Organic Light Emitting Diode and Device Comprising the Same

Abstract

The present invention relates to an organic light emitting diode comprising a substrate, an anode, a cathode, an emission layer, an electron injection layer and an electron transport layer stack; and to a display device or lighting device comprising the same.

Claims

1. An organic light emitting diode comprising a substrate, an anode, a cathode, a first emission layer, an electron injection layer and a second electron transport layer stack, wherein the second electron transport layer stack is arranged between the first emission layer and the electron injection layer; wherein at least one of the first electron transport layer stack and the second electron transport layer stack comprises independently a first electron transport layer and a second electron transport layer; the first electron transport layer comprises a compound of Formula (I)
(Ar.sup.1-A.sub.c).sub.a-X.sub.b  (I); a and b are independently 1 or 2; c is independently 0 or 1; Ar.sup.1 is independently selected from C.sub.6 to C.sub.60 aryl or C.sub.2 to C.sub.42 heteroaryl, wherein each Ar.sup.1 may be substituted with one or two 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 S 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; wherein each C.sub.6 to C.sub.12 aryl substituent on Ar.sup.1 and each C.sub.3 to C.sub.11 heteroaryl substituent on Ar.sup.1 may be substituted with C.sub.1 to C.sub.4 alkyl or halogen; A is independently selected from C.sub.6 to C.sub.30 aryl, wherein each A may be substituted with one or two substituents independently selected from the group consisting of C.sub.6 to C.sub.12 aryl 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 S 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; wherein each C.sub.6 to C.sub.12 aryl substituent on A may be substituted with C.sub.1 to C.sub.4 alkyl or halogen; X is independently selected from the group consisting of C.sub.2 to C.sub.42 heteroaryl and C6 to C.sub.60 aryl, wherein each X may be substituted with one or two 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 S 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; wherein each C.sub.6 to C.sub.12 aryl substituent on X and each C.sub.3 to C.sub.11 heteroaryl substituent on X may be substituted with C.sub.1 to C.sub.4 alkyl or halogen; the molecular dipole moment of the compound of formula (I) is ≥0 D and ≤4 D; the second electron transport layer comprises a compound of Formula (II)
(Ar.sup.2).sub.m-(Z.sub.k-G).sub.n  (II); m and n are independently 1 or 2; k is independently 0, 1 or 2; Ar.sup.2 is independently selected from the group consisting of C.sub.2 to C.sub.42 heteroaryl and C.sub.6 to C.sub.60 aryl, wherein each Ar.sup.2 may be substituted with one or two 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 S 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; wherein each C.sub.6 to C.sub.12 aryl substituent on Ar.sup.2 and each C.sub.3 to C.sub.11 heteroaryl substituent on Ar.sup.2 may be substituted with C.sub.1 to C.sub.4 alkyl or halogen; Z is independently selected from C.sub.6 to C.sub.30 aryl, wherein each Z may be substituted with one or two substituents independently selected from the group consisting of C.sub.6 to C.sub.12 aryl 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 S 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; wherein each C.sub.6 to C.sub.12 aryl substituent on Z may be substituted with C.sub.1 to C.sub.4 alkyl or halogen; G is chosen so that the dipole moment of a compound G-phenyl is ≥1 D and ≤7 D; and the first electron transport layer and the second electron transport layer are free of an electrical dopant; characterized in that the organic light emitting diode further comprises a p-type layer; the p-type layer is arranged between the anode and the first emission layer; and the p-type layer comprises a radialene compound.

2. The organic light emitting diode according to claim 1, wherein the radialene compound is a 3-radialene compound or a 4-radialene compound.

3. The organic light emitting diode according to claim 1, wherein at least 50% of peripheral atoms of the radialene compound are selected from F, Cl, Br, I and N.

4. The organic light emitting diode according to claim 1, wherein the p-type layer is a hole injection layer, a hole transport layer or a hole generating layer.

5. The organic light emitting diode according to claim 1, wherein p-type layer comprises at least two radialene compounds, wherein the at least two radialene compounds are stereoisomers.

