1. Patent Search
  2. Details

MATERIALS FOR ORGANIC ELECTROLUMINESCENT DEVICES

20220177478 · 2022-06-09

    Inventors

    Cpc classification

    International classification

    Abstract

    The 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) ##STR00541## where the symbols used are as follows: A, B are each selected from the group consisting of N Ar.sup.1, C═O, C═S, C═NR, BR, PR, P(═O)R, SO and SO.sub.2, with the proviso that one of the symbols A and B is NAr.sup.1 and the other of the symbols A and B is C═O, C═S, C═NR, BR, PR, P(═O)R, SO or SO.sub.2; Cy together with the two carbon atoms shown explicitly is a group of the following formula (2): ##STR00542## where the dotted bonds indicate the linkage of this group in formula (1); X is the same or different at each instance and is CR′ or N; or the two X groups are a group of the following formula (3): ##STR00543## Y, Z is the same or different at each instance and is CR or N; A.sup.1 is the same or different at each instance and is NAr.sup.3, O, S or C(R).sub.2; Ar.sup.1, Ar.sup.2, Ar.sup.3 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; Ar.sup.1 here may form a ring system with an adjacent R′ radical; 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, preferably 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, heteroaliphatic, aromatic or heteroaromatic ring system; in addition, two R′ radicals together may also form an aliphatic or heteroaliphatic ring system; in addition R′ may form a ring system with an adjacent Ar.sup.1 radical; 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.sup.1 is 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 in each case 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, 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 having 1 to 20 carbon atoms, in which one or more hydrogen atoms may also be replaced by F.

    2. A compound as claimed in claim 1, selected from the compounds of the formulae (4) and (5) ##STR00544## where the symbols used have the definitions given in claim 1.

    3. A compound as claimed in claim 1, wherein one of the A and B groups is NAr.sup.1 and the other of the A and B groups is C═O, P(═O)R, BR or SO.sub.2.

    4. A compound as claimed in claim 1, selected from the compounds of the formulae (4a), (4b), (5a) and (5b) ##STR00545## where the symbols used have the definitions given in claim 1.

    5. A compound as claimed in claim 1, selected from the compounds of the formulae (4a-1), (4b-1), (5a-1) and (5b-1) ##STR00546## where the symbols used have the definitions given in claim 1.

    6. A compound as claimed in claim 1, selected from the compounds of the formulae (4a-2), (4b-2), (5a-2) and (5b-2) ##STR00547## where the symbols used have the definitions given in claim 1.

    7. A compound as claimed in claim 1, selected from the compounds of the formulae (4a-3), (4b-3), (5a-3) and (5b-3) ##STR00548## where the symbols used have the definitions given in claim 1.

    8. A compound as claimed in claim 1, selected from the compounds of the formulae (6-2) to (9-2) ##STR00549## where the symbols used have the definitions given in claim 1.

    9. A compound as claimed in claim 1, selected from the compounds of the formulae (10-1) and (11-1) ##STR00550## where the symbols used have the definitions given in claim 1.

    10. A process for preparing a compound as claimed in claim 1, characterized by the following steps: (1) synthesis of the base skeleton as yet unsubstituted by the Ar.sup.1, Ar.sup.2 and optionally Ar.sup.3 groups; and (2) introduction of the Ar.sup.1, Ar.sup.2 and optionally Ar.sup.3 groups by a C—N coupling reaction.

    11. A formulation comprising at least one compound as claimed in claim 1 and at least one further compound and/or at least one solvent.

    12. A method comprising utilizing the compound as claimed in claim 1 in an electronic device.

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

    14. The electronic device as claimed in claim 13 which is an organic electroluminescent device, characterized in that the compound is used in an emitting layer as matrix material for phosphorescent emitters or for emitters that exhibit TADF (thermally activated delayed fluorescence), and/or 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.

