Phenoxazine derivatives for organic electroluminescent devices

Abstract

The present invention relates to the compounds of the formulae (1) and (2) and to organic electroluminescent devices, in particular blue-emitting devices, in which these compounds are used as host material or dopant in the emitting layer and/or as hole-transport material and/or as electron-transport material. ##STR00001##

Claims

1. A compound of formula (1) or formula (2): ##STR00210## wherein Ar is an aromatic ring system selected from one of the following formulae (ArN-1) to (ArN-24) and (ArN-26), ##STR00211## ##STR00212## ##STR00213## ##STR00214## where the groups (ArN-1) to (ArN-24) and (ArN-26), are optionally substituted by one or more radicals R.sup.2; Ar.sup.1 is, on each occurrence, identically or differently, a group of formulae (Ar1′-1) through (Ar1′-4): ##STR00215## wherein the dashed bond denotes the linking to Ar.sup.S or to a phenoxazine structure if A.sup.S is absent; V is, on each occurrence, identically or differently, CR.sup.2 or N or two adjacent groups V are a group of formula (V-1) or (V-2); ##STR00216## wherein the dashed bonds denote the linking of these units; Ar.sup.2 is, on each occurrence, identically or differently, an aryl group having 10 to 18 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2; A.sup.S is, on each occurrence, identically or differently, an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, optionally substituted by one or more radicals R.sup.2; E.sup.1, E.sup.2, and E.sup.3 are, on each occurrence, identically or differently, selected from the group consisting of B(R.sup.1), C(R.sup.1).sub.2, Si(R.sup.1).sub.2, C═O, C═NR.sup.1, C═C(R.sup.1).sub.2, O, S, S═O, SO.sub.2, N(R.sup.1), P(R.sup.1), and P(═O)R.sup.1; or E.sup.1, E.sup.2 and/or E.sup.3 is a group of formula (E-1): ##STR00217## wherein the dashed bonds denote the bonding to the 5-membered ring comprising E.sup.1, E.sup.2, or E.sup.3; R, and R.sup.3 are, on each occurrence, identically or differently, H, D, F, Br, Cl, 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, S(═O)R.sup.4, S(═O).sub.2R.sup.4, a straight-chain alkyl or alkoxy group having 1 to 20 C atoms or a branched or cyclic alkyl or alkoxy group having 3 to 20 C atoms or an alkenyl or alkynyl group having 2 to 20 C atoms, optionally substituted by one or more radicals R.sup.4 and wherein one or more CH.sub.2 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, an aromatic or heteroaromatic ring system having 5 to 30 aromatic ring atoms, optionally substituted by one or more radicals R.sup.4, or an aryloxy or heteroaryloxy group having 5 to 30 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.4, wherein two adjacent radicals R, and/or two adjacent radicals R.sup.3 are optionally linked to one another and optionally define an aliphatic or aromatic ring; R.sup.1 is selected, identically or differently on each occurrence, from the group consisting of H, D, F, a straight-chain alkyl group having 1 to 10 C atoms or a branched or cyclic alkyl group having 3 to 10 C atoms, optionally substituted by one or more radicals R.sup.4; R.sup.2 is selected, identically or differently on each occurrence, from the group consisting of H, D, F, a straight-chain alkyl group having 1 to 10 C atoms or a branched or cyclic alkyl group having 3 to 10 C atoms, optionally substituted by one or more radicals R.sup.4, a phenyl group, optionally substituted by one or more radicals R.sup.4; R.sup.4 is, on each occurrence, identically or differently, H, D, F, Br, Cl, I, C(═O)R.sup.5, CN, Si(R.sup.5)3, N(R.sup.5).sub.2, P(═O)(R.sup.5).sub.2, S(═O)R.sup.5, S(═O).sub.2R.sup.5, a straight-chain alkyl or alkoxy group having 1 to 20 C atoms or a branched or cyclic alkyl or alkoxy group having 3 to 20 C atoms or an alkenyl or alkynyl group having 2 to 20 C atoms, optionally substituted by one or more radicals R.sup.5 and wherein one or more CH.sub.2 groups are optionally replaced by —R.sup.5C═CR.sup.5—, —C≡C—, Si(R.sup.5)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, an aromatic or heteroaromatic ring system having 5 to 30 aromatic ring atoms, optionally substituted by one or more radicals R.sup.5, or an aryloxy or heteroaryloxy group having 5 to 30 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.5, where two adjacent radicals R.sup.4 are optionally linked to one another and optionally define an aliphatic or aromatic ring; R.sup.5 is, on each occurrence, identically or differently, H or an aliphatic, aromatic, and/or heteroaromatic hydrocarbon radical having 1 to 20 C atoms, wherein H atoms are optionally replaced by F; and wherein two adjacent radicals R.sup.5 also optionally define a mono- or polycyclic aliphatic or aromatic ring system with one another; a, b, c, and d are, identically or differently, selected from 0 or 1; wherein a =0, b =0, c =0, or d =0 denotes that the corresponding bridge is not present; wherein a+b=1 or 2; and c+d=1 or 2; f is, identically or differently, on each occurrence 0, 1, 2, or 3; g and h are, identically or differently, on each occurrence 0, 1, or 2; wherein g+a+b ≤3 and h+c+d≤3; m is, identically or differently, on each occurrence 0, 1, 2, 3, or 4; and i is, identically or differently, on each occurrence 0, 1, 2, or 3, wherein i=0 denotes that the group Ar.sup.S is absent and replaced by a single bond.

