Compound and an Organic Semiconducting Layer, an Organic Electronic Device and a Display or Lighting Device Comprising the Same

Abstract

The present invention relates to a compound of Formula (I): an organic semiconducting layer comprising the same, an organic electronic device comprising the organic semiconducting layer and a display device or a lighting device comprising the organic electronic device.

Claims

1. Compound of Formula (I) ##STR00038## wherein Ar.sup.1 is a substituted or unsubstituted C.sub.16 to C.sub.36 condensed aryl group comprising at least four fused rings and at least two of the fused rings share at least two carbon atoms with each other, wherein the one or more substituent(s), if present in Ar.sup.1, are independently selected from the group consisting of C.sub.6 to C.sub.18 aryl, C.sub.3 to C.sub.20 heteroaryl, D, F, CN, C.sub.1 to C.sub.16 alkyl, C.sub.1 to C.sub.16 alkoxy, nitrile, PY(R).sub.2, OR, SR, (C═O)R, (C═O)N(R).sub.2, Si(R).sub.3, (S═O)R, and (S═O).sub.2R, wherein, Y is O or S, R are independently selected from C.sub.1-C.sub.20 linear alkyl, C.sub.1-C.sub.20 alkoxy, C.sub.1-C.sub.20 thioalkyl, C.sub.3-C.sub.20 branched alkyl, C.sub.3-C.sub.20 cyclic alkyl, C.sub.3-C.sub.20 branched alkoxy, C.sub.3-C.sub.20 cyclic alkoxy, C.sub.3-C.sub.20 branched thioalkyl, C.sub.3-C.sub.20 cyclic thioalkyl, C.sub.6-C.sub.20 aryl and C.sub.3-C.sub.20 heteroaryl; X.sup.1 and X.sup.2 are nitrogen, or X.sup.1 is C—(Ar.sup.2).sub.2 and X.sup.2 is C—(Ar.sup.5).sub.d; L.sup.1 may represent a single bond or is a C.sub.6 to C.sub.24 arylene group; L.sup.2 is a substituted or unsubstituted C.sub.6 to C.sub.30 arylene group, substituted or unsubstituted C.sub.3 to C.sub.25 heteroarylene group, wherein the one or more substituent(s), if present in L.sup.2, are independently selected from the group consisting of C.sub.6 to C.sub.18 aryl, C.sub.3 to C.sub.20 heteroaryl, D, F, CN, C.sub.1 to C.sub.16 alkyl, C.sub.1 to C.sub.16 alkoxy, nitrile, PY(R).sub.2 with Y being O or S, OR, SR, (C═O)R, (C═O)N(R).sub.2, Si(R).sub.3, (S═O)R, and (S═O).sub.2R, wherein, Y is O or S, R are independently selected from C.sub.1-C.sub.20 linear alkyl, C.sub.1-C.sub.20 alkoxy, C.sub.1-C.sub.20 thioalkyl, C.sub.3-C.sub.20 branched alkyl, C.sub.3-C.sub.20 cyclic alkyl, C.sub.3-C.sub.20 branched alkoxy, C.sub.3-C.sub.20 cyclic alkoxy, C.sub.3-C.sub.20 branched thioalkyl, C.sub.3-C.sub.20 cyclic thioalkyl, C.sub.6-C.sub.20 aryl and C.sub.3-C.sub.20 heteroaryl; Ar.sup.2, Ar.sup.3, Ar.sup.4, Ar.sup.5 and Ar.sup.6 are independently selected from the group consisting of substituted or unsubstituted C.sub.6 to C.sub.30 aryl, substituted or unsubstituted C.sub.2 to C.sub.30 heteroaryl, wherein the one or more substituent(s), if present in Ar.sup.2, Ar.sup.3, Ar.sup.4, Ar.sup.5 and Ar.sup.6, are independently selected from the group consisting of D, F, CN, C.sub.1 to C.sub.16 alkyl, C.sub.1 to C.sub.16 alkoxy, nitrile, and PY(R).sub.2, OR, SR, (C═O)R, (C═O)N(R).sub.2, Si(R).sub.3, (S═O)R, and (S═O).sub.2R, wherein Y is O or S, R are independently selected from C.sub.1-C.sub.20 linear alkyl, C.sub.1-C.sub.20 alkoxy, C.sub.1-C.sub.20 thioalkyl, C.sub.3-C.sub.20 branched alkyl, C.sub.3-C.sub.20 cyclic alkyl, C.sub.3-C.sub.20 branched alkoxy, C.sub.3-C.sub.20 cyclic alkoxy, C.sub.3-C.sub.20 branched thioalkyl, C.sub.3-C.sub.20 cyclic thioalkyl, C.sub.6-C.sub.20 aryl and C.sub.3-C.sub.20 heteroaryl; and a, b, c, d and e are independently selected from 0 or 1, wherein 2≤a+b+c+d+e≤5; provided that if X.sup.1 is C—(Ar.sup.2).sub.2 and X.sup.2 is C—(Ar.sup.5).sub.d, and b and d are 1 and a+b+c+d+e=2, then Ar.sup.2, Ar.sup.3, Ar.sup.4, Ar.sup.5 and Ar.sup.6 are independently selected from the group consisting of substituted or unsubstituted C.sub.6 to C.sub.30 aryl.

