Compounds for organic electroluminescent devices

Abstract

The present invention relates to crosslinkable compounds, to the crosslinked compounds obtained from these compounds, and to processes for the preparation thereof. The invention is furthermore directed to the use of these compounds in electronic devices and to the corresponding electronic devices themselves.

Claims

1. A compound of the formula (1), ##STR00062## where the following applies to the symbols and indices used: Ar.sup.1 is, identically or differently on each occurrence, a group of the following formula (2), ##STR00063## where the structure of the formula (2) can be linked at any desired positions to Ar.sup.2 and Ar.sup.3 or to N or to further groups Ar.sup.1 for n>1; Y is N if the group of the formula (2) is linked via this N to Ar.sup.2 or Ar.sup.3 or N or Ar.sup.1 for n>1 or is, identically or differently on each occurrence, NR, O, S, CRCR, CR.sub.2CR.sub.2 or a group of the following formula (3), ##STR00064## where the dashed bonds denote the linking of the group; or Y may furthermore also stand for CR.sub.2 if two adjacent groups X together stand for a group of the formula (4), (5) or (6); X is C if the group of the formula (2) is linked via this X to Ar.sup.2 or Ar.sup.3 or N or Ar.sup.1 for n>1 or is, identically or differently on each occurrence, CR or N; or two adjacent groups X together stand for a group of the following formula (4), (5) or (6), ##STR00065## where the dashed bonds denote the linking of the group; Z is C if the group of the formula (4) or formula (5) or formula (6) is linked via this X to Ar.sup.2 or Ar.sup.3 or N or Ar.sup.1 for n>1 or is on each occurrence, identically or differently, CR or N; Y.sup.1 is on each occurrence, identically or differently, CR.sub.2, NR, O or S; Ar.sup.2, Ar.sup.3 is on each occurrence, identically or differently, an aryl or heteroaryl group having 5 to 18 aromatic ring atoms, which may be substituted by one or more radicals R; Ar.sup.4 to Ar.sup.7 are selected, identically or differently on each occurrence, from the group consisting of phenyl, ortho-, meta- or para-biphenyl, ortho-, meta- or para-terphenyl, linear or branched quaterphenyl, fluorenyl, spirobifluorenyl and carbazolyl, each of which may be substituted by one or more radicals R; R is on each occurrence, identically or differently, H, D, F, Cl, Br, I, N(R.sup.1).sub.2, CN, NO.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, alkoxy or thioalkoxy group having 1 to 40 C atoms or an alkenyl or alkynyl group having 2 to 40 C atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 40 C atoms, each of which may be substituted by one or more radicals R.sup.1, where one or more non-adjacent CH.sub.2 groups may be replaced by R.sup.1CCR.sup.1, CC, Si(R.sup.1).sub.2, CO, CS, CNR.sup.1, P(O)(R.sup.1), SO, SO.sub.2, NR.sup.1, O, S or CONR.sup.1 and where one or more H atoms may be replaced by D, F, Cl, Br, I or CN, 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.1, or an aryloxy or heteroaryloxy group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R.sup.1, or an aralkyl or heteroaralkyl group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R.sup.1, or a diarylamino group, diheteroarylamino group or arylheteroarylamino group having 10 to 40 aromatic ring atoms, which may be substituted by one or more radicals R.sup.1; two or more radicals R here may also form a mono- or polycyclic, aliphatic, aromatic and/or benzo-fused ring system with one another; R.sup.1 is on each occurrence, identically or differently, H, D, F or an aliphatic, aromatic and/or heteroaromatic hydrocarbon radical having 1 to 20 C atoms, in which, in addition, one or more H atoms may be replaced by F; two or more substituents R.sup.1 here may also form a mono- or polycyclic, aliphatic or aromatic ring system with one another; n is 1, 2, 3 or 4; m is 1, 2 or 3; q, r is, identically or differently on each occurrence, 0, 1, 2 or 3; wherein at least two of the groups Ar.sup.4 to Ar.sup.7 are each substituted by a group of the following formula (7):
-L-(Ar.sup.8).sub.p-Qformula (7) in which: L is, identically or differently on each occurrence, a spacer group or a direct bond; Ar.sup.8 is, identically or differently on each occurrence, an aromatic or heteroaromatic ring system having 5 to 24 aromatic ring atoms, which may be substituted by one or more radicals R; Q is, identically or differently on each occurrence, a crosslinkable group; p is, identically or differently on each occurrence, 0 or 1.