2. The compound of claim 1, wherein a+c=1 and b+d=0 or b+d=1 and a+c=0.

3. The compound of claim 1, wherein Ar.sup.2 is selected from the group consisting of naphthyl, anthracyl, phenanthryl, chrysenyl, and pyrenyl, wherein each of which is optionally substituted by one or more radicals R.sup.2.

4. The compound of claim 1, wherein the compound is selected from group consisting of compounds of formulae (1-1-a), (2-1-a), and (2-2-a): ##STR00218## wherein Ar.sup.2 is a group of formulae (Ar2-1) through (Ar2-3) ##STR00219## wherein the dashed bond denotes the linking to the phenoxazine structure and * indicates the linking position to the group E.sup.2; and wherein each free position on the naphtyl group in formulae (Ar2-1) through (Ar2-3) is optionally substituted by a radical R.sup.2; with the proviso that in formula (1-1-a), V is C when the linking to the phenoxazine structure or a phenyl phenoxazine structure takes place via V.

5. The compound of claim 1, wherein the compound is selected from group consisting of compounds of formulae (1-1-b) through (2-2-d): ##STR00220## ##STR00221## ##STR00222## wherein formulae (1-1-b) through (2-2-d) have two phenyl rings condensed on a central oxazine ring, and wherein each free position of the two phenyl rings condensed on the central oxazine ring in formulae (1-1-b) through (2-2-d) is optionally substituted by a radical R.

6. The compound of claim 1, wherein E.sup.1, E.sup.2, and E.sup.3 are, on each occurrence, identically or differently, selected from the group consisting of C(R.sup.1).sub.2, Si(R.sup.1).sub.2, O, N, S, and groups of formula (E-1).

7. The compound of claim 1, wherein R and R.sup.3 are selected, identically or differently on each occurrence, from the group consisting of H, D, F, CN, a straight-chain alkyl group having 1 to 20 C atoms or a branched or cyclic alkyl group having 3 to 20 C atoms, optionally substituted by one or more radicals R.sup.4 and wherein one or more CH.sub.2 groups are optionally replaced by —R.sup.4C═CR.sup.4—, —C≡C—, C═O, —O—, —S—, an aromatic or heteroaromatic ring system having 5 to 30 aromatic ring atoms, which in each case is optionally substituted by one or more radicals R.sup.4, and wherein two adjacent radicals R, and/or two adjacent radicals R.sup.3 are optionally linked to one another and optionally define an aliphatic or aromatic ring.

8. A process for preparing a compound of claim 1, comprising introducing aryl groups as substituents para to the N atom of a phenoxazine derivative via one or more transition metal-catalysed coupling reactions.

9. An oligomer, polymer or dendrimer comprising one or more compounds of claim 1, wherein the bond(s) to the polymer, oligomer, or dendrimer are optionally localised at any desired position(s) in formula (1) or in formula (2) substituted by R or R.sup.2.

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

11. A formulation comprising at least one polymer, oligomer, or dendrimer of claim 9 and at least one solvent.

12. An electronic device comprising at least one compound of claim 1.

13. An electronic device comprising at least one polymer, oligomer, or dendrimer according to claim 9.

14. The electronic device of claim 12, wherein the electronic device is 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, light-emitting electrochemical cells, organic laser diodes, and organic electroluminescent devices.

15. The electronic device of claim 13, wherein the electronic device is 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, light-emitting electrochemical cells, organic laser diodes, and organic electroluminescent devices.

16. The electronic device of claim 12, wherein the electronic device is selected from the group consisting of organic electroluminescent devices and wherein the compound is employed in one or more of the following functions: as a blue emitter in an emitting layer, as a hole-transport material in a hole-transport or hole-injection layer, as a matrix material in an emitting layer, as an electron-blocking material; and as an exciton-blocking material.

