Materials for organic electroluminescent devices

Abstract

The present invention relates to compounds of the formula (1) which are suitable for use in electronic devices, in particular organic electroluminescent devices, and to electronic devices which comprise these compounds. ##STR00001##

Claims

1. An organic electroluminescent device (OLED) comprising at least one compound of the formula (1) in an emitting layer or an electron-blocking layer, ##STR00583## where the following applies to the symbols and indices used: Y is S, O, or NAr.sup.N; X stands, on each occurrence, identically or differently, for N, CR.sup.1, C(Ar.sup.L).sub.nAr.sup.1 or C(Ar.sup.L).sub.nAr.sup.2; Ar.sup.L, Ar.sup.N stand on each occurrence, identically or differently, 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.2; Ar.sup.1, Ar.sup.2 stand on each occurrence, identically or differently, 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.3; where the compound of formula (1) comprises at least one group Ar.sup.1 or Ar.sup.2, which stands for a heteroaromatic ring system of formula (Cbz-1): ##STR00584## where the dashed bond indicates the bonding of A.sup.1 or Ar.sup.2 to the structure of formula (1) or to Ar.sup.L; V stands, on each occurrence, identically or differently, for CR.sup.3 or N; or V stands for C when it is bonded to the structure of formula (1) or to Ar.sup.L or two adjacent groups V stand for a group of formula (V-1) or (V-2), ##STR00585## where the dashed bonds in formulae (V-1) and (V-2) indicate the bonding to the group of formula (Cbz-1); Z is on each occurrence, identically or differently, CR.sup.3 or N; E.sup.1, E.sup.2 are, on each occurrence, identically or differently, selected from a single bond, B(R.sup.0), C(R.sup.0).sub.2, Si(R.sup.0).sub.2, C═O, C═NR.sup.0), C═C(R.sup.0).sub.2, O, S, S═O, SO.sub.2, N(R.sup.0), P(R.sup.0) and P(═O)R.sup.0, where at least one of the two groups E.sup.1 and E.sup.2 present in the same ring, is not a single bond; R.sup.0 stands on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CN, a straight-chain alkyl, alkoxy or thioalkyl groups having 1 to 40 C atoms or branched or a cyclic alkyl, alkoxy or thioalkyl groups having 3 to 40 C atoms, each of which may be substituted by one or more radicals R.sup.4, where in each case 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, P(═O)(R.sup.4), SO, SO.sub.2, 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.sup.2, an aromatic or heteroaromatic ring systems 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 groups having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R.sup.4, where two adjacent substituents R.sup.0 may form an aliphatic or aromatic ring system together, which may be substituted by one or more radicals R.sup.4; R.sup.1, R.sup.2, R.sup.3 stand on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CHO, CN, C(═O)Ar, P(═O)(Ar).sub.2, S(═O)Ar, S(═O).sub.2Ar, N(R.sup.4).sub.2, N(Ar).sub.2, NO.sub.2, Si(R.sup.4).sub.3, B(OR.sup.4).sub.2, OSO.sub.2R.sup.4, a straight-chain alkyl, alkoxy or thioalkyl groups having 1 to 40 C atoms or branched or a cyclic alkyl, alkoxy or thioalkyl groups having 3 to 40 C atoms, each of which may be substituted by one or more radicals R.sup.4, where in each case 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, P(═O)(R.sup.4), SO, SO.sub.2, 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, an aromatic or heteroaromatic ring systems 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 groups having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R.sup.4; where two adjacent substituents R.sup.1, two adjacent substituents R.sup.2 and/or two adjacent substituents R.sup.3 may form an aliphatic or aromatic ring system together, which may be substituted by one or more radicals R.sup.4; R.sup.4 stands on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CHO, CN, C(═O)Ar, P(═O)(Ar).sub.2, S(═O)Ar, S(═O).sub.2Ar, N(R.sup.5).sub.2, N(Ar).sub.2, NO.sub.2, Si(R.sup.5).sub.3, B(OR.sup.5).sub.2, OSO.sub.2R.sup.5, a straight-chain alkyl, alkoxy or thioalkyl groups having 1 to 40 C atoms or branched or a cyclic alkyl, alkoxy or thioalkyl groups having 3 to 40 C atoms, each of which may be substituted by one or more radicals R.sup.5, where in each case 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, P(═O)(R.sup.5), SO, SO.sub.2, 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, an aromatic or heteroaromatic ring systems 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 groups having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R.sup.5; where two adjacent substituents R.sup.4 may form an aliphatic or aromatic ring system together, which may be substituted by one or more radicals R.sup.5; Ar is, on each occurrence, identically or differently, an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case also be substituted by one or more radicals R.sup.5; R.sup.5 stands on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CN, a straight-chain alkyl, alkoxy or thioalkyl groups having 1 to 20 C atoms or branched or cyclic alkyl, alkoxy or thioalkyl groups having 3 to 20 C atoms, where in each case one or more non-adjacent CH.sub.2 groups may be replaced by SO, SO.sub.2, O, S and where one or more H atoms may be replaced by D, F, Cl, Br or I, or an aromatic or heteroaromatic ring system having 5 to 24 aromatic ring atoms; n is an integer equal to 0, 1, 2 or 3.