2. Compound according to claim 1 wherein the compound of Formula (I) has the following Formula (II) ##STR00039##

3. Compound according to claim 1, wherein the compound of Formula (I) has the following Formula (III) ##STR00040##

4. Compound according to claim 1, wherein Ar.sup.1 is selected from the group consisting of tetracenyl, fluoranthenyl, pyrenyl, and chrysenyl.

5. Compound according to claim 1, wherein L.sup.1 represents a single bond or is selected from phenylene, biphenylene, triphenylene and naphthylene.

6. Compound according to claim 1, wherein L.sup.2 is selected from substituted or unsubstituted phenylene, substituted or unsubstituted biphenylene, substituted or unsubstituted triphenylene and substituted or unsubstituted naphthylene.

7. Compound according to claim 1, wherein 2≤a+b+c+d+e≤4.

8. Compound according to claim 1, wherein Ar.sup.2, Ar.sup.3, Ar.sup.4, Ar.sup.5 and Ar.sup.6 are independently selected from the group consisting of substituted or unsubstituted C.sub.6 to C.sub.30 aryl, substituted or unsubstituted C.sub.2 to C.sub.30 heteroaryl, wherein the one or more substituent(s), if present in Ar.sup.2, Ar.sup.3, Ar.sup.4, Ar.sup.5 and Ar.sup.6, are independently selected from the group consisting of D, F, CN, C.sub.1 to C.sub.16 alkyl, C.sub.1 to C.sub.16 alkoxy, nitrile, and PY(R).sub.2, wherein, Y being O or S, R are independently selected from C.sub.1-C.sub.20 linear alkyl, C.sub.1-C.sub.20 alkoxy, C.sub.3-C.sub.20 branched alkyl, C.sub.3-C.sub.20 cyclic alkyl, C.sub.3-C.sub.20 branched alkoxy, C.sub.3-C.sub.20 cyclic alkoxy, C.sub.6-C.sub.20 aryl and C.sub.3-C.sub.20 heteroaryl.

9. Organic semiconducting layer comprising the compound of Formula (I) according to claim 1.

10. Organic semiconducting layer according to claim 9, wherein the organic semiconducting layer further comprises a metal, a metal salt or an organic metal complex.

11. Organic electronic device comprising the organic semiconducting layer according to claim 9.

12. Organic electronic device according to claim 11 further comprising an emission layer, an anode and a cathode, wherein the organic semiconducting layer is arranged between the emission layer and the cathode.

13. Organic electronic device according to claim 12 further comprising an electron transport layer, wherein the organic semiconducting layer is contacting sandwiched between the emission layer and the electron transport layer.

14. Display device comprising the organic electronic device according to claim 11.

15. Lighting device comprising the organic electronic device according to claim 11.

16. Organic electronic device according to claim 12, wherein the organic semiconductor layer is in direct contact with the emission layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0216] These and/or other aspects and advantages of the present invention will become apparent and more readily appreciated from the following description of the exemplary embodiments, taken in conjunction with the accompanying drawings, of which:

[0217] FIG. 1 is a schematic sectional view of an organic light-emitting diode (OLED), according to an exemplary embodiment of the present invention;

[0218] FIG. 2 is a schematic sectional view of an OLED, according to an exemplary embodiment of the present invention.

