Compound, Organic Semiconducting Material Comprising the Same, Organic Electronic Device Comprising the Same and Display Device Comprising the Same

Abstract

The present invention relates to a compound, an organic semiconducting material comprising the same, an organic electronic device comprising the same and a display device comprising the same.

##STR00001##

Claims

1. Compound of formula (1) ##STR00070## wherein Hy.sup.1 has the formula (2) ##STR00071## R.sup.1 and R.sup.2 are independently selected from C.sub.6 to C.sub.60 aryl or C.sub.2 to C.sub.42 heteroaryl; R.sup.1 and R.sup.2 may independently be substituted with one or more substituents independently selected from the group consisting of C.sub.6 to C.sub.12 aryl, C.sub.3 to C.sub.11 heteroaryl, and C.sub.1 to C.sub.6 alkyl, D, C.sub.1 to C.sub.6 alkoxy, C.sub.3 to C.sub.6 branched alkyl, C.sub.3 to C.sub.6 cyclic alkyl, C.sub.3 to C.sub.6 branched alkoxy, C.sub.3 to C.sub.6 cyclic alkoxy, partially or perfluorinated C.sub.1 to C.sub.6 alkyl, partially or perfluorinated C.sub.1 to C.sub.6 alkoxy, partially or perdeuterated C.sub.1 to C.sub.6 alkyl, partially or perdeuterated C.sub.1 to C.sub.6 alkoxy, halogen, CN or PY(R.sup.10).sub.2, wherein Y is selected from O, S or Se, and R.sup.10 is independently selected from C.sub.6 to C.sub.12 aryl, C.sub.3 to C.sub.12 heteroaryl, C.sub.1 to C.sub.6 alkyl, C.sub.1 to C.sub.6 alkoxy, partially or perfluorinated C.sub.1 to C.sub.6 alkyl, partially or perfluorinated C.sub.1 to C.sub.6 alkoxy, partially or perdeuterated C.sub.1 to C.sub.6 alkyl, partially or perdeuterated C.sub.1 to C.sub.6 alkoxy; each C.sub.6 to C.sub.12 aryl substituent on R.sup.1 and/or R.sup.2 and each C.sub.3 to C.sub.11 heteroaryl substituent on R.sup.1 and/or R.sup.2 may independently be substituted with C.sub.1 to C.sub.4 alkyl or halogen; Hy.sup.2 has the formula (3) ##STR00072## wherein R.sup.3 to R.sup.5 are independently selected from C.sub.6 to C.sub.60 aryl or C.sub.2 to C.sub.42 heteroaryl; R.sup.3 to R may independently be substituted with one or more substituents independently selected from the group consisting of C.sub.6 to C.sub.12 aryl, C.sub.3 to C.sub.11 heteroaryl, and C.sub.1 to C.sub.6 alkyl, D, C.sub.1 to C.sub.6 alkoxy, C.sub.3 to C.sub.6 branched alkyl, C.sub.3 to C.sub.6 cyclic alkyl, C.sub.3 to C.sub.6 branched alkoxy, C.sub.3 to C.sub.6 cyclic alkoxy, partially or perfluorinated C.sub.1 to C.sub.6 alkyl, partially or perfluorinated C.sub.1 to C.sub.6 alkoxy, partially or perdeuterated C.sub.1 to C.sub.6 alkyl, partially or perdeuterated C.sub.1 to C.sub.6 alkoxy, halogen, CN or PY(R.sup.10).sub.2, wherein Y is selected from O, S or Se, and R.sup.10 is independently selected from C.sub.6 to C.sub.12 aryl, C.sub.3 to C.sub.12 heteroaryl, C.sub.1 to C.sub.6 alkyl, C.sub.1 to C.sub.6 alkoxy, partially or perfluorinated C.sub.1 to C.sub.6 alkyl, partially or perfluorinated C.sub.1 to C.sub.6 alkoxy, partially or perdeuterated C.sub.1 to C.sub.6 alkyl, partially or perdeuterated C.sub.1 to C.sub.6 alkoxy; each C.sub.6 to C.sub.12 aryl substituent on R.sup.3 to R.sup.5 and each C.sub.3 to C.sub.11 heteroaryl substituent on R.sup.3 to R.sup.5 may independently be substituted with C.sub.1 to C.sub.4 alkyl or halogen; at least one of R.sup.3 to R.sup.5 has the formula (4) ##STR00073## *.sup.3-L.sup.2-Hy.sup.3 is bond at *.sup.3 to the remaining structure of formula (3); L.sup.2 is a single bond or phenylene; Hy.sup.3 is C.sub.3 to C.sub.42 heteroaryl comprising at least one unsubstituted 6-membered N-containing heteroaromatic ring, wherein L.sup.2 and Hy.sup.3 are bonded via a single bond between L.sup.2 and the 6-membered N-containing heteroaromatic ring; or between L.sup.2 and a condensed ring system with two or three condensed rings, wherein one of the two or three rings is the 6-membered N-containing heteroaromatic ring; L.sup.1 is selected from substituted or unsubstituted C.sub.6 to C.sub.60 arylene; L.sup.1 may be substituted with one or more substituents independently selected from the group consisting of C.sub.6 to C.sub.12 aryl, C.sub.3 to C.sub.11 heteroaryl, and C.sub.1 to C.sub.6 alkyl, D, C.sub.1 to C.sub.6 alkoxy, C.sub.3 to C.sub.6 branched alkyl, C.sub.3 to C.sub.6 cyclic alkyl, C.sub.3 to C.sub.6 branched alkoxy, C.sub.3 to C.sub.6 cyclic alkoxy, partially or perfluorinated C.sub.1 to C.sub.6 alkyl, partially or perfluorinated C.sub.1 to C.sub.6 alkoxy, partially or perdeuterated C.sub.1 to C.sub.6 alkyl, partially or perdeuterated C.sub.1 to C.sub.6 alkoxy, halogen, CN or PY(R.sup.10).sub.2, wherein Y is selected from O, S or Se, and R.sup.10 is independently selected from C.sub.6 to C.sub.12 aryl, C.sub.3 to C.sub.12 heteroaryl, C.sub.1 to C.sub.6 alkyl, C.sub.1 to C.sub.6 alkoxy, partially or perfluorinated C.sub.1 to C.sub.6 alkyl, partially or perfluorinated C.sub.1 to C.sub.6 alkoxy, partially or perdeuterated C.sub.1 to C.sub.6 alkyl, partially or perdeuterated C.sub.1 to C.sub.6 alkoxy; each C.sub.6 to C.sub.12 aryl substituent on L and each C.sub.3 to C.sub.11 heteroaryl substituent on L may independently be substituted with C.sub.1 to C.sub.4 alkyl or halogen; L.sup.1 comprises at least one 6-membered aromatic ring, wherein the 6-membered aromatic ring has the formula (5) or (6) ##STR00074## Hy.sup.1 is bonded at *.sup.1 via a single bond to L.sup.1; and Hy.sup.2 is bonded at *.sup.2 via a single bond to L.sup.2; wherein the following compounds are excluded: ##STR00075##

