Materials for organic electroluminescent devices

Abstract

The present invention relates to a compound of formula (I) or (II), which is suitable for use as functional material in an electronic device, in particular as emitter material in an organic electroluminescent device.

Claims

1. A compound of formula (I) or formula (II): ##STR00186## wherein X is selected from the group consisting of C(R.sup.1).sub.2, Si(R.sup.1).sub.2, Ge(R.sup.1).sub.2, O, S, NR.sup.1, and Se; V is, on each occurrence, identically or differently, selected from the group consisting of N or CR.sup.2; Ar.sup.1 and Ar.sup.2 are, identically or differently, selected from group consisting of formulae (3) through (8): ##STR00187## wherein Ar.sup.1 and Ar.sup.2 are connected to the 5-membered ring of formula (I) or (II) via one group Y of one of formulae (3) through (8); Y is C if the 5-membered ring of formula (I) or (II) is bonded to Y and is CR.sup.3 or N if the 5-membered ring of formula (I) or (II) is not bonded to the group Y; E is, on each occurrence, identically or differently, a divalent bridge selected from the group consisting of B(R.sup.1), C(R.sup.1).sub.2, Si(R.sup.1).sub.2, CO, CNR.sup.1, CC(R.sup.1).sub.2, O, S, SO, SO.sub.2, N(R.sup.1), P(R.sup.1), and P(O)R.sup.1; W is C if a bridge E is bonded to the group W and is CR.sup.3 or N if no bridge E is bonded to the group W; R.sup.1, R.sup.2, and R.sup.3 is, 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, wherein these groups are each optionally substituted by one or more radicals R.sup.4 and wherein one or more CH.sub.2 groups in these groups are optionally replaced by R.sup.4CCR.sup.4, CC, Si(R.sup.4).sub.2, CO, CNR.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, which in each case is 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, and wherein two or more substituents R.sup.1, two or more substituents R.sup.2, or two or more substituents R.sup.3 are optionally linked to one another so as to define a ring; 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).sub.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, where these groups are each optionally substituted by one or more radicals R.sup.5 and wherein one or more CH.sub.2 groups in these groups are optionally replaced by R.sup.5CCR.sup.5, CC, Si(R.sup.5).sub.2, CO, CNR.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, which in each case is 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, and wherein two or more radicals R.sup.4 are optionally linked to one another so as to define a ring; R.sup.5 is on each occurrence, identically or differently, H, D, F, or an aliphatic, aromatic, or heteroaromatic organic radical having 1 to 20 C atoms, wherein one or more H atoms are optionally replaced by D or F; and a, b, c, d, e, and f are, on each occurrence, identically or differently, 0 or 1, with the proviso that a +b =1 or 2, c +d =1 or 2, and e +f =1 or 2, wherein when a =0, or b =0, or c =0, or d 0, or e =0, or f=0, in each case the corresponding bridge X is not present.

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

3. The compound of claim 1, wherein X is selected from C(R.sup.1).sub.2, Si(R.sup.1).sub.2, O, or S.

4. The compound of claim 1, wherein E is, on each occurrence, identically or differently, a divalent bridge selected from the group consisting of C(R.sup.1).sub.2, Si(R.sup.1).sub.2, O, S, and N(R.sup.1), more preferably C(R.sup.1).sub.2.

5. The compound of claim 1, wherein E is C(R.sup.1).sub.2.

6. The compound of claim 1, wherein V is CR.sup.2.

7. The compound of claim 1, wherein Ar.sup.1 and Ar.sup.2 are, identically or differently, selected from one of formulae (3-1) through (8-3): ##STR00188## ##STR00189## ##STR00190## ##STR00191##

8. The compound of claim 1, wherein Ar.sup.1 and Ar.sup.2 are, identically or differently, selected from one of the following formulae (3-1-1) to (8-3-2): ##STR00192## ##STR00193## ##STR00194## ##STR00195## ##STR00196## ##STR00197## wherein the dashed lines represent the bonds to the 5-membered ring of formula (I) or (II).