2. The OLED according to claim 1, characterized in that the group Y is selected from O or S.

3. The OLED according to claim 1, characterized in that V stands, on each occurrence, identically or differently, for CR.sup.3 or N.

4. The OLED according to claim 1, wherein the compound is selected from the compounds of formulae (2-1) to (2-6) as listed below, ##STR00586## where the symbols V, Y, Ar.sup.1, Al.sup.2, Ar.sup.L and Ar.sup.N the index n have the same meaning as in claim 1, the symbol X also has the same meaning as in claim 1, with the proviso that X stands for C in formulae (2-5) and (2-6) if it is bonded to the adjacent carbazole unit or the group Ar.sup.L.

5. The OLED according to claim 1, wherein n is on each occurrence, identically or differently, 0 or 1, wherein when n is 1, then the group Ar.sup.L is present and stands for a group of formula (Cbz-2): ##STR00587## where the dashed bonds indicate the bonding to the group A.sup.1 or Ar.sup.2 and to the structure of formula (1), and where the symbols V and have the same meaning as in claim 1.

6. The OLED according to claim 1, wherein the compound is selected from the compounds of formulae (3-1) to (3-6) as listed below, ##STR00588## ##STR00589## where the symbols V, Y, Ar.sup.1, Ar.sup.2 and have the same meaning as in claim 1, the symbol X has the same meaning as in claim 1 in formulae (3-1) to (3-4), the symbol X also has the same meaning as in claim 1, with the proviso that X stands for C in formulae (3-5) and (3-6) if it is bonded to the adjacent carbazole unit.

7. The OLED according to claim 1, wherein the compound comprises at least one group A.sup.1 or Ar.sup.2, which stands for a group of formula (Cbz-1a), ##STR00590## where the dashed bond indicates the bonding to the structure of formula (1) or to ArL.

8. The OLED according to claim 1, wherein the compound is selected from the compounds of formulae (4-1) to (4-6) as listed below, ##STR00591## ##STR00592## where the symbols X, V, Y, Ar.sup.1, Ar.sup.2 and Ar.sup.N have the same meaning as in claim 1.

9. The OLED according to claim 1, wherein Ar.sup.N is, on each occurrence, identically or differently, selected from the group consisting of phenyl, biphenyl, terphenyl, quaterphenyl, fluorene, spirobifluorene, naphthalene, anthracene, phenanthrene, triphenylene, fluoranthene, indole, benzofuran, benzothiophen, dibenzofuran, dibenzothiophene, carbazole, indenocarbazole, indolocarbazole, pyridine, pyrimidine, pyrazine, pyridazine, triazine, quinolone, benzopyridine, benzopyridazine, benzopyrimidine, quinazoline, benzimidazole, or a combination of two or three of these groups, each of which may be substituted by one or more radicals R.sup.2.

10. The OLED according to claim 1, wherein the compound is employed as a matrix material for emitters, a hole-transport-material or an electron-transport material.

11. The OLED according to claim 1, wherein the compound is employed as a matrix material in an emitting layer comprising said at least one compound and at least one emitter.

