MIXTURE OF TWO HOST MATERIALS, AND ORGANIC ELECTROLUMINESCENT DEVICE COMPRISING SAME

Abstract

The present invention relates to an organic electroluminescent device containing a mixture which comprises an electron-transporting host material and a hole-transporting host material, to a formulation comprising a mixture of the host materials and to a mixture comprising the host materials. The electron-transporting host material corresponds to a compound of the formula (1) from the class of compounds containing two triazine units. The hole-transporting host material corresponds to a compound of the formula (2) from the class of the biscarbazoles or derivatives thereof.

Claims

1.-15. (canceled)

16. An organic electroluminescent device comprising an anode, a cathode and at least one organic layer, comprising at least one light-emitting layer, where the at least one light-emitting layer comprises at least one compound of the formula (1) as host material 1 and at least one compound of the formula (2) as host material 2, ##STR00594## where the following applies to the symbols and indices used: Y is selected from O, S, C(CH.sub.3).sub.2, C(phenyl).sub.2 or ##STR00595##  where * marks the C atom that is bonded to the remainder of the formula (1); L is selected from one of the divalent linkers L-1 to L-26, ##STR00596## ##STR00597## ##STR00598## ##STR00599##  where the linkers L-1 to L-26 may also be substituted by one or more substituents R; W is O, S or C(CH.sub.3).sub.2; a is 0 or 1; b is 0 or 1; R is selected on each occurrence, identically or differently, from the group consisting of CN, a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 20 C atoms or a branched or cyclic alkyl, alkoxy or thioalkyl group having 3 to 20 C atoms, an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, an aryloxy or heteroaryloxy group having 5 to 40 aromatic ring atoms, or an aralkyl or heteroaralkyl group having 5 to 40 aromatic ring atoms; Ar1 is on each occurrence, in each case independently of one another, an aryl or heteroaryl group having 5 to 40 aromatic ring atoms, which may be substituted by one or more radicals R; K, M are in each case, independently of one another, an aromatic ring system having 6 to 40 aromatic ring atoms which is unsubstituted or partially or fully deuterated or monosubstituted by R*, if x and y denote 0 and if x.sub.1 and y.sub.1 denote 0, or K, M in each case, independently of one another, together with X or X.sup.1, form a heteroaromatic ring system having 14 to 40 ring atoms as soon as the value of x, x1, y and/or y1 denotes 1; x, x1 are in each case, independently on each occurrence, 0 or 1; y, y1 are in each case, independently on each occurrence, 0 or 1; X and X.sup.1 are in each case, independently of one another on each occurrence, a bond or C(R#).sub.2; R.sup.0 is on each occurrence, independently of one another, an unsubstituted or partially or fully deuterated aromatic ring system having 6 to 18 C atoms; R* is dibenzofuranyl or dibenzothiophenyl; R# is on each occurrence, independently of one another, a straight-chain or branched alkyl group having 1 to 4 C atoms and c, d, e and f are, independently of one another, 0 or 1.

17. The organic electroluminescent device according to claim 16, wherein Y in host material 1 denotes O.

18. The organic electroluminescent device according to claim 16, wherein host material 2 conforms to one of the formulae (2a), (2b) or (2c), ##STR00600## where the symbols and indices X, X.sup.1, R.sup.0, c, d, e and f used have a meaning as in claim 16 and K and M in compounds of the formula (2a) in each case, independently of one another, denote an aromatic ring system having 6 to 40 aromatic ring atoms which is unsubstituted or partially or fully deuterated or monosubstituted by R*; M in compounds of the formula (2b) denotes an aromatic ring system having 6 to 40 aromatic ring atoms which is unsubstituted or partially or fully deuterated or monosubstituted by R*; K in compounds of the formula (2b), together with X, forms a heteroaromatic ring system having 14 to 40 ring atoms and x and y in compounds of the formula (2b) in each case, independently of one another, denote 0 or 1 and the sum of x and y denotes at least 1; and K and M in compounds of the formula (2c) in each case, independently of one another, together with X or X.sup.1, form a heteroaromatic ring system having 14 to 40 ring atoms and x, x1, y and y1 in compounds of the formula (2c) in each case, independently of one another, denote 0 or 1 and the sum of x and y denotes at least 1 and the sum of x1 and yl denotes at least 1.

