultaneously have high efficiency, a low voltage and a long lifetime. In addition, it is advantageous that, when the emitter concentration is reduced from 18% to 12% to 6%, the voltage becomes lower and at the same time the efficiency becomes higher, without significantly adversely affecting the lifetime. By contrast, Example 2 shows that on use of an emitter which does not correspond to the invention in the same matrix system, the efficiency is significantly weaker. Likewise, a reduction in the emitter concentration does not result in a reduction in the voltage, but instead, on the contrary, in an increase. Conversely, the use of a mixture which is not in accordance with the invention of an electron-conducting matrix material and a hole-conducting matrix material with the emitter from Example 1 results in OLEDs having an increased operating voltage (see Example 3).

[0227] Only the combination according to the invention of suitable emitters, as defined in the present invention, with two electron-transporting matrices results in OLEDs which simultaneously exhibit good performance data in all three parameters efficiency, voltage and lifetime (and do so in side effect at low emitter concentration). The fact that this effect is not restricted to the materials or layer architectures specifically selected in Example 1 is demonstrated by the further working examples from Example 4, in which further materials are combined in accordance with the invention, in some cases also with other electron- or hole-blocking layers.

TABLE-US-00004 TABLE 1 Structure of the OLEDs HTL2 EBL EML HBL ETL Ex. Thickness Thickness Thickness Thickness Thickness Green OLEDs 1a HTM EBM eM1:eM4:G1 ETM1 ETM1:ETM2 220 nm 20 nm (44%:44%:12%) 10 nm (50%:50%) 30 nm 30 nm 1b HTM EBM eM1:eM4:G1 ETM1 ETM1:ETM2 220 nm 20 nm (47%:47%:6%)  10 nm (50%:50%) 30 nm 30 nm 1c HTM EBM eM1:eM4:G1 ETM1 ETM1:ETM2 220 nm 20 nm (41%:41%:18%) 10 nm (50%:50%) 30 nm 30 nm 2a HTM EBM eM1:eM4:Irppy ETM1 ETM1:ETM2 (comparison) 220 nm 20 nm (44%:44%:12%) 10 nm (50%:50%) 30 nm 30 nm 2b HTM EBM eM1:eM4:Irppy ETM1 ETM1:ETM2 (comparison) 220 nm 20 nm (47%:47%:6%)  10 nm (50%:50%) 30 nm 30 nm 2c HTM EBM eM1:eM4:Irppy ETM1 ETM1:ETM2 (comparison) 220 nm 20 nm (41%:41%:18%) 10 nm (50%:50%) 30 nm 30 nm 3a HTM EBM hM1:eM4:G1 ETM1 ETM1:ETM2 (comparison) 220 nm 20 nm (44%:44%:12%) 10 nm (50%:50%) 30 nm 30 nm 3b HTM EBM hM1:eM4:G1 ETM1 ETM1:ETM2 (comparison) 220 nm 20 nm (47%:47%:6%)  10 nm (50%:50%) 30 nm 30 nm 3c HTM EBM hM1:eM4:G1 ETM1 ETM1:ETM2 (comparison) 220 nm 20 nm (41%:41%:18%) 10 nm (50%:50%) 30 nm 30 nm 4a HTM EBM eM1:eM5:G1 