2. Compound according to claim 1, wherein R.sup.1 and R.sup.2 are independently selected from unsubstituted C.sub.6 to C.sub.60 aryl.

3. Compound according to claim 1, wherein R.sup.1 and R.sup.2 are independently selected from phenyl and biphenyl-yl.

4. Compound according to claim 1, wherein the structure according to formula (4) is selected from the following formulas (7) to (11) ##STR00076##

5. Compound according to claim 1, wherein R.sup.3 and R.sup.5 are independently selected from C.sub.6 to C.sub.60 aryl and R.sup.4 has the formula (4) and the structure according to formula (4) is selected from the following formulas (7) to (11) ##STR00077##

6. Compound according to claim 1, wherein the 6-membered aromatic ring comprised in L.sup.1 has the formula (6) ##STR00078##

7. Compound according to claim 1, wherein L.sup.1 has a formula selected from the following formulas (13) to (16) ##STR00079##

8. Compound according to claim 1, wherein L.sup.2 is a single bond.

9. Compound according to claim 1, wherein the compound has a |LUMOLUMO+1|0.08 eV.

10. Compound according to claim 9, wherein the compound meets the following requirement: 0.04|LUMOLUMO+1|0.08 eV.

11. Organic semiconducting material comprising the compound according to claim 1.

12. Organic semiconducting material according to claim 11, wherein the organic semiconducting material further comprises an n-dopant.

13. Organic electronic device comprising the organic semiconducting material according to claim 11.

14. Organic electronic device according to claim 13, wherein the organic electronic device is an organic light emitting diode.

15. Display device comprising the organic electronic device according to claim 14.

Description

DESCRIPTION OF THE DRAWINGS

[0346] The aforementioned components, as well as the claimed components and the components to be used in accordance with the invention in the described embodiments, are not subject to any special exceptions with respect to their size, shape, material selection and technical concept such that the selection criteria known in the pertinent field can be applied without limitations.

[0347] Additional details, characteristics and advantages of the object of the invention are disclosed in the dependent claims and the following description of the respective figures which in an exemplary fashion show preferred embodiments according to the invention. Any embodiment does not necessarily represent the full scope of the invention, however, and reference is made therefore to the claims and herein for interpreting the scope of the invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the present invention as claimed.

[0348] FIG. 1 is a schematic sectional view of an organic electronic device, according to an exemplary embodiment of the present invention;

[0349] FIG. 2 is a schematic sectional view of an organic light-emitting diode (OLED), according to an exemplary embodiment of the present invention;

[0350] FIG. 3 is a schematic sectional view of an OLED, according to an exemplary embodiment of the present invention.