6. The organic light emitting diode according to claim 1, wherein the radialene compound is selected from the following compounds of formula C1 to C24, C40 and C195 ##STR00686## ##STR00687## ##STR00688## ##STR00689## ##STR00690## ##STR00691## ##STR00692## ##STR00693##

7. The organic light emitting diode according to claim 1, wherein Ar.sup.1 is independently selected from the group consisting of phenyl, naphthyl, anthracenyl, fluoranthenyl, xanthenyl, spiro-xanthenyl, fluorenyl, spiro-fluorenyl, triphenylsilyl, tetraphenylsilyl or a group having the formula (IIa) ##STR00694## wherein the asterisk symbol “*” represents the binding position for binding the group of formula (IIa) to A; and R.sup.1 to R.sup.5 are independently selected from the group consisting of H, C.sub.6 to C.sub.12 aryl and C.sub.4 to C.sub.10 heteroaryl.

8. The organic light emitting diode according to claim 1, wherein A is selected from the group consisting of phenylene, naphthylene, biphenylene and terphenylene which may be substituted or unsubstituted, respectively.

9. The organic light emitting diode according to claim 1, wherein X is independently selected from the group consisting of triazinyl, 1,2-diazinyl, 1,3-diazinyl, 1,4-diazinyl, quinazolinyl, benzoquinazolinyl, benzimidazolyl, quinolinyl, benzoquinolinyl benzoacridinyl, dibenzoacridinyl, fluoranthenyl, anthracenyl, naphthyl, triphenylenyl, phenathrolinyl, and dinaphthofuranyl which may be substituted or unsubstituted, respectively.

10. The organic light emitting diode according to claim 1, wherein Ar.sup.2 is independently selected from the group consisting of pyridinyl, triazinyl, 1,2-diazinyl, 1,3-diazinyl, 1,4-diazinyl, quinazolinyl, benzoquinazolinyl, benzimidazolyl, quinolinyl, benzoquinolinyl benzoacridinyl, dibenzoacridinyl, fluoranthenyl, anthracenyl, naphthyl, triphenylenyl, phenathrolinyl, and dinaphthofuranyl which may be substituted or unsubstituted, respectively.

11. The organic light emitting diode according to claim 1, wherein G is selected from the group consisting of dialkylphosphinyl, diarylphosphinyl, alkylarylphosphinyl, nitrile, benzonitrile, nicotinonitrile, amide-yl, carbamide-yl and C.sub.2 to C.sub.17 heteroaryl; the respective G may include one or more substituents attached to the group, wherein the one or more substituents are selected from the group consisting of phenyl, methyl, ethyl, and pyridyl.

12. The organic light emitting diode according to claim 1, wherein G independently selected from the group consisting of dimethylphosphinyl, diphenylphosphinyl, 2-phenyl-1H-benzo[d]imidazolyl, 2-ethyl-1H-benzo[d]imidazolyl, 2-phenylbenzo[h]quinolinyl, pyridinyl, 2,2′-bipyridinyl, 5-phenylbenzo[4,5]imidazo[1,2-a]quinolinyl, 9-phenyl-1,10-phenanthrolinyl and (pyridine-2-yl)imidazo[1,5-a]pyridinyl.

13. The organic light emitting diode according to claim 1, wherein G is selected such that the compound G-phenyl is represented by one of the following structures ##STR00695## ##STR00696## ##STR00697## ##STR00698## ##STR00699## ##STR00700## ##STR00701##

14. The organic light emitting diode according to claim 1, wherein the compound of Formula (II) is selected from B-1 to B-26 ##STR00702## ##STR00703## ##STR00704## ##STR00705## ##STR00706## ##STR00707## ##STR00708## ##STR00709## ##STR00710##

15. The organic light emitting diode according to claim 1, wherein the second electron transport layer further comprises a compound (III), wherein the compound (III) comprises 8 to 13 aromatic or heteroaromatic rings.

16. The organic light emitting diode according to claim 1, wherein the compound (III) comprises 1 to 5 heteroaromatic rings.

17. The organic light emitting diode according to claim 1, wherein, if the compound (III) comprises two or more heteroaromatic rings, the heteroaromatic rings are separated from each other by at least one aromatic ring which is free of a heteroatom.