ETM1 ETM1:ETM2 220 nm 20 nm (44%:44%:12%) 10 nm (50%:50%) 30 nm 30 nm 4b HTM EBM eM1:eM5:G1 ETM1 ETM1:ETM2 220 nm 20 nm (47%:47%:6%)  10 nm (50%:50%) 30 nm 30 nm 4c HTM EBM eM1:eM5:G1 ETM1 ETM1:ETM2 220 nm 20 nm (41%:41%:18%) 10 nm (50%:50%) 30 nm 30 nm 5a HTM EBM hM2:eM2:G1 ETM1 ETM1:ETM2 (comparison) 220 nm 20 nm (44%:44%:12%) 10 nm (50%:50%) 30 nm 30 nm 5b HTM EBM hM2:eM5:G1 ETM1 ETM1:ETM2 (comparison) 220 nm 20 nm (47%:47%:6%)  10 nm (50%:50%) 30 nm 30 nm 5c HTM EBM hM2:eM5:G1 ETM1 ETM1:ETM2 (comparison) 220 nm 20 nm (41%:41%:18%) 10 nm (50%:50%) 30 nm 30 nm 6a HTM EBM eM2:eM4:G1 eM2 ETM1:ETM2 220 nm 20 nm (44%:44%:12%) 10 nm (50%:50%) 30 nm 30 nm 6b HTM EBM eM2:eM4:G1 eM2 ETM1:ETM2 220 nm 20 nm (47%:47%:6%)  10 nm (50%:50%) 30 nm 30 nm 6c HTM EBM eM2:eM4:G1 eM2 ETM1:ETM2 220 nm 20 nm (41%:41%:18%) 10 nm (50%:50%) 30 nm 30 nm 7a HTM EBM eM1:eM4:G1 ETM1 ETM1:ETM2 220 nm 20 nm (24%:70%:6%)  10 nm (50%:50%) 30 nm 30 nm 7b HTM EBM eM1:eM4:G1 ETM1 ETM1:ETM2 220 nm 20 nm (70%:24%:6%)  10 nm (50%:50%) 30 nm 30 nm 8  HTM — eM1:eM4:G1 ETM1 ETM1:ETM2 240 nm (44%:44%:12%) 10 nm (50%:50%) 30 nm 30 nm 9  HTM — eM1:eM4:G1 — ETM1:ETM2 240 nm (44%:44%:12%) (50%:50%) 30 nm 40 nm 10  HTM EBM eM3:eM4:G1 ETM1 ETM1:ETM2 220 nm 20 nm (47%:47%:6%)  10 nm (50%:50%) 30 nm 30 nm 11  HTM EBM eM5:eM6:G1 ETM1 ETM1:ETM2 220 nm 20 nm (47%:47%:6%)  10 nm (50%:50%) 30 nm 30 nm 12  HTM EBM eM1:eM4:G2 ETM1 ETM1:ETM2 220 nm 20 nm (47%:47%:6%)  10 nm (50%:50%) 30 nm 30 nm 13  HTM EBM eM1:eM4:G3 ETM1 ETM1:ETM2 220 nm 20 nm (47%:47%:6%)  10 nm (50%:50%) 30 nm 30 nm Red OLEDs 14  HTM — eM1:hM1:R1 — ETM1:ETM2 (comparison) 280 nm (63%:31%:6%)  (50%:50%) 40 nm 30 nm 15a  HTM — eM1:eM4:Irpiq — ETM1:ETM2 (comparison) 280 nm (47%:47%:3%)  (50%:50%) 40 nm 30 nm 15b  HTM — eM1:eM4:Irpiq — ETM1:ETM2 (comparison) 280 nm (47%:47%:7%)  (50%:50%) 40 nm 30 nm 16a  HTM — eM1:eM4:R1 — ETM1:ETM2 280 nm (47%:47%:3%)  (50%:50%) 40 nm 30 nm 16b  HTM — eM1:eM4:R1 — ETM1:ETM2 280 nm (47%:47%:7%)  (50%:50%) 40 nm 30 nm Yellow OLEDs 17a  HTM EBM hM1:eM1:Y1 ETM1 ETM1:ETM2 (comparison) 220 nm 20 nm (41%:41%:18%) 10 nm (50%:50%) 30 nm 30 nm 17b  HTM EBM hM1:eM1:Y1 ETM1 ETM1:ETM2 (comparison) 220 nm 20 nm (44%:44%:12%) 10 nm (50%:50%) 30 nm 30 nm 17c  HTM EBM hM1:eM1:Y1 ETM1 ETM1:ETM2 (comparison) 220 nm 20 nm (47%:47%:6%)  10 nm (50%:50%) 30 nm 30 nm 18a  HTM EBM eM1:eM4:Y1 ETM1 ETM1:ETM2 220 nm 20 nm (41%:41%:18%) 10 nm (50%:50%) 30 nm 30 nm 18b  HTM EBM eM1:eM4:Y1 ETM1 ETM1:ETM2 220 nm 20 nm (44%:44%:12%) 10 nm (50%:50%) 30 nm 30 nm 18c  HTM EBM eM1:eM4:Y1 ETM1 ETM1:ETM2 220 nm 20 nm (47%:47%:6%)  10 nm (50%:50%) 30 nm 30 nm

