Spirobifluorene derivative-based materials for electronic devices

Abstract

The present application relates to spirobifluorene derivatives of a formula (I), to the use thereof in electronic devices, and to processes for preparing said derivatives.

Claims

1. A compound of the formula (I) ##STR00320## which is optionally substituted at one or more positions shown as unsubstituted in the base structure of formula (I) by one R.sup.1 radical each; and which has the following definitions of the variables: Y is selected from a single bond, O, S and Se; Z is selected from O, S and Se; E is the same or different at each instance and is a single bond or an aromatic or heteroaromatic ring system which has 6 to 30 aromatic ring atoms and is optionally substituted by one or more R.sup.2 radicals; A is the same or different at each instance and is a group of the formula (A1), (A2) or (A3) which is bonded via the bond marked with #; ##STR00321## wherein N is a nitrogen atom, Ar.sup.2 is the same or different at each instance and is an aromatic or heteroaromatic ring system which has 6 to 30 aromatic ring atoms and is optionally substituted by one or more R.sup.2 radicals; X is the same or different at each instance and is a single bond or a group selected from BR.sup.2, C(R.sup.2).sub.2, Si(R.sup.2).sub.2, C?O, O, S, S?O, SO.sub.2, NR.sup.2, PR.sup.2 and P(?O)R.sup.2; R.sup.1 is the same or different at each instance and is selected from H, D, F, C(?O)R.sup.3, CN, Si(R.sup.3).sub.3, P(?O)(R.sup.3).sub.2, OR.sup.3, S(?O)R.sup.3, S(?O).sub.2R.sup.3, straight-chain alkyl or alkoxy groups having 1 to 20 carbon atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 carbon atoms, alkenyl or alkynyl groups having 2 to 20 carbon atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where two or more R.sup.1 radicals is optionally joined to one another and optionally forms a ring; where the alkyl, alkoxy, alkenyl and alkynyl groups mentioned and the aromatic ring systems and heteroaromatic ring systems mentioned optionally each is substituted by one or more R.sup.3 radicals; and where one or more CH.sub.2 groups in the alkyl, alkoxy, alkenyl and alkynyl groups mentioned is optionally replaced by R.sup.3C?CR.sup.3, C?C, Si(R.sup.3).sub.2, C?O, C?NR.sup.3, C(?O)O, C(?O)NR.sup.3, NR.sup.3, P(?O)(R.sup.3), O, S, SO or SO.sub.2; R.sup.2 is the same or different at each instance and is selected from H, D, F, C(?O)R.sup.3, CN, Si(R.sup.3).sub.3, N(R.sup.3).sub.2, P(?O)(R.sup.3).sub.2, OR.sup.3, S(?O)R.sup.3, S(?O).sub.2R.sup.3, straight-chain alkyl or alkoxy groups having 1 to 20 carbon atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 carbon atoms, alkenyl or alkynyl groups having 2 to 20 carbon atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where two or more R.sup.2 radicals is optionally joined to one another and optionally forms a ring; where the alkyl, alkoxy, alkenyl and alkynyl groups mentioned and the aromatic ring systems and heteroaromatic ring systems mentioned optionally each is substituted by one or more R.sup.3 radicals; and where one or more CH.sub.2 groups in the alkyl, alkoxy, alkenyl and alkynyl groups mentioned is optionally replaced by R.sup.3C?CR.sup.3, C?C, Si(R.sup.3).sub.2, C?O, C?NR.sup.3, C(?O)NR.sub.3, NR.sup.3, P(?O)(R.sup.3), O, S, SO or SO.sub.2; R.sup.3 is the same or different at each instance and is selected from H, D, F, 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, straight-chain alkyl or alkoxy groups having 1 to 20 carbon atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 carbon atoms, alkenyl or alkynyl groups having 2 to 20 carbon atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where two or more R.sup.1 or R.sup.2 radicals is optionally joined to one another and optionally forms a ring; where the alkyl, alkoxy, alkenyl and alkynyl groups mentioned and the aromatic ring systems and heteroaromatic ring systems mentioned optionally each is substituted by one or more R.sup.4 radicals; and where one or more CH.sub.2 groups in the alkyl, alkoxy, alkenyl and alkynyl groups mentioned is 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.sub.4, NR.sup.4, P(?O)(R.sup.4), O, S, SO or SO.sub.2; R.sup.4 is the same or different at each instance and is selected from H, D, F, CN, alkyl groups having 1 to 20 carbon atoms, aromatic ring systems having 6 to 40 aromatic ring atoms and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where two or more R.sup.4 radicals is optionally joined to one another and optionally forms a ring; and where the alkyl groups, aromatic ring systems and heteroaromatic ring systems mentioned is optionally substituted by F or CN; q is the same or different at each instance and is 0 or 1, where at least one q in formula (A2) is 1; a, b, c, and d are the same or different at each instance and are 0 or 1, where at least one of the indices a, b, c and d is 1, and where, in the case that one or more of the indices a, b, c and d are 0, an R.sup.1 group is attached at the position in question.