19. The organic electroluminescent device according to claim 16, wherein L in host material 1 is selected from the divalent linkers L-1 to L-13 and L-24 to L-26.

20. The organic electroluminescent device according to claim 16, wherein the device is an electroluminescent device selected from organic light-emitting transistors (OLETs), organic field-quench devices (OFQDs), organic light-emitting electrochemical cells (OLECs, LECs, LEECs), organic laser diodes (O-lasers) and organic light-emitting diodes (OLEDs).

21. The organic electroluminescent device according to claim 16, wherein, besides the light-emitting layer (EML), the device comprises a hole-injection layer (HIL), a hole-transport layer (HTL), an electron-transport layer (ETL), an electron-injection layer (EIL) and/or a hole-blocking layer (HBL).

22. The organic electroluminescent device according to claim 16, wherein the light-emitting layer, besides the at least one host material 1 and the at least one host material 2, comprises at least one phosphorescent emitter.

23. The organic electroluminescent device according to claim 22, wherein the phosphorescent emitter conforms to the formula (3), ##STR00601## where the symbols and indices for this formula (3) have the meaning: n+m is 3, n is 1 or 2, m is 2 or 1, X is N or CR, R is H, D or a branched or linear alkyl group having 1 to 10 C atoms or a partially or fully deuterated branched or linear alkyl group having 1 to 10 C atoms or a cycloalkyl group having 4 to 7 C atoms, which may be partially or fully substituted by deuterium.

24. A process for the production of a device according to claim 16, wherein the light-emitting layer is applied by gas-phase deposition or from solution.

25. The process according to claim 24, wherein the at least one compound of the formula (1) and the at least one compound of the formula (2) are deposited from the gas phase, successively or simultaneously from at least two material sources, optionally with the at least one phosphorescent emitter, and form the light-emitting layer.

26. The process according to claim 24, wherein the at least one compound of the formula (1) and the at least one compound of the formula (2) are deposited from the gas phase as a mixture, successively or simultaneously with the at least one phosphorescent emitter, and form the light-emitting layer.

27. The process according to claim 24, wherein the at least one compound of the formula (1) and the at least one compound of the formula (2) are applied from a solution together with the at least one phosphorescent emitter in order to form the light-emitting layer.

28. A mixture comprising at least one compound of the formula (1) and at least one compound of the formula (2), ##STR00602## where the following applies to the symbols and indices used: Y is selected from O, S, C(CH.sub.3).sub.2, C(phenyl).sub.2 or ##STR00603##  where * marks the C atom that is bonded to the remainder of the formula (1); L is selected from one of the divalent linkers L-1 to L-26, ##STR00604## ##STR00605## ##STR00606##  where the linkers L-1 to L-26 may also be substituted by one or more substituents R; W is O, S or C(CH.sub.3).sub.2; a is 0 or 1; b is 0 or 1; R is selected on each occurrence, identically or differently, from the group consisting of CN, a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 20 C atoms or a branched or cyclic alkyl, alkoxy or thioalkyl group having 3 to 20 C atoms, an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, an aryloxy or heteroaryloxy group having 5 to 40 aromatic ring atoms, or an aralkyl or heteroaralkyl group having 5 to 40 aromatic ring atoms; Ar.sub.1 is on each occurrence, in each case independently of one another, an aryl or heteroaryl group having 5 to 40 aromatic ring atoms, which may be substituted by one or more radicals R; K, M are in each case, independently of one another, an aromatic ring system having 6 to 40 aromatic ring atoms which is unsubstituted or partially or fully deuterated or monosubstituted by R*, if x and y denote 0 and if x.sub.1 and y1 denote 0, or K, M in each case, independently of one another, together with X or X.sup.1, form a heteroaromatic ring system having 14 to 40 ring atoms as soon as the value of x, x1, y and/or y1 denotes 1; x, x1 are in each case, independently on each occurrence, 0 or 1; y, y1 are in each case, independently on each occurrence, 0 or 1; X and X.sup.1 are in each case, independently of one another on each occurrence, a bond or C(R#).sub.2; R.sup.0 is on each occurrence, independently of one another, an unsubstituted or partially or fully deuterated aromatic ring system having 6 to 18 C atoms; R* is dibenzofuranyl or dibenzothiophenyl; R# is on each occurrence, independently of one another, a straight-chain or branched alkyl group having 1 to 4 C atoms; and c, d, e and f are, independently of one another, 0 or 1.

