MATERIALS FOR ELECTRONIC DEVICES

Abstract

The present application relates to compounds of a formula (I), to the use thereof in organic electroluminescent devices, and to processes for preparing these compounds.

Claims

1-15. (canceled)

16. A compound of formula (I): ##STR00104## wherein ##STR00105## is a benzene ring optionally substituted in each instance by one or more radicals R.sup.1; ##STR00106## is the same or different in each instance and is selected from the group consisting of units of formulae (Ar.sup.2-1) or (Ar.sup.2-2) ##STR00107## wherein the bond denoted with * is the bond via which the unit is fused to the Ar.sup.1 group, and the bond denoted with # is the bond via which the unit is fused to the Ar.sup.3 group; Y is the same or different in each instance and is C(R.sup.2).sub.2 or Si(R.sup.2).sub.2; ##STR00108## is the same or different in each instance and is selected from the group consisting of aromatic ring systems having 6 to 30 aromatic ring atoms and heteroaromatic ring systems having 5 to 30 aromatic ring atoms, each of which is optionally substituted by radicals R.sup.3; R.sup.1, R.sup.2, and R.sup.3 are the same or different in each instance and are selected from H, D, F, C(O)R.sup.4, CN, Si(R.sup.4).sub.3, N(R.sup.4).sub.2, P(O)(R.sup.4).sub.2, OR.sup.4, S(O)R.sup.4, S(O).sub.2R.sup.4, straight-chain alkyl or alkoxy groups having 1 to 20 carbon atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 carbon atoms, alkenyl or alkynyl groups having 2 to 20 carbon atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; wherein two or more radicals R.sup.1, R.sup.2, and/or R.sup.3 are optionally bonded to one another and optionally define a ring; and wherein the alkyl, alkoxy, alkenyl, and alkynyl groups and the aromatic and heteroaromatic ring systems are each optionally substituted by one or more radicals R.sup.4; and wherein one or more CH.sub.2 groups in the alkyl, alkoxy, alkenyl, and alkynyl groups are optionally replaced by R.sup.4CCR.sup.4, CC, Si(R.sup.4).sub.2, CO, CNR.sup.4, C(O)O, C(O)NR.sup.4, NR.sup.4, P(O)(R.sup.4), O, S, SO, or SO.sub.2; R.sup.4 is the same or different in each instance and is selected from H, D, F, C(O)R.sup.5, CN, Si(R.sup.5).sub.3, N(R.sup.5).sub.2, P(O)(R.sup.5).sub.2, OR.sup.5, S(O)R.sup.5, S(O).sub.2R.sup.5, straight-chain alkyl or alkoxy groups having 1 to 20 carbon atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 carbon atoms, alkenyl or alkynyl groups having 2 to 20 carbon atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; wherein two or more radicals R.sup.4 are optionally bonded to one another and optionally define a ring; wherein the alkyl, alkoxy, alkenyl, and alkynyl groups and the aromatic and heteroaromatic ring systems are each optionally substituted by one or more radicals R.sup.5; and wherein one or more CH.sub.2 groups in the alkyl, alkoxy, alkenyl, and alkynyl groups are optionally replaced by R.sup.5CCR.sup.5, CC, Si(R.sup.5).sub.2, CO, CNR.sup.5, C(O)O, C(O)NR.sup.5, NR.sup.5, P(O)(R.sup.5), O, S, SO or SO.sub.2; R.sup.5 is the same or different in each instance and is selected from H, D, F, CN, alkyl groups having 1 to 20 carbon atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; wherein two or more radicals R.sup.5 are optionally bonded to one another and optionally define a ring; and wherein the alkyl groups, aromatic ring systems, and heteroaromatic ring systems are optionally substituted by F or CN.

17. The compound of claim 16, wherein the compound is a compound of formula (I-C): ##STR00109##

18. The compound of claim 16, wherein the compound is symmetric with respect to a mirror plane through the middle and at right angles to the longitudinal axis of the elongated molecule.

19. The compound of claim 16, wherein Ar.sup.1 is a group of formulae (Ar.sup.1-1) or (Ar.sup.1-2): ##STR00110## wherein the bonds denoted with * are the bonds via which the Ar.sup.1 group is fused to the two adjacent Ar.sup.2 groups.