2. The compound according to claim 1, wherein Y is a single bond and Z is O or S.

3. The compound according to claim 1, wherein Y is O and S and Z is O or S.

4. The compound according to claim 1, wherein E is the same or different at each instance and is selected from a single bond and a divalent group derived from benzene, biphenyl, terphenyl, fluorene, spirobifluorene, indenofluorene, carbazole, dibenzofuran or dibenzothiophene, each optionally substituted by R.sup.2 radicals, or a combination of two or more of these groups, where not more than 30 aromatic ring atoms are present in the E group.

5. The compound according to claim 1, wherein X is a single bond.

6. The compound according to claim 1, wherein A is the same or different at each instance and is a group of the formula (A-1) or (A-3).

7. The compound according to claim 1, wherein Ar.sup.2 is the same or different at each instance and is selected from phenyl, biphenyl, terphenyl, fluorenyl, spirobifluorenyl, indenofluorenyl, naphthyl, phenanthrenyl, furanyl, benzofuranyl, dibenzofuranyl, thiophenyl, benzothiophenyl, dibenzothiophenyl, carbazolyl, indolocarbazolyl and indenocarbazolyl, each of which may be substituted by one or more R.sup.2 radicals.

8. The compound according to claim 1, wherein R.sup.1 is the same or different at each instance and is selected from H, F, CN, methyl, tert-butyl, phenyl, biphenyl, dibenzofuran, dibenzothiophene and carbazole.

9. The compound according to claim 1, wherein R.sup.1 is H.

10. The compound according to claim 1, wherein exactly one of the indices a, b, c and d is 1 and the other indices are 0; or in that exactly two of the indices a, b, c and d are 1, and the other indices are 0.

11. The compound according to claim 1, wherein the index d is 0, and in that exactly one or exactly two of the indices a, b and c are 1.

12. The compound according to claim 1, wherein the compound corresponds to the following embodiment of formula (I-A) ##STR00322## wherein variables that occur are as defined as in claim 1.

13. A process for preparing the compound of the formula (I) according to claim 1, which comprises first preparing a spirobifluorene base skeleton and, in a later step, via an organometallic coupling reaction, an arylamino or carbazole group or an aryl or heteroaryl group substituted by an arylamino or carbazole group is introduced.

14. Oligomers, polymers or dendrimers containing one or more compounds of formula (I) according to claim 1, wherein the bond(s) to the polymer, oligomer or dendrimer may be localized at any desired positions substituted by R.sup.1 or R.sup.2 in formula (I).

15. A formulation comprising at least one compound according to claim 1, and at least one solvent.

16. An electronic device comprising at least one compound according to claim 1.

17. The electronic device according to claim 16, wherein the device is an organic electroluminescent device comprising anode, cathode and at least one emitting layer, where at least one organic layer of the device, which may be an emitting layer, a hole transport layer or another layer, comprises the at least one compound.

18. The electronic device according to claim 17, wherein the at least one organic layer is selected from a hole transport layer and an emitting layer.

19. The electronic device according to claim 17, wherein the at least one organic layer is selected from an electron blocker layer, and an emitting layer comprising one or more phosphorescent emitters.

Description

WORKING EXAMPLES

A) Synthesis Examples

Example 1: Synthesis of Compounds (I-1) to (I-26)

(1) ##STR00081##

Synthesis of 1-(2-bromophenyl)dibenzothiophene A-1

(2) 80 g (351 mmol) of dibenzothiophene-1-boronic acid (CAS: 1245943-60-5), 83 g (351 mmol) of 1,2-dibromobenzene and 8.2 g (7.02 mmol) of Pd(Ph.sub.3P).sub.4 are suspended in 700 ml of dioxane. Added gradually to this suspension are 440 ml (877 mmol) of 2 M potassium carbonate solution, and the reaction mixture is heated under reflux for 18 h. After cooling, the organic phase is removed, filtered through silica gel, washed three times with 200 ml of water and then concentrated to dryness. The residue is purified by chromatography on silica gel. Yield: 101 g (297 mmol), 85% of theory, purity by HPLC>97%.