[0351] FIG. 4 is a schematic sectional view of an OLED comprising a charge generation layer and two emission layers, according to an exemplary embodiment of the present invention.

[0352] Hereinafter, the figures are illustrated in more detail with reference to examples. However, the present disclosure is not limited to the following figures.

[0353] Herein, when a first element is referred to as being formed or disposed on or onto a second element, the first element can be disposed directly on the second element, or one or more other elements may be disposed there between. When a first element is referred to as being formed or disposed directly on or directly onto a second element, no other elements are disposed there between.

[0354] FIG. 1 is a schematic sectional view of an organic electronic device 100, according to an exemplary embodiment of the present invention. The organic electronic device 100 includes a substrate no, an anode 120, a photoactive layer (PAL) 125, an organic semiconductor layer comprising a compound of formula (1) 160. The organic semiconductor layer comprising compound of formula (1) 160 is formed on the PAL 125. Onto the organic semiconductor layer 160, a cathode 190 is disposed.

[0355] FIG. 2 is a schematic sectional view of an organic light-emitting diode (OLED) 100, according to an exemplary embodiment of the present invention. The OLED 100 includes a substrate 110, an anode 120, a hole injection layer (HIL) 130, a hole transport layer (HTL) 140, an emission layer (EML) 150, an electron transport layer (ETL) 160. The electron transport layer (ETL) 160 is formed on the EML 150. Onto the electron transport layer (ETL) 160, an electron injection layer (EIL) 180 is disposed. The cathode 190 is disposed directly onto the electron injection layer (EIL) 180.

[0356] Instead of a single electron transport layer 160, optionally an electron transport layer stack (ETL) can be used.

[0357] FIG. 3 is a schematic sectional view of an OLED 100, according to another exemplary embodiment of the present invention. FIG. 3 differs from FIG. 2 in that the OLED 100 of FIG. 3 comprises an electron blocking layer (EBL) 145 and a hole blocking layer (HBL) 155.

[0358] Referring to FIG. 3, the OLED 100 includes a substrate 110, an anode 120, a hole injection layer (HIL) 130, a hole transport layer (HTL) 140, an electron blocking layer (EBL) 145, an emission layer (EML) 150, a hole blocking layer (HBL) 155, an electron transport layer (ETL) 160, an electron injection layer (EIL) 180 and a cathode electrode 190.

[0359] Preferably, the organic semiconductor layer comprising a compound of Formula (1) may be an ETL.

[0360] FIG. 4 is a schematic sectional view of an OLED 100, according to another exemplary embodiment of the present invention. FIG. 4 differs from FIG. 3 in that the OLED 100 of FIG. 4 further comprises a charge generation layer (CGL) and a second emission layer (151).

[0361] Referring to FIG. 4, the OLED 100 includes a substrate 110, an anode 120, a first hole injection layer (HIL) 130, a first hole transport layer (HTL) 140, a first electron blocking layer (EBL) 145, a first emission layer (EML) 150, a first hole blocking layer (HBL) 155, a first electron transport layer (ETL) 160, an n-type charge generation layer (n-type CGL) 185, a hole generating layer (p-type charge generation layer; p-type GCL) 135, a second hole transport layer (HTL) 141, a second electron blocking layer (EBL) 146, a second emission layer (EML) 151, a second hole blocking layer (EBL) 156, a second electron transport layer (ETL) 161, a second electron injection layer (EIL) 181 and a cathode 190.

[0362] Preferably, the organic semiconductor layer comprising a compound of Formula (1) may be an n-type CGL.

[0363] Preferably, the organic semiconductor layer comprising a compound of Formula (1) may be the first ETL, n-type CGL and/or second ETL.

[0364] While not shown in FIG. 1, FIG. 2, FIG. 3 and FIG. 4, a sealing layer may further be formed on the cathode electrodes 190, in order to seal the OLEDs 100. In addition, various other modifications may be applied thereto.

[0365] Hereinafter, the embodiments are illustrated in more detail with reference to examples.

[0366] However, the present disclosure is not limited to the following examples.

DETAILED DESCRIPTION

[0367] The invention is furthermore illustrated by the following examples which are illustrative only and non-binding.

EXPERIMENTAL PART

Melting Point

[0368] The melting point (mp) is determined as peak temperatures from the DSC curves of the above TGA-DSC measurement or from separate DSC measurements (Mettler Toledo DSC822e, heating of samples from room temperature to completeness of melting with heating rate 10 K/min under a stream of pure nitrogen. Sample amounts of 4 to 6 mg are placed in a 40 L Mettler Toledo aluminum pan with lid, a <1 mm hole is pierced into the lid).