20. The compound of claim 16, wherein Ar.sup.2 is a group of formula (Ar.sup.2-1).

21. The compound of claim 16, wherein Y is C(R.sup.2).sub.2.

22. The compound of claim 16, wherein Ar.sup.3 is the same or different in each instance and is selected from the following groups: ##STR00111## ##STR00112## wherein the bond denoted with # is the bond via which the Ar.sup.1 group is fused to the adjacent Ar.sup.2 group, the groups are optionally substituted by radicals R.sup.3 at the positions shown as unsubstituted, and X is the same or different in each instance and is N or CR.sup.3.

23. The compound of claim 16, wherein the compound is a compound of formula (I-1): ##STR00113##

24. The compound of claim 16, wherein the value of the triplet level of the compound is greater than the value of the singlet level of the compound divided by 2.

25. A process for preparing the compound of claim 16, comprising the steps conducted in the following sequence: i) reacting two compounds each containing a furan group and a compound containing the Ar.sup.1 unit in an organometallic coupling reaction; ii) reacting an ester group bonded to the Ar.sup.1 unit and present in the compound to a tertiary alcohol group bonded to the same Ar.sup.1 unit; and iii) performing a ring-closure reaction of the tertiary alcohol group to form an alkylene bridge between the Ar.sup.1 unit and the furan ring.

26. An oligomer, polymer, or dendrimer containing one or more compounds of claim 16, wherein the bond(s) to the polymer, oligomer, or dendrimer are optionally localized at any desired position substituted by R.sup.1, R.sup.2, or R.sup.3 in formula (I).

27. A formulation comprising at least one compound of claim 16 and at least one solvent.

28. A formulation comprising at least one oligomer, polymer or dendrimer of claim 26 and at least one solvent.

28. An electronic device selected from the group consisting of organic integrated circuits, organic field-effect transistors, organic thin-film transistors, organic light-emitting transistors, organic solar cells, organic optical detectors, organic photoreceptors, organic field-quench devices, organic light-emitting electrochemical cells, organic laser diodes, and organic electroluminescent devices, wherein the electronic device comprises at least one compound of claim 16.

29. An electronic device selected from the group consisting of organic integrated circuits, organic field-effect transistors, organic thin-film transistors, organic light-emitting transistors, organic solar cells, organic optical detectors, organic photoreceptors, organic field-quench devices, organic light-emitting electrochemical cells, organic laser diodes, and organic electroluminescent devices, wherein the electronic device comprises at least one oligomer, polymer, or dendrimer of claim 26.

30. The electronic device of claim 28, wherein the electronic device is selected from the group consisting of organic electroluminescent devices comprising an anode, a cathode, an emitting layer, and optionally further organic layers, wherein the at least one compound is present as a matrix compound in combination with one or more emitting compounds in the emitting layer, or is present as emitting compound in combination with one or more matrix compounds in the emitting layer, or is present as hole-transporting compound in a layer arranged between anode and emitting layer.

31. The electronic device of claim 29, wherein the electronic device is selected from the group consisting of organic electroluminescent devices comprising an anode, a cathode, an emitting layer, and optionally further organic layers, wherein the at least one oligomer, polymer, or dendrimer is present as a matrix compound in combination with one or more emitting compounds in the emitting layer, or is present as emitting compound in combination with one or more matrix compounds in the emitting layer, or is present as hole-transporting compound in a layer arranged between anode and emitting layer.

