Materials for organic electroluminescent devices

Abstract

The present invention relates to compounds, which are suitable for use in electronic devices, and to electronic devices, in particular organic electroluminescent devices, containing said compounds.

Claims

1. A compound of formula (1): ##STR00583## where the symbols used are as follows: X two adjacent X are a group of the following formula (2) or (3), and the remaining X are the same or different at each instance and are CR or N; ##STR00584## where the dotted bonds indicate the linkage of this group in the formula (1); Y is the same or different at each instance and is CR′ or N; Ar is the same or different at each instance and is an aromatic or heteroaromatic ring system which has 5 to 40 aromatic ring atoms and may be substituted by one or more R radicals; R, R′ is the same or different at each instance and is H, D, F, Cl, Br, I, N(Ar′).sub.2, N(R.sup.1).sub.2, OAr′, SAr′, CN, NO.sub.2, OR.sup.1, SR.sup.1, COOR.sup.1, C(═O)N(R.sup.1).sub.2, Si(R.sup.1).sub.3, B(OR.sup.1).sub.2, C(═O)R.sup.1, P(═O)(R.sup.1).sub.2, S(═O)R.sup.1, S(═O).sub.2R.sup.1, OSO.sub.2R.sup.1, a straight-chain alkyl group having 1 to 20 carbon atoms or an alkenyl or alkynyl group having 2 to 20 carbon atoms or a branched or cyclic alkyl group having 3 to 20 carbon atoms, where the alkyl, alkenyl or alkynyl group may in each case be substituted by one or more R.sup.1 radicals, where one or more nonadjacent CH.sub.2 groups may be replaced by Si(R.sup.1).sub.2, C═O, NR.sup.1, O, S or CONR.sup.1, or an aromatic or heteroaromatic ring system which has 5 to 60 aromatic ring atoms, and may be substituted in each case by one or more R.sup.1 radicals; at the same time, two R radicals together may also form an aliphatic or heteroaliphatic ring system; in addition, two R′ radicals together may also form an aliphatic, heteroaliphatic, aromatic or heteroaromatic ring system; Ar′ is the same or different at each instance and is an aromatic or heteroaromatic ring system which has 5 to 40 aromatic ring atoms and may be substituted by one or more R.sup.1 radicals; R.sup.1 the same or different at each instance and is H, D, F, Cl, Br, I, N(R.sup.2).sub.2, CN, NO.sub.2, OR.sup.2, SR.sup.2, Si(R.sup.2).sub.3, B(OR.sup.2).sub.2, C(═O)R.sup.2, P(═O)(R.sup.2).sub.2, S(═O)R.sup.2, S(═O).sub.2R.sup.2, OSO.sub.2R.sup.2, a straight-chain alkyl group having 1 to 20 carbon atoms or an alkenyl or alkynyl group having 2 to 20 carbon atoms or a branched or cyclic alkyl group having 3 to 20 carbon atoms, where the alkyl, alkenyl or alkynyl group may each be substituted by one or more R.sup.2 radicals, where one or more nonadjacent CH.sub.2 groups may be replaced by Si(R.sup.2).sub.2, C═O, NR.sup.2, O, S or CONR.sup.2 and where one or more hydrogen atoms in the alkyl, alkenyl or alkynyl group may be replaced by D, F, Cl, Br, I or CN, or an aromatic or heteroaromatic ring system which has 5 to 40 aromatic ring atoms and may be substituted in each case by one or more R.sup.2 radicals; at the same time, two or more R.sup.1 radicals together may form an aliphatic ring system; R.sup.2 is the same or different at each instance and is H, D, F, CN or an aliphatic, aromatic or heteroaromatic organic radical.

2. The compound as claimed in claim 1, selected from the structures of the formulae (4) to (15): ##STR00585## ##STR00586## where the symbols used have the definitions given in claim 1.

3. The compound as claimed in claim 1, characterized in that the group of the formula (2) is selected from the formulae (2a) to (2e) and in that the group of the formula (3) is selected from the formula (3a): ##STR00587## ##STR00588## where the symbols used have the definitions given in claim 1 and the R′ radicals do not form an aromatic or heteroaromatic ring system with one another.

4. The compound as claimed in claim 1, characterized in that not more than one of the symbols X and Y is N in total.

5. The compound as claimed in claim 1, selected from the structures of the formulae (4a) to (15a): ##STR00589## ##STR00590## ##STR00591## where the symbols used have the definitions given in claim 1.

6. The compound as claimed in claim 1, selected from the structures of the formulae (4b) to (15c): ##STR00592## ##STR00593## ##STR00594## ##STR00595## where the symbols used have the definitions given in claim 1.

7. The compound as claimed in claim 1, characterized in that Ar is an aromatic or heteroaromatic ring system which has 6 to 24 aromatic ring atoms and may be substituted by one or more R radicals.