Glass Transition Temperature

[0369] The glass transition temperature (Tg) is measured under nitrogen and using a heating rate of 10 K per min in a Mettler Toledo DSC 822e differential scanning calorimeter as described in DIN EN ISO 11357, published in March 2010.

Rate Onset Temperature

[0370] The rate onset temperature (T.sub.RO) is determined by loading 100 mg compound into a VTE source. As VTE source a point source for organic materials may be used as supplied by Kurt J. Lesker Company (www.lesker.com) or CreaPhys GmbH (http://www.creaphys.com). The VTE source is heated at a constant rate of 15 K/min at a pressure of less than 10.sup.5 mbar and the temperature inside the source measured with a thermocouple. Evaporation of the compound is detected with a QCM detector which detects deposition of the compound on the quartz crystal of the detector. The deposition rate on the quartz crystal is measured in Angstrom per second. To determine the rate onset temperature, the deposition rate is plotted against the VTE source temperature. The rate onset is the temperature at which noticeable deposition on the QCM detector occurs. For accurate results, the VTE source is heated and cooled three time and only results from the second and third run are used to determine the rate onset temperature.

[0371] To achieve good control over the evaporation rate of an organic compound, the rate onset temperature may be in the range of 200 to 255 C. If the rate onset temperature is below 200 C. the evaporation may be too rapid and therefore difficult to control. If the rate onset temperature is above 255 C. the evaporation rate may be too low which may result in low tact time and decomposition of the organic compound in VTE source may occur due to prolonged exposure to elevated temperatures.

[0372] The rate onset temperature is an indirect measure of the volatility of a compound. The higher the rate onset temperature the lower is the volatility of a compound.

Reduction Potential

[0373] The reduction potential is determined by cyclic voltammetry with potenioststic device Metrohm PGSTAT30 and software Metrohm Autolab GPES at room temperature. The redox potentials given at particular compounds were measured in an argon de-aerated, dry 0.1M TH F solution of the tested substance, under argon atmosphere, with 0.1M tetrabutylammonium hexafluorophosphate supporting electrolyte, between platinum working electrodes and with an Ag/AgCl pseudo-standard electrode (Metrohm Silver rod electrode), consisting of a silver wire covered by silver chloride and immersed directly in the measured solution, with the scan rate 100 mV/s. The first run was done in the broadest range of the potential set on the working electrodes, and the range was then adjusted within subsequent runs appropriately. The final three runs were done with the addition of ferrocene (in 0.1M concentration) as the standard. The average of potentials corresponding to cathodic and anodic peak of the studied compound, after subtraction of the average of cathodic and anodic potentials observed for the standard Fc.sup.+/Fc redox couple, afforded finally the values reported above. All studied compounds as well as the reported comparative compounds showed well-defined reversible electrochemical behaviour.

Dipole Moment

[0374] The dipole moment |{right arrow over ()}| of a molecule containing N atoms is given by:

[00001]$\stackrel{.fwdarw.}{}=\underset{i}{\overset{N}{.Math.}}{q}_i\stackrel{.fwdarw.}{r_{\mathrm{.Math.}}}.Math.\stackrel{.fwdarw.}{}.Math.=\sqrt{{}_x^2+{}_y^2+{}_z^2}$

[0375] where q.sub.i and r.sub.i are the partial charge and position of atom i in the molecule.

[0376] The dipole moment is determined by a semi-empirical molecular orbital method.

[0377] The geometries of the molecular structures are optimized using the hybrid functional B3LYP with the 6-31G* basis set in the gas phase as implemented in the program package TURBOMOLE V6.5 (TURBOMOLE GmbH, Litzenhardtstrasse 19, 76135 Karlsruhe, Germany). If more than one conformation is viable, the conformation with the lowest total energy is selected to determine the bond lengths of the molecules.

Calculated HOMO and LUMO

[0378] The HOMO and LUMO are calculated with the program package TURBOMOLE V6.5 (TURBOMOLE GmbH, Litzenhardtstrasse 19, 76135 Karlsruhe, Germany). The optimized geometries and the HOMO and LUMO energy levels of the molecular structures are determined by applying the hybrid functional B3LYP with a 6-31G* basis set in the gas phase.

[0379] If more than one conformation is viable, the conformation with the lowest total energy is selected.