2. The compound according to claim 1, wherein the group Ar.sup.1 is selected, identically or differently on each occurrence, from the groups of the formulae (8) to (27), ##STR00066## ##STR00067## ##STR00068## ##STR00069## where Y, Y.sup.1 and R have the meanings given in claim 1, and no radical R is present at the positions at which the structure is bonded to Ar.sup.2 or Ar.sup.3 or to the nitrogen or to a further group Ar.sup.1 for n>1; the groups can each be bonded via any desired positions.

3. The compound according to claim 1, wherein the group Ar.sup.1 is selected, identically or differently on each occurrence, from the structures of the formulae (8a) to (27b), ##STR00070## ##STR00071## ##STR00072## ##STR00073## ##STR00074## ##STR00075## ##STR00076## ##STR00077## where Y, Y.sup.1 and R have the meanings given in claim 1, and the dashed bond indicates the position at which the structure is bonded to Ar.sup.2 or Ar.sup.3 or to the nitrogen or to Ar.sup.1 for n>1.

4. The Compound according to claim 1, wherein Ar.sup.2 and Ar.sup.3 is selected, identically or differently on each occurrence, from 1,2-phenylene, 1,3-phenylene or 1,4-phenylene, each of which may be unsubstituted or substituted by one or more radicals R.

5. The compound according to claim 1, wherein the compound contains between 2 and 8 groups of the formula (7).

6. The compound according to claim 1, wherein L is a single bond or L is a linear or branched alkylene group having 1 to 20 C atoms, in which one or more non-adjacent CH.sub.2 groups may be replaced by O, S, NH, N(CH.sub.3), NCO, NCOO, NCON, CO, OCO, SCO, OCOO, COS, COO, CH(halogen)-, CH(CN), CHCH or CC, or a cyclic alkyl group.

7. The compound according to claim 1, wherein Ar.sup.8 is selected from 1,2-phenylene, 1,3-phenylene or 1,4-phenylene, each of which may be unsubstituted or substituted by one or more radicals R.

8. The compound according to claim 1, wherein the group Q is selected from terminal or cyclic alkenyl groups, terminal alkynyl groups, arylvinyl groups, acrylic acid derivatives, alkenyloxy or perfluoroalkenyloxy derivatives, groups which undergo a ring-opening polymerisation, in particular oxetane and oxirane derivatives, or silanes.

9. A compound or layer obtained by crosslinking the groups Q of the compound according to claim 1, where the crosslinking is optionally carried out in a layer.

10. A process for the production of a crosslinked layer, comprising applying the compound according to claim 1 from solution to form a layer, and crosslinking the layer.

11. A method comprising utilizing the compound according to claim 1 in an electronic device.

12. A method comprising utilizing the compound or layer according to claim 9 in an electronic device.

13. An electronic device comprising one or more compounds according to claim 1 in an electronic device.

14. An electronic device comprising the compound or layer according to claim 9 in an electronic device.

15. The electronic device according to claim 14, wherein the device is an organic electroluminescent device, comprising the following structure: anode/optionally layer comprising a conductive polymer/one or more layers according to claim 9/emission layer and cathode.

16. The electronic device according to claim 13, wherein on or more compounds according to claim 1 are used in a hole-transport layer or in a hole-injection layer, where this layer may also be doped.

17. The electronic device according to claim 13, wherein the compounds according to claim 9 are used in a hole-transport layer or in a hole-injection layer, where this layer may also be doped.