29. The mixture according to claim 28, wherein the mixture consists of at least one compound of the formula (1), at least one compound of the formula (2) and a phosphorescent emitter.

30. A formulation comprising the mixture according to claim 28 and at least one solvent.

Description

EXAMPLE 1: PRODUCTION OF THE OLEDS

[0223] The use of the material combinations according to the invention in OLEDs compared with material combinations from the prior art is presented in Examples V1 to Ex28 below (see Tables 6 and 7).

[0224] Pretreatment for Examples V1 to Ex28: Glass plates coated with structured ITO (indium tin oxide) in a thickness of 50 nm are, before coating, treated firstly with an oxygen plasma, followed by an argon plasma. These plasma-treated glass plates form the substrates to which the OLEDs are applied.

[0225] The OLEDs have basically the following layer structure: substrate/hole-injection layer (HIL)/hole-transport layer (HTL)/electron-blocking layer (EBL)/emission layer (EML)/optional hole-blocking layer (HBL)/electron-transport layer (ETL)/optional electron-injection layer (EIL) and finally a cathode. The cathode is formed by an aluminium layer with a thickness of 100 nm. The precise structure of the OLEDs is shown in Table 6. The materials required for the production of the OLEDs are shown in Table 8. The device data of the OLEDs are listed in Table 7.

[0226] Examples V1, V2 und V3 are comparative examples with a hole-transporting host in accordance with the prior art WO2017/178311. Examples Ex1, Ex2 and Ex3 use corresponding material combinations according to the invention in the EML.

[0227] Examples V4 and V5 are comparative examples for the OLED according to the invention of Example Ex4 and Examples V6 and V7 are comparative examples for the OLED according to the invention of Example Ex5 with symmetrically substituted electron-transporting host materials in accordance with the prior art. Compound VG1 is derived, for example, from US2016329502. Compound VG2 is described, for example, in US20140299192.

[0228] Examples Ex6 to Ex28 likewise show data of OLEDs according to the invention.

[0229] All materials are applied by thermal vapour deposition in a vacuum chamber. The emission layer here always consists of at least one matrix material (also host material), in the sense of the invention at least two matrix materials, and an emitting dopant (emitter), which is admixed with the matrix material or matrix materials in a certain proportion by volume by co-evaporation. An expression such as E1:IC3:TEG1 (33%:60%:7%) here means that material E1 is present in the layer in a proportion by volume of 33% as host material 1, compound IC3 as host material 2 is present in a proportion of 60% and TEG1 is present in a proportion of 7% in a layer with a thickness of 30 nm. Analogously, the electron-transport layer may also consist of a mixture of two materials.

[0230] The OLEDs are characterised by standard methods. For this purpose, the electroluminescence spectra and current/voltage/luminous density characteristic lines (IUL characteristic lines) are measured. EQE and the current efficiency CE (in cd/A) are calculated therefrom. The calculation of the CE is carried out assuming Lambert emission characteristics.

[0231] The lifetime LT is defined as the time after which the luminous density on operation with constant current density j0 in mA/cm.sup.2 drops from an initial luminous density L0 (in cd/m.sup.2) to a certain proportion L1 (in cd/m.sup.2). An expression L1/L0=80% in Table 7 means that the lifetime indicated in column LT corresponds to the time (in h) after which the luminous density drops to 80% of its initial value (L0).