Synthesis Procedure

5-(5-(3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-3,6-diphenylpyrazin-2-yl)isoquinoline (Compound E3)

##STR00061##

[0380] 1.sup.st Step. 2-(3-(5-chloro-3,6-diphenylpyrazin-2-yl)phenyl)-4,6-diphenyl-1,3,5-triazine

[0381] A 3-neck round-bottom flask was flushed with nitrogen and charged with 2,4-diphenyl-6-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-1,3,5-triazine (CAS 1269508-31-7, 1 eq, 40.0 g), 2,5-dichloro-3,6-diphenylpyrazine (CAS 74134-61-5, 0.95 eq, 26.3 g), tetrakis(triphenylphosphine)palladium(0) (CAS 14221-01-3, 0.025 eq, 2.7 g), potassium carbonate (CAS 584-08-7, 2 eq, 25.4 g). Deaerated mixture of 368 ml dioxane and 92 ml water was added. Reaction was running 2 days at 50 C. under a nitrogen atmosphere. Yellow suspension was formed. Reaction was cooled down and precipitate was filtered and washed with dioxane, water and methanol. Raw product was dissolved in chlorobenzene and filtrated through a silica pad, solvent was evaporated at reduced pressure. Final purification was done by sublimation. Yield: 22.8 g (45%).

2.SUP.nd .Step. 5-(5-(3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-3,6-diphenylpyrazin-2-yl)isoquinoline

[0382] A 3-neck round-bottom flask was flushed with nitrogen and charged with 2-(3-(5-chloro-3,6-diphenylpyrazin-2-yl)phenyl)-4,6-diphenyl-1,3,5-triazine (no CAS available, 1 eq, 20.0 g), isoquinolin-5-ylboronic acid (CAS 371766-08-4, 1.5 eq, 9.0 g), tetrakis(triphenylphosphine)palladium(0) (CAS 14221-01-3, 0.02 eq, 0.8 g), potassium carbonate (CAS 584-08-7, 2 eq, 9.6 g). Deaerated mixture of 200 ml dioxane and 40 ml water was added. Reaction was running for 22 hours at 60 C. under a nitrogen atmosphere. After cooling down to room temperature brown suspension was formed. Raw solid material was filtered, dissolved in 600 ml chloroform and vigorously stirred for 3 hours with 30 ml 3% solution of sodium diethyldithiocarbamate. Organic phase was washed with water, dried over magnesium sulfate; filtered and the solvent was removed on a rotary evaporator. Final purification was done by sublimation. Light orange powder. Yield: 20.1 g (77%). (ESI-APCI-MS: 667).

2-(3-(3,6-diphenyl-5-(pyridin-3-yl)pyrazin-2-yl)phenyl)-4,6-diphenyl-1,3,5-triazine (Compound E4)

##STR00062##

[0383] 1.sup.st Step. 2-chloro-3,6-diphenyl-5-(Pyridin-3-yl)pyrazine

[0384] A 5-liter glass reactor was charged with 2,5-dichloro-3,6-diphenylpyrazine (CAS 74134-61-5, 1 eq, 105.4 g), 3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridine (CAS 329214-79-1, 1.05 eq, 75.4 g), tetrakis(triphenylphosphine)palladium(0) (CAS 14221-01-3, 0.05 eq, 20.2 g), potassium carbonate (CAS 584-08-7, 2 eq, 96.7 g). Deaerated mixture of 1800 ml toluene/tetrahydrofuran (THF)/water (1:1:1) was added. Reaction was running 3 days at 65 C. under a nitrogen atmosphere. After reaction completion, solvent volume was reduced on rotary evaporator to 200 ml, extracted into dichloromethane (DCM) and washed with 200 ml brine.

[0385] Organic phase was dried and chromatographed (1.5 kg silica gel, 5% ethyl acetate in chloroform). Resulting product was stirred in 600 ml hexane/chloroform (5:1) at reflux for 2 h., filtered off and dried. Yield: 46.3 g (38%).

2.SUP.nd .Step. 2-(3-(3,6-diphenyl-5-(pyridin-3-yl)pyrazin-2-yl)phenyl)-4,6-diphenyl-1,3,5-triazine

[0386] A 3-neck round-bottom flask was flushed with nitrogen and charged with 2-chloro-3,6-diphenyl-5-(pyridin-3-yl)pyrazine (no CAS available, 1 eq, 9.5 g), 2,4-diphenyl-6-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-1,3,5-triazine (CAS 1269508-31-7, 1 eq, 12.0 g), [1,1-Bis(diphenylphosphino)ferrocene]dichloropalladium(II) (CAS 72287-26-4, 0.02 eq, 0.4 g), potassium carbonate (CAS 584-08-7, 2 eq, 7.6 g). Deaerated mixture of 120 ml dioxane and 30 ml water was added. Reaction was running at 55 C. under a nitrogen atmosphere overnight. Next day orange suspension was formed, reaction was cooled down; precipitate was filtered and washed with water and methanol. Product was dissolved in 800 ml chloroform and filtered through a silica pad. Final purification was done by sublimation. White solid. Yield: 12.1 g (71%) (ESI-MS: 617).

