6,9,15,18-tetrahydro-s-indaceno[1,2-b:5,6-b′]difluorene derivatives and use thereof in electronic devices

Abstract

The present application relates to a compound of a formula (I) or formula (II) which is suitable for use as functional material in an electronic device, especially as emitter material in an organic electroluminescent device.

Claims

1. A compound of formula (II-1-4): ##STR00165## wherein Z.sup.1 is the same or different at each instance and is CR.sup.1 or N; Z.sup.2 is the same or different at each instance and is CR.sup.2 or N; X.sup.1 is, the same or differently in each instance, BR.sup.3, C(R.sup.3).sub.2, C(R.sup.3).sub.2—C(R.sup.3).sub.2, —C(R.sup.3).sub.2—O—, —C(R.sup.3).sub.2—S, —R.sup.3C═CR.sup.3—, —R.sup.3C═N—, Si(R.sup.3).sub.2, Ge(R.sup.3).sub.2, —Si(R.sup.3).sub.2—Si(R.sup.3).sub.2—, C═O, O, S, Se, S═O, SO.sub.2, NR.sup.3, PR.sup.3, or P(═O)R.sup.3, wherein two or more radicals R.sup.3 are optionally joined to one another and optionally define a ring; R.sup.1, R.sup.2, and R.sup.3 is, the same or differently in each instance, H, D, F, Cl, Br, I, 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, a straight-chain alkyl or alkoxy group having 1 to 20 carbon atoms, a branched or cyclic alkyl or alkoxy group having 3 to 20 carbon atoms, an alkenyl or alkynyl group having 2 to 20 carbon atoms, an aromatic or heteroaromatic ring system having 5 to 30 aromatic ring atoms, or an aryloxy or heteroaryloxy group having 5 to 30 aromatic ring atoms, wherein the abovementioned groups are each optionally substituted by one or more radicals R.sup.4, wherein one or more CH.sub.2 groups in the abovementioned groups are optionally replaced by —R.sup.4C═CR.sup.4—, —C≡C—, Si(R.sup.4).sub.2, C═O, C═NR.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, wherein one or more hydrogen atoms in the abovementioned groups are optionally replaced by D, F, Cl, Br, I, or CN, and wherein two radicals are optionally joined to one another and optionally form a ring; R.sup.4 is, the same or differently in each instance, H, D, F, Cl, Br, I, 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).sub.2R.sup.5, S(═O).sub.2R.sup.5, a straight-chain alkyl or alkoxy group having 1 to 20 carbon atoms, a branched or cyclic alkyl or alkoxy group having 3 to 20 carbon atoms, an alkenyl or alkynyl group having 2 to 20 carbon atoms, an aromatic or heteroaromatic ring system having 5 to 30 aromatic ring atoms, or an aryloxy or heteroaryloxy group having 5 to 30 aromatic ring atoms, wherein the abovementioned groups are each optionally substituted by one or more radicals R.sup.5, wherein one or more CH.sub.2 groups in the abovementioned groups are optionally replaced by —R.sup.5C═CR.sup.5—, —C≡C—, Si(R.sup.5).sub.2, C═O, C═NR.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, wherein one or more hydrogen atoms in the abovementioned groups are optionally replaced by D, F, Cl, Br, I, or CN, and wherein two or more radicals R.sup.4 are optionally joined to one another and optionally define a ring; R.sup.5 is, the same or differently in each instance, H, D, F, Cl, Br, I, CN, a straight-chain alkyl or alkoxy group having 1 to 20 carbon atoms, a branched or cyclic alkyl or alkoxy group having 3 to 20 carbon atoms, an alkenyl or alkynyl group having 2 to 20 carbon atoms, an aromatic or heteroaromatic ring system having 5 to 30 aromatic ring atoms, or an aryloxy or heteroaryloxy group having 5 to 30 aromatic ring atoms, wherein two or more radicals R.sup.5 are optionally joined to one another and optionally define a ring.

2. The compound of claim 1, wherein X.sup.1 is, the same or differently in each instance, selected from the group consisting of C(R.sup.3).sub.2, —C(R.sup.3).sub.2—C(R.sup.3).sub.2—, —C(R.sup.3).sub.2—O—, Si(R.sup.3).sub.2, O, S, and NR.sup.3, wherein two or more radicals R.sup.3 are optionally joined to one another and optionally define a ring.