18. A formulation comprising at least one compound according to claim 1 and one or more solvents.

Description

EXAMPLES

(1) The following syntheses are carried out, unless indicated otherwise, under a protective-gas atmosphere in dried solvents. The solvents and reagents can be purchased, for example, from Sigma-ALDRICH or ABCR. The figures in square brackets for literature-known chemical compounds relate to the CAS number.

Example 1

Synthesis of Compound 3

(2) ##STR00051##
a) Synthesis of Compound 2

(3) 100 g (136 mmol; 1.0 eq.) of compound 1 [57102-64-4], 135 g (0.53 mol; 3.9 eq.) of bis(pinacolato)diborane and 160 g (1.63 mol; 12 eq.) of potassium acetate are suspended in 1.11 of degassed dioxane in a flask which has been dried by heating. The suspension is degassed for 30 minutes, and 4.40 g (5.44 mmol; 0.04 eq.) of PdCl.sub.2(dppf).CH.sub.2Cl.sub.2 as catalyst are then added. The reaction mixture is heated under reflux for 72 hours. The brown precipitate is filtered and washed with 11 of water. Dichloromethane is added to the solid obtained, and the mixture is extracted with water. The organic phases are combined, dried over Na.sub.2SO.sub.4, filtered, and the solvents are removed in vacuo, giving 68.0 mmol (50%, HPLC purity 95%) of a brown solid. Compound 2 obtained is recrystallised twice from o-xylene and then extracted with hot o-xylene over aluminium oxide, giving a pale-beige solid, which is recrystallised from DMF. The product is subsequently recrystallised a number of times from anisole until an HPLC purity of 99.2% is achieved. The yield is 22.9 g (31.2 mmol), corresponding to 22.9% of theory.

(4) b) Synthesis of Compound 3

(5) 22.9 g (31.2 mmol; 1.0 eq.) of compound 2, 22.1 g (78.1 mmol; 2.5 eq.) of 1-bromo-4-iodobenzene and 10.6 g of sodium carbonate (99.9 mmol; 3.2 eq.) are suspended in a mixture of degassed water/toluene/dioxane (185/160/90 ml). The suspension is degassed for 30 minutes, and 721 mg (0.625 mmol; 0.02 eq.) of Pd(PPh.sub.3).sub.4 are then added. The reaction mixture is subsequently heated under reflux for 27 hours and filtered when the reaction is complete. The white-beige solid is washed with each of water, toluene and finally with heptane, and the residue is dried at 85 C. in a vacuum drying cabinet. The crude product obtained (24.5 mmol) is recrystallised from DMF and subsequently from chlorobenzene until an HPLC purity of 99% has been achieved. The yield is 7.95 g (10 mmol), corresponding to 32% of theory.

Example 2

Synthesis of Compound 8

(6) ##STR00052##
a) Synthesis of Compound 5

(7) 5.00 g (33.0 mmol; 1.0 eq.) of 4-formylphenylboronic acid (compound 4) are suspended in 30 ml of toluene. 1.9 ml of ethylene glycol (33.0 mmol; 1.0 eq.) are then added. The reaction mixture is stirred under reflux for 2.5 hours, and the water obtained is removed continuously using a water separator. The reaction mixture is cooled to room temperature, and the solvents are removed in vacuo. The yield is 5.86 g (33.0 mmol), corresponding to 100% of theory.

(8) b) Synthesis of Compound 6

(9) 5.86 g (33.0 mmol; 1.0 eq.) of compound 5 are suspended in 150 ml of toluene with 10.0 g of aluminium oxide (acidic). 11.3 ml of ethylene glycol (200 mmol; 6.0 eq.) are then added. The reaction mixture is stirred under reflux for 24 hours. When the reaction is complete, the batch is filtered, and the aluminium oxide is washed with dichloromethane. The organic phases are combined, and the solvents are removed in vacuo. The yield is 7.00 g (32.0 mmol), corresponding to 97% of theory.