2-(2-(3,6-diphenyl-5-(6-phenylpyridin-3-yl)pyrazin-2-yl)phenyl)-4,6-diphenyl-1,3,5-triazine (Compound E6)

##STR00063##

1.SUP.st .Step. 2-(2-(5-chloro-3,6-diphenylpyrazin-2-yl)phenyl)-4,6-diphenyl-1,3,5-triazine

[0387] A 3-neck round-bottom flask was flushed with nitrogen and charged with 2,5-dichloro-3,6-diphenylpyrazine (CAS 74134-61-5, 1 eq, 20.8 g), 2,4-diphenyl-6-(2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-1,3,5-triazine (CAS 1696425-27-0, 1 eq, 30.0 g), tetrakis(triphenylphosphine)palladium(0) (CAS 14221-01-3, 0.05 eq, 4.0 g), potassium carbonate (CAS584-08-7, 2 eq, 19.1 g). Deaerated mixture of THF/toluene/water (1:1:1) 540 ml was added. Reaction was running under an argon atmosphere for 44 hours at reflux. Then the reaction mixture was cooled down and extracted in DCM, washed with aq. K2C.sub.6O3. Combined organic phases were dried and purified by column chromatography (2 kg silica gel, 50% DCM in petroleum ether). Yield: 16.1 g (41%).

2.SUP.nd .Step. 2-(2-(3,6-diphenyl-5-(6-phenylpyridin-3-yl)pyrazin-2-yl)phenyl)-4,6-diphenyl-1,3,5-triazine

[0388] A 3-neck round-bottom flask was flushed with nitrogen and charged with 2-(2-(5-chloro-3,6-diphenylpyrazin-2-yl)phenyl)-4,6-diphenyl-1,3,5-triazine (no CAS found, 1 eq, 11.1 g), (6-phenylpyridin-3-yl)boronic acid (CAS 155079-10-0, 1.5 eq, 5.8 g), bis(triphenylphosphine)-palladium-II-chloride (CAS 13965-03-2, 0.03 eq, 0.4 g), potassium carbonate (CAS 584-08-7, 4 eq, 10.6 g). Deaerated mixture of THF/water (3:1) 200 ml was added. Reaction was running under an argon atmosphere for 1 hour at reflux. Then the reaction mixture was cooled down and extracted with DCM, the extract was washed with aq. K2C6O3. Combined organic phases were dried and purified by column chromatography (goo g silica gel, eluent DCM). Final purification was done by sublimation. White powder. Yield: 10.6 g (79%) (ESI-MS: 693)

2-(3-(3,6-diphenyl-5-(6-phenylpyridin-3-yl)pyrazin-2-yl)phenyl)-4,6-diphenyl-1,3,5-triazine (Compound E1)

##STR00064##

1.SUP.st .Step. 2-chloro-3,6-diphenyl-5-(6-phenylpyridin-3-yl)pyrazine

[0389] A 3-neck round-bottom flask was flushed with nitrogen and charged with 2,5-dichloro-3,6-diphenylpyrazine (CAS 74134-61-5, 1 eq, 30.0 g), (6-phenylpyridin-3-yl)boronic acid (CAS 155079-10-0, 1.3 eq, 25.8 g), tetrakis(triphenylphosphine)palladium(0) (CAS 14221-01-3, 0.02 eq, 2.3 g), potassium carbonate (CAS 584-08-7, 2 eq, 27.5 g). Deaerated mixture of 550 ml dioxane and 100 ml water was added. Reaction was running at 50 C. under a nitrogen atmosphere for 2 days. Then the reaction mixture was cooled down, solvent was evaporated. Raw product was dissolved in 1 L DCM and washed with 200 ml water, dried over MgSO4 and filtered through a silica pad. Solvent was evaporated under reduced pressure and the product was chromatographed (460 g silica gel, DCM/hexane 2:1). Yield: 14.3 g (35%).

2.SUP.nd .Step. 2-(3-(3,6-diphenyl-5-(6-phenylpyridin-3-yl)pyrazin-2-yl)phenyl)-4,6-diphenyl-1,3,5-triazine

[0390] A 3-neck round-bottom flask was flushed with nitrogen and charged with 2,4-diphenyl-6-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-1,3,5-triazine (CAS 1269508-31-7, 1.1 eq, 12.1 g), 2-chloro-3,6-diphenyl-5-(6-phenylpyridin-3-yl)pyrazine (no CAS found, 1 eq, 10.6 g), tetrakis(triphenylphosphine)palladium(0) (CAS 14221-01-3, 0.02 eq, 0.6 g), potassium carbonate (CAS 584-08-7, 2 eq, 7.0 g). Deaerated mixture of 400 ml dioxane and 30 ml water was added. Reaction was running at 50 C. under a nitrogen atmosphere overnight.