(3) In a manner analogous to the synthesis of compound A-1 described, the following compounds are prepared:

(4) TABLE-US-00001 Reactant 1 Reactant 2 Product Yield A-2 1245943-60-5 70% A-3 162607-19-4 75% A-4 162607-19-4 0 60% A-5 108847-76-3 55% A-6 636607-99-3 67% A-13 108847-76-3 73% A-14 00 636607-99-3 01 02 81%

Synthesis of Intermediate B-1

(5) 56.3 g (166 mmol) of 1-(2-bromophenyl)dibenzothiophene A-1 are initially charged in 700 ml of THF at ?78? C. At this temperature, 70 ml of BuLi (2.5 M in hexane) are added dropwise. After 1 hour, 45.2 g (174 mmol) of 2-bromofluoren-9-one in 200 ml of THF are added dropwise. The mixture is left to stir at room temperature overnight, added to ice-water and extracted with dichloromethane. The combined organic phases are washed with water and dried over sodium sulphate. The solvent is removed under reduced pressure and the residue, without further purification, is heated with 90 ml of HCl and 1 l of AcOH at 75? C. overnight. After cooling, the precipitated solid is filtered off with suction and washed twice with 150 ml of water and three times with 150 ml each time of ethanol, and finally recrystallized from heptane. Yield: 59 g (117 mmol), 71%; purity about 98% by .sup.1H NMR.

(6) In a manner analogous to the synthesis of compound B-1 described, the following compounds are prepared:

(7) TABLE-US-00002 Reactant 1 Reactant 2 Product Yield B-2 03 04 4269-17-4 05 62% B-3 06 07 486-25-9 08 70% B-4 09 0 3096-56-8 70% B-5 3096-49-9 81% B-6 154851-21-3 75% B-7 115033-91-5 0 60% B-8 58775-13-6 68% B-9 58775-11-4 75% B-10 14348-75-5 62% B-11 0 24313-53-9 62% B-11 3096-56-8 70% B-12 14348-75-5 65% B-13 0 4269-17-4 75% B-14 3096-56-8 68% B-17 154851-21-3 67% B-18 0 74% B-19 3096-56-8 65% B-20 486-25-9 72% B-21 486-25-9 68%

Synthesis of Compound (1-1)

(8) 13.7 g (38 mmol) of biphenyl-4-yl(9,9-dimethyl-9H-fluoren-2-yl)amine and 17.4 g (38 mol) of the bromo-spiro derivative B-1 are dissolved in 300 ml of toluene. The solution is degassed and saturated with N.sub.2. Thereafter, 1.52 ml (1.52 mmol) of a 1 M tri-tert-butylphosphine solution and 170 mg (0.76 mmol) of Pd(AcO).sub.2 are added thereto, and then 9.0 g of sodium tert-butoxide (94.2 mmol) are added. The reaction mixture is heated to boiling under a protective atmosphere for 5 h. The mixture is subsequently partitioned between toluene and water, and the organic phase is washed three times with water and dried over Na.sub.2SO.sub.4 and concentrated by rotary evaporation. After the crude product has been filtered through silica gel with toluene, the remaining residue is recrystallized from heptane/toluene and finally sublimed under high vacuum. The purity is 99.9% (HPLC). The yield of compound (1-1) is 22.7 g (77% of theory).

Synthesis of compounds (I-2) to (I-26)

(9) In a manner analogous to the synthesis of compound (1-1) described in Example 1, the following compounds (1-2) to (1-26) are also prepared:

(10) TABLE-US-00003 Reactant 1 Reactant 2 Product Yield 1-2 0 75% 1-3 75% 1-4 73% 1-5 0 78% 1-6 80% 1-7 70% 1-8 0 75% 1-9 81% 1-10 78% 1-11 70% 1-12 0 76% 1-13 70% 1-14 65% 1-15 00 (2 eq) 01 60% 1-16 02 03 (2 eq) 04 70% 1-17 05 06 07 78% 1-18 08 09 (2 eq) 0 80% 1-19 67% 1-20 75% 1-21 80% 1-22 0 75% 1-23 80% 1-24 65% 1-25 0 77% 1-26 67%

Example 2: Synthesis of Compounds 2-1 to 2-9

(11) ##STR00235##

Spirofluorene-Boronic Ester Derivative (C-1)

(12) 36 g (74.2 mmol) of the spirofluorene-bromo derivative B11, 22.6 g (89 mmol) of bis(pinacolato)diborane and 21.8 g (222 mmol) of potassium acetate are suspended in 400 ml of DMF. To this suspension is added 1.82 g (2.23 mmol) of 1,1-bis(diphenylphosphino)ferrocenedichloropalladium(II) complex with DCM. The reaction mixture is heated under reflux for 16 h. After cooling, the organic phase is removed, washed three times with 400 ml of water and then concentrated to dryness. The residue is recrystallized from toluene (37 g, 94% yield).

