Materials for organic electroluminescent devices

Abstract

The present invention relates to fluorene derivatives and to electronic devices in which these compounds are used as matrix material in the emitting layer and/or as hole-transport material and/or as electron-blocking or exciton-blocking material and/or as electron-transport material.

Claims

1. A mixture comprising at least one compound of the formula (1) and at least one further compound ##STR00058## where Y is C(R.sup.1).sub.2, O or NR.sup.3; X is on each occurrence, identically or differently, CR.sup.1 or N, where a maximum of three groups X in each ring stand for N; A is on each occurrence, identically or differently, CR.sup.2 or N, where a maximum of three groups A in each ring stand for N; R.sup.1, R.sup.2 are on each occurrence, identically or differently, H, D, Cl, Br, I, F, CN, NO.sub.2, N(R.sup.4).sub.3, Si(R.sup.4).sub.3, B(OR.sup.4).sub.2, C(═O)R.sup.4, P(═O)(R.sup.4).sub.2, S(═O)R.sup.4, S(═O).sub.2R.sup.4, —CR.sup.4═CR.sup.4—, OSO.sub.2R.sup.4, a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 40 C atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 40 C atoms or an alkenyl or alkynyl group having 2 to 40 C atoms, each of which may be substituted by one or more radicals R.sup.4, where one or more non-adjacent CH.sub.2 groups may be replaced by R.sup.4C═CR.sup.4, C≡C, Si(R.sup.4).sub.2, Ge(R.sup.4).sub.2, Sn(R.sup.4).sub.2, C═O, C═S, C═Se, C═NR.sup.4, P(═O)(R.sup.4), SO, SO.sub.2, NR.sup.4, O, S or CONR.sup.4 and where one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO.sub.2, or an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R.sup.4, or an aryloxy or heteroaryloxy group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R.sup.4, or aralkyl or heteroaralkyl group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R.sup.4; two or more adjacent substituents R.sup.1 together with the atoms to which they are bonded or two or more adjacent substituents R.sup.2 together with the atoms to which they are bonded may also form a mono- or polycyclic, aliphatic or aromatic ring system with one another; characterised in that at least one R.sup.1 which is bonded to X stands for triazine, which may be substituted by one or more radicals R.sup.4, or in that at least one R.sup.2 stands for a 6-membered heteroaromatic group, which may be substituted by one or more radicals R.sup.4, and at least one radical R.sup.1 simultaneously stands for an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R.sup.4; R.sup.3 is on each occurrence, identically or differently, an aromatic or heteroaromatic ring system having 5 to 60 ring atoms, which may in each case be substituted by one or more radicals R.sup.4, or an aryloxy or heteroaryloxy group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R.sup.3, or a combination of these systems; R.sup.4 is on each occurrence, identically or differently, H, D, F, Cl, Br, I, CN, NO.sub.2, N(R.sup.5).sub.3, Si(R.sup.5).sub.3, B(OR.sup.5).sub.2, C(═O)R.sup.5, P(═O)(R.sup.5).sub.2, S(═O)R.sup.5, S(═O).sub.2R.sup.5, —CR.sup.5═CR.sup.5—, OSO.sub.2R.sup.5, a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 40 C atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 40 C atoms or an alkenyl or alkynyl group having 2 to 40 C atoms, each of which may be substituted by one or more radicals R.sup.5, where one or more non-adjacent CH.sub.2 groups may be replaced by R.sup.5C═CR.sup.5, C≡C, Si(R.sup.5).sub.2, Ge(R.sup.5).sub.2, Sn(R.sup.5).sub.2, C═O, C═S, C═Se, C═NR.sup.5, P(═O)(R.sup.5), SO, SO.sub.2, NR.sup.5, O, S or CONR.sup.5 and where one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO.sub.2, or an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R.sup.5, or an aryloxy or heteroaryloxy group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R.sup.5, or aralkyl or heteroaralkyl group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R.sup.5; two or more radicals R.sup.4 here may also form a mono- or polycyclic, aliphatic or aromatic ring system with one another together with the atoms to which they are bonded; R.sup.5 is on each occurrence, identically or differently, an aliphatic, aromatic and/or heteroaromatic hydrocarbon radical having 1 to 20 C atoms; two or more radicals R.sup.5 here may also form a mono- or polycyclic, aliphatic or aromatic ring system with one another together with the atoms to which they are bonded.