(10) c) Synthesis of Compound 7

(11) 14.5 g of 2-(4-1,3-dioxolan-2-ylphenyl)-1,3,2-dioxaborolane (compound 6) (66.0 mmol; 1.0 eq.), 18.7 g of 1-bromo-4-iodobenzene (66.0 mmol; 1.0 eq.) and 18.2 g of sodium carbonate (132 mmol; 2.0 eq.) are suspended in a mixture of degassed water/toluene (85/220 ml). The suspension is degassed for 30 minutes, and 763 mg (0.66 mmol; 0.01 eq.) of Pd(PPh.sub.3).sub.4 are subsequently added. The reaction mixture is stirred under reflux for 24 hours and, when the reaction is complete, washed with 75 ml of a hydrogencarbonate solution (0.6 M; pH=8.2). The organic phase is dried over Na.sub.2SO.sub.4, filtered, and the solvents are removed in vacuo. The yellow solid obtained is stirred in 25 ml of heptane at 60 C. for 3 hours. The suspension is subsequently filtered, the solid is dissolved in dichloromethane and filtered through Celite. After removal of the solvent in vacuo, the yield is 13.3 g (43.6 mmol), corresponding to 66% of theory.

(12) d) Synthesis of Compound 8

(13) 3.80 g of 2-(4-bromobiphenyl-4-yl)-1,3-dioxolane (compound 7) (12.0 mmol; 1.0 eq.), 2.60 g of 9,9-dimethyl-9H-fluoren-2-ylamine (12.0 mmol; 1.0 eq.) and 1.80 g of sodium tert-butoxide (19.0 mmol; 1.5 eq.) are suspended in 30 ml of degassed toluene and degassed for 30 minutes. 28.0 mg (0.031 mmol; 0.026 eq.) of Pd(dba).sub.3 and 39.0 mg (0.062 mmol; 0.052 eq.) of BINAP are initially introduced in 10 ml of degassed toluene in a 20 ml beaded-rim vial. The catalyst solution is degassed for 15 minutes and added to the reaction mixture. The batch is heated under reflux for 5 hours. When the reaction is complete, 50 ml of toluene are added, and the reaction mixture is washed with water. The organic phase is dried over Na.sub.2SO.sub.4, filtered, and the solvents are removed in vacuo. The orange-brown solid is recrystallised from heptane/toluene (4:3). The yield is 2.90 g (6.70 mmol) of a yellow solid, corresponding to 54% of theory.

Example 3

Synthesis of Compound 9

(14) ##STR00053##

(15) 7.00 g of compound 3 (8.81 mmol; 1 eq), 8.40 g (19.4 mmol; 2.2 eq.) of compound 8 and 2.54 g of sodium tert-butoxide (26.4 mmol; 3 eq.) are suspended in 200 ml of degassed toluene and degassed for 20 minutes. 0.264 ml of tri-tert-butylphosphine 1M in toluene (0.264 mmol; 0.03 eq.) and 19.8 mg of Pd(OAc).sub.2 (0.088 mmol; 0.001 eq.) in 2 ml of degassed toluene are subsequently added to the reaction mixture. The batch is heated at 110 C. for 30 hours, and, when the reaction is complete, 200 ml of ethyl acetate and 120 ml of saturated NaHCO.sub.3 solution are added. The aqueous phase is extracted with 3200 ml of ethyl acetate. The organic phase is dried over Na.sub.2SO.sub.4, filtered, and the solvents are removed in vacuo. The solid is stirred in warm toluene, cooled and filtered. The yield is 7.13 g (4.75 mmol) of a yellow solid, corresponding to 54% of theory.

Example 4

Synthesis of Compound 10

(16) ##STR00054##

(17) 6.50 g of compound 9 (4.30 mmol; 1 eq), dissolved in 200 ml of chloroform, and 100 ml of a 7% aqueous HCl solution are heated at 75 C. for 1 hour. When the reaction is complete, the organic phase is washed with 3200 ml of water, dried over Na.sub.2SO.sub.4 and filtered. The solvents are removed in vacuo, and the yellow residue is recrystallised in a mixture of chloroform/heptane and then tetrahydrofuran/acetonitrile. The yield is 1.95 g (1.38 mmol) of a yellow solid, corresponding to 32% of theory.