8. The compound as claimed in claim 1, characterized in that Ar is selected from the group consisting of phenyl, biphenyl, terphenyl, quaterphenyl, fluorenyl, spirobifluorenyl, naphthyl, indolyl, benzofuranyl, benzothienyl, carbazolyl, dibenzofuranyl, dibenzothienyl, indenocarbazolyl, indolocarbazolyl, pyridyl, pyrimidinyl, pyrazinyl, pyridazinyl, triazinyl, quinolinyl, quinazolinyl, benzimidazolyl, phenanthryl, triphenylenyl or a combination of two or three of these groups, each of which may be substituted by one or more R radicals.

9. A process for preparing the compound as claimed in claim 1, characterized in that the base structure of the compound without the Ar group is first synthesized and, in a next step, the Ar group is introduced.

10. A formulation comprising at least one compound as claimed in claim 1 and at least one further compound.

11. An electronic device comprising at least one compound as claimed in claim 1.

12. An organic electroluminescent device, characterized in that the compound in claim 1 is used in an emitting layer as matrix material for phosphorescent or fluorescent emitters or for emitters that exhibit TADF, or in that the compound is used in an electron transport layer and/or in a hole blocker layer and/or in a hole transport layer and/or in an exciton blocker layer.

13. The electronic device as claimed in claim 12, characterized in that the compound is used as matrix material in an emitting layer in combination with a further matrix material selected from the group consisting of biscarbazoles, bridged carbazoles, triarylamines and carbazoleamines.

14. The compound as claimed in claim 1, wherein R, R′ is the same or different at each instance and is H, D, F, Cl, Br, I, N(Ar′).sub.2, N(R.sup.1).sub.2, OAr′, SAr′, CN, NO.sub.2, OR.sup.1, SR.sup.1, COOR.sup.1, C(═O)N(R.sup.1).sub.2, Si(R.sup.1).sub.3, B(OR.sup.1).sub.2, C(═O)R.sup.1, P(═O)(R.sup.1).sub.2, S(═O)R.sup.1, S(═O).sub.2R.sup.1, OSO.sub.2R.sup.1, a straight-chain alkyl group having 1 to 20 carbon atoms or an alkenyl or alkynyl group having 2 to 20 carbon atoms or a branched or cyclic alkyl group having 3 to 20 carbon atoms, where the alkyl, alkenyl or alkynyl group may in each case be substituted by one or more R.sup.1 radicals, where one or more nonadjacent CH.sub.2 groups may be replaced by Si(R.sup.1).sub.2, C═O, NR.sup.1, O, S or CONR.sup.1, or an aromatic or heteroaromatic ring system which has 5 to 40 aromatic ring atoms, and may be substituted in each case by one or more R.sup.1 radicals; at the same time, two R radicals together may also form an aliphatic or heteroaliphatic ring system; in addition, two R′ radicals together may also form an aliphatic, heteroaliphatic, aromatic or heteroaromatic ring system.

15. The compound as claimed in claim 1, wherein R.sup.2 is the same or different at each instance and is H, D, F, CN or a hydrocarbyl radical, having 1 to 20 carbon atoms, in which one or more hydrogen atoms is optionally replaced by F.

16. The compound as claimed in claim 1, wherein R.sup.2 is the same or different at each instance and is H, F, an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 10 carbon atoms, which is optionally substituted by an alkyl group having 1 to 4 carbon atoms.

17. The compound as claimed in claim 1, wherein R.sup.2 is the same or different at each instance and is H, F, an alkyl group having 1 to 4 carbon atoms or an unsubstituted aryl group having 6 to 10 carbon atoms.

Description

EXAMPLES

Synthesis Examples

(1) The syntheses which follow, unless stated otherwise, are conducted under protective gas atmosphere in dried solvents. The solvents and reagents can be purchased from ALDRICH or ABCR. The numbers given for the reactants that are not commercially available are the corresponding CAS numbers.

a) N-(2-Chlorophenyl)pyrido[1,2-a]benzimidazole-8-amine

(2) ##STR00359##

(3) 33 g (135 mmol) of 8-bromopyrido[1,2-a]benzimidazole, 68.2 g (710 mmol) of sodium tert-butoxide, 613 mg (3 mmol) of palladium(II) acetate and 3.03 g (5 mmol) of dppf are dissolved in 1.3 l of toluene and stirred under reflux for 5 h. The reaction mixture is cooled down to room temperature, extended with toluene and filtered through Celite. The filtrate is concentrated under reduced pressure and the residue is crystallized from toluene/heptane. The product is isolated as a colorless solid. Yield: 32 g (112 mmol); 82% of theory.