    Description

    EXAMPLES

    Synthesis Examples

    [0138] The syntheses which follow, unless stated otherwise, are conducted under a 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) Ethyl 2-(1H-indol-3-yl)-1H-indole-3-carboxylate

    [0139] ##STR00372##

    [0140] 10 g of potassium hydroxide are dissolved in 20 ml of water, diluted with 80 ml of 95% ethanol and used to charge a reaction flask. The flask is cooled in an ice bath. A dropping funnel is used to add a solution of 10 g (362 mmol) of N-methyl-N-nitroso-p-toluenesulfonamide in 150 ml of diethyl ether. This is followed by distillation, with an ice bath positioned beneath the collecting flask and a water bath (65° C.) beneath the reaction flask. The yellow diazomethane/diethyl ether mixture is distilled over. Once the yellow color in the reaction flask has disappeared, the distillation is complete. Subsequently, a further 50 ml of diethyl ether is added. The yellow distillate contains diazomethane (about 30 mmol).

    [0141] Esterification:

    [0142] To an ice-cooled solution of 8.2 g (30 mmol) of 2-(1H-indol-3-yl)-1H-indole-3-carboxylic acid (synthesis: see example 1d) in a 1:1 ether/ethanol mixture (200 ml) is gradually added the ethereal diazomethane solution until no further evolution of gas is observed and the pale yellow color persists. Just enough acetic acid is added for the yellow color to disappear, and then the solvent is removed. Yield: 8.2 g (26 mmol); 90% of theory.

    b) Ethyl 3-(3-nitroso-1H-indol-2-yl)-1H-indole-2-carboxylate

    [0143] ##STR00373##

    [0144] An initial charge of 7.9 g (26 mmol) of ethyl 3-(1H-indol-2-yl)-1H-indole-2-carboxylate in 50 ml of acetic acid is cooled to 18° C. Added dropwise thereto is a solution of 1.6 g (23.19 mmol) of sodium nitrite dissolved in 3 ml of water, in the course of which the temperature should not exceed 20° C. This is followed by stirring at room temperature for 30 min, and then addition of the mixture to ice-water. The solids are filtered off with suction and washed with methanol. The yield is 6.2 g (25.8 mmol); 73% of theory.

    [0145] The following compounds can be obtained analogously:

    TABLE-US-00004 Reactant Product Yield 1b [00374]embedded image [00375]embedded image 68% 2b [00376]embedded image [00377]embedded image 65% 3b [00378]embedded image [00379]embedded image 73%

    c) Cyclization

    [0146] ##STR00380##

    [0147] 43 g (129 mmol) of ethyl 3-(3-nitroso-1H-indol-2-yl)-1H-indole-2-carboxylate and 60 g (931 mmol) of zinc powder are stirred in 500 ml of acetic acid at 80° C. for 12 h. The mixture is cooled down, and the precipitated solids are filtered off with suction. The residue is recrystallized from DMF. Yield: 24.6 g (90 mmol); 70% of theory.

    [0148] The following compounds can be obtained analogously:

    TABLE-US-00005 Reactant Product Yield 1c [00381]embedded image [00382]embedded image 68% 2c [00383]embedded image [00384]embedded image 65% 3c [00385]embedded image [00386]embedded image 71%

    d) 2-Bromo-1-phenylindole-3-carboxylic acid

    [0149] ##STR00387##

    [0150] 49.5 g (165 mmol) of 2-bromo-1-phenylindole-3-carboxyaldehyde, 200 ml of 2-methyl-2-butene and 600 ml of dioxane are initially charged at room temperature. Added dropwise thereto is a solution of 81.9 g (902 mmol) of NaClO.sub.2 and 81.9 g (590 mmol) of NaH.sub.2PO.sub.4H.sub.2O in 410 ml of water. After 2.5 h, 20 g of NaClO.sub.2 and 20 g of NaH.sub.2PO.sub.4H.sub.2O are again added, and 10 g each of the two salts after 5 h. The solution is extracted twice with 300 ml of ethyl acetate, concentrated and extracted with 300 ml of 1% NaOH. The aqueous phase is brought to pH 3 with HCl, and the precipitated product is separated off. The yield is 36.5 g (121 mmol); 70% of theory.