[0219] FIG. 3 is a schematic sectional view of a tandem OLED comprising a charge generation layer, according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION

[0220] Reference will now be made in detail to the exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The exemplary embodiments are described below, in order to explain the aspects of the present invention, by referring to the figures.

[0221] 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.

[0222] FIG. 1 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 no, 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.

[0223] Instead of a single electron transport layer 160, optionally an electron transport layer stack (ETL) can be used.

[0224] FIG. 2 is a schematic sectional view of an OLED 100, according to another exemplary embodiment of the present invention. FIG. 2 differs from FIG. 1 in that the OLED 100 of FIG. 2 comprises an electron blocking layer (EBL) 145 and a hole blocking layer (HBL) 155.

[0225] Referring to FIG. 2, 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.

[0226] Preferably, the organic semiconducting layer comprising a compound of Formula (I) may be an HBL.

[0227] FIG. 3 is a schematic sectional view of a tandem OLED 200, according to another exemplary embodiment of the present invention. FIG. 3 differs from FIG. 2 in that the OLED 100 of FIG. 3 further comprises a charge generation layer (CGL) and a second emission layer (151).

[0228] Referring to FIG. 3, the OLED 200 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.

[0229] Preferably, the organic semiconducting layer comprising a compound of Formula (I) may be the first ETL, e-type CGL and/or second ETL.

[0230] While not shown in FIG. 1, FIG. 2 and FIG. 3, a sealing layer may further be formed on the cathode electrodes 190, in order to seal the OLEDs 100 and 200. In addition, various other modifications may be applied thereto.

[0231] Hereinafter, one or more exemplary embodiments of the present invention will be described in detail with, reference to the following examples. However, these examples are not intended to limit the purpose and scope of the one or more exemplary embodiments of the present invention.

Experimental Data

[0232] Preparation of Compounds of Formula (I)

[0233] Compounds of formula (I) may be synthesized as shown below.

##STR00024##

[0234] A flask was flushed with nitrogen and charged with compound (1) (49.8 mmol), compound (2) (54.8 mmol), Pd(PPh3).sub.4 (1.0 mmol), and potassium carbonate (99.6 mmol). A mixture of deaerated THF/water (4:1, 300 mL) was added and the reaction mixture was heated to 75° C. under a nitrogen atmosphere overnight. After cooling down to room temperature, solvents were removed under reduced pressure. Resulting crude was dissolved in dichloromethane (400 mL) and the organic phase was washed first with NaDTC(aq.) (3×300 mL) and the with water (3×300 mL). After drying over MgSO.sub.4, the organic phase was filtered through a florisil pad. After rinsing with additional dichloromethane (1000 mL), the filtrate was concentrated under reduced pressure to a minimal volume and acetonitrile (350 mL) was added. The precipitate was collected by suction filtration and dissolved again in dichloromethane (400 mL) and the solution was concentrated under reduced pressure to a minimal volume and acetonitrile (300 mL) was added.

[0235] The precipitate was collected by suction filtration to yield compound D (compound of formula 1) after drying. Final purification was achieved by sublimation.

Synthesis of 3-(3′,4′,5′-triphenyl-[1,1′:2′,1″-terphenyl]-4-yl)fluoranthene (D-1)