18. The organic light emitting diode according to claim 1, wherein the first electron transport layer and the second electron transport layer are in direct contact with each other.

19. The organic light emitting diode according to claim 1, wherein the second electron transport layer is in direct contact with the electron injection layer.

20. The organic light emitting diode according to claim 1, wherein the electron injection layer comprises a metal a metal salt, or an organic alkali metal complex.

21. A device comprising the organic light emitting diode according to claim 1, wherein the device is a display device or a lighting device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0834] 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:

[0835] FIG. 1 is a schematic sectional view of an organic light-emitting diode (OLED), according to an exemplary embodiment of the present invention;

[0836] FIG. 2 is a schematic sectional view of an OLED, according to an exemplary embodiment of the present invention.

[0837] FIG. 3 is a schematic sectional view of an organic light-emitting diode (OLED), according to an exemplary embodiment of the present invention with an anode comprising anode sub-layers.

DETAILED DESCRIPTION

[0838] 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.

[0839] 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.

[0840] 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 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) stack 160 comprising a first electron transport layer 161 and a second electron transport layer 162. 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.

[0841] 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.

[0842] Referring to FIG. 2, the OLED 100 includes a substrate no, 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, an electron transport layer (ETL) stack 160 comprising a first electron transport layer 161 and a second electron transport layer 162, an electron injection layer (EIL) 180 and a cathode electrode 190.

[0843] FIG. 3 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, wherein the anode 120 comprises a first anode sub-layer 121, a second anode sub-layer 122, and a third anode sub-layer 123, a hole injection layer (HIL)130, a hole transport layer (HTL) 140, an emission layer (EML) 150, an electron transport layer (ETL) stack 160 comprising a first electron transport layer 161 and a second electron transport layer 162. 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.

[0844] While not shown in FIG. 1 to 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.

[0845] 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.

DETAILED DESCRIPTION

[0846] Dipole Moment

[0847] The dipole moment ∥{right arrow over (μ)}∥ of a molecule containing N atoms is given by:

[00003]$\stackrel{.fwdarw.}{\mu }=\underset{i}{\overset{N}{.Math.}}{q}_i{\stackrel{.fwdarw.}{r}}_i.Math.\stackrel{.fwdarw.}{\mu }.Math.=\sqrt{{\mu }_x^2+{\mu }_y^2+{\mu }_z^2}$

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

[0848] The dipole moment is determined by a semi-empirical molecular orbital method.

[0849] 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.

[0850] Calculated HOMO and LUMO

[0851] 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. If more than one conformation is viable, the conformation with the lowest total energy is selected.

[0852] Measurement of OLED Performance

[0853] To assess the performance of the OLED devices 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 0 V and 10 V. 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 (calibrated by Deutsche Akkreditierungsstelle (DAkkS)) for each of the voltage values. The cd/A efficiency at 10 mA/cm.sup.2 is determined by interpolating the luminance-voltage and current-voltage characteristics, respectively.

[0854] As applicable, Lifetime LT of the device can be measured at ambient conditions (20° C.) and 30 mA/cm.sup.2, using a Keithley 2400 sourcemeter, and recorded in hours.

[0855] 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.

[0856] The increase in operating voltage ΔU is used as a measure of the operating voltage stability of the device. This increase is determined during the LT measurement and by subtracting the operating voltage at the start of operation of the device from the operating voltage after 50 hours.

ΔU=[U(50 h)−U(0 h)]

The smaller the value of AU the better is the operating voltage stability.

[0857] Synthesis of Radialenes

[0858] The synthesis of radialene compounds in accordance with the present disclosure is disclosed in US 2008/0265216 A1, US 2010/0102709 A1, and WO2015/007729 A1 the disclosure of which is incorporated herein by reference.