    [0151] The following compound can be obtained analogously:

    TABLE-US-00006 Reactant Product Yield 1d [00388]embedded image [00389]embedded image 78%

    e) 3-Bromo-N,1-diphenylindole-2-carboxamide

    [0152] ##STR00390##

    [0153] To an initial charge of 73 g (230 mmol) of 3-bromo-1-phenylindole-2-carboxylic acid in 1300 ml of methylene chloride are added 10 drops of DMF. At room temperature, 86.3 ml (1020 mmol) of oxalyl chloride in 400 ml of methylene chloride are added dropwise, and the mixture is stirred at 45° C. for 5 h. The solvent is removed under reduced pressure. The solids are dissolved in 200 ml of CH.sub.2Cl.sub.2 and cooled to 0° C. Subsequently, 21 ml (230 mmol) of aniline are added dropwise and then the mixture is left to stand at room temperature for 2 h. After addition of 100 ml of saturated NaHCO.sub.3 solution, the organic phase is separated off and the residue is recrystallized from toluene. Yield: 73 g (187 mmol); 81% of theory.

    [0154] The following compounds can be prepared analogously:

    TABLE-US-00007 Reactant 1 Reactant 2 Product Yield 1e [00391]embedded image [00392]embedded image [00393]embedded image 65% 2e [00394]embedded image [00395]embedded image [00396]embedded image 54% 3e [00397]embedded image [00398]embedded image [00399]embedded image 46%

    f) Cyclization

    [0155] ##STR00400##

    [0156] Under protective gas, 15.7 g (45 mmol) of 3-bromo-N-phenyl-1H-indole-2-carboxamide, 5 g (2.2 mmol) of Pd(OAc).sub.2, 10 g (4.5 mmol) of tri-2-furylphosphine and 12 g (90 mmol) of K.sub.2CO.sub.3 in 1000 ml DMF are stirred at 150° C. for 30 h. The solution is diluted with water and extracted twice with ethyl acetate. The combined organic phases are dried over Na.sub.2SO.sub.4 and concentrated by rotary evaporation. The residue is purified by chromatography (EtOAc/hexane: 2/3). The residue is recrystallized from toluene. The yield is 8.8 g (25 mmol), 70% of theory.

    [0157] The following compounds can be prepared analogously:

    TABLE-US-00008 Reactant Product Yield 1f [00401]embedded image [00402]embedded image 65% 2f [00403]embedded image [00404]embedded image 68% 3f [00405]embedded image [00406]embedded image 56%

    g) 5-(9-Phenylcarbazol-3-yl)-2,9-dihydropyrido[3,4-b]indol-1-one

    [0158] ##STR00407##

    [0159] 19.1 (73 mmol) of 5-bromo-2,9-dihydropyrido[3,4-b]indol-1-one, 20.8 g (75 mmol) of phenylcarbazole-3-boronic acid and 14.7 g (139 mmol) of sodium carbonate are suspended in 200 ml of toluene, 52 ml of ethanol and 100 ml of water. 80 mg (0.69 mmol) of tetrakistriphenylphosphinepalladium(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 residue is recrystallized from heptane/dichloromethane. The yield is 25 g (60 mmol); 83% of theory.

    [0160] The following compounds can be prepared analogously:

    TABLE-US-00009 Reactant 1 Reactant 2 Product Yield 1g [00408]embedded image [00409]embedded image [00410]embedded image 72% 2g [00411]embedded image [00412]embedded image [00413]embedded image 70% 3g [00414]embedded image [00415]embedded image [00416]embedded image 72% 4g [00417]embedded image [00418]embedded image [00419]embedded image 71% 5g [00420]embedded image [00421]embedded image [00422]embedded image 68%

    h) 9-(4,6-Diphenyl-1,3,5-triazin-2-yl)-5-(9-phenylcarbazol-3-yl)-2H-pyrido[3,4-b]indol-1-one

    [0161] ##STR00423##

    [0162] 41 g (51 mmol) of 5-(9-phenylcarbazol-3-yl)-2,9-dihydropyrido[3,4-b]indol-1-one and 16 g (60 mmol) of 2-chloro-4,6-diphenyl-[1,3,5]triazine 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 removed, 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 (1:4)). The yield is 38 g (58 mmol); 60% of theory.