12. The OLED according to claim 11, wherein the emitter is a phosphorescent material.

13. The OLED according to claim 11, wherein Y is O or NAr.sup.N.

Description

A) SYNTHESES 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 corresponding CAS numbers are also indicated in each case from the compounds known from the literature.

a) 3-Benzo[d]imidazo[2,1-b]thiazol-2-yl-9-phenyl-9H-carbazole

(2) ##STR00302##

(3) 39.2 g (155 mmol) of 2-bromo-benzo[d]imidazo[2,1-b]thiazole, 59 g (169 mmol) of N-phenylcarbazole-3-boronic acid and 36 g (340 mmol) of sodium carbonate are suspended in 1000 mL of ethylene glycol dimethyl ether and 280 mL of water. Subsequently, 1.8 g (1.5 mmol) of tetrakies (triphenylphosphine)-palladium(0) are added to this suspension, and the reaction mixture is heated under reflux during 16 h. After cooling, the organic phase is separated off, filtered over silica gel, washed three times with 200 mL of water and then concentrated to dryness. The yield is 46 g (113 mmol), corresponding to 73% of the theory.

(4) Analogously, the following compounds are prepared:

(5) TABLE-US-00006 Educt 1 Educt 2 Product Yield  1a 03 04 05 65%  2a 06 07 08 67%  3a 09 0 76%  4a 71%  5a 70%  6a 0 70%  7a 63%  8a 57%  9a  6% 10a 0 72% 11a 78% 12a 74% 13a 0 80% 14a 88% 15a 65% 16a 0 61% 17a 76% 18a 70% 19a 75% 20a 0 72% 21a 68% 22a 65% 23a 0 78%

b) 2-Bromo-3-phenyl-benzo[d]imidazo[2,1-b]thiazole

(6) ##STR00372##

(7) 35 g (100 mmol) of 3-phenyl-benzo[d]imidazo[2,1-b]thiazole are suspended in 400 ml of DMF and then little by little mixed with, in total, 18.8 g (100 mmol) of N-bromosuccinimide at −150° C. The mixture is then mixed for 18 hours. After cooling, the reaction mixture is concentrated using a rotavapor, dissolved with dichloromethane and washed with water. It is then dried, concentrated, and then recrystallized from toluene to arrive at a purity of 97%. The yield is 30 g (93 mmol), corresponding to 67% of the theory.

(8) Analogously, the following compounds are prepared:

(9) TABLE-US-00007 Educt 1 Product Yield  1b 48%  2b 73%  3a 70%  4b 0 63%  5b 69%  6b 66%  7b 71%  8b 81%  9b 0 84% 10b 83% 11b 80% 12b 54% 13b 50% 14b 00 71% 15b 01 02 87% 16b 03 04 77% 17b 05 06 78% 18b 07 08 79% 19b 09 0 65% 20b 60% 21b 61% 22b 80%

(10) Analogously, the following compounds are prepared:

(11) TABLE-US-00008 Educt 1 Educt 2 Product Yield 24a 65% 25a 0 67% 26a 76% 27a 71% 28a 0 70% 29a 70% 30a 63% 31a 0 57% 32a 6% 33a 72% 34a 78% 35a 0 74% 36a 80% 37a 88% 38a 0 65% 39a 61% 40a 76% 41a 0 70% 42a 75% 43a 72% 45a 68% 46a 0 60% 47a 61% 48a 63% 49a 0 71% 50a 68% 51a 66% 52a 00 77% 53a 01 02 03 69% 54a 04 05 06 90% 55a 07 08 09 56% 56a 0 75% 57a 65% 58a 67% 59a 0 66% 60a 71% 61a 74% 62a 0 65%

c) 3-(2,9-diphenyl-9H-benzo[d]imidazo[1,2-a]imidazol-3-yl)-9-phenyl-9H-carbazole

(12) ##STR00531##

(13) A degassed solution of 29 g (146 mmol) of iodobenzene and 69 g (146 mmol) of 9-phenyl-3-(2-phenyl-9H-benzo[d]imidazo[1,2-a]imidazol-3-yl).sub.9H-carbazole, in 700 mL of toluene, is saturated with N2 during 1 h.