2. The Mixture according to claim 1, wherein the compound of formula (1) is selected from a compound of the formula (2), (3), (4), (5), (6), (7), (8), (9), (10), (11), (12), (13), (14) or (15): ##STR00059## ##STR00060## ##STR00061## where the symbols and indices used have the meanings indicated in claim 1.

3. The mixture according to claim 1, wherein, if at least one group R.sup.1 stands for triazine, this is 1,3,5-triazine or 1,2,4-triazine, which may in each case be substituted by one or more radicals R.sup.4 and where the radicals R.sup.4 which are not equal to hydrogen or deuterium preferably stand for an aromatic or heteroaromatic ring system; or in that, if at least one group R.sup.2 stands for a 6-membered heteroaromatic group, this is selected from triazine, pyrimidine, pyrazine, pyridazine or pyridine, each of which may be substituted by one or more radicals R.sup.4 and where the radicals R.sup.4 which are not equal to hydrogen or deuterium preferably stand for an aromatic or heteroaromatic ring system.

4. The mixture according to claim 1, wherein the triazine substituents R.sup.1 and R.sup.2 and the pyrimidine substituents R.sup.2 are selected from the groups depicted below: ##STR00062## ##STR00063## ##STR00064## ##STR00065## where the dashed bond indicates the link from this group to the skeleton.

5. The mixture according to claim 1, wherein the compound of formula (1) is a compound of the formula (16) or (17): ##STR00066##

6. The mixture according to claim 1, wherein the compound of formula (1) is selected from compounds of the formulae (20), (21), (24) or (25): ##STR00067##

7. The mixture according to claim 1, wherein the compound of formula (1) is a compound of formulae (29) or (31): ##STR00068##

8. The mixture according to claim 1, wherein the at least one further material is a matrix material.

9. The mixture according to claim 8, wherein the matrix material is a hole transport material.

10. The mixture according to claim 1 further comprising a phosphorescent or fluorescent compound.

11. A formulation comprising at least one mixture according to claim 1 and one or more solvent.

12. An electronic devices comprising at least one mixture according to claim 1, where the electronic device is selected from the group consisting of organic electroluminescent devices (OLEDs, PLEDs), organic field-effect transistors (O-FETs), organic thin-film transistors (O-TFTs), organic light-emitting transistors (O-LETs), organic integrated circuits (O-ICs), organic solar cells (O-SCs), organic field-quench devices (O-FQDs), light-emitting electrochemical cells (LECs), organic laser diodes (O-lasers) and organic photoreceptors.

13. The electronic device of claim 12, wherein the device is an organic electroluminescent device.

Description

EXAMPLES

(1) The following syntheses are carried out, unless indicated otherwise, under a protective-gas atmosphere in dried solvents. Starting material 8 and solvents are commercially available, for example from ALDRICH. Compounds 1 and 5 can be prepared in accordance with WO 09/124627. Compound 2 can be prepared analogously to J. Mater. Chem. 2007, 17, 3714-3719.

Example 1: Preparation of Compound 4

(2) ##STR00052##
a) Preparation of Compound 3:

(3) 850 ml of dimethyl sulfoxide, 25.18 g (1.1 molar equivalents, 0.099 mol) of bis(pinacolato)diborane and 25.66 g (2.9 molar equivalents, 0.261 mol) of potassium acetate are added to 35.0 g (1 molar equivalent, 0.090 mol) of compound 2. 2.25 g (3 mmol) of 1,1-bis(diphenylphosphino)ferrocene-palladium(II) chloride (complex with dichloromethane (1:1), Pd 13%) are subsequently added. The batch is heated at 100° C. for 3 h, then cooled to room temperature, and 400 ml of water are added. The mixture is extracted with ethyl acetate, and the combined organic phases are then dried over sodium sulfate and evaporated under reduced pressure. Purification is carried out by recrystallisation (heptane) and gives a beige solid (81.3%).