    [0163] At 8 h, 14 h and 15 h, the residue is recrystallized from toluene and finally sublimed under high vacuum (p=5×10-5 mbar). The purity is 99.9%.

    [0164] The following compounds can be prepared analogously:

    TABLE-US-00010 Reactant 1 Reactant 2 Product Yield  1h [00424]embedded image [00425]embedded image [00426]embedded image 61 %  2h [00427]embedded image [00428]embedded image [00429]embedded image 64%  3h [00430]embedded image [00431]embedded image [00432]embedded image 67%  4h [00433]embedded image [00434]embedded image [00435]embedded image 67%  5h [00436]embedded image [00437]embedded image [00438]embedded image 70%  6h [00439]embedded image [00440]embedded image [00441]embedded image 68%  7h [00442]embedded image [00443]embedded image [00444]embedded image 66%  8h [00445]embedded image [00446]embedded image [00447]embedded image 68%  9h [00448]embedded image [00449]embedded image [00450]embedded image 71% 10h [00451]embedded image [00452]embedded image [00453]embedded image 65% 11h [00454]embedded image [00455]embedded image [00456]embedded image 59% 12h [00457]embedded image [00458]embedded image [00459]embedded image 70% 13h [00460]embedded image [00461]embedded image [00462]embedded image 56% 14h [00463]embedded image [00464]embedded image [00465]embedded image 71% 15h [00466]embedded image [00467]embedded image [00468]embedded image 77% 16h [00469]embedded image [00470]embedded image [00471]embedded image 70% 17h [00472]embedded image [00473]embedded image [00474]embedded image 76% 18h [00475]embedded image [00476]embedded image [00477]embedded image 80%

    j) 9-(4,6-Diphenyl-1,3,5-triazin-2-yl)-2-phenyl-5-(9-phenylcarbazol-3-yl)pyrido[3,4-b]indol-1-one

    [0165] ##STR00478##

    [0166] 27 g (41 mmol) of 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-(9-phenylcarbazol-3-yl)-2H-pyrido[3,4-b]indol-1-one and 61.2 g (85 mmol) of 4-iodobenzene, 44.7 g (320 mmol) of potassium carbonate, 3 g (16 mmol) of copper(I) iodide and 3.6 g (16 mmol) of 1,3-di(pyridin-2-yl)propane-1,3-dione are stirred in 100 ml of DMF at 150° C. for 30 h. The solution is diluted with water and extracted twice with ethyl acetate. The combined organic phases are dried over Na.sub.2SO.sub.4 and concentrated by rotary evaporation. The residue is purified by chromatography (EtOAc/hexane: 2/3), recrystallized from toluene and finally sublimed under high vacuum (p=5×10.sup.−5 mbar). The purity is 99.9%. The yield is 21 g (28 mmol); 70% of theory.

    [0167] The following compounds can be obtained analogously:

    TABLE-US-00011 Reactant 1 Reactant 2 Product Yield  1j [00479]embedded image [00480]embedded image [00481]embedded image 70%  2j [00482]embedded image [00483]embedded image [00484]embedded image 74%  3j [00485]embedded image [00486]embedded image [00487]embedded image 73%  4j [00488]embedded image [00489]embedded image [00490]embedded image 75%  5j [00491]embedded image [00492]embedded image [00493]embedded image 79%  6j [00494]embedded image [00495]embedded image [00496]embedded image 79%  7j [00497]embedded image [00498]embedded image [00499]embedded image 69%  8j [00500]embedded image [00501]embedded image [00502]embedded image 78%  9j [00503]embedded image [00504]embedded image [00505]embedded image 76% 10j [00506]embedded image [00507]embedded image [00508]embedded image 68% 11j [00509]embedded image [00510]embedded image [00511]embedded image 71% 12j [00512]embedded image [00513]embedded image [00514]embedded image 69% 13j [00515]embedded image [00516]embedded image [00517]embedded image 80% 14j [00518]embedded image [00519]embedded image [00520]embedded image 61% 15j [00521]embedded image [00522]embedded image [00523]embedded image 79% 16j [00524]embedded image [00525]embedded image [00526]embedded image 76%

    [0168] Production of the OLEDs

    [0169] Examples E1 to E5 which follow (see table 1) present the use of the materials of the invention in OLEDs.