(4) The following compounds can be prepared in an analogous manner:

(5) TABLE-US-00002 Reactant 1 Reactant 2 Product Yield 1a 0 77% 2a 79% 3a 80% 4a 0 75% 5a 69% 6a 88% 7a 0 83% 8a 82% 9a 77% 10a 73% 11a 0 84% 12a 85% 13a 69%

b) Cyclization

(6) ##STR00399##

(7) 30 g (103 mmol) of N-(2-chlorophenyl)pyrido[1,2-a]benzimidazole-8-amine, 56 g (409 mmol) of potassium carbonate, 4.5 g (12 mmol) of tricyclohexylphosphine tetrafluoroborate and 1.38 g (6 mmol) of palladium(II) acetate are suspended in 500 ml of dimethylacetamide and stirred under reflux for 6 h. After cooling, the reaction mixture is stirred with 300 ml of water and 400 ml. The organic phase is separated off and filtered through a short Celite bed, and then the solvent is removed under reduced pressure. The crude product is subjected to hot extraction with toluene and recrystallized from toluene. Yield: 22.8 g (88 mmol) of the a+b mixture; 87% of theory; purity: 98.0% by HPLC. After recrystallization from EA/toluene (1:3) and subsequent workup, 60% a and 20% b are obtained.

(8) The following compounds can be prepared in an analogous manner:

(9) TABLE-US-00003 Yield Reactant Product a Product b a, b 1b 00 01 02 58%, 18% 2b 03 04 05 65%, 13% 3b 06 07 78% 4b 08 09 0 61%, 19% 5b 57%, 12% 6b 80% 7b 64%, 11% 8b 0 63%, 13% 9b 60%, 15% 10b 81% 11b 57%, 16% 12b 0 50% 18%

c) Buchwald Coupling

(10) ##STR00433##

(11) 4.2 g (106 mmol) of 60% NaH in mineral oil is dissolved in 300 ml of dimethylformamide under protective atmosphere. 279 g (106 mmol) of compound (b a) is dissolved in 250 ml of DMF and added dropwise to the reaction mixture. After 1 h at room temperature, a solution of 2-chloro-4,6-diphenyl-[1,3,5]-triazine (34.5 g, 0.122 mol) in 200 ml of THE is added dropwise. The reaction mixture is stirred at room temperature for 12 h and then poured onto ice. After warming to room temperature, the solids that precipitate out are filtered and washed with ethanol and heptane. The residue is subjected to hot extraction with toluene, recrystallized from toluene/n-heptane and finally sublimed under high vacuum. The purity is 99.9%. The yield is 43 g (89 mmol), corresponding to 83% of theory.

(12) The following compounds can be prepared in an analogous manner:

(13) TABLE-US-00004 Reactant 1 Reactant 2 Product Yield 1c 84% 2c 81% 3c 0 82% 4c 82% 5c 85% 6c 0 75% 7c 74% 8c 73% 9c 0 77% 10c 76% 11c 68% 12c 75% 13c 0 82% 14c 87% 15c 70% 16c 0 73% 17c 79% 18c 71% 19c 0 65% 20c 66% 21c 65% 22c 62% 23c 00 01 02 60% 24c 03 04 05 63% 25c 06 07 08 68% 26c 09 0 76% 27c 70% 28c 72%

d) 2-[(Z)-(1-Phenylindolin-3-ylidene)methyl]-3-vinylimidazo[1,2-a]pyridine

(14) ##STR00518##

(15) 14 g (51 mmol) of 2-[(Z)-indolin-3-ylidenemethyl]-3-vinylimidazo[1,2-a]pyridine and 8.4 g (54 mmol) of bromobenzene are dissolved in 400 ml of toluene under an argon atmosphere. 1.0 g (5 mmol) of tri-tert-butylphosphine is added and the mixture is stirred under an argon atmosphere. 0.6 g (2 mmol) of Pd(OAc).sub.2 is added and the mixture is stirred under an argon atmosphere, and then 9.5 g (99 mmol) of sodium tert-butoxide are added. The reaction mixture is stirred under reflux for 24 h. After cooling, the organic phase is separated, washed three times with 200 ml of water, dried over MgSO.sub.4 and filtered, and the solvent is removed under reduced pressure. The residue is purified by column chromatography using silica gel (eluent: DCM/heptane (1:3)). The residue is subjected to hot extraction with toluene, recrystallized from toluene/n-heptane and finally sublimed under high vacuum. The yield is 16.1 g (46 mmol), corresponding to 90% of theory.

(16) The following compounds are obtained in an analogous manner:

(17) TABLE-US-00005 Reactant 1 Reactant 2 Product Yield 1d 0 75% 2d 80% 3d 81% 4d 0 76% 5d 83% 6d 78% 7d 79%

e) Bromination

(18) ##STR00540##

(19) 739 g(190 mmol) of compound 25c is suspended in 1800 ml of DMF. 34 g (190 mmol) of NBS is added to this suspension in portions and the mixture is stirred in the dark for 2 h. Thereafter, water/ice is added and the solids are removed and washed with ethanol. The isomers are separated by recrystallization. The yield is 60 g (129 mmol), corresponding to 70% of theory.