Description

WORKING EXAMPLES

A) Synthesis Examples

A-1) Synthesis of the Base Skeleton of the Compounds

[0096] ##STR00059##

A-1-1) Synthesis of Compound I

[0097] The compound with RH (Ia) is commercially available. Analogous compounds with RH, if they are not commercially available, are obtainable by the following method or by methods described in WO 2012/165612 A1, A. S. K. Hashmi, Tetrahedron, 65 (2009) 9021-9029, or Org. Biomol. Chem. 2014, 12, 4747-4753:

[0098] When RH, for example the compound Ib specified below, the synthesis is conducted as follows:

##STR00060##

A-1-1-1) General Scheme for Synthesis of Compounds of the I Type

[0099] ##STR00061##

A-1-1-2) Specific Method of Preparing the Compound Ib

[0100] ##STR00062##

[0101] A 500 ml two-neck flask is initially charged with 35 g (206 mmol) of biphenyl-2-ol, 85.3 g (617 mmol) of potassium carbonate and 47 ml (308 mmol) of 2-bromo-1,1-diethoxyethane in 200 ml of anhydrous DMF and the mixture is refluxed for 16 hours until conversion is complete. Subsequently, the reaction is cooled down to room temperature and 400 ml of water are added. The organic phase is extended with 300 ml of toluene. The phases are separated and the aqueous phase is extracted twice with 200 ml of toluene. The combined organic phases are washed three times with 20% sodium hydroxide solution, filtered through silica gel and concentrated to dryness under reduced pressure. The residue is dissolved in 600 ml of anhydrous toluene and initially charged in a 1 l two-neck flask with a water separator, 5 g of Amberlyst 15 are added and the mixture is stirred at 125 C. for 15 hours. After cooling to room temperature, the reaction mixture is filtered and concentrated under reduced pressure. After purification by column chromatography (heptane/toluene 9:1), 31 g (160 mmol; 78% of theory) of colourless oil are obtained.

##STR00063##

[0102] A 1 l two-neck flask is initially charged with 36 g (185 mmol) of the compound obtained above and 24.7 g (97 mmol) of bis(pinacolato)diboron in 400 ml of heptane. Subsequently, 123 mg (0.19 mmol) of (1,5-cyclooctadiene)(methoxy)iridium(I) dimer and 99.5 mg (037 mmol) of 4,4-di-tert-butyl-2,2-dipyridyl are added and the mixture is stirred at 35 C. for 16 h. The precipitated solid is filtered off with suction and washed with heptane and dried under reduced pressure. Yield: 51 g (159 mmol; 86% of theory) of colourless solid.

A-1-2) Synthesis of III Using the Example of Diethyl 2,5-bis(benzofuran-2-yl)terephthalate (ArH) (IIIa)

[0103] ##STR00064##

[0104] A 2 l four-neck flask is initially charged with 35 g (0.09 mol) of diethyl 2,5-dibromoterephthalate, 33.5 g (0.2 mol) of benzofuran-2-ylboronic acid and 46.9 g (0.19 mol) of tripotassium phosphate monohydrate in 800 ml of toluene/dioxane/water (2:1:1). After adding 413 mg (1.8 mmol) of palladium acetate and 3.36 g (11 mmol), the mixture is refluxed for one hour. Subsequently, the reaction is cooled down to room temperature and the organic phase is extended with ethyl acetate. The phases are separated and the aqueous phase is extracted twice with 300 ml of ethyl acetate. The combined organic phases are washed with water, dried over sodium sulphate, filtered and concentrated under reduced pressure. The residue is admixed with 400 ml of methanol and stirred at 60 C. for 20 minutes. After cooling to room temperature, the solids are filtered and dried under reduced pressure. Yield: 40.9 g (0.09 mol, 98%) of yellow solid.

[0105] In an analogous manner, it is also possible to prepare the following compounds:

TABLE-US-00002 Reactant 1 Reactant 2 Product Yield IIIa [00065] [00066] [00067] 98% IIIb [00068] [00069] [00070] 91%

A-1-3) Synthesis of IV Using the Example of 2-[2,5-bis(benzofuran-2-yl)-4-(1-hydroxy-1-methylethyl)phenyl]propan-2-ol (ArH) (IVa)