Use of Mixtures According to the Invention in OLEDs

[0232] The material combinations according to the invention can be employed in the emission layer in phosphorescent green OLEDs. The combinations according to the invention of compounds E1 to E16 compounds BC1 to BC17 are employed in Examples Ex1 and Ex28 as matrix material in the emission layer, as described in Table 6.

[0233] On comparison of the examples according to the invention with the corresponding comparative examples (see above), it is clearly evident that the examples according to the invention in each case exhibit a clear advantage in the device lifetime.

TABLE-US-00006 TABLE 6 Structure of the OLEDs HTL IL EBL HBL EIL Thick- Thick- Thick- EML Thick- ETL Thick- Ex. ness ness ness Thickness ness Thickness ness V1 HTCN SpMA1 SpMA2 E1:IC3:TEG1 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (33%:60%:7%) 30 nm 10 nm (50%:50%) 30 nm 1 nm Ex1 HTCN SpMA1 SpMA2 E1:BC1:TEG1 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (33%:60%:7%) 30 nm 10 nm (50%:50%) 30 nm 1 nm V2 HTCN SpMA1 SpMA2 E1:IC3:TEG2 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (28%:60%:12%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex2 HTCN SpMA1 SpMA2 E1:BC1:TEG2 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (28%:60%:12%) 40 nm 5 nm (50%:50%) 30 nm 1 nm V3 HTCN SpMA1 SpMA2 E1:IC3:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (33%:60%:7%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex3 HTCN SpMA1 SpMA2 E1:BC1:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (33%:60%:7%) 40 nm 5 nm (50%:50%) 30 nm 1 nm V4 HTCN SpMA1 SpMA2 VG1:BC2:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (38%:50%:12%) 40 nm 5 nm (50%:50%) 30 nm 1 nm V5 HTCN SpMA1 SpMA2 VG2:BC2:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (38%:50%:12%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex4 HTCN SpMA1 SpMA2 E1:BC2:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (38%:50%:12%) 40 nm 5 nm (50%:50%) 30 nm 1 nm V6 HTCN SpMA1 SpMA2 VG1:BC3:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (38%:50%:12%) 40 nm 5 nm (50%:50%) 30 nm 1 nm V7 HTCN SpMA1 SpMA2 VG2:BC3:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (38%:50%:12%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex5 HTCN SpMA1 SpMA2 E1:BC3:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (38%:50%:12%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex6 HTCN SpMA1 SpMA2 E1:BC4:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (33%:60%:7%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex7 HTCN SpMA1 SpMA2 E2:BC3:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (33%:60%:7%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex8 HTCN SpMA1 SpMA2 E2:BC4:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (33%:60%:7%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex9 HTCN SpMA1 SpMA2 E3:BC5:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (33%:60%:7%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex10 HTCN SpMA1 SpMA2 E3:BC7:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (33%:60%:7%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex11 HTCN SpMA1 SpMA2 E4:BC6:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (33%:60%:7%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex12 HTCN SpMA1 SpMA2 E4:BC8:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (33%:60%:7%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex13 HTCN SpMA1 SpMA2 E5:BC1:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (33%:60%:7%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex14 HTCN SpMA1 SpMA2 E5:BC9:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (33%:60%:7%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex15 HTCN SpMA1 SpMA2 E6:BC3:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (33%:60%:7%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex16 HTCN SpMA1 SpMA2 E6:BC10:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (33%:60%:7%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex17 HTCN SpMA1 SpMA2 E7:BC10:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (33%:60%:7%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex18 HTCN SpMA1 SpMA2 E8:BC13:TEG2 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (28%:60%:12%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex19 HTCN SpMA1 SpMA2 E9:BC5:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (33%:60%:7%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex20 HTCN SpMA1 SpMA2 E10:BC5:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (33%:60%:7%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex21 HTCN SpMA1 SpMA2 E11:BC6:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (38%:50%:12%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex22 HTCN SpMA1 SpMA2 E12:BC12:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (38%:50%:12%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex23 HTCN SpMA1 SpMA2 E13:BC5:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (38%:50%:12%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex24 HTCN SpMA1 SpMA2 E14:BC11:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (33%:60%:7%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex25 HTCN SpMA1 SpMA2 E15:BC14:TEG2 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (28%:60%:12%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex26 HTCN SpMA1 SpMA2 E16:BC15:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (33%:60%:7%) 40 nm 5 nm (50%:50%) 30 nm 1 nm Ex27 HTCN SpMA1 SpMA2 E9:BC16:TEG3 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (33%:60%:7%) 40 nm 5 nm (50%:50%) 30 nm 1 nm E2x8 HTCN SpMA1 SpMA2 E2:BC17:TEG2 ST2 ST2:LiQ LiQ 5 nm 230 nm 20 nm (28%:60%:12%) 40 nm 5 nm (50%:50%) 30 nm 1 nm