9. The compound of claim 1, wherein it is a compound of formula (I) or formula (II): ##STR00198## wherein X is C(R.sup.1).sub.2, Si(R.sup.1).sub.2, O, or S; V is CR.sup.2; Ar.sup.1 and A.sup.2 is, identically or differently, selected from the group consisting of formulae (3-1) through (8-3): ##STR00199## ##STR00200## ##STR00201## ##STR00202## wherein E is C(R.sup.1).sub.2 and Y is C if the 5-membered ring of formula (I) or (II) is bonded to Y and CR.sup.3 otherwise; R.sup.1, R.sup.2, and R.sup.3 is on each occurrence, identically or differently, H, D, F, CN, Si(R.sup.4).sub.3, N(R.sup.4).sub.2, a straight-chain alkyl or alkoxy group having 1 to 10 C atoms or a branched or cyclic alkyl or alkoxy group having 3 to 10 C atoms, where these groups are each optionally substituted by one or more radicals R.sup.4 and wherein one or more CH.sub.2 groups in these groups are optionally replaced by CC, R.sup.4CCR.sup.4, Si(R.sup.4).sub.2, CO, CNR.sup.4,NR.sup.4, O, S, C(O)O, or C(O)NR.sup.4, an aromatic or heteroaromatic ring system having 5 to 20 aromatic ring atoms, which in each case is optionally substituted by one or more radicals R.sup.4, and wherein two radicals R.sup.1 are optionally linked to one another so as to define a ring, two radicals R.sup.2 are optionally linked to one another so as to define a ring, or two radicals R.sup.3 are optionally linked to one another so as to define a ring; and R.sup.4 is on each occurrence, identically or differently, H, D, F, CN, Si(R.sup.5).sub.3, N(R.sup.5).sub.2, a straight-chain alkyl or alkoxy group having 1 to 10 C atoms or a branched or cyclic alkyl or alkoxy group having 3 to 10 C atoms, where these groups are each optionally substituted by one or more radicals R.sup.5 and wherein one or more CH.sub.2 groups in these groups are optionally replaced by CC, R.sup.5CCR.sup.5, Si(R.sup.5).sub.2, CO, CNR.sup.5, NR.sup.5, O, S, C(O)O, or C(O)NR.sup.5, or an aromatic or heteroaromatic ring system having 5 to 20 aromatic ring atoms, which in each case is optionally substituted by one or more radicals R.sup.5, and wherein two or more radicals R.sup.4 are optionally linked to one another so as to define a ring.

10. 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 (I) or (II) which are substituted by R.sup.1, R.sup.2, or R.sup.3.

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

12. A formulation comprising at least one polymer, oligomer, or dendrimer of claim 10 and at least one solvent.

13. An electronic device comprising at least one compound of claim 1, 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, organic light-emitting electrochemical cells, organic laser diodes, and organic electroluminescent devices.

14. The electronic device of claim 13, wherein the electronic device is an organic electroluminescent device, wherein the organic electroluminescent device comprises an anode, a cathode, and at least one emitting layer, and wherein at least one layer of the electronic device selected from the group consisting of emitting layers, electron-transport layers, electron-injection layers, and hole-blocking layers, comprises the at least one compound.

15. The electronic device of claim 13, wherein the electronic device comprises a compound of claim 1, wherein the compound is a fluorescent compound and is present in an emitting layer.

16. A process for preparing a compound of claim 1, comprising reacting a 5-membered ring boronic ester derivative and a halogenated aromatic or heteroaromatic group via a CC Suzuki coupling reaction.

Description

WORKING EXAMPLES

A) Synthesis Examples

(1) A-1) Variant I:

(2) ##STR00137##
Synthesis of Compound 1a

(3) Compound Int-b1 (43.25 g, 98.44 mmol), Compound Int-a1 (15 g, 46.88 mmol), sodium metaborate tetrahydrate (19.39 g, 140.63 mmol) and hydrazine hydroxide are suspended in 200 mL of water and 600 mL of tetrahydrofuran. The solution is then degassed and argon-saturated.

(4) Bis(triphenylphosphin)palladium(II) chloride (1.32 g, 1.88 mmol) is then added to the reaction mixture and the mixture is heated overnight at 60 C. The suspension is then cooled, filtrated and the rest is extracted in a Soxhlet extractor with chlorobenzene. Finally, the solid product is stirred and heated in chlorobenzene. As a result, a yellow solid (purity 99.55%, HPLC) is obtained with a yield of 9.91 g (12.6 mmol, 25%).