(4) b) Preparation of Compound 4:

(5) 10.97 g (1 molar equivalent, 0.017 mol) of compound 1, 33.14 g (4.4 molar equivalents, 0.076 mol) of compound 3 and 29.42 g (8.0 molar equivalents, 0.139 mol) of tripotassium phosphate are suspended in 250 ml of toluene, 125 ml of dioxane and 325 ml of water. 1.270 g (4.2 mmol) of tri-o-tolylphosphine and then 0.156 g (0.7 mmol) of palladium(II) acetate are added to this suspension, and the reaction mixture is heated under reflux for 40 h. After cooling, the organic phase is separated off. The aqueous phase is extracted with dichloromethane, and the combined organic phases are then dried over sodium sulfate, filtered and evaporated under reduced pressure. The residue is recrystallised from dimethylformamide and extracted with hot toluene. The yield is 9.4 g (6.1 mmol), corresponding to 35.1% of theory.

Example 2: Preparation of Compound 9

(6) ##STR00053##
a) Preparation of Compound 6:

(7) 20 g (32.1 mmol) of compound 5 are suspended in 10 ml of chloroform and 50 ml of glacial acetic acid with 3.4 g (19.2 mmol) of iodic acid and 4.9 g (19.2 mmol) of iodine, and the mixture is heated at 80° C. After a TLC check, the batch is cooled to room temperature and 250 ml of water are added. The mixture is extracted with methylene chloride, and the combined organic phases are then dried using sodium sulfate, filtered and evaporated under reduced pressure. Purification is carried out by washing (ethanol) and recrystallisation (toluene/ethyl acetate) and gives a colourless solid (15.3 g; 64% of theory).

(8) b) Preparation of Compound 7:

(9) The synthesis of compound 7 is carried out analogously to that of compound 3. The yield is 7.0 g (9.2 mmol), corresponding to 46% of theory.

(10) c) Preparation of Compound 9:

(11) The synthesis of compound 9 is carried out analogously to that of compound 4. The yield is 4.48 g (5.2 mmol), corresponding to 57% of theory.

Example 3: Preparation of Compound 11

(12) ##STR00054##
a) Preparation of Compound 10:

(13) The synthesis of compound 10 is carried out analogously to that of compound 1. 79.8 g (91.9% of theory) of a solid are obtained.

(14) b) Preparation of Compound 11:

(15) 10.0 g (1 molar equivalent, 21 mmol) of compound 10, 20.1 g (2.2 molar equivalents, 46 mmol) of compound 3 and 53.3 g (11.9 molar equivalents, 251 mmol) of tripotassium phosphate are suspended in 200 ml of toluene, 200 ml of dioxane and 200 ml of water. This mixture is degassed using argon for 15 min, and 458 mg (1.50 mmol) of tri-o-tolylphosphine and then 230 mg (1.03 mmol) of palladium(II) acetate are then added. The reaction mixture is heated under reflux for 16 h, during which a white precipitate deposits. After cooling, 0.60 l of water and 1 l of dichloromethane are added, and the organic phase is separated off. The organic phase is extracted three times with water. The combined organic phases are freed from solvents under reduced pressure. The residue obtained is stirred with 200 ml of hot ethanol, filtered off with suction and washed with further ethanol, leaving a virtually colourless solid. Recrystallisation from dioxane gives 1.90 g (2.04 mmol, 96.5% of theory) of a colourless solid.