[0236] ##STR00025##

[0237] To synthesis compound D-1 a flask was flushed with nitrogen and charged with 3-bromofluoranthene (1′) (14.0 g, 49.8 mmol), 4,4,5,5-tetramethyl-2-(3′,4′,5′-triphenyl-[1,1′:2′,1″-terphenyl]-4-yl)-1,3,2-dioxaborolane (3) (32.0 g, 54.3 mmol), Pd(PPh3).sub.4 (1.2 g, 1.0 mmol), and potassium carbonate (13.8 g, 99.6 mmol). A mixture of deaerated THF/water (4:1, 300 mL) was added and the reaction mixture was heated to 75° C. under a nitrogen atmosphere overnight. After cooling down to room temperature, solvents were removed under reduced pressure. Resulting crude was dissolved in dichloromethane (400 mL) and the organic phase was washed first with NaDTC(aq.) (3×300 mL) and the with water (3×300 mL). After drying over MgSO.sub.4, the organic phase was filtered through a florisil pad. After rinsing with additional dichloromethane (1000 mL), the filtrate was concentrated under reduced pressure to a minimal volume and acetonitrile (350 mL) was added. The precipitate was collected by suction filtration and dissolved again in dichloromethane (400 mL) and the solution was concentrated under reduced pressure to a minimal volume and acetonitrile (300 mL) was added. The precipitate was collected by suction filtration to yield 28.2 g of C-1 after drying. Final purification was achieved by sublimation, m/z=658 (M.sup.+).

Synthesis of 3-(3′,4′,5′-triphenyl-[1,1′:2′,1″-terphenyl]-3-yl)fluoranthene (D-2)

[0238] ##STR00026##

[0239] To synthesis compound C-2 a flask was flushed with nitrogen and charged with 3-bromofluoranthene (1′) (14.0 g, 49.8 mmol), 4,4,5,5-tetramethyl-2-(3′,4′,5′-triphenyl-[1,1′:2′,1″-terphenyl]-3-yl)-1,3,2-dioxaborolane (4) (30.6 g, 52.3 mmol), Pd(dppf)Cl2 (0.18 g, 0.25 mmol), and potassium carbonate (13.8 g, 99.6 mmol), A mixture of deaerated Toluene/Ethanol/water (10:1:5, 320 mL) was added and the reaction mixture was heated to 70° C. under a nitrogen atmosphere for 2 hours. After cooling down to room temperature, crude reaction solution was washed with water (1×50 mL). After drying over MgSO.sub.4, the organic phase was filtered through a florisil pad. After rinsing with additional toluene (100 mL), the filtrate was concentrated under reduced pressure to 100 mL and n-hexane (150 mL) was added. The precipitate was collected by suction filtration, triturated in cyclohexane (900 mL) and recrystallized in DMF (37 mL), Finally it was washed with isopropanol (2×40 mL) to yield 17.4 g of D-2 after drying. Final purification was achieved by sublimation, m/z=658 (M.sup.+).

Synthesis of 2-(4-(fluoranthen-3-yl)phenyl)-3,5,6-triphenylpyrazine (E-1)

[0240] ##STR00027##

[0241] Compound (5) was obtained from 943442-81-7 via standard Suzuki-Miyaura conditions

[0242] Compound (E-1) was synthesized analogue to (D-1) by reacting compound (1′) (CAS 13438-50-1) with compound (5). 9.4 g (62%) of (E-1) were obtained after drying. Final purification was achieved by sublimation, m/z=585 (M+H+).

[0243] Melting Point

[0244] 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 μL Mettler Toledo aluminum pan with lid, a <1 mm hole is pierced into the lid).

[0245] According to another aspect of the present invention the compound of formula (I) may have a melting point of about ≥200° C. and about ≤280° C., preferably about ≥210° C. and about ≤275° C., further preferred about a ≥215° C. and about ≤270° C.

[0246] Glass Transition Temperature

[0247] The glass transition temperature (Tg) is measured under nitrogen and using a heating rate of 10 K per min in a Mettler Toledo DSC 822c differential scanning calorimeter as described in DIN EN ISO 11357, published in March 2010.

[0248] According to another aspect of the present invention the compound of formula (I) According to another embodiment the compound of formula 1 may have a glass transition temperature Tg of about ≥115° C. and about ≤280° C., preferably about ≥130° C. and about ≤250° C., further preferred about ≥135° C. and about ≤220° C., in addition preferred about ≥140° C. and about ≤190° C.

[0249] Rate Onset Temperature

[0250] 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 is 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 Ångstrom 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.

[0251] To achieve good control over the evaporation rate of an organic compound, the rate onset temperature may be in the range of 200° C. to 260° 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 260° 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.

[0252] 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.

[0253] 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.

[0254] According to another aspect of the present invention the compound of formula (I) may have a rate onset temperature T.sub.RO of about ≥200° C. and about ≤350° C., preferably about ≥220° C. and about ≤350° C., further preferred about ≥250° C. and about ≤300° C.