[0391] Next day gray suspension was formed, reaction was cooled down, precipitate was filtrated and washed with dioxane, water and methanol. Obtained raw product was dissolved in 1100 ml chloroform, filtrated through silica pad. Solvent was evaporated and product was recrystallized from THF. Final purification was done by sublimation. White powder. Yield: 8.7 g (53%)

2-(3-(3,6-diphenyl-5-(3-(pyridin-4-yl)phenyl)pyrazin-2-yl)phenyl)-4,6-diphenyl-1,3,5-triazine (Compound E2)

##STR00065##

1.SUP.st .Step. 2-(3-(5-chloro-3,6-diphenylpyrazin-2-yl)phenyl)-4,6-diphenyl-1,3,5-triazine

[0392] A 3-neck round-bottom flask was flushed with nitrogen and charged with 2,4-diphenyl-6-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-1,3,5-triazine (CAS 1269508-31-7, 1 eq, 40.0 g), 2,5-dichloro-3,6-diphenylpyrazine (CAS 74134-61-5, 0.95 eq, 26.3 g), tetrakis(triphenylphosphine)palladium(0) (CAS 14221-01-3, 0.025 eq, 2.7 g), potassium carbonate (CAS 584-08-7, 2 eq, 25.4 g). Deaerated mixture of 368 ml dioxane and 92 ml water was added. Reaction was running 2 days at 50 C. under a nitrogen atmosphere. Yellow suspension was formed. Reaction was cooled down and precipitate was filtered and washed with dioxane, water and methanol. Raw product was dissolved in chlorobenzene and filtrated through a silica pad, solvent was evaporated at reduced pressure. Final purification was done by sublimation. Yield: 22.8 g (45%).

2.SUP.nd .Step. 2-(3-(3,6-diphenyl-5-(3-(Pyridin-4-yl)phenyl)pyrazin-2-yl)phenyl)-4,6-diphenyl-1,3,5-triazine

[0393] A 3-neck round-bottom flask was flushed with nitrogen and charged with 2-(3-(5-chloro-3,6-diphenylpyrazin-2-yl)phenyl)-4,6-diphenyl-1,3,5-triazine (no CAS available, 1 eq, 19.5 g), 4-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)pyridine (CAS 1009033-83-3, 1.6 eq 15.3 g), tetrakis(triphenylphosphine)palladium(0) (CAS 14221-01-3, 0.02 eq 0.8 g), potassium carbonate (CAS 584-08-7, 2 eq, 9.4 g). Deaerated mixture of 280 ml dioxane and 70 ml water was added. Reaction was running 2 days at 60 C. under a nitrogen atmosphere. Brown suspension was formed. Reaction was cooled down and precipitate was filtrated and washed with dioxane, water and methanol. Raw product was dissolved in 370 ml toluene and filtered hot through silica pad. Final purification was done by sublimation. Pale yellow powder. Yield: 9.2 g (40%) (ESI-MS: 693)

3-(5-(3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-3,6-diphenylpyrazin-2-yl)quinolone (Compound E5)

##STR00066##

1.SUP.st .Step. 2-(3-(5-chloro-3,6-diphenylpyrazin-2-yl)phenyl)-4,6-diphenyl-1,3,5-triazine

[0394] A 3-neck round-bottom flask was flushed with nitrogen and charged with 2,4-diphenyl-6-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-1,3,5-triazine (CAS 1269508-31-7, 1 eq, 40.0 g), 2,5-dichloro-3,6-diphenylpyrazine (CAS 74134-61-5, 0.95 eq, 26.3 g), tetrakis(triphenylphosphine)palladium(0) (CAS 14221-01-3, 0.025 eq, 2.7 g), potassium carbonate (CAS 584-08-7, 2 eq, 25.4 g). Deaerated mixture of 368 ml dioxane and 92 ml water was added. Reaction was running 2 days at 50 C. under a nitrogen atmosphere. Yellow suspension was formed. Reaction was cooled down and precipitate was filtered and washed with dioxane, water and methanol. Raw product was dissolved in chlorobenzene and filtrated through a silica pad, solvent was evaporated at reduced pressure. Final purification was done by sublimation. Yield: 22.8 g (45%).

2.SUP.nd .Step. 3-(5-(3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-3,6-diphenylpyrazin-2-yl)quinoline

[0395] A 3-neck round-bottom flask was flushed with nitrogen and charged with 2-(3-(5-chloro-3,6-diphenylpyrazin-2-yl)phenyl)-4,6-diphenyl-1,3,5-triazine (no CAS available, 1 eq, 20.0 g), quinoline-3-ylboronic acid (CAS 191162-39-7, 1.4 eq, 8.4 g), tetrakis(triphenylphosphine)palladium(0) (CAS 14221-01-3, 0.02 eq, 0.8 g), potassium carbonate (CAS 584-08-7, 2 eq, 9.6 g). Deaerated mixture of 140 ml dioxane and 40 ml water was added. Reaction was running 4 days at 80 C. under a nitrogen atmosphere. Brown suspension was formed. Reaction was cooled down and precipitate was filtrated and washed with water and methanol. Raw product was dissolved in 850 ml chloroform, the solution filtered through a silica pad, evaporated and the raw material recrystallized from toluene. Final purification was done by sublimation. White powder. Yield: 15.2 g (64%) (ESI-MS: 667).