17. The electronic device of claim 13, wherein the electronic device is selected from the group consisting of organic electroluminescent devices and wherein the polymer, oligomer or dendrimer is employed in one or more of the following functions: as a blue emitter in an emitting layer, as a hole-transport material in a hole-transport or hole-injection layer, as a matrix material in an emitting layer, as an electron-blocking material; and as an exciton-blocking material.

Description

WORKING EXAMPLES

A) Synthesis Examples

(1) A-1) Compound A

(2) The syntheses were performed according to the following general scheme:

(3) ##STR00159##

(4) TABLE-US-00003 Compound 0 Yield % Int-a1 79 Int-a2 83 Int-a3 70 Int-a4 87 Int-a5 75

(5) Compound Int-a1

(6) Phenoxazine (23 g, 0.12 mol), p-Bromphenylbenzene (31.22 g, 0.13 mol) and sodium tert-butoxide (35.83 g, 0.37 mol) are suspended in 800 ml of toluene. The solution is degassed and saturated with argon. Thereafter, palladium (II) acetate (1.37 g, 1.88 mmol) and tri-tert-butylphosphine (solution 1 mol/L toluene, 0.01 mol) are added. The reaction mixture is heated overnight under reflux. The suspension is cooled and then treated with water. The collected organic phases are concentrated under vacuum and the remaining solid is purified by hot extraction. The yield is 32.4 g (0.1 mol, 79% of the theory d. Theory) as a white solid.

(7) The compounds Int-a2 to Int-a5 are prepared analogously to Int-a1.

(8) Compounds Int-F-H (Compound Int-a6) and

(9) Compound Int-F-Ph (Compound Int-a7)

(10) ##STR00166##

(11) Step 1:

(12) Preparation of Int-F-H

(13) 10 g (54.6 mmol) Phenoxazine, 14.2 g (82 mmol) 1,3-dichloro-2-fluoro-benzene and 25 g (0.11 mol) potassium phosphate were dissolved in 250 mL DMF and stirred 16 hours at reflux. After cooling down to room temperature 300 ml toluene and 500 ml water was added and the phases were separated. The organic phase was washed with water (3×300 ml) and the aqueous phase was extracted two times with toluene. The combined organic phases were reduced to dryness and purified by recrystallization from toluene/heptane.

(14) Yield: 16 g (0.05 mol; 90%)

(15) Preparation of Int-F-Ph

(16) ##STR00167##

(17) This compound can be prepared analogously to Int-F-H (yield 89%).

(18) Step 2:

(19) Int-F-H:

(20) 14 g (43 mmol) 10-(2,6-Dichloro-phenyl)-10H-phenoxazine, 13.7 g (107 mmol) phenyl boronic acid, 26 g (171 mmol) caesium fluoride and 1.6 g (2.1 mmol) trans-dichlorobis(tricyclohexyl-phosphine)palladium (II) were refluxed in 600 ml dioxane for 16 hours. After cooling down to room temperature toluene (300 ml) and water (400 ml) was added. The organic phase was washed with water (3×300 ml) and the aqueous phase was extracted two times with toluene. The combined organic phases were reduced to dryness and purified by recrystallization from toluene/heptane.

(21) Yield: 14.6 g (35 mmol; 82%)

(22) For Int-F-Ph:

(23) ##STR00168##

(24) Compound can be prepared analogously to Int-F-H (yield 78%)

(25) TABLE-US-00004 Compound Yield % Int-b1 0 98 Int-b2 95 Int-b3 89 Int-b4 93 Int-b5 85 Int-b6 89 Int-b7 86

(26) Compound Int-b1

(27) The compound Int-a1 (32 g, 0.1 mol) is dissolved in 800 ml of glacial acetic acid and 800 ml of chloroform. Subsequently, N-Bromsucchinimid (34.8 g, 0.2 mol) is added slowly in the dark. After 4 hours, the reaction is quenched with water and the organic phase washed several times with water. The resulting solid is extracted twice from hot ethanol. The yield is 43.8 g (0.1 mol, 98% of the theory) as a white solid.

(28) The compounds Int-b2 to Int-b7 are prepared analogously to Int-b1.