3. The compound of claim 2, wherein X.sup.1 is C(R.sup.3).sub.2.

4. The compound of claim 1, wherein R.sup.1 is, the same or differently in each instance, selected from the group consisting of H, CN, N(R.sup.4).sub.2, and aromatic and heteroaromatic ring systems having 5 to 30 aromatic ring atoms, wherein the abovementioned groups are each optionally substituted by one or more radicals R.sup.4.

5. The compound of claim 1, wherein R.sup.2 is H or D.

6. The compound of claim 1, wherein R.sup.3 is, the same or differently in each instance, selected from the groups consisting of straight-chain alkyl groups having 1 to 20 carbon atoms and branched alkyl groups having 3 to 20 carbon atoms.

7. A compound of formulae (D1) through (D4): ##STR00166## ##STR00167##

8. An oligomer, polymer, or dendrimer comprising one or more compounds of claim 1, wherein the bond(s) to the polymer, oligomer, or dendrimer is optionally localized at any position(s) substituted by R.sup.1 and/or R.sup.2 in formula (II-1-4).

9. A formulation comprising at least one compound claim 1 and at least one solvent.

10. A formulation comprising at least one polymer, oligomer or dendrimer of claim 8 and at least one solvent.

11. 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 comprising at least one compound of claim 1.

12. 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 comprising at least one oligomer, polymer, or dendrimer of claim 8.

13. The electronic device of claim 11, wherein the electronic device is selected from the group consisting of an organic electroluminescent device comprising a cathode, an anode, and at least one organic layer, wherein the at least one organic layer comprises the at least one compound.

14. The electronic device of claim 12, wherein the electronic device is selected from the group consisting of an organic electroluminescent device comprising a cathode, an anode, and at least one organic layer, wherein the at least one organic layer comprises the at least one oligomer, polymer, or dendrimer.

15. The electronic device of claim 11, wherein the compound is present as a hole transport material in a hole transport layer, as an emitting compound in an emitting layer, or as a matrix compound in an emitting layer.

16. The electronic device of claim 12, wherein the oligomer, polymer, or dendrimer is present as a hole transport material in a hole transport layer, as an emitting compound in an emitting layer, or as a matrix compound in an emitting layer.

17. A process for preparing the compound of claim 1, comprising at least one metal-catalysed coupling reaction and at least one ring closure reaction.

18. The compound of claim 1, wherein Z.sup.1 is CR.sup.1, Z.sup.2 is CR.sup.2 and X.sup.1 is C(R.sup.3).sub.2.

19. The compound of claim 1, wherein the compound is a compound of Formula (II-1-4-1): ##STR00168##

20. The compound of claim 18, wherein R.sup.1 is, the same or differently in each instance, selected from the group consisting of H, CN, N(R.sup.4).sub.2, and aromatic and heteroaromatic ring systems having 5 to 30 aromatic ring atoms, wherein the abovementioned groups are each optionally substituted by one or more radicals R.sup.4; R.sup.2 is H or D; and R.sup.3 is, the same or differently in each instance, selected from the groups consisting of straight-chain alkyl groups having 1 to 20 carbon atoms and branched alkyl groups having 3 to 20 carbon atoms.

Description

WORKING EXAMPLES

(1) A) Synthesis Examples

(2) The procedure is according to the following general scheme:

(3) ##STR00133## ##STR00134##

(4) Analogously, the following compound is used as the starting point:

(5) TABLE-US-00004 Compound I-b

(6) Compound II-a

(7) I-a, 2,8-dibromo-6,12-dihydro-6,6,12,12-tetraoctylindeno[1,2-b]fluorene, (100 g, 116 mmol), bis(pinacolato)diborane (64.9 g, 256 mmol) and potassium acetate (75.2 g, 767 mmol) are suspended in 1 L of tetrahydrofuran. The solution is degassed and saturated with argon. Thereafter, PdCl.sub.2(dppf)-CH.sub.2Cl.sub.2 (1.9 g, 2.3 mmol) is added. The reaction mixture is heated to boiling under protective gas atmosphere for 16 h, then cooled down to room temperature and concentrated under reduced pressure. The solids are admixed with a mixture of dichloromethane and water and extracted by shaking. The phases are separated and the aqueous phase is extracted twice with dichloromethane. The combined organic phases are washed with water, dried over sodium sulphate, filtered and concentrated under reduced pressure. The crude product is filtered with toluene through SiO.sub.2/Al.sub.2O.sub.3 and then the solvent is removed under reduced pressure. The remaining residue is stirred with methanol and then filtered. The yield is 94.5 g (81% of theory, purity about 95%).

(8) The following compound is prepared in an analogous manner:

(9) TABLE-US-00005 Compound Yield II-b 71%

(10) Compound III-a

(11) II-a (85 g, 84.6 mmol), ethyl 1-bromonaphthalene-2-carboxylate (54.3 g, 194 mmol) and sodium carbonate (32.5 g, 306 mmol) are suspended in a mixture of water/toluene/ethanol (ratio 1:2:1, 3 l). The solution is degassed and saturated with argon. Thereafter, tetrakis(triphenylphosphine)palladium(0) (1.95 g, 1.7 mmol) is added. The reaction mixture is heated to boiling under a protective gas atmosphere for 16 h. The phases are separated and the aqueous phase is extracted twice with toluene. The combined organic phases are washed with water, dried over sodium sulphate, filtered and then concentrated under reduced pressure. The mixture is filtered through Celite with toluene and the solvent is then removed under reduced pressure. The remaining residue is stirred with methanol and then filtered. The yield is 89.0 g (96% of theory).

(12) The following compound is prepared in an analogous manner:

(13) TABLE-US-00006 Compound Yield III-b 0 73%

(14) Compound IV-a

(15) To III-a (89 g, 81 mmol) in 1 l of anhydrous tetrahydrofuran is added dropwise a mixture of anhydrous cerium chloride (41.9 g, 170 mmol) and 500 ml of anhydrous tetrahydrofuran at a temperature between 0° C. and 5° C. The reaction mixture is stirred at this temperature for 1 h. Subsequently, 400 ml of saturated aqueous ammonium chloride solution are added dropwise at a temperature between 0° C. and 20° C. The suspension obtained is filtered. The phases are then separated and the aqueous phase is extracted twice with 200 ml of ethyl acetate. The combined organic phases are concentrated under reduced pressure. The yield is 59.8 g (69% of theory).

(16) The following compound is prepared in an analogous manner:

(17) TABLE-US-00007 Compound Yield IV-b 48%

(18) Compound V-a

(19) Methanesulphonic acid (10.8 ml, 16 mmol) is added dropwise to a mixture of polyphosphoric acid (16.4 g, 167 mmol) and 700 ml of dichloromethane at a temperature of 0° C. Subsequently, a suspension of IV-a (59.8 g, 56 mmol) in 800 ml of dichloromethane is slowly added dropwise at 0° C. The reaction mixture is stirred at 0° C. for 2 h. 800 ml of ethanol are added and the reaction mixture is then stirred for 30 min. The solvent is removed under reduced pressure and the remaining residue is recrystallized twice with a mixture of toluene and heptane. The yield is 46.3 g (80% of theory).

(20) The following compound is prepared in an analogous manner:

(21) TABLE-US-00008 Compound Yield V-b 39%

(22) Compound VI-a

(23) V-a (41.3 mg, 40 mmol) is dissolved in 11 of dichloromethane. Subsequently, at 0° C., Br.sub.2 (12.74 g, 79.7 mmol) in 300 ml of dichloromethane is added dropwise. The reaction mixture is stirred at room temperature overnight. 200 ml of sodium thiosulphate solution are added and the reaction mixture is stirred for 30 min. Subsequently, the phases are separated. The organic phase is washed with water, dried over sodium sulphate and concentrated by rotary evaporation. The reaction mixture is filtered through SiO.sub.2 and Al.sub.2O.sub.3 with toluene and concentrated by rotary evaporation. The remaining residue is recrystallized twice in toluene/heptane. The yield is 40.8 g (86% of theory).