Example 5

Synthesis of Compound 11 According to the Invention

(18) ##STR00055##

(19) 0.91 g (2.6 mmol; 4 eq.) of methyltriphenylphosphonium bromide are suspended in 15 ml of dried THF at 0 C. under argon. 0.29 g (2.6 mmol; 4 eq.) of potassium tert-butoxide is added in portions to the reaction mixture, which is then stirred with ice-cooling for 40 minutes. 1.0 g (0.7 mmol; 1.0 eq.) of compound 10 are dissolved in 50 ml of THF and added. The ice bath is removed after 30 minutes, and the reaction mixture is stirred at room temperature for 6 days. 60 ml of water and 120 ml of ethyl acetate are added, the organic phase is washed with 250 ml of water, dried over Na.sub.2SO.sub.4 and evaporated in a rotary evaporator. The residue is washed with 220 ml of methanol, filtered, recrystallised from chloroform/methanol and chromatographed on silica gel with dichloromethane/heptane (1/3). The yield is 0.43 g (0.3 mmol) of a pale-yellow solid, corresponding to 43% of theory.

Example 6

Synthesis of Compound 13

(20) ##STR00056##

(21) 2.00 g (3.5 mmol; 1 eq.) of compound 12 [790674-48-5], 3.35 g (7.7 mmol; 2.2 eq.) of compound 8 and 1.01 g of sodium tert-butoxide (10.5 mmol; 3 eq.) are dissolved in 30 ml of degassed toluene and degassed for 20 minutes. 0.105 ml of tri-tert-butylphosphine 1M in toluene (0.105 mmol; 0.03 eq.) and 7.8 mg of Pd(OAc).sub.2 (0.035 mmol; 0.001 eq.) in 5 ml of degassed toluene are subsequently added to the reaction mixture. The batch is heated at 110 C. for 2.5 hours. When the reaction is complete, 200 ml of ethyl acetate are added, and the reaction mixture is filtered through Celite. The organic phase is washed with 260 ml of saturated NaHCO.sub.3 solution, dried over Na.sub.2SO.sub.4, filtered, and the solvents are removed in vacuo. The solid is stirred in warm heptane/toluene, cooled and filtered. The yield is 3.40 g (2.88 mmol) of a yellow solid, corresponding to 82% of theory.

Example 7

Synthesis of Compound 14

(22) ##STR00057##

(23) 3.50 g of compound 13 (2.97 mmol; 1 eq), dissolved in 40 ml of chloroform, and 10 ml of a 3.5% aqueous HCl solution are heated at 75 C. overnight. When the reaction is complete, the organic phase is washed with 30 ml of saturated solution NaHCO.sub.3 and 2200 ml of water, dried over Na.sub.2SO.sub.4 and filtered. The solvents are removed in vacuo, and the yellow residue is recrystallised from toluene/heptane and from chloroform/heptane. The yield is 2.9 g (2.66 mmol) of a yellow solid, corresponding to 90% of theory.

Example 8

Synthesis of Compound 15 According to the Invention

(24) ##STR00058##

(25) 3.00 g (9.2 mmol; 4 eq.) of methyltriphenylphosphonium bromide are suspended in 100 ml of dried THF at 0 C. under argon. 1.03 g (9.2 mmol; 4 eq.) of potassium tert-butoxide are added in portions to the reaction mixture, which is then stirred with ice-cooling for 30 minutes. 2.5 g (2.3 mmol; 1.0 eq.) of compound 14 is dissolved in 100 ml of THF and added. The ice bath is removed after 30 minutes, and the reaction mixture is stirred at room temperature for 1 hour. 120 ml of water and 200 ml of DCM are added, the organic phase is washed with 250 ml of water, dried over Na.sub.2SO.sub.4 and evaporated in a rotary evaporator. The residue is washed with 220 ml of methanol, filtered and recrystallised from chloroform/methanol and DMF/methanol. The yield is 1.75 g (1.6 mmol) of a pale-yellow solid, corresponding to 70% of theory.