[0106] A 4 l four-neck flask is initially charged with 46.6 g (0.2 mol) of anhydrous cerium chloride in 300 ml of anhydrous THF and cooled to 0 C. Subsequently, 40.9 g (0.09 mol) of diethyl 2,5-bis(benzofuran-2-yl)terephthalate, dissolved in 700 ml of anhydrous THF, are slowly added dropwise thereto, in such a way that the internal temperature remains below 5 C. On completion of addition, the mixture is stirred at this temperature for one hour. On completion of conversion, 400 ml of saturated ammonium chloride solution are added dropwise thereto, such that the temperature remains below 20 C. The suspension obtained is filtered and the solids are washed with ethyl acetate. The filtrate is washed thoroughly with ethyl acetate and then the phases are separated. The aqueous phase is extracted twice with ethyl acetate (200 ml). The combined organic phases are dried over sodium sulphate and then concentrated under reduced pressure. After adding 400 ml of heptane, the mixture is then stirred at 60 C. for 30 minutes. The desired product precipitates out as a pale yellow solid. Yield: 35 g (82 mmol, 92%)

[0107] In an analogous manner, it is also possible to prepare the following compounds:

TABLE-US-00003 Reactant 1 Reactant 2 Product Yield IVa [00071] MeMgCl [00072] 92% IVb [00073] MeMgCl [00074] 79%

A-1-4) Synthesis of V Using the Example of ArH (Va)

[0108] ##STR00075##

[0109] A 2 l four-neck flask is initially charged with 24 g (0.25 mol) of polyphosphoric acid in 200 ml of dichloromethane and cooled to 0 C. At this temperature, 16 ml of methanesulphonic acid are added dropwise. Subsequently, 35 g (0.08 mol) of IVa, dissolved in 900 ml of dichloromethane, are slowly added dropwise at 0 C. and stirring is continued at this temperature for two hours. On completion of conversion, the reaction is admixed with 100 ml of ethanol and stirred for 30 minutes. A further 700 ml of ethanol are added to the reaction mixture and the dichloromethane is removed under reduced pressure. The precipitated solid is filtered. The further purification is effected by means of hot extraction over aluminium oxide with toluene/heptane 1:2 and repeated recrystallization from heptane/toluene. After sublimation twice at 10.sup.5 bar and >250 C., the product is obtained in an HPLC purity of >99.9%. Yield: 8.4 g (22 mmol; 27%) of pale yellow solid.

[0110] In an analogous manner, it is possible to prepare the following compounds:

TABLE-US-00004 Reactant 1 Product Yield Va [00076] [00077] 27% Vb [00078] [00079] 52%

A-2) Introduction of Substituents in the Base Skeleton of the Compound by Bromination and Suzuki Reaction

[0111] ##STR00080##

A-2-1) Bromination of Va Using the Example of VI

[0112] ##STR00081##

[0113] A 1 l four-neck flask is initially charged with 15 g (38.5 mmol) of Va in 400 ml of dichloromethane, 14 g (78.6 mmol) of NBS and 568 mg (1.9 mmol) of iron(III) bromide are added, and the mixture is stirred at room temperature for 18 hours. The reaction mixture is filtered and the solids are washed with ethanol. The filtrate is concentrated under reduced pressure and the precipitated solid is filtered off and washed with a little ethanol. The two solids are combined, dissolved in toluene and filtered through aluminium oxide. After further recrystallization from heptane and toluene, the product is obtained as a yellow solid.

[0114] Yield: 11.7 g (21 mmol; 56%)

A-2-2) Synthesis of VIIa

[0115] ##STR00082##

[0116] A 1 l four-neck flask is initially charged with 20 g (36 mmol) of VIa, 10 g (82 mmol) of phenylboronic acid and 18.6 g (81 mmol) of tripotassium phosphate monohydrate in 600 ml of toluene/dioxane/water (1:1:1). Subsequently, 161 mg (0.72 mmol) of palladium acetate and 1.3 g (4.32 mmol) of tri-o-tolylphosphine are added and the mixture is refluxed for 16 h until conversion is complete. After cooling to room temperature, the organic phase is extended with 300 ml of ethyl acetate and the phases are separated. The aqueous phase is extracted twice with ethyl acetate. The combined organic phases are dried over sodium sulphate and then concentrated under reduced pressure. Subsequently, the solid obtained is hot-extracted over aluminium oxide (toluene/heptane). The precipitated solid is filtered and recrystallized repeatedly from toluene/heptane. After sublimation twice (10.sup.6 bar, >300 C.), the product is obtained as a pale yellow solid with an HPLC purity of >99.9%. Yield: 9.3 g (17 mmol; 48%).