(13) In a manner analogous thereto, the following compounds are prepared:

(14) TABLE-US-00004 Reactant 1 Product Yield C-2 62% C-3 70% C-4 0 70% C-5 81% C-6 87% C-7 85% C-10 70%

Biphenyl-2-yl(biphenyl-4-yl)(4-chlorophenyl)amine (D-1)

(15) ##STR00250##

(16) 23.8 g of biphenyl-2-yl(biphenyl-4-yl)amine (74 mmol) and 21.2 g of 4-chloroiodobenzene (89 mmol) are dissolved in 500 ml of toluene. The solution is degassed and saturated with N.sub.2. Thereafter, 3 ml (3 mmol) of a 1 M tri-tert-butylphosphine solution and 0.33 g (1.48 mmol) of palladium(II) acetate are added thereto, and then 10.7 g of sodium tert-butoxide (111 mmol) are added. The reaction mixture is heated to boiling under a protective atmosphere for 12 h. The mixture is subsequently partitioned between toluene and water, and the organic phase is washed three times with water and dried over Na.sub.2SO.sub.4 and concentrated by rotary evaporation. After the crude product has been filtered through silica gel with toluene, the remaining residue is recrystallized from heptane/toluene. The yield is 29 g (90% of theory).

(17) In a manner analogous thereto, the following compounds are prepared:

(18) TABLE-US-00005 Reactant 1 Reactant 2 Product Yield D-2 78% D-3 80% D-4 81% D-5 0 92% D-6 85% D-7 75% C-8 0 89%

Synthesis of Compound (2-1)

(19) 18.0 g (32 mmol) of spirofluorene pinacolboronic ester derivative C-1 and 15.3 g (32 mmol) of chloro derivative D-1 are suspended in 360 ml of dioxane and 9.8 g of caesium fluoride (64 mmol). 1.19 g (1.6 mmol) of bis(tricyclohexylphosphine)palladium dichloride are added to this suspension, and the reaction mixture is heated under reflux for 16 h. After cooling, the organic phase is removed, filtered through silica gel, washed three times with 100 ml of water and then concentrated to dryness. After the crude product has been filtered through silica gel with toluene, the remaining residue is recrystallized from heptane/toluene and finally sublimed under high vacuum. The purity is 99.9%. The yield is 18 g (70% of theory).

Synthesis of Compounds (2-2) to (2-9)

(20) In a manner analogous to the synthesis of compound (2-1) described, the following compounds (2-2) to (2-9) are also prepared:

(21) TABLE-US-00006 Reactant 1 Reactant 2 Product Yield 2-2 72% 2-3 71% 2-4 0 82% 2-5 89% 2-6 69% 2-7 55% 2-8 0 72% 2-9 76%

Example 3: Synthesis of Compounds 3-1 to 3-4

(22) ##STR00296##

(23) 12.2 g (50 mmol) of 3-phenylcarbazole and 21 g (42 mmol) of the bromo-spiro derivative are dissolved in 300 ml of toluene. The solution is degassed and saturated with N.sub.2. Thereafter, 1.68 ml (1.68 mmol) of a 1 M tri-tert-butylphosphine solution and 770 mg (0.84 mmol) of Pd.sub.2(dba).sub.3 are added thereto, and then 6.18 g of sodium tert-butoxide (63 mmol) are added. The reaction mixture is heated to boiling under a protective atmosphere for 26 h. The mixture is subsequently partitioned between toluene and water, and the organic phase is washed three times with water and dried over Na.sub.2SO.sub.4 and concentrated by rotary evaporation. After the crude product has been filtered through silica gel with toluene, the remaining residue is recrystallized from heptane/toluene and finally sublimed under high vacuum. The purity is 99.9% (HPLC). The yield of compound (3-1) is 13.5 g (58% of theory).

Synthesis of Compounds (3-2) to (3-4)

(24) In a manner analogous to the synthesis of compound (3-1) described in Example 1, the following compounds (3-2) to (3-4) are also prepared:

(25) TABLE-US-00007 Reactant 1 Reactant 2 Product Yield 3-2 1257220-47-5 38% 3-3 00 01 1427738-11-1 02 45% 3-4 03 04 05 43%

B) Device Examples

(26) OLEDs of the invention and OLEDs according to the prior art are produced by a general method according to WO 04/058911, which is adapted to the circumstances described here (e.g. materials).