Example 9

Electroluminescent Devices

(26) The production of an organic light-emitting diode (OLED) processed from solution has already been described many times in the literature (for example in WO 2004/037887). In order to explain the present invention by way of example, OLEDs are produced by spin coating with material 1 and comparative material 1.

(27) A typical OLED has the structure shown below, where material 1 according to the invention fulfils the function of a hole-transport layer (HTL).

(28) TABLE-US-00001 3 nm/100 nm Cathode Ba/Al 80 nm EML EML 20 nm HTL Material 1 or comparison 1 80 nm Buffer PEDOT:PSS Anode ITO

(29) A glass coated with indium tin oxide (ITO) represents the substrate. This is cleaned with deionised water and a detergent in a clean room and then activated by a UV/ozone plasma treatment. A layer of PEDOT:PSS (Baytron P VAI 4083sp from H.C. Starck (now Heraeus Clevios) which is supplied as an aqueous dispersion) with a thickness of 80 nm is then applied by spin coating, likewise in the clean room. The spin rate required depends on the degree of dilution and the specific spin-coater geometry (typically for 80 nm: 4500 rpm). In order to remove residual water from the layer, the substrates are dried by heating on a hot plate at 180 C. for 10 minutes. Then, in inert-gas atmosphere (nitrogen or argon), firstly 20 nm of the HTL layer are applied. The application is carried out by spin coating from a toluene solution. This layer is subsequently heated at 180 C. for 1 hour in order to activate the crosslinking process. 80 nm of the emission layer EML are then subsequently applied by means of spin coating, likewise from a toluene solution. This layer is dried by heating at 180 C. for 10 minutes.

(30) Material 1:

(31) ##STR00059##
Comparison 1 (in Accordance with WO 2010/097155):

(32) ##STR00060##
n=0.9, m=0.1
Degree of polymerisation: 250

(33) The materials used for the emission layer (EML) is a mixture of two matrix materials (M1 and M2) and a phosphorescent green emitter (E1) in a mixing ratio (based on the weight) of M1:M2:E1=2:2:1.

(34) ##STR00061##

(35) A Ba/Al cathode is subsequently applied by vapour deposition through a shadow mask (high-purity metals from Aldrich, particularly barium 99.99%); vapour-deposition units from Lesker or others, typical vacuum level 510.sup.6 mbar; layer thickness Ba/Al 3 nm/100 nm). In order to protect the cathode against air and atmospheric moisture, the OLEDs are finally encapsulated and then characterised.

(36) The current/voltage/luminous density (IVL) characteristic line of the OLEDs is obtained by increasing the applied voltage in steps (typically from 0 to max. 10 V in 0.2 V steps) and for each measurement point measuring the current through the devices and the resultant photocurrent of a calibrated photodiode which is located directly above the OLED. Important parameters are the measured current efficiency [luminous density/current density [cd/A]] and voltage, in each case at a luminous density of 1000 cd/m.sup.2. For measurement of the electroluminescence spectrum and the colour of the OLEDs, the emitted light is conducted into a spectrometer (Ocean Optics) via an optical fibre. The colour coordinates (CIE: Commission International de l'clairage, 1931 standard observer) can be calculated from the measured spectrum. A further important parameter is the lifetime (LT). LT50 denotes the time by which the initial luminous density (here 1000 cd/m.sup.2) has dropped to half on operation at constant current density.

(37) The results on use of the material according to the invention and the comparative material are summarised in Table 1.

(38) TABLE-US-00002 TABLE 1 Current efficiency [cd/A] @ U [V] @ LT50 [h] @ 1000 cd/m.sup.2 1000 cd/m.sup.2 CIE [x/y] 1000 cd/m.sup.2 Comparison 1 30 5.6 0.34/0.62 41000 Material 1 38 5.1 0.34/0.62 53000

(39) As can be seen from the results in Table 1, material 1 according to the invention exhibits an advantage with respect to operating voltage, current efficiency and lifetime compared with the comparative material.