TABLE-US-00007 TABLE 7 Data of the OLEDs j0 L1/L0 LT Ex. (mA/cm.sup.2) (%) (h) V1 40 80 270 Ex1 40 80 350 V2 40 80 980 Ex2 40 80 1250 V3 40 80 460 Ex3 40 80 620 V4 40 80 480 V5 40 80 560 Ex4 40 80 820 V6 40 80 530 V7 40 80 610 Ex5 40 80 910 Ex6 40 80 690 Ex7 40 80 580 Ex8 40 80 650 Ex9 40 80 600 Ex10 40 80 620 Ex11 40 80 580 Ex12 40 80 640 Ex13 40 80 590 Ex14 40 80 640 Ex15 40 80 550 Ex16 40 80 610 Ex17 40 80 705 Ex18 40 80 1100 Ex19 40 80 730 Ex20 40 80 690 Ex21 40 80 940 Ex22 40 80 1055 Ex23 40 80 990 Ex24 40 80 770 Ex25 40 80 790 Ex26 40 80 735 Ex27 40 80 645 Ex28 40 80 970

TABLE-US-00008 TABLE 8 Materials used [00473] [00474] [00475] [00476] [00477] [00478] [00479] [00480] [00481] [00482] [00483] [00484] [00485] [00486] [00487] [00488] [00489] [00490] [00491] [00492] [00493] [00494] [00495] [00496] [00497] [00498] [00499] [00500] [00501] [00502] [00503] [00504] [00505] [00506] [00507] [00508] [00509] [00510] [00511] [00512] [00513] [00514] [00515] [00516] [00517] [00518] [00519]

EXAMPLE 2: SYNTHESIS OF HOST MATERIALS AND PRECURSORS THEREOF

a) 2-Dibenzofuran-1-yl-4,6-diphenyl-1,3,5-triazine

[0234] ##STR00520##

[0235] 23 g (110.0 mmol) of dibenzofuran-1-boronic acid, 29.5 g (110.0 mmol) of 2-chloro-4,6-diphenyl-1,3,5-triazine and 21 g (210.0 mmol) of sodium carbonate are suspended in 500 ml of ethylene glycol diamine ether and 500 ml of water. 913 mg (3.0 mmol) of tri-o-tolylphosphine and then 112 mg (0.5 mmol) of palladium(II) acetate are added to this suspension, and the reaction mixture is heated under reflux for 16 h. After cooling, the organic phase is separated off, filtered through silica gel, washed three times with 200 ml of water and subsequently evaporated to dryness. The residue is recrystallised from toluene and from dichloromethane/heptane. The yield is 37 g (94 mmol), corresponding to 87% of theory.