(20) The following compounds are prepared in an analogous manner:

(21) TABLE-US-00006 Reactant Product Yield 1e 59% 2e 56% 3e 57% 4e 55%

f) Suzuki Reaction

(22) ##STR00549##

(23) 71 g (154 mmol) of compound e, 50 g (172 mmol) of N-phenylcarbazole-3-boronic acid and 36 g (340 mmol) of sodium carbonate are suspended in 1000 ml of ethylene glycol dimethyl ether and 280 ml of water. 1.8 g (1.5 mmol) of tetrakis(triphenylphosphine)palladium(0) are added to this suspension, and the reaction mixture is heated under reflux for 16 h. After cooling, the organic phase is removed, filtered through silica gel, washed three times with 200 ml of water and then concentrated to dryness. The yield is 73 g (104 mmol), corresponding to 68% of theory.

(24) The following compounds are prepared in an analogous manner:

(25) TABLE-US-00007 Reactant 1 Reactant 2 Product Yield 1j 0 57% 2j 60% 3j 64% 4j 0 59% 5j 78% 6j 56%
Production of the OLEDs

(26) Examples E1 to E6 which follow (see table 1) present the use of the materials of the invention in OLEDs.

(27) Pretreatment for examples E1-E6: Glass plaques coated with structured ITO (indium tin oxide) of thickness 50 nm are treated prior to coating with an oxygen plasma, followed by an argon plasma. These plasma-treated glass plaques form the substrates to which the OLEDs are applied. The OLEDs basically have the following layer structure: substrate/hole injection layer (HIL)/hole transport layer (HTL)/electron blocker layer (EBL)/emission layer (EML)/optional hole blocker layer (HBL)/electron transport layer (ETL)/optional electron injection layer (EIL) and finally a cathode. The cathode is formed by an aluminum layer of thickness 100 nm. The exact structure of the OLEDs can be found in table 1. The materials required for production of the OLEDs are shown in table 2.

(28) All materials are applied by thermal vapor deposition in a vacuum chamber. In this case, the emission layer always consists of at least one matrix material (host material) and an emitting dopant (emitter) which is added to the matrix material(s) in a particular proportion by volume by co-evaporation. Details given in such a form as IC1:IC2:TER5 (55%:35%:10%) mean here that the material IC1 is present in the layer in a proportion by volume of 55%, IC2 in a proportion by volume of 35% and TER5 in a proportion by volume of 10%. Analogously, the electron transport layer may also consist of a mixture of two materials.

(29) The OLEDs are characterized in a standard manner. The electroluminescence spectra are determined at a luminance of 1000 cd/m.sup.2, and the CIE 1931 x and y color coordinates are calculated therefrom.

(30) Use of Materials of the Invention in OLEDs

(31) The materials of the invention can be used in the emission layer in phosphorescent red OLEDs. The inventive compounds EG1 to EG6 can be used in examples E1 to E6 as matrix material in the emission layer. The color coordinates of the electroluminescence spectra of the OLEDs from these experiments are CIEx=0.67 and CIEy=0.33. The materials are thus suitable for use in the emission layer of red OLEDs.

(32) TABLE-US-00008 TABLE 1 Structure of the OLEDs HIL HTL EBL EML HBL ETL EIL Ex. thickness thickness thickness thickness thickness thickness thickness E1 HATCN SpMA1 SpMA3 EG1:TER5 — ST2:LiQ — 5 nm 125 nm 10 nm (95%:5%) (50%:50%) 40 nm 35 nm E2 HATCN SpMA1 SpMA3 EG2:TER5 — ST2:LiQ — 5 nm 125 nm 10 nm (95%:5%) (50%:50%) 40 nm 35 nm E3 HATCN SpMA1 SpMA3 EG3:IC2:TER5 — ST2:LiQ — 5 nm 125 nm 10 nm (60%:35%:5%) (50%:50%) 40 nm 35 nm E4 HATCN SpMA1 SpMA3 EG4:TER5 — ST2:LiQ — 5 nm 125 nm 10 nm (95%:5%) (50%:50%) 40 nm 35 nm E5 HATCN SpMA1 SpMA3 IC1:EG5:TER5 — ST2:LiQ — 5 nm 125 nm 10 nm (25%:70%:5%) (50%:50%) 40 nm 35 nm E6 HATCN SpMA1 SpMA3 IC3:EG6:TER5 ST2 ST2:LiQ — 5 nm 125 nm 10 nm (47%:48%:5%) 5 nm (50%:50%) 40 nm 30 nm

(33) TABLE-US-00009 TABLE 2 Structural formulae of the materials for the OLEDs 0 0