(24) Compound VII-a

(25) VI-a (20 g, 16.5 mmol), dibenzofuran-4-ylboronic acid (7.7 g, 36.3 mmol) and tripotassium phosphate monohydrate (15.2 g, 66 mmol) are suspended in a mixture of toluene/dioxane/water (1:1:1, 600 ml). Subsequently, palladium acetate (74 mg, 0.33 mol) and tri(o-tolyl)phosphine (602 mg, 2.0 mmol) are added. The reaction mixture is heated to boiling for 16 h. After the reaction mixture has been cooled down to room temperature, the organic phase is extended with 300 ml of ethyl acetate. The phases are separated and the aqueous phase is extracted twice with ethyl acetate. The combined organic phases are dried over sodium sulphate and then concentrated under reduced pressure. The mixture is filtered through alumina with toluene and the remaining residue is then recrystallized repeatedly in toluene/heptane. The yield is 18.3 g (82% of theory).

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

(27) TABLE-US-00009 Com- pound Yield VII-b 73% VII-c 64% VII-d 37% VII-e 48% VII-f 0 54% VII-g 61%

(28) B) Emission Data

(29) The compound of the formula (I), or formula (II), is dissolved in toluene and then absorption spectra and/or photoluminescence spectra of the corresponding compound of the formula (I), or formula (II), are recorded.

(30) Absorption spectra are measured on the Lambda 9 instrument, UV/VIS/NIR spectrometer, from Perkin Elmer. Photoluminescence spectra are measured on the F-4500 instrument, fluorescence spectrophotometer, from Hitachi.

(31) B-1) Emission Data of Comparative Compound (1)

(32) ##STR00152##

(33) TABLE-US-00010 Maxima [nm].sup.3 Absorption.sup.1 362 380 402 Emission.sup.2 409 432 458

(34) B-2) Emission Data of Target Compound (1)

(35) ##STR00153##

(36) TABLE-US-00011 Maxima [nm].sup.3 Absorption.sup.1 371 391 414 Emission.sup.2 420 445 473 .sup.1absorption measurement .sup.2emission measurement .sup.3maxima of the absorption and emission peaks in nm; the primary maximum in nm is underlined

(37) On excitation, the comparative compound (1) based on a benzoindenofluorene base skeleton emits ultraviolet and violet light with wavelengths of 409 nm, 432 nm and 458 nm.

(38) It has now been found that, surprisingly, the inventive compounds of the formula (I), or formula (II), based on an extended bisindenofluorene base skeleton have emissions shifted to greater wavelengths. The target compound (1) especially has emissions which are partly within the wavelength range of blue visible light. Thus, the target compound 1 has emission peaks at 420 nm, 445 nm and 473 nm.

(39) Therefore, the target compound (1) has blue emission on excitation and is accordingly suitable for use as a blue singlet emitter in electronic devices.

(40) c) Device Examples: Production of the OLEDs

(41) OLEDs of the invention and OLEDs according to the prior art are produced by a general method according to WO 2004/058911. The production of solution-based OLEDs is described, for example, in WO 2004/037887 and in WO 2010/097155. In the examples which follow, the two production processes were combined, such that layers up to and including the emission layer of the OLED are processed from solution and the subsequent layers (e.g. electron transport layer of the OLED) are applied by vapour deposition under reduced pressure. The above-described general methods are combined as follows and matched to the circumstances described here (variation in layer thicknesses, materials).

(42) In the examples which follow (see tables 1 and 2), 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 (20 nm)/hole transport layer (HTL, 20 nm)/emission layer (EML, 60 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 substrate is coated with a buffer of Pedot:PSS (poly(3,4-ethylenedioxy-2,5-thiophene) polystyrenesulphonate), purchased from Heraeus Precious Metals GmbH & Co. KG. Spin-coating is effected under air from water. The layer is subsequently baked at 180° C. for 10 minutes. The hole transport layer and the emission layer are applied to the substrates thus coated. The structures of the materials used in the OLED are shown in Table 2, where HTL represents the material of the hole transport layer, where EIL represents the material of the electron injection layer, and where ETL represents the material of the electron transport layer.