TABLE-US-00005 TABLE 2 Results of vacuum-processed OLEDs EQE (%) [power eff.] Voltage (V) CIE x/y LT50 (h) Ex. 10 mA/cm.sup.2 10 mA/cm.sup.2 10 mA/cm.sup.2 50 mA/cm.sup.2 Green OLEDs 1a 19.8 4.3 0.34/0.63 500 [55.3 lmW] 1b 21.0 4.0 0.32/0.64 400 [63.1 lm/W] 1c 17.2 4.7 0.35/0.62 500 [43.9 lmW/] 2a 15.3 4.3 0.30/0.64 300 (comparison) [41.4 lm/W] 2b 15.6 4.7 0.31/0.64 250 (comparison) [38.8 lmW/] 2c 15.0 4.1 0.31/0.64 300 (comparison) [42.9 lm/W] 3a 21.2 5.0 0.33/0.64 400 (comparison) [50.9 lm/W] 3b 22.2 4.8 0.33/0.64 400 (comparison) [55.4 lm/W] 3c 19.7 5.4 0.32/0.65 400 (comparison) [43.7 lm/W] 4a 20.0 4.3 0.34/0.63 600 [55.8 lm/W] 4b 21.2 4.0 0.32/0.64 400 [63.6 lm/W] 4c 16.8 4.5 0.35/0.62 500 [44.8 lm/W] 5a 19.6 5.0 0.33/0.64 300 (comparison) [47.0 lm/W] 5b 21.2 4.7 0.34/0.63 350 (comparison) [54.1 lm/W] 5c 19.4 5.5 0.32/0.65 400 (comparison) [42.3 lm/W] 6a 20.4 4.4 0.34/0.63 500 [55.6 lm/W] 6b 21.5 4.1 0.32/0.64 500 [62.9 lm/W] 6c 18.2 4.6 0.35/0.62 600 [47.5 lm/W] 7a 19.9 4.3 0.33/0.64 450 [55.1 lm/W] 7b 20.8 3.9 0.33/0.63 400 [63.4 lm/W] 8  19.4 4.1 0.34/0.63 600 [56.4 lm/W] 9  19.3 4.1 0.34/0.63 600 [56.5 lm/W] 10  20.5 4.0 0.32/0.63 400 [61.5 lm/W] 11  19.5 4.1 0.33/0.63 350 [57.1 lm/W] 12  19.7 4.0 0.36/0.62 350 [58.1 lm/W] 13  19.3 3.9 0.33/0.64 300 [59.0 lm/W] Red OLEDs 14  16.2 3.9 0.70/0.30 700 (comparison) 15a  13.5 3.7 0.68/0.32 1400 (comparison) 15b  13.2 3.7 0.68/0.32 1700 (comparison) 16a  16.7 3.5 0.70/0.30 3500 16b  16.2 3.7 0.70/0.30 5000 Yellow OLEDs 17a  17.9 4.7 0.48/0.52 850 (comparison) 17b  18.0 4.8 0.48/0.52 800 (comparison) 17c  18.3 4.6 0.46/0.53 600 (comparison) 18a  18.9 4.4 0.48/0.52 1000 18b  18.4 4.2 0.48/0.52 900 18c  16.0 4.1 0.46/0.53 750

TABLE-US-00006 TABLE 3 Structural formulae of the materials used [00367] HTM [00368] EBM [00369] eM1 [00370] eM2 [00371] eM3 [00372] eM4 [00373] eM5 [00374] eM6 [00375] hM1 [00376] hM2 [00377] G1 [00378] G2 [00379] G3 [00380] Y1 [00381] Irppy [00382] Irpiq [00383] R1 [00384] ETM1 [00385] ETM2/Liq

TABLE-US-00007 TABLE 4 HOMO, LUMO, S.sub.1 and T.sub.1 of the materials used Material HOMO [eV] LUMO [eV] S1 [eV] T1 [eV] eM1 −5.47 −2.60 2.87 2.72 eM2 −5.68 −2.55 3.09 2.69 eM3 −5.67 −2.49 3.07 2.75 eM4 −5.95 −2.54 3.27 2.68 eM5 −5.94 −2.60 3.21 2.66 eM6 −5.76 −2.58 3.14 2.72 hM1 −5.32 −1.84 3.24 2.80 hM2 −5.21 −1.58 3.14 2.73