(14) Subsequently, 2.09 ml (8.5 mmol) of P(tBu).sub.3 are mixed with the mixture followed by 1.38 g (6.1 mmol) of palladium(II)acetate and by the addition of 17.5 g (184 mmol) of NaOtBu in the solid state. The reaction mixture is then heated under reflux during 1 h. After cooling to room temperature, 500 mL of water are carefully added. The aqueous phase is washed with 3×50 ml of toluene, dried over MgSO.sub.4 and the solvent is removed in vacuo. The crude product is then purified by chromatography on silica gel using heptane/acetic acid ester (20:2). The residue is recrystallized from toluene and finally sublimated in high vacuum (p=5×10.sup.−6 mbar).

(15) The yield is 64 g (116 mmol), corresponding to 80% of the theory.

(16) Analogously, the following compounds are prepared:

(17) TABLE-US-00009 Educt 1 Educt 2 Product Yield  1c 58%  2c 60%  3c 0 57%  4c 62%  5c 63%  6c 64%  7c 0 75%  8c 68%  9c 62% 10c 0 73% 11c 76% 12c 70%

B) FABRICATION OF OLEDS

(18) The following examples V1 to E8 (see Table 1 and 2) show data of various OLEDs.

(19) Substrate Pre-Treatment of Examples V1-E8:

(20) Glass plates with structured ITO (50 nm, indium tin oxide) form the substrates on which the OLEDs are processed. Before evaporation of the OLED materials, the substrates are cleaned in a wet process (using filtered deionized water and the detergent “Extran” of Merck KGaA). Subsequently the clean and dry substrates are exposed to a UV-Ozone plasma and then coated with a layer of 20 nm PEDOT:PSS (Poly(3,4-ethylendioxythiophen) poly(styrolsulfonate), by using an aqueous solution of CLEVIOS™ P VP AI 4083 purchased from Heraeus Precious Metals GmbH, Germany, for better processing. Before evaporating OLED materials onto the glass substrates, these are dried for 15 minutes at 170° C.

(21) The OLEDs have in principle the following layer structure: substrate/hole-transport layer (HTL)/optional interlayer (IL)/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 exact layer structure is denoted in Table 1 (ITO, PEDOT:PSS and Aluminium layers are omitted for clarity). The materials used for the OLED fabrication are presented in Table 3.

(22) All materials are applied by thermal vapour deposition in a vacuum chamber. 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 IC1:M1:TEG1 (55%:35%:10%) here means that material IC1 is present in the layer in a proportion by volume of 55%, M1 is present in the layer in a proportion of 35% and TEG1 is present in the layer in a proportion of 10%. Analogously, the electron-transport layer may also consist of a mixture of two materials.

(23) The OLEDs are characterised by standard methods. For this purpose, the electroluminescence spectra, the external quantum efficiency (EQE1000, measured in % at 1000 cd/m.sup.2) and the voltage (U1000, measured at 1000 cd/m.sup.2 in V) are determined from current/voltage/luminance characteristic lines (IUL characteristic lines) assuming a Lambertian emission profile. Lifetime LT is defined as the time in hours (h), after which the starting brightness is reduced to a certain level L1 in % of the starting brightness. Here L0; j0=4000 cd/m.sup.2 and L1=70% in Table 2 means, that the starting brightness is reduced from 4000 cd/m.sup.2 to 2800 cd/m.sup.2 after the time in hours (h) of column “LT”. Analogously, L0; j0=20 mA/cm.sup.2, L1=80% means, that the starting brightness at a current density of 20 mA/cm.sup.2 after the time “LT” in hours (h), is reduced to 80% of its starting value.

(24) The device data of various OLEDs is summarized in Table 2. The examples V1-V4 are comparison examples according to the state-of-the-art. The examples E.sup.1-E8 show data of OLEDs according to the invention.

(25) In the following section, several examples are described in more detail to show the advantages of the inventive OLEDs.

(26) Use of Inventive Compounds as Host Material in Phosphorescent OLEDs

(27) The use of the inventive compounds in the emitting layer (EML) or in the electron-blocking layer (EBL) results in significantly improved OLED device data compared to state-of-the-art materials, especially with respect to lifetime.

(28) The use of the inventive materials EgO1-Eg04 in combination with 105 and the green dopant TEG1 in phosphorescent green OLEDs results in an improved lifetime compared to devices with the materials SdT01-SdT02 (comparison of examples V1-V4 with E.sup.1-E8).