[0255] Pinole Moment

[0256] The dipole moment |{right arrow over (μ)}| of a molecule containing N atoms is given by:

[00001]$\stackrel{.fwdarw.}{\mu }=\underset{i}{\overset{N}{.Math.}}{q}_i\stackrel{.fwdarw.}{r_1}$$.Math.\stackrel{.fwdarw.}{\mu }.Math.=\sqrt{{\mu }_x^2+{\mu }_y^2+{\mu }_z^2}$

where q.sub.1 and {right arrow over (r.sub.1)} are the partial charge and position of atom i in the molecule.

[0257] The dipole moment is determined by a semi-empirical molecular orbital method.

[0258] 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. If more than one conformation is viable, the conformation with the lowest total energy is selected to determine the bond lengths of the molecules.

[0259] Calculated HOMO and LUMP

[0260] The HOMO and LUMO are calculated with the program package TURBOMOLE V6.5. 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. If more than one conformation is viable, the conformation with the lowest total energy is selected.

[0261] According to another aspect of the present invention the compound of formula (I) may have a HOMO energy level (eV) in the range from about −6.00 eV to about −4.50 eV, preferably from about −5.85 eV to about −5.00 eV.

[0262] According to another aspect of the present invention the compound of formula (I) may have a LUMO energy level (eV) in the range from about −2.30 eV to about −1.70 eV, preferably about −2.30 eV to about −1.77 eV, further preferred from about −2.20 eV to about −1.77 eV.

[0263] General Procedure for Fabrication of OLEDs

[0264] For top emission devices, inventive examples 1 and 2, and comparative example 1 in Table 2, a glass substrate was cut to a size of 50 mm×50 mm×0.7 mm, ultrasonically cleaned with isopropyl alcohol for 5 minutes and then with pure water for 5 minutes, and cleaned again with UV ozone for 30 minutes. 100 nm Ag were deposited on the glass substrate at a pressure of 10.sup.−5 to 10.sup.−7 mbar to form the anode.

[0265] Then, 92 vol.-% Biphenyl-4-yl(9,9-diphenyl-9H-fluoren-2-yl)-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-amine (CAS 1242056-42-3) with 8 vol.-% 2,2′,2″-(cyclopropane-1,2,3-triylidene)tris(2-(p-cyanotetrafluorophenyl)acetonitrile) was vacuum deposited on the anode, to form a HIL having a thickness of 10 nm. Then, Biphenyl-4-yl(9,9-diphenyl-9H-fluoren-2-yl)-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-amine was vacuum deposited on the HIL, to form a HTL having a thickness of 118 nm.

[0266] Then, N,N-bis(4-(dibenzo[b,d]furan-4-yl)phenyl)-[1,1′:4′,1″-terphenyl]-4-amine (CAS 1198399-61-9) was vacuum deposited on the HTL, to form an electron blocking layer (EBL) having a thickness of 5 nm.

[0267] Then, 97 vol-% H09 (Sun Fine Chemicals) as EML host and 3 vol.-% BD200 (Sun Fine Chemicals) as fluorescent blue dopant were deposited on the EBL, to form a blue-emitting EML with a thickness of 20 nm.

[0268] Then the auxiliary ETL was formed with a thickness of 5 nm by depositing the compound of formula 1 according to the inventive example 1 and example 2 and comparative compound 1 according to the comparative example 1 on the emission layer (EML).

[0269] Then, the electron transporting layer was formed on the auxiliary electron transport layer by depositing 7-(4-(4-([1,1′-biphenyl]-2-yl)-6-phenyl-1,3,5-triazin-2-yl)phenyl)dibenzo[c,h]acridine (ETM-1, CAS 2378599-81-4) with a the thickness of 31 nm. The electron transport layer comprises 50 wt-% matrix compound and 50 wt-% of LiQ, see Table 2.

[0270] Then, the electron injection layer was formed on the electron transporting layer by deposing Yb with a thickness of 2 nm.

[0271] Ag was evaporated at a rate of 0.01 to 1 Å/s at 10.sup.−7 mbar to form a cathode with a thickness of 11 nm.