[0859] General Procedure for Fabrication of OLEDs

[0860] Blue Fluorescent OLED

TABLE-US-00010 c d Layer Material [vol %] [nm] Cap F1 100 75 Cathode Ag:Mg 90:10 13 EIL Yb 100 2 EIL LiQ 100 1 ETL tested 100 30 matrix a-ETL E4 100 5 EML H09: 97:3 20 BD200 EBL F3 100 5 HTL F1 or 100 various F2 HIL F1: p- various 10 dopant or F2: p- dopant Anode ITO/ — 10/120/8 Ag/ ITO

[0861] Auxiliary Materials [0862] F.sub.1 is

##STR00674##

(CAS 1242056-42-3, N-([1,1′-biphenyl]-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amine)

[0863] F2 is

##STR00675##

(CAS 1364603-07-5, N-([1,1′-biphenyl]-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9′-spirobi[fluoren]-2-amine)

[0864] F3 is

##STR00676##

(CAS 1613079-70-1, N-([1,1′-biphenyl]-4-yl)-9,9-diphenyl-N-(4-(triphenylsilyl)phenyl)-9H-fluoren-2-amine)

[0865] E4 is

##STR00677##

(CAS 203236-4-8, 2,4-diphenyl-6-(4′,5′,6′-triphenyl-[1,1′: 2′1″: 3″ 1′″:3′″,1″″quinquephenyl]-3′″-yl)-1,3,5-triazine)

[0866] F7 is

##STR00678##

CAS 105598-27-4, Dipyrazino[2,3-f:2′,3′-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile, CN-HAT

[0867] H09 is an emitter host and BD200 is a blue fluorescent emitter, both commercially available from SFC, Korea.

[0868] ITO is indium tin oxide

[0869] Tested ETL Matrix Compounds

[0870] E1 is

##STR00679##

(CAS 2437303-42-7, 2-([1,1′-biphenyl]-3-yl)-4-phenyl-6-(3-(10-phenylanthracen-9-yl)phenyl)-1,3,5-triazine)

[0871] E2 is

##STR00680##

(CAS 2437303-43-8, (3-(10-(3-(2,6-diphenylpyrimidin-4-yl)phenyl)anthracen-9-yl)phenyl)dimethylphosphine oxide)

[0872] E3 is

##STR00681##

(CAS 2253724-56-8, (3-(4-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)naphthalen-1-yl)phenyl)dimethylphosphine oxide)

[0873] Tested Radialene Compounds

(CAS 1224447-88-4, 4,4′,4″-((1E,1′E,1″E)-cyclopropane-1,2,3-triylidenetris(cyanomethanylylidene))tris(2,3,5,6-tetrafluorobenzonitrile))

[0874] C5 is

##STR00682##

(CAS 1073338-86-9, alpha-[2,3-Bis[cyano(4-cyano-2,3,5,6-tetrafluorophenyl)methylene]cyclopropylidene]-2,3,5,6-tetrafluoro-4-(trifluoromethyl)benzeneacetonitrile)

[0875] C12 is

##STR00683##

(CAS 1946859-27-3, (2E,2′E,2″E)-2,2′,2″-(cyclopropane-1,2,3-triylidene)tris(2-(2,3,5-trifluoro-6-(trifluoromethyl)pyridin-4-yl)acetonitrile))

[0876] C40 is

##STR00684##

4-((E)-cyano((2E,3Z)-2-(cyano(2,3,5,6-tetrafluoro-4-(trifluoromethyl)phenyl)methylene)-3-(cyano(4-cyano-2-(trifluoromethyl)phenyl)methylene)cyclopropylidene)methyl)-2-(trifluoromethyl)benzonitrile

[0877] C195 is

##STR00685##

(CAS 1946861-54-6, alpha-[2,3-Bis[cyano(4-cyano-2,3,5,6-tetrafluorophenyl)methylene]cyclopropylidene]-2,4,6-tris(trifluoromethyl)-5-pyrimidineacetonitrile)

[0878] General Procedure for Fabrication of Blue Fluorescent OLEDs

[0879] As backplanes for displays are very expensive, the OLEDs were fabricated on a glass substrates.

[0880] For Examples 1 to 16 and comparative examples 1 to 9 in Table 5, a glass substrate with an anode layer comprising a first anode sub-layer of 120 nm Ag, a second anode sub-layer of 8 nm ITO and a third anode sub-layer of 10 nm ITO was cut to a size of 50 mm×50 mm×0.7 mm, ultrasonically washed with water for 60 minutes and then with isopropanol for 20 minutes. The liquid film was removed in a nitrogen stream, followed by plasma treatment to prepare the anode layer. The plasma treatment was performed in nitrogen atmosphere or in an atmosphere comprising 97.6 vol.-% nitrogen and 2.4 vol.-% oxygen.