    [0170] Pretreatment for examples E1 to E5: Glass plates 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 plates form the substrates to which the OLEDs are applied.

    [0171] 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.

    [0172] 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:EG1:TEG1 (45%:45%:10%) mean here that the material IC1 is present in the layer in a proportion by volume of 45%, EG1 in a proportion by volume of 45% and TEG1 in a proportion by volume of 10%. Analogously, the electron transport layer may also consist of a mixture of two materials.

    [0173] The OLEDs are characterized in a standard manner. For this purpose, electroluminescence spectra, current efficiency (CE, measured in cd/A) and external quantum efficiency (EQE, measured in %) are determined as a function of luminance, calculated from current-voltage-luminance characteristics assuming Lambertian emission characteristics. 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. The results thus obtained can be found in table 3.

    [0174] Use of the Materials of the Invention in OLEDs

    [0175] The compounds EG1 to EG5 of the invention are used in examples E1 to E5 as matrix material in the emission layer of phosphorescent green OLEDs.

    TABLE-US-00012 TABLE 1 Structure of the OLEDs HIL HTL EBL EML HBL ETL EIL Ex. thickness thickness thickness thickness thickness thickness thickness E1 HATCN SpMA1 SpMA2 IC1:EG1:TEG1 ST2 ST2:LiQ (50%:50%) LiQ 5 nm 230 nm 20 nm (64%:29%:7%) 40 nm 5 nm 30 nm 1 nm E2 HATCN SpMA1 SpMA2 EG2:TEG1 ST2 ST2:LiQ (50%:50%) LiQ 5 nm 230 nm 20 nm (88%:12%) 40 nm 5 nm 30 nm 1 nm E3 HATCN SpMA1 SpMA2 IC1:EG3:TEG1 ST2 ST2:LiQ (50%:50%) LiQ 5 nm 230 nm 20 nm (49%:44%:7%) 40 nm 5 nm 30 nm 1 nm E4 HATCN SpMA1 SpMA2 IC1:EG4:TEG1 ST2 ST2:LiQ (50%:50%) LiQ 5 nm 230 nm 20 nm (49%:44%:7%) 40 nm 5 nm 30 nm 1 nm E5 HATCN SpMA1 SpMA2 EG5:IC2:TEG1 ST2 ST2:LiQ (50%:50%) LiQ 5 nm 230 nm 20 nm (49%:44%:7%) 40 nm 5 nm 30 nm 1 nm E6 HATCN SpMA1 SpMA2 EG5:IC3:TEG1 ST2 ST2:LiQ (50%:50%) LiQ 5 nm 230 nm 20 nm (49%:44%:7%) 40 nm 5 nm 30 nm 1 nm

    TABLE-US-00013 TABLE 2 Structural formulae of the materials for the OLEDs [00527]embedded image [00528]embedded image [00529]embedded image [00530]embedded image [00531]embedded image [00532]embedded image [00533]embedded image [00534]embedded image [00535]embedded image [00536]embedded image [00537]embedded image [00538]embedded image [00539]embedded image [00540]embedded image

    TABLE-US-00014 TABLE 3 Data of the OLEDs U1000 SE1000 EQE 1000 CIE x/y at Ex. (V) (cd/A) (%) 1000 cd/m.sup.2 E1 3.1 69 18 0.34/0.62 E2 3.4 72 20 0.35/0.61 E3 3.3 71 19 0.35/0.62 E4 3.2 70 18 0.34/0.61 E5 3.6 66 17 0.35/0.61 E6 3.2 66 21 0.35/0.61