(5) Synthesis of Compounds 1b to 1k

(6) The compounds 1b to 1k (see below) are synthesised analogously to the process described above for the synthesis of compound 1a.

(7) The structure of the different intermediate products is given below.

(8) TABLE-US-00003 Intermediate compounds Synthesis Int-a1 Adv. Synth. Catal. 2003, 345, 1103-1106 Int-a2 Org. Lett. 2013, 15, 5970- 5973 Int-a3 0 Commercially available Int-a4 J. Am. CHem. Soc. 2009, 131, 6070-6071 Int-a5 Tetrahedron 2012, 68, 9982-9998 und Adv. Synth. Catal. 2003, 345, 1103-1106 Int-a6 Commercialy available Int-b1 WO2014/037077 Int-b2 WO2010/049050 Int-b3 WO2014/106522 Int-b4 WO2010/049050 Int-b5 WO2008/006449 Int-b6 WO2014/037077 Int-b7 0 WO2013065589

(9) The following table represents the structure of the compounds 1a to 1 k as well as the corresponding yields.

(10) TABLE-US-00004 Yield % Int-a1 Int-b1 1a 25 Int-a1 Int-b2 1b 43 Int-a1 Int-b6 1c 32 Int-a2 Int-b1 1d 48 Int-a3 Int-b4 1e 18 Int-a4 Int-b3 1f 27 Int-a4 Int-b5 1g 38 Int-a5 Int-b1 1h 31 Int-a5 Int-b3 1i 27 Int-a6 Int-b1 0 1j 44 Int-a6 Int-b4 1k 39 Int-a1 Int-b7 1l 37
A-2) Variant II:
First Step

(11) ##STR00163##
Second Step

(12) ##STR00164##
Synthesis of the Intermediate Compound Int-c1

(13) Compound Int-b1 (13.73 g, 31.25 mmol), Compound Int-a1 (10 g, 31.25 mmol) and potassium carbonate (6.47 g, 46.87 mmol) are suspended in 250 mL of water and 250 mL of tetrahydrofuran. The solution is then degassed and argon-saturated. Tetrakis(triphenylphosphin)palladium(0) chloride (1.08 g, 0.94 mmol) is then added to the reaction mixture and the mixture is heated overnight at 100 C. The mixture is then cooled, the aqueous and organic phases are separated and the aqueous phase is extracted several times with toluene. After removing the solvent, the rest is extracted in a Soxhlet extractor with toluene and recrystallized once from toluene. As a result, a yellow solid (purity 98%, HPLC) is obtained with a yield of 14.16 g (15.62 mmol, 82%).

(14) Synthesis of Intermediate Compounds Int-c2 to Int-c4

(15) The intermediate compounds Int-c2 to Int-c4 (see below) are synthesised analogously to the process described above for the synthesis of the intermediate compound Int-c1.

(16) The structure of the different intermediate products and their respective yield is given in the table below.

(17) TABLE-US-00005 Int-a Int-b Int-c Yield % Int-a1 Int-b1 Int-c1 82 Int-a2 Int-b1 Int-c2 75 Int-a4 Int-b3 Int-c3 87 Int-a6 Int-b4 Int-c4 62
Synthesis of Compound 2a

(18) Int-b2 (9.50 g, 28.18 mmol), Int-c1 (14.16 g, 25.62 mmol), sodium metaborate tetrahydrate (5.29 g, 38.43 mmol) and hydrazine hydroxide are suspended in 100 mL of water and 300 mL of tetrahydrofuran. The solution is then degassed and argon-saturated. Bis(triphenylphosphin)palladium(II) chloride (0.36 g, 0.51 mmol) is then added to the reaction mixture and the mixture is heated overnight at 60 C. The suspension is then cooled, filtrated and the rest is extracted in a Soxhlet extractor with chlorobenzene. Finally, the solid product is stirred and heated in chlorobenzene. As a result, a yellow solid (purity 99.89%, HPLC) is obtained with a yield of 9.01 g (13.32 mmol, 52%).

(19) Synthesis of Compound 2b to 2e

(20) The compounds 2b to 2e (see below) are synthesised analogously to the process described above for the synthesis of compound 2a.