[0881] Then, a HIL matrix compound and a radialene compound (Examples 1 to 16) or F7 (comparative examples 1 to 9) were co-deposited in vacuum on the anode layer, to form a hole injection layer (HIL) having a thickness of 10 nm. The composition of the HIL can be seen in Table 5.

[0882] Then, the same HIL matrix compound was vacuum deposited on the HIL, to form a HTL having a thickness of 123 nm.

[0883] Then N-[(1,1′-biphenyl]-4-yl)-9,9-diphenyl-N-(4-(triphenylsilyl)phenyl)-9H-fluoren-2-amine (CAS 1613079-70-1) was vacuum deposited on the HTL, to form an electron blocking layer (EBL) having a thickness of 5 nm.

[0884] Then 97 vol.-% H09 (Sun Fine Chemicals, Korea) as EML host and 3 vol.-% BD200 (Sun Fine Chemicals, Korea) as fluorescent blue emitter dopant were deposited on the EBL, to form a blue-emitting first emission layer (EML) with a thickness of 20 nm.

[0885] Then a hole blocking layer was formed with a thickness of 5 nm by depositing 2-(3′-(9,9-dimethyl-9H-fluoren-2-yl)-[1,1′-biphenyl]-3-yl)-4,6-diphenyl-1,3,5-triazine on the emission layer EML.

[0886] Then the electron transporting layer ETL having a thickness of 30 nm was formed on the hole blocking layer by depositing the tested ETL matrix compound, see Table 5, on the hole blocking layer.

[0887] Then a first electron injection layer EIL1 having a thickness of 1 nm was formed on the ETL by depositing LiQ on the ETL.

[0888] Then a second electron injection layer ETL2 having a thickness of 2 nm was formed on the EIL1 by depositing Yb on the EIL1.

[0889] Then Ag:Mg (90:10 vol.-%) was evaporated at a rate of 0.01 to 1 Å/s at 107 mbar to form a cathode layer with a thickness of 13 nm on the EIL2.

[0890] Then, compound of formula F1 was deposited on the cathode layer to form a capping layer with a thickness of 75 nm.

[0891] 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.

[0892] 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/i.sup.2 using an Instrument Systems CAS-140CT array spectrometer (calibrated by Deutsche Akkreditierungsstelle (DAkkS)) for each of the voltage values. The cd/A efficiency at 10 mA/cm.sup.2 is determined by interpolating the luminance-voltage and current-voltage characteristics, respectively.

[0893] 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. 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.

[0894] To determine the voltage stability over time U(50-1 hour), a current density of at 30 mA/cm.sup.2 was applied to the device. The operating voltage was measured after 1 hour and after 50 hours, followed by calculation of the voltage stability for the time period of 1 hour to 50 hours. The higher the value of U(50-1 hour), the worse the voltage stability over time.

[0895] Technical Effect of the Invention

[0896] Table 5 shows the setup and the operating voltage of one device according to comparative examples 1 to 9 and to examples 1 to 16 according to the invention.

[0897] In comparative example 1, the hole injection layer comprises compound F7 and HIL matrix compound F1. The doping concentration is 8 vol.-%. The ETL comprises compound F2. The operating voltage is 3.89 V, the efficiency is 7.53 cd/A, the LT is 25 hours and the voltage rise over time U(5-1 hour) is 1.161 V.

[0898] In example 1, the hole injection layer comprises radialene compound C40 and HIL matrix compound F1. Example 1 differs from comparative example 1 in the radialene compound. The operating voltage is improved to 3.66 V, the lifetime is improved to 34 hours. The voltage rise over time is substantially improved from over 1 V in comparative example 1 to 0.042 V in example 1.

[0899] In comparative example 2, the hole injection layer comprises compound F7 and HIL matrix compound F1. The doping concentration is reduced to 5 vol.-%. Compared to comparative example 1, the operating voltage is worse at 3.95 V, the efficiency is improved to 7.62 cd/A, the lifetime is worse at 20 hours. The voltage rise over time is still very high at 1.09 V.