[0236] The following compounds can be obtained analogously:

TABLE-US-00009 Starting material 1 Starting material 2 Product Yield 1a [00521] [00522] [00523] 63% 2a [00524] [00525] [00526] 61% 3a [00527] [00528] [00529] 60% 4a [00530] [00531] [00532] 64% 5a [00533] [00534] [00535] 58% 6a [00536] [00537] [00538] 64% 7a [00539] [00540] [00541] 75% 8a [00542] [00543] [00544] 65% 9a [00545] [00546] [00547] 68% 10a [00548] [00549] [00550] 62% 11a [00551] [00552] [00553] 57% 12a [00554] [00555] [00556] 64% 13a [00557] [00558] [00559] 61%

b) 2-(8-Bromodibenzofuran-1-yl)˜4,6-diphenyl-1,3,5-triazine

[0237] ##STR00560##

[0238] 70 g (190.0 mmol) of 2-dibenzofuran-1-yl-4,6-diphenyl-1,3,5-triazine are suspended in 2000 ml of acetic acid (100%) and 2000 ml of sulfuric acid (95˜98%). 34 g (190 mmol) of NBS are added in portions to this suspension, and the mixture is stirred in the dark for 2 hours. Water/ice is then added, and the solid is separated off and rinsed with ethanol. The residue is recrystallised from toluene. The yield is 80 g (167 mmol), corresponding to 87% of theory.

[0239] The following compounds are prepared analogously:

TABLE-US-00010 Starting material 1 Product Yield 1b [00561] [00562] 83%

[0240] In the case of thiophene derivatives, nitrobenzene is employed instead of sulfuric acid and elemental bromine is employed instead of NBS.

c) 2,4-Diphenyl-6-[8-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)dibenzofuran-1-yl]-1,3,5-triazine

[0241] ##STR00563##

[0242] 60 g (125 mmol) of the 2-(8-bromodibenzofuran-1-yl)˜4,6-diphenyl-1,3,5-triazine together with 39 g (1051 mmol) of bis(pinacolato)diborane (CAS 73183˜34˜3) are dissolved in 900 ml of dry DMF in a 500 ml flask under protective gas and degassed for 30 minutes. 37 g (376 mmol) of potassium acetate and 1.9 g (8.7 mmol) of palladium acetate are subsequently added, and the batch is heated at 80° C. overnight. When the reaction is complete, the mixture is diluted with 300 ml of toluene and extracted with water. The solvent is removed on a rotary evaporator, and the product is recrystallised from heptane. Yield: 61 g (117 mmol), 94% of theory.

[0243] The following compounds are prepared analogously:

TABLE-US-00011 Starting material 1 Product Yield 1c [00564] [00565] 98%

d) 2-[4-[9-(4,6-Diphenyl-1,3,5-triazin-2-yl)dibenzofuran-2-yl]phenyl]˜4,6-diphenyl-1,3,5-triazine

[0244] ##STR00566##

[0245] 68.7 g (110.0 mmol) of 2,4-diphenyl-6-[8-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)dibenzofuran-1-yl]-1,3,5-triazine, 42 g (110.0 mmol) of 2-(4-bromophenyl)˜4,6-diphenyl-1,3,5-triazine and 21 g (210.0 mmol) of sodium carbonate are suspended in 500 ml of ethylene glycol diamine ether and 500 ml of water. 913 mg (3.0 mmol) of tri-o-tolylphosphine and then 112 mg (0.5 mmol) of palladium(II) acetate are added to this suspension, and the reaction mixture is heated under reflux for 16 h. After cooling, the organic phase is separated off, filtered through silica gel, washed three times with 200 ml of water and subsequently evaporated to dryness. The product is purified by column chromatography on silica gel with toluene/CHCl.sub.3 (1:1) and finally sublimed in a high vacuum (p=5×10.sup.−7 mbar) (purity 99.9%). The yield is 64 g (81 mmol), corresponding to 70% of theory.

[0246] The following compounds can be prepared analogously:

TABLE-US-00012 Starting material 1 Starting material 2 Product Yield 1d [00567] [00568] [00569] 61% 2d [00570] [00571] [00572] 65% 3d [00573] [00574] [00575] 67% 4d [00576] [00577] [00578] 69% 5d [00579] [00580] [00581] 65% 6d [00582] [00583] [00584] 66% 7d [00585] [00586] [00587] 62% 8d [00588] [00589] [00590] 64% 9d [00591] [00592] [00593] 76%