(21) TABLE-US-00006 Int-b Int-c 2 Yield % Int-b2 Int-c1 2a 52 Int-b4 Int-c2 0 2b 43 Int-b2 Int-c3 2c 38 Int-b5 Int-c4 2d 56 Int-b3 Int-c1 2e 51

B) Device Examples: Production of OLEDs

(22) OLEDs according to the invention and OLEDs in accordance with the prior art are produced by a general process in accordance with WO 2004/058911, which is adapted to the circumstances described here (layer-thickness variation, materials).

(23) The data for various OLEDs comprising a compound according to the invention (E1 to E5) or a compound according to the prior art (V1 to V3) are presented below (see Tables 1 to 3). The substrates used are glass plates coated with structured ITO (indium tin oxide) in a thickness of 50 nm. The OLEDs basically have the following layer structure: substrate/Buffer/hole-injection layer (95% HTL1+5% HIL, 20 nm)/hole-transport layer (HTL2, 195 nm)/emission layer (20 nm)/electron-transport layer (ETL, 20 nm)/electron-injection layer (EIL, 3 nm) and finally a cathode. The cathode is formed by an aluminium layer with a thickness of 100 nm. The buffer layer consists of 20 nm thick Clevios P VP Al 4083 (Heraues Clevios GmbH, Leverkusen), which is processed from solution by spin-coating. All other materials are applied by thermal vapour deposition in a vacuum chamber. The precise structure of the OLEDs is shown in Table 1. The materials required for the production of the OLEDs are shown in Table 3.

(24) The emission layer here always consists of at least one matrix material (host material) 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 H1:D1 (97%:3%) here means that material H1 is present in the layer in a proportion by volume of 97% and D1 is present in the layer in a proportion of 3%. Analogously, the electron-transport layer may also consist of a mixture of two materials.

(25) The OLEDs are characterised by standard methods. For this purpose, the electroluminescence spectra, the current efficiency (measured in cd/A), the power efficiency (measured in Im/W), the external quantum efficiency (EQE, measured in percentage) as a function of the luminous density as calculated from current/voltage/luminous density characteristic lines (IUL characteristic lines) assuming Lambert emission characteristics, and the lifetime are determined. The electroluminescence spectra are determined at a luminous density of 1000 cd/m.sup.2, and the CIE 1931 x and y colour coordinates are calculated therefrom. The expression EQE @ 1000 cd/m.sup.2 denotes the external quantum efficiency at an operating luminous density of 1000 cd/m.sup.2. LT95 @ 1000 cd/m.sup.2 is the lifetime until the OLED has dropped from a luminance of 1000 cd/m.sup.2 to 95% of the initial intensity, i.e. to 950 cd/m.sup.2. The data for the various OLEDs are summarised in Table 2.

(26) Use of Compounds According to the Invention as Emitter Material in Fluorescent OLEDs

(27) In particular, compounds according to the present invention are suitable as fluorescent blue dopants (emitter) in OLEDs when mixed into a host material (matrix). In comparison with present state-of-the-art dopants (reference VD1, VD2) the samples comprising the compounds according to the invention are highly efficient and exhibit a significantly improved lifetime.

(28) TABLE-US-00007 TABLE 1 Structure of the OLEDs Experiment EML V1 H1(97%):VD1(3%) V2 H2(97%):VD1(3%) V3 H1(97%):VD2(3%) E1 H1(97%):D1(3%) E2 H2(97%):D1(3%) E3 H1(97%):D2(3%) E4 H2(97%):D2(3%) E5 H1(97%):D3(3%)

(29) TABLE-US-00008 TABLE 2 Data for the OLEDs EQE LT95 @ 1000 @ 1000 cd/m2 cd/m.sup.2 CIE Ex. % [h] x y V1 7.8 110 0.13 0.13 V2 7.5 90 0.13 0.14 V3 8.0 90 0.13 0.16 E1 8.1 160 0.15 0.18 E2 8.0 150 0.14 0.16 E3 8.3 180 0.15 0.17 E4 8.1 130 0.14 0.16 E5 8.3 150 0.14 0.14

(30) TABLE-US-00009 TABLE 3 Structures of the materials used HIL HTL1 HTL2 H1 H2 VD1 0 VD2 ETL EIL D1 D2 D3