(27) In the inventive examples which follow, the data for various OLEDs are presented. Substrates used are glass plates coated with structured ITO (indium tin oxide) of thickness 50 nm. The OLEDs have the following general layer structure: substrate/p-doped hole transport layer (HIL)/hole transport layer (HTL)/electron blocker layer (EBL)/emission layer (EML)/electron transport layer (ETL)/electron injection layer (EIL) and finally a cathode. The cathode is formed by an aluminium layer of thickness 100 nm. The materials required for production of the OLEDs are shown in Table 1.

(28) All materials are applied by thermal vapour deposition in a vacuum chamber. In this case, the emission layer always consists of at least one matrix material (host material) and an emitting dopant (emitter) which is added to the matrix material(s) in a particular proportion by volume by co-evaporation. Details given in such a form as H1:SEB(5%) mean here that the material H1 is present in the layer in a proportion by volume of 95% and SEB in a proportion by volume of 5%. In an analogous manner, the electron transport layers or the hole injection layers may also consist of a mixture of two or more materials. The number in brackets after the materials indicates the particular layer thickness in which the aformentioned materials are present.

(29) The OLEDs are characterized in a standard manner. For this purpose, the external quantum efficiency (EQE, measured in percent) is determined as a function of luminance, calculated from current-voltage-luminance characteristics (IUL characteristics) assuming Lambertian radiation characteristics, and the lifetime. The parameter EQE @ 10 mA/cm.sup.2 refers to the external quantum efficiency at a current density of 10 mA/cm.sup.2. LD80 @ 60 mA/cm.sup.2 is the lifetime before the OLED, given a starting brightness at constant current of 60 mA/cm.sup.2, has fallen to 80% of the starting intensity.

(30) TABLE-US-00008 TABLE 1 Structures of the materials used 06 F4TCNQ 07 HIM 08 H1 09 SEB 0 ETM LiQ HTM1 HTM2 HTM3 HTM4 HTMv1 HTMv2 HTMv3 HTMv4

Example 1

(31) The inventive compound HTM1 and the comparative compound HTMv1 are compared with one another in a blue stack. The structure of the stack is as follows: HIM:F4TCNQ(5%)(20 nm)/HIM(175 nm)/HTM1(20 nm)/H1:SEB(5%)(20 nm)/ETM:LiQ(50%)(30 nm)/LiQ(1 nm). In the comparative example, rather than HTM1, HTMv1 is evaporated in the layer in question. The evaluation of the external quantum efficiencies at 10 mA/cm.sup.2 for the experiments conducted shows the following results: HTM1 achieves 8.1% EQE, whereas HTMv1 reaches only 6.6%. The operating voltage of the OLED comprising inventive material at 3.86 V is also well above the voltage across the diode in the case of the comparative material at 10 mA/cm.sup.2. This is 4.08 V in the comparative case and is accordingly 6% higher.

Example 2

(32) A further inventive material HTM2 is compared with the direct analogue HTMv2 having a twisted dibenzofuran unit. This OLED component has the following architecture: HIM:F4TCNQ(5%)(20 nm)/HIM(175 nm)/HTM2(20 nm) bzw. HTMv2 (20 nm)/H1:SEB(5%)(20 nm)/ETM:LiQ(50%)(30 nm)/LiQ(1 nm). Here too, the advantage of the inventive compound is apparent. The external quantum efficiency in the case of the sample comprising HTM2 is 7.5%, whereas the comparative sample only manages 7.2% EQE at a current density of 10 mA/cm.sup.2.

Example 3

(33) A further component having the layer structure HIM:F4TCNQ(5%)(20 nm)/HIM(175 nm)/HTM3(20 nm)/H1:SEB(5%)(20 nm)/ETM:LiQ(50%)(30 nm)/LiQ(1 nm) is produced. In the comparative experiment, HTM3 is replaced by HTMv3. The component comprising the inventive substance in the EBL achieves an external quantum efficiency at 10 mA/cm.sup.2 of 7.3%. The component having the comparative substance in the same functional layer achieves only 7.0%.

Example 4

(34) Finally, the compounds HTM4 und HTMv4 are also tested in a singlet blue stack: HIM:F4TCNQ(5%)(20 nm)/HIM(175 nm)/HTM4(20 nm)/H1:SEB(5%)(20 nm)/ETM:LiQ(50%)(30 nm)/LiQ(1 nm). In the comparative test, rather than HTM4, HTMv4 is introduced into the EBL. The inventive substance shows an external quantum efficiency at 10 mA/cm.sup.2 of 7.5%. The comparative compound achieves only 7.2% EQE at 10 mA/cm.sup.2.