(29) The use of the inventive materials EgO1 to Eg04 in the electron blocking layer (EBL) of the OLED results in a significantly decreased voltage compared to devices with the materials SdT01 and SdT02 (comparison of examples V1-V4 with E.sup.1-E8).

(30) TABLE-US-00010 TABLE 1 OLED layer structure Ex. HIL IL HTL EBL EML HBL ETL EIL V1 SpA1 HATCN SpMA1 — IC5:SdT01:TEG1 ST2 ST2:LiQ — 70 nm 5 nm 70 nm (47%:47%:6%) 10 nm (50%:50%) 30 nm 30 nm V2 SpA1 HATCN SpMA1 — IC5:SdT02:TEG1 ST2 ST2:LiQ — 70 nm 5 nm 70 nm (47%:47%:6%) 10 nm (50%:50%) 30 nm 30 nm V3 SpA1 HATCN SpMA1 SdT01 IC1:TEG1 ST2 ST2:LiQ — 70 nm 5 nm 70 nm 20 nm (90%:10%) 10 nm (50%:50%) 30 nm 30 nm V4 SpA1 HATCN SpMA1 SdT02 IC1:TEG1 ST2 ST2:LiQ — 70 nm 5 nm 70 nm 20 nm (90%:10%) 10 nm (50%:50%) 30 nm 30 nm E1 SpAl HATCN SpMA1 — IC5:Eg01:TEG1 ST2 ST2:LiQ — 70 nm 5 nm 70 nm (47%:47%:6%) 10 nm (50%:50%) 30 nm 30 nm E2 SpA1 HATCN SpMA1 — IC5:Eg02:TEG1 ST2 ST2:LiQ — 70 nm 5 nm 70 nm (47%:47%:6%) 10 nm (50%:50%) 30 nm 30 nm E3 SpA1 HATCN SpMA1 — IC5:Eg03:TEG1 ST2 ST2:LiQ — 70 nm 5 nm 70 nm (47%:47%:6%) 10 nm (50%:50%) 30 nm 30 nm E4 SpA1 HATCN SpMA1 — IC5:Eg04:TEG1 ST2 ST2:LiQ — 70 nm 5 nm 70 nm (47%:47%:6%) 10 nm (50%:50%) 30 nm 30 nm E5 SpA1 HATCN SpMA1 Eg01 IC1:TEG1 ST2 ST2:LiQ — 70 nm 5 nm 70 nm 20 nm (90%:10%) 10 nm (50%:50%) 30 nm 30 nm E6 SpA1 HATCN SpMA1 Eg02 IC1:TEG1 ST2 ST2:LiQ — 70 nm 5 nm 70 nm 20 nm (90%:10%) 10 nm (50%:50%) 30 nm 30 nm E7 SpA1 HATCN SpMA1 Eg03 IC1:TEG1 ST2 ST2:LiQ — 70 nm 5 nm 70 nm 20 nm (90%:10%) 10 nm (50%:50%) 30 nm 30 nm E8 SpA1 HATCN SpMA1 Eg04 IC1:TEG1 ST2 ST2:LiQ — 70 nm 5 nm 70 nm 20 nm (90%:10%) 10 nm (50%:50%) 30 nm 30 nm

(31) TABLE-US-00011 TABLE 2 OLED device data U1000 L.sub.1 LD Bsp. (V) L.sub.0; j.sub.0 % (h) V1 3.0-3.3 20 mA/cm.sup.2 80 30-50 V2 3.0-3.3 20 mA/cm.sup.2 80 40-60 E1 3.0-3.3 20 mA/cm.sup.2 80  80-100 E2 3.0-3.3 20 mA/cm.sup.2 80 100-120 E3 3.0-3.3 20 mA/cm.sup.2 80 100-120 E4 3.0-3.3 20 mA/cm.sup.2 80  80-100 V3 4.1-4.6 20 mA/cm.sup.2 80 V4 3.9-4.5 20 mA/cm.sup.2 80 E5 3.4-3.7 20 mA/cm.sup.2 80 E6 3.2-3.5 20 mA/cm.sup.2 80 E7 3.2-3.5 20 mA/cm.sup.2 80 E8 3.4-3.7 20 mA/cm.sup.2 80

(32) TABLE-US-00012 TABLE 3 Chemical structures of the OLED materials 0 0