(43) The hole transport layer consists of the polymer HTL, of the structure shown in Table 2, which was synthesized according to WO 2010/097155. The polymer is dissolved in toluene, such that the solution has a solids content of about 5 g/I, in order to achieve a layer thickness of 20 nm by means of spin-coating. The layers are spun on in an atmosphere of inert gas, argon in the present case, and baked at 180° C. for 60 min.

(44) The emission layer (EML) always consists of at least one matrix material (host=H) and an emitting compound (emitter, dopant=D) which is added to the matrix material in a particular proportion by weight. Details given in such a form as H1:D1 (92%:8%) mean here that the matrix material H1 is present in the emission layer in a proportion by weight of 92% and the emitting compound D1 in a proportion by weight of 8%. The mixture for the emission layer is dissolved in toluene, such that the solution has a solids content of about 18 g/l, in order to achieve a layer thickness of 60 nm by means of spin-coating. The layers are spun on in an atmosphere of inert gas, argon in the present case, and baked at 140° C. for 10 min. The matrix materials H and the dopants D used are shown in Table 1. The structures of the materials used in the emission layer of the OLED are shown in Table 2.

(45) The materials for the electron transport layer and for the cathode are applied by thermal vapour deposition in a vacuum chamber. The electron transport layer, for example, may consist of more than one material, the materials being added to one another by co-evaporation in a particular proportion by volume. Details given in such a form as ETM:EIL (50%:50%) mean here that the ETM and EIL materials are present in the layer in a proportion by volume of 50% each. In the present case, the electron transport layer consists of the matrix material ETL with a layer thickness of 20 nm and the electron injection layer consists of the material EIL with a layer thickness of 3 nm. The material ETL and the material EIL are shown in Table 2.

(46) 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 emission characteristics, from current-voltage-luminance characteristics (IUL characteristics), and finally the lifetime of the components is determined. 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 lifetime is the time LD80 @10 mA/cm.sup.2 that passes before the starting brightness at an operating current density of 10 mA/cm.sup.2 has dropped by 20%. The data obtained for the various OLEDs are collated in Table 1.

(47) D) Use of the Compounds of the Invention as Emitters in Fluorescent OLEDs

(48) The compounds of the invention D1, D2, D3 and D4 are used individually as emitters in the emitting layer of OLEDs (for structure see Table 2). The matrix material used in the emitting layer is the compound H1 or H2. The OLEDs obtained are 11 to 16. They exhibit very good lifetime (LD80) with deep blue emission (Table 1). Compared to emitter materials known in the prior art (C-D1 and C-D2; cf. C1 to C3), the quantum efficiency is improved and the lifetime (LD80) is distinctly improved.

(49) Especially the comparison with the material C-D2 shows the improvement which is achieved by the extended bisindenofluorene base skeleton of the invention compared to the bisindenofluorene base skeleton known in the prior art.

(50) TABLE-US-00012 TABLE 1 Data of the OLEDs EQE @ LD80 Host Dopant 1000 cd/m.sup.2 @ 10 mA/cm.sup.2 CIE Example 92% 8% % [h] x y C1 H1 V-D1 3.1 140 0.142 0.102 C2 H2 V-D1 3.1 160 0.141 0.108 C3 H1 V-D2 2.9 140 0.144 0.132 I1 H1 D1 3.9 220 0.142 0.116 I2 H2 D1 4.1 250 0.141 0.121 I3 H1 D2 3.8 290 0.131 0.150 I4 H1 D3 3.8 180 0.157 0.098 I5 H2 D3 3.9 200 0.152 0.101 I6 H1 D4 4.2 290 0.145 0.120

(51) TABLE-US-00013 TABLE 2 Structures of the materials used H1 H2 C-D1 C-D2 D1 0 D2 D3 D4

(52) In addition, the compounds of the invention have good solubility in nonpolar solvents and are consequently suitable for processing from solution. As a result, electronic devices having blue-fluorescent emitters are obtained, which have advantageous performance data.

(53) Alternatively or additionally, the compounds of the invention can also be used as matrix material in the emission layer (EML), as hole transport material in the hole transport layer (HTL), as electron transport material in the electron transport layer (ETL) or as hole injection material in a hole injection layer (HIL) of an OLED.