Example 4: Preparation of Compound 15

(16) ##STR00055##
a) Preparation of Compound 12:

(17) The synthesis of compound 12 is carried out analogously to that of compound 3. The yield is 590 mg (1.04 mmol), corresponding to 25% of theory.

(18) b) Preparation of Compound 14:

(19) The synthesis of compound 14 is carried out analogously to that of compound 8. 6.80 g (9.39 mmol, 27% of theory) of a beige solid are obtained.

(20) c) Preparation of Compound 15:

(21) The synthesis of compound 15 is carried out analogously to that of compound 11. The yield is 8.00 g (47.0 mmol), corresponding to 66% of theory.

Example 5: Production and Characterisation of Organic Electroluminescent Devices Comprising the Compounds According to the Invention

(22) The structures of TEG (synthesised in accordance with WO 04/026886), TMM-1 (synthesised in accordance with DE 102008036982.9) and TMM-2 (synthesised in accordance with WO 09/124627), and compounds TMM-3 to 6 according to the invention are depicted below for clarity.

(23) ##STR00056## ##STR00057##

(24) Materials according to the invention can be used from solution, where they result in significantly simpler devices which nevertheless have good properties. The production of such components is based on the production of polymeric light-emitting diodes (PLEDs), which has already been described a number of times in the literature (for example in WO 04/037887). In the present case, the compounds according to the invention or likewise soluble comparative compounds (TMM-1 and TMM-2) are dissolved in toluene or chlorobenzene. The typical solids content of such solutions is between 16 and 25 g/l if, as here, the layer thickness of 80 nm which is typical for a device is to be achieved by means of spin coating. FIG. 1 shows the typical structure of a device of this type. Structured ITO substrates and the material for the so-called buffer layer (PEDOT, actually PEDOT:PSS) are commercially available (ITO from Technoprint and others, PEDOT:PSS as Clevios Baytron P aqueous dispersion from H. C. Starck). The interlayer used serves for hole injection; in this case, HIL-012 from Merck is used. The emission layer is applied by spin coating in an inert-gas atmosphere, in the present case argon, and dried by heating at 120° C. for 10 min. Finally, a cathode comprising barium and aluminium is applied by vacuum vapour deposition. A hole-blocking layer and/or an electron-transport layer can also be applied between the emitting layer and the cathode by vapour deposition, and the interlayer may also be replaced by one or more layers, which merely have to satisfy the condition that they are not detached again by the subsequent processing step of deposition of the emitting layer from solution.

(25) The devices are characterised by standard methods; the OLED examples mentioned have not yet been optimised. Table 1 summarises the data obtained. The two triplet matrix materials are present in the ratio 1:1 (based on the weight of the compounds) in each of Examples 8, 13 and 14. In the case of the processed devices, it is evident here that the materials according to the invention are superior to those previously available in terms of efficiency and/or lifetime.

(26) The structure of the organic electroluminescent device is shown in FIG. 1.

(27) TABLE-US-00001 TABLE 1 Results using solution-processed materials in the device configuration of FIG. 1 Max. Voltage Lifetime [h], eff. [V] initial EML [cd/ at 100 CIE luminance Ex. 80 nm A] cd/m.sup.2 (x, y) 1000 cd/m.sup.2 6 TMM-2:TEG 9 5.7 0.34/0.66 1200 (comp.) 7 TMM-1:TEG 14 3.8 0.35/0.68 9200 (comp.) 8 TMM-1:TMM-2: 20 3.6 0.32/0.63 12000 (comp.) TEG 9 TMM-3:TEG 22 3.7 0.33/0.63 15000 10 TMM-4:TEG 23 3.5 0.33/0.63 18000 11 TMM-5:TEG 29 3.6 0.34/0.62 22000 12 TMM-6 TEG 28 3.5 0.33/0.63 20000 13 TMM-5:TMM-2: 33 4.5 0.34/0.62 28000 TEG 14 TMM-6:TMM-2: 32 4.2 0.33/0.62 29000 TEG