[0272] A cap layer of Biphenyl-4-yl(9,9-diphenyl-9H-fluoren-2-yl)-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-amine (CAS 1242056-42-3) was formed on the cathode with a thickness of 75 nm.

[0273] The OLED stack is protected from ambient conditions by encapsulation of the device with a glass slide. Thereby, a cavity is formed, which includes a getter material for further protection.

[0274] To assess the performance of the inventive examples compared to the prior art, the current efficiency is measured at 20° C. The current-voltage characteristic is determined using a Keithley 2635 source measure unit, by sourcing a voltage in V and measuring the current in mA flowing through the device under test. The voltage applied to the device is varied in steps of 0.1V in the range between 0V and 10V. Likewise, the luminance-voltage characteristics and CIE coordinates are determined by measuring the luminance in cd/m.sup.2 using an Instrument Systems CAS-140CT array spectrometer for each of the voltage values. The cd/A efficiency at 10 mA/cm2 is determined by interpolating the luminance-voltage and current-voltage characteristics, respectively.

[0275] Lifetime LT of the device is measured at ambient conditions (20° C.) and 30 mA/cm.sup.2, using a Keithley 2400 sourcemeter, and recorded in hours.

[0276] The brightness of the device is measured using a calibrated photo diode. The lifetime LT is defined as the time till the brightness of the device is reduced to 97% of its initial value.

[0277] The light output in external efficiency EQE and power efficiency (lm/W efficiency) are determined at 10 mA/cm2 for top emission devices.

[0278] To determine the efficiency EQE in % the light output of the device is measured using a calibrated photodiode.

[0279] To determine the power efficiency in lm/W, in a first step the luminance in candela per square meter (cd/m2) is measured with an array spectrometer CAS140 CT from Instrument Systems which has been calibrated by Deutsche Akkreditierungsstelle (DAkkS). In a second step, the luminance is then multiplied by n and divided by the voltage and current density.

Technical Effect of the Invention

[0280] The OLED device with electron transport layer 1 consisting of compound of formula 1 showed improved life time (LT97 at 30 mA/cm2 (h)) as compared to the OLED device with electron transport layer 1 consisting of comparative compound 1 with a comparable OLED performance parameters e.g, voltage and efficiency (Table 2).

[0281] While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims Therefore, the aforementioned embodiments should be understood to be exemplary but not limiting the present invention in any way.

TABLE-US-00001 TABLE 1 Properties of compound D-1 and D-2 of inventive example 1 and 2 and compound E-1 Dipole Referred mp Tg TRO HOMO LUMO moment to as: Structure (° C.) (° C.) (° C.) (eV) (eV) (Debye) Compound D-1 [00028] 262 135 228 −5.50 −1.78 1.21 Compound D-2 [00029] 230 129 216 −5.57 −1.78 1.02 Compound D-31 [00030] — — — −4.17 −2.16 1.01 Compound D-32 [00031] — — — −5.42 −1.77 1.03 Compound D-33 [00032] — — — −5.48 −1.82 1.20 Compound E-1 [00033] 237 121 222 −5.54 −1.88 0.58 Compound E-3 [00034] — — — −5.63 −1.96 3.08

TABLE-US-00002 TABLE 1 Performance of an organic electroluminescent device comprising an electron transport layer 1 comprising a compound of formula 1 Concen- tration of Concen- Oper- cd/A matrix tration ating effi- com- Alkali of voltage ciency LT97 Thick- pound or- alkali Thick- at 10 at 10 at 30 ness Matrix in ganic organic ness mA/ mA/ mA/ ETL1 com- ETL2 com- complex ETL2 cm.sup.2 cm.sup.2 cm.sup.2 Compound in ETL1 (nm) pound (vol-%) plex (vol.-%) (nm) (V) (cd/A) (h) Comparative example 1 [00035] 5 ETM-1 50 LiQ 50 31 3.7 7.9 47 CC-1 Example 1 [00036] 5 ETM-1 50 LiQ 50 31 3.6 7.0 80 D-1 Example 2 [00037] 5 ETM-1 50 LiQ 50 31 3.6 6.9 98 D-2

[0282] 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.