(29) TABLE-US-00005 Compound Yield % A1 59 A2 52 A3 0 46 A6 54 A7 57

(30) Compound A1

(31) The compound Int-b1 (20 g, 0.04 mol), 2-(9,9-dimethylfluorene)-4,4,5,5-tetramethyldioxaborolane (27.27 g, 0.085 mol) and tripotassium phosphate monohydrate (37.35 g, 0.16 mol) are suspended in 200 ml water, 200 ml of toluene and 200 ml of 1,4-dioxane. The solution is degassed and saturated with argon. Subsequently, palladium (II) acetate (0.36 g, 1.6 mmol) and tri-ortho-tolylphosphine (1.48 g, 4.87 mmol) are added and the reaction boiled overnight under reflux. The suspension is cooled down and then treated with water. The collected organic phases are concentrated under vacuum and the remaining solid is purified by hot extraction (toluene) and recrystallization (toluene and then EtOAc) purified. The yield is 17.0 g (23.6 mmol, 59% of the theory) as a yellow solid.

(32) The compounds A2 to A7 are prepared analogously to A1.

(33) A-2) Compounds B

(34) The syntheses were performed according to the following general scheme:

(35) ##STR00183##

(36) TABLE-US-00006 Int-c Yield % Int-c1 66 Int-c2 75 Int-c3 82 Int-c4 62

(37) Compound Int-c1

(38) The compound Int-b1 (21.45 g, 0.05M), Bispinacolatodiborane (31.35 g, 0.12 mol) and potassium acetate (30.3 g, 0.31 mol) are suspended in 500 ml of 1,4-dioxane. The reaction mixture is degassed and saturated with argon. Then [1,1′-bis-diphenylphosphino-ferrocene] palladium (11) dichloride (3.35 g, 4.1 mmol) is added and the reaction is stirred overnight under reflux. The suspension is cooled down and filtered directly over alumina. The resulting solid is stirred in hot ethanol. The yield is 17.25 g (0.033 mol, 66% of the theory) as a white solid.

(39) The compounds Int-c2 to Int-c4 are prepared analogously to Int-c1.

(40) TABLE-US-00007 Int-d Yield % Int-d1 0 65 Int-d3 63

(41) Compound Int-d1

(42) The compound Int-c1 (17 g, 0.033 mol), 1-bromo-phenyl-ethyl ester (18.74 g, 0.067 mol) and tripotassium phosphate monohydrate (30.39 g, 0.132 mol) are suspended in 50 ml water, 50 ml of toluene and 50 ml 1,4-dioxane. The solution is degassed and saturated with argon. Subsequently, palladium (II) acetate (0.29 g, 1.32 mmol) and tri-ortho-tolylphosphine (1.21 g, 3.96 mmol) are added and the reaction is boiled overnight under reflux. The suspension is cooled down and then treated with water. The collected organic phases are concentrated under vacuum and the remaining solid is purified by hot extraction (toluene) and recrystallization (toluene/heptane). The yield is 14.1 g (00.21 mol, 65% of the theory) as a yellow solid.

(43) The compound Int-d3 is prepared analogously to Int-d1.

(44) TABLE-US-00008 Int-e Yield % Int-e1 95 Int-e3 93

(45) Compound Int-e1

(46) Cerium (Ill) chloride (11.3 g, 0.046 mol) is initially added to dry THF, then the compound Int-d1 (14 g, 0.021 mol) is dissolved in dry THF and the solution is added dropwise to the reaction mixture, which is subsequently stirred for one hour. Afterwards, a solution of MeMgCl (3M in THF, 0.13 mol) is added to the reaction mixture dropwise. After 2 hours, the reaction is heated overnight to room temperature. Under ice cooling, the reaction is quenched with water. After phase separation, the organic phase is dried and the solvent evaporated. The organic phase is then purified via recrystallisation from heptane/toluene. The yield is 12.5 g (0.02 mol, 95% of the theory) as a yellow solid.

(47) The compound Int-e3 is prepared analogously to Int-e1.

(48) TABLE-US-00009 B Yield % B1 82 B3 87

(49) Compound B1

(50) Polyphosphoric acid (13.1 g, 0.13 mol) and methanesulfonic acid (12.5 g, 0.13 mol) are placed in a flask. Then, a solution comprising the compound Int-e1 (12 g, 0.019 mol) suspended in DCM is slowly added into the reaction mixture, which is cooled down with an ice bath. The reaction mixture is further stirred during 2 hours and is subsequently treated with ethanol. After adding water, a phase separation occurs. The organic phase is washed with water, then dried and then the solvent is evaporated. The remaining residue is recrystallized several times from toluene/heptane.

(51) The yield is 8.65 g (0.15 mol, 77% of the theory) as a yellow solid.

(52) The compound B3 is prepared analogously to BI.