General Procedure for Fabrication of OLEDs

[0396] For the top emission OLED devices a substrate with dimensions of 150 mm150 mm0.7 mm was ultrasonically cleaned with a 2% aqueous solution of Deconex FPD 211 for 7 minutes and then with pure water for 20 minutes, and dried for 15 minutes in a spin rinse dryer. Subsequently, Ag was deposited as anode at a pressure of 10-5 to 10-7 mbar.

[0397] Then, HT-1 and D-1 were vacuum co-deposited on the anode to form a HIL. Then, HT-1 was vacuum deposited on the HIL to form an HTL. Then, HT-2 was vacuum deposited on the HTL to form an electron blocking layer (EBL).

[0398] Afterwards the emission layer was formed on the EBL by co-deposition of HOST-1 and EMTITER-1.

[0399] The hole blocking layer (HBL) was formed on the emission layer by depositing compound ET-1.

[0400] Then, the compound of Formula (1) (selected from compounds E1 to E6), respectively the comparative compound (selected from compounds C1 to C4), was vacuum co-deposited with LiQ in the ratio 1:1 onto the hole blocking layer to form the electron transport layer.

[0401] Then, the electron injection layer is formed by depositing Yb.

[0402] A cap layer of HT-1 is formed on the cathode.

[0403] The details of the layer stack in the top emission OLED devices are given below. A slash / separates individual layers. Layer thicknesses are given in squared brackets [ . . . ], mixing ratios in wt % or vol % are given in round brackets ( . . . ):

Layer Stack Details Used in the OLED Device Examples:

[0404] Ag [100 nm]/HT-1:D-1 (wt % 92:8) [10 nm]/HT-1 [128 nm]/HT-2 [5 nm]/HOST-1:EMITTER-1 (vol % 97:3) [20 nm]/ET-1 [5 nm]/Compound of formula 1 or comparative compound [31 nm]/Yb [2 nm]/Ag:Mg (vol % 90:10) [13 nm]/HT-1 [75 nm].

TABLE-US-00001 TABLE 1 List of compounds used IUPAC name Reference HT-1 N-([1,1-biphenyl]-4-yl)-9,9-dimethyl- US2016322581 N-(4-(9-phenyl-9H-carbazol-3-yl)phe- nyl)-9H-fluoren-2-amine [CAS 1242056-42-3] HT-2 N-([1,1-biphenyl]-4-yl)-9,9-diphenyl- WO2014088047 N-(4-(triphenylsilyl)phenyl)-9H-fluoren- 2-amine [CAS 1613079-70-1] D-1 4,4,4-((1E,1E,1E)-cyclopropane- US2008265216 1,2,3-triylidenetris(cyanomethanylyli- dene))tris(2,3,5,6-tetrafluoro- benzonitrile) [CAS 1224447-88-4] HOST-1 H09 (Fluorescent-blue host material) Commercially available from Sun Fine Chemicals, Inc, S. Korea EMITTER-1 BD200 (Fluorescent-blue emitter Commercially material) available from Sun Fine Chemicals, Inc, S. Korea ET-1 2-(3-(9,9-dimethyl-9H-fluoren-2-yl)- WO 2016105141 [1,1-biphenyl]-3-yl)-4,6-diphenyl- 1,3,5-triazine [CAS 1955543-57-3] LiQ 8-Hydroxyquinolinolato-lithium WO2013079217 [CAS 850918-68-2]

Inventive Compounds E1 to E6:

##STR00067## ##STR00068##

Comparative Compound C1-C4

##STR00069##

TABLE-US-00002 TABLE 2 OLED device performance Voltage; 10 C.sub.eff; 10 CIE mA/cm.sup.2 mA/cm.sup.2 OLED devices ETL 1931y [V] [cd/A] Comparative-1 C1 0.042 3.75 6.9 Comparative-2 C2 0.042 3.8 6.8 Comparative-3 C3 3.60 6.4 Comparative 4 C4 3.61 5.9 OLED-1 E1 0.041 3.55 7.8 OLED-2 E2 0.039 3.53 7.6 OLED-3 E3 0.040 3.55 7.7 OLED-4 E4 0.039 3.55 7.5 OLED-5 E5 0.039 3.57 7.2 OLED-6 E6 0.040 3.59 7.6

[0405] As it can be seen from Table 2, the inventive devices OLED-1 to OLED-6 show improved driving voltage and improved efficiency in comparison to the comparative devices 1 to 4.

[0406] The features disclosed in the foregoing description and in the dependent claims may, both separately and in any combination thereof, be material for realizing the aspects of the disclosure made in the independent claims, in diverse forms thereof.