[0117] In an analogous manner, it is possible to prepare the following compounds:

TABLE-US-00005 Reactant 1 Reactant 2 Product VII Yield VIIa [00083] VI [00084] 48% VIIb [00085] VI [00086] 37% VIIc [00087] VI [00088] 46% VIId [00089] VI [00090] 43% VIIe [00091] VI [00092] 49% VIIf [00093] VI [00094] 47%

B) Device Examples

[0118] OLEDs of the invention and OLEDs according to the prior art are produced by a general method according to WO 04/058911, which is adapted to the circumstances described here (variation in layer thickness, materials).

[0119] In the examples which follow (see tables 1 to 3), the data of various OLEDs are presented. Substrates used are glass substrates coated with structured ITO (indium tin oxide) of thickness 50 nm. The OLEDs basically have the following layer structure: substrate/buffer/hole injection layer 1 (95% HTL1+5% HIL, 20 nm)/hole transport layer (HTL2, thickness stated in Table 1)/emission layer (EML, 20 nm)/electron transport layer (ETL, 20 nm)/electron injection layer (EIL, 3 nm) and finally a cathode. The cathode is formed by an aluminium layer of thickness 100 nm. The buffer applied by spin-coating is a 20 nm-thick layer of Clevios P VP Al 4083 (sourced from Heraeus Clevios GmbH, Leverkusen). All the rest of the materials are applied by thermal vapour deposition in a vacuum chamber. The structure of the OLEDs is shown in Table 1. The materials used are shown in Table 3.

[0120] The emission layer (EML) always consists of at least one matrix material (host=H) and an emitting compound (dopant=D) which is added to the matrix material in a particular proportion by volume by co-evaporation. Details given in such a form as H1:D1 (95%:5%) mean here that the material H1 is present in the layer in a proportion by volume of 95% and D1 in a proportion of 5%.

[0121] The OLEDs are characterized in a standard manner. For this purpose, the electroluminescence spectra are recorded, and the current efficiency (measured in cd/A) and the external quantum efficiency (EQE, measured in percent) are calculated as a function of luminance, assuming Lambertian radiation characteristics, from current-voltage-luminance characteristics (IUL characteristics). The electroluminescence spectra are recorded at a luminance of 1000 cd/m.sup.2, and the CIE 1931 x and y colour coordinates are calculated therefrom. The parameter EQE @ 1000 cd/m.sup.2 refers to the external quantum efficiency at an operating luminance of 1000 cd/m.sup.2. The data obtained for the various OLEDs are collated in Table 2.

Use of the Compounds of the Invention as Matrix in Fluorescent OLEDs

[0122] The compounds of the invention H1 and H2 are used individually as matrix in the emitting layer of OLEDs (for structure see Table 3). The emitter material used in the emitting layer is the compound D. The OLEDs obtained are 11 and 12. They exhibit very good external quantum efficiencies (EQEs) with deep blue emission (Table 2).

Use of the Compounds of the Invention as Hole Transport Materials in OLEDs

[0123] Example I3, in which the compound of the invention H1 is used as hole transport material in the hole transport layer, likewise shows good external quantum efficiency with deep blue emission (Table 2). This demonstrates the good suitability of the compounds of the invention as hole-transporting compounds.

TABLE-US-00006 TABLE 1 Structure of the OLEDs Ex. HTL (20 nm) EML (thickness/20 nm) I1 HTL2 H-1(95%):D(5%) I2 HTL2 H-2(95%):D(5%) I3 H-1 BH (95%):D(5%)

TABLE-US-00007 TABLE 2 Data of the OLEDs EQE [%] @ Ex. 1000 cd/m.sup.2 CIE x CIE y I1 6.3 0.139 0.143 I2 6.5 0.142 0.135 I3 5.7 0.142 0.158

TABLE-US-00008 TABLE 3 Structures of the materials used [00095] HIL [00096] ETL [00097] HTL1 [00098] EIL [00099] HTL2 [00100] H-1 [00101] H-2 [00102] D [00103] BH