[0900] In example 2, the hole injection layer comprises radialene compound C5 and HIL matrix compound F1. Example 2 differs from comparative example 2 in the radialene compound. The operating voltage is improved to 3.66 V and the lifetime is improved to 38 hours. The voltage rise over time is substantially improved from over 1 in comparative example 2 to 0.029 Vin example 2.

[0901] In comparative example 3, the hole injection layer comprises compound F7 and HIL matrix compound F1. The doping concentration is reduced to 2 vol.-%. Compared to comparative example 2, the operating voltage is worse at 4.24 V, the efficiency is reduced to 6.89 cd/A, the lifetime is worse at 12 hours. The voltage rise over time is worse at 1.285 V.

[0902] In example 3, the hole injection layer comprises radialene compound C12 and HIL matrix compound F1. Example 3 differs from comparative example 3 in the radialene compound. The operating voltage is improved to 3.62 V, the efficiency is improved to 8.62 cd/A and the lifetime is improved to 40 hours. The voltage rise over time is substantially improved from over 1V in comparative example 3 to 0.015 V in example 3.

[0903] In example 4, the hole injection layer comprises radialene compound C195 and HIL matrix compound F1. Example 4 differs from comparative example 3 in the radialene compound. The operating voltage is improved to 3.63 V, the efficiency is improved further to 8.87 cd/A and the lifetime is improved to 45 hours. The voltage rise over time is substantially improved from over 1V in comparative example 3 to 0.017 Vin example 4.

[0904] In comparative example 4, the hole injection layer comprises compound F7 and HIL matrix compound F2. The doping concentration is increased to 14 vol.-%. Compared to comparative example 1, the operating voltage is worse at 3.96 V, the efficiency is reduced to 6.65 cd/A, the lifetime is improved to 48 hours. The voltage rise over time is worse at 1.781 V.

[0905] In example 5, the hole injection layer comprises radialene compound C40 and IL matrix compound F2. Example 5 differs from comparative example 4 in the radialene compound. The operating voltage is improved to 3.4 V, the efficiency is improved to 7.21 cd/A, the lifetime is improved to 67 hours. The voltage rise over time is substantially improved from over 1 V in comparative example 4 to 0.009 V in example 5.

[0906] In example 6, the hole injection layer comprises radialene compound C5 and HIL matrix compound F2. Example 6 differs from comparative example 4 in the radialene compound and in the doping concentration. The operating voltage is improved to 3.41 V, the efficiency is improved to 7.05 cd/A and the lifetime is improved to 66 hours. The voltage rise over time is substantially improved from over 1 in comparative example 4 to 0.025 V in example 6.

[0907] In example 7, the hole injection layer comprises radialene compound C12 and HIL matrix compound F2. Example 7 differs from comparative example 4 in the radialene compound and in the doping concentration. The operating voltage is improved to 3.41 V, the efficiency is improved to 7.48 cd/A and the lifetime is improved to 74 hours. The voltage rise over time is substantially improved from over 1 in comparative example 4 to 0.023 V in example 7.

[0908] In example 8, the hole injection layer comprises radialene compound C195 and HIL matrix compound F2. Example 8 differs from comparative example 4 in the radialene compound and in the doping concentration. The operating voltage is improved to 3.42 V, the efficiency is improved to 7.29 cd/A and the lifetime is improved to 76 hours. The voltage rise over time is substantially improved from over 1 in comparative example 4 to 0.028 V in example 8.

[0909] In comparative example 6, the hole injection layer comprises compound F7 and HIL matrix compound F1. The doping concentration is 8 vol.-%. The ETL comprises a mixture of compounds E1 and E3 in a ratio of 70 to 30 wt.-%. Comparative example 6 differs from comparative example 1 in the ETL composition. The operating voltage is worse at 3.93 V, the efficiency is worse at 7.41 cd/A, the LT is improved to 42 hours and the voltage rise over time U(50-1 hour) is worse at 1.245 V.

[0910] In example 9, the hole injection layer comprises radialene compound C40 and IL matrix compound F1. Example 9 differs from comparative example 6 in the radialene compound. The operating voltage is improved to 3.68 V, the efficiency