B) Device Examples

(53) Fabrication of OLED devices

(54) The manufacturing of the OLED devices is performed accordingly to WO 04/05891 with adapted film thicknesses and layer sequences. The following examples V1 to E5 (see Table 1) show data of various OLED devices.

(55) Substrate Pre-Treatment of Examples V1-E5:

(56) Glass plates with structured ITO (50 nm, indium tin oxide) are coated with 20 nm PEDOT:PSS (Poly(3,4-ethylenedioxythiophene) poly(styrene-sulfonate, CLEVIOS™ P VP AI 4083 from Heraeus Precious Metals GmbH Germany, spin-coated from a water-based solution) to form the sub-strates on which the OLED devices are fabricated.

(57) The OLED devices have in principle the following layer structure: Substrate, ITO (50 nm), Buffer (20 nm), Hole injection layer (HTL1 95%, HIL 5%) (20 nm), Hole transporting layer (HTL1) (see table 1), Emissive layer (EML) (20 nm), Electron transporting layer (ETL) (30 nm), Electron injection layer (EIL) (3 nm), Cathode.

(58) The cathode is formed by an aluminium layer with a thickness of 100 nm. The detailed stack sequence is shown in Table 1. The materials used for the OLED fabrication are presented in Table 3.

(59) 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=H) and an emitting dopant (emitter=D), which is mixed with the matrix material or matrix materials in a certain proportion by volume by co-evaporation. An expression such as H1:D1 (97%:3%) here means that material H1 is present in the layer in a proportion by volume of 97%, whereas D1 is present in the layer in a proportion of 3%. Analogously, the electron-transport layer may also consist of a mixture of two or more materials.

(60) The OLED devices are characterised by standard methods. For this purpose, the electroluminescence spectra, the current efficiency (measured in cd/A) and the external quantum efficiency (EQE, measured in % at 1000 cd/m.sup.2) are determined from current/voltage/luminance characteristic lines (IUL characteristic lines) assuming a Lambertian emission profile. The electroluminescence (EL) spectra are recorded at a luminous density of 1000 cd/m.sup.2 and the CIE 1931 x an y coordinates are then calculated from the EL spectrum. EQE @ 1000 cd/m.sup.2 is defined as the external quantum efficiency at luminous density of 1000 cd/m.sup.2. For all experiments, the lifetime LT95 is determined. The lifetime LT95 @1000 cd/m.sup.2 is defined as the time after which the initial luminous density of 1000 cd/m.sup.2 has dropped by 5%. The device data of various OLED devices is summarized in Table 2.

(61) The example V1 represents the comparative example according to the state-of-the-art. The examples E1-E5 show data of inventive OLED devices.

(62) In the following section several examples are described in more detail to show the advantages of the inventive OLED devices.

(63) Use of Inventive Compounds as Emitting Material in Fluorescent OLEDs

(64) The inventive compounds are especially suitable as an emitter (dopant) when blended into a fluorescent blue matrix to form the emissive layer of a fluorescent blue OLED device. The representative examples are D1, D2, D3, D4 and D5. Comparative compound for the state-of-the-art is represented by VD (structures see table 3).

(65) The use of the inventive compound as an emitter (dopant) in a fluorescent blue OLED device results in significantly improved device data (E1, E2, E3, E4 and E5) compared to state-of-the-art example (V1), especially in term of external quantum efficiency and device lifetime. This demonstrates the applicability of the inventive compound as emitting material in fluorescent blue OLED devices. The material can be also used also as hole transporting material.

(66) TABLE-US-00010 TABLE 1 Stack sequence of OLEDs Example HTL (20 nm) EML (Dicke/20 nm) V1 HTL2 BH1 (97%):VD (3%) E1 HTL2 BH1 (97%):D1 (3%) E2 HTL2 BH1 (97%):D2 (3%) E3 HTL2 BH1 (97%):D3 (3%) E4 HTL2 BH1 (97%):D4 (3%) E5 HTL2 BH1 (97%):D5 (3%)

(67) TABLE-US-00011 TABLE 2 Device data of OLEDs EQE [%] @ LT 95 [h] @ Example CIE x CIE y 1000 cd/m.sup.2 1000 cd/m.sup.2 V1 0.14 0.18 6.2 80 E1 0.15 0.17 6.8 150 E2 0.14 0.14 6.5 200 E3 0.14 0.15 6.7 100 E4 0.15 0.13 6.9 130 E5 0.15 0.13 6.8 170

(68) TABLE-US-00012 TABLE 3 Chemical structure of OLED materials HTL1 00 HTL2 01 02 03 D1 04 D2 05 D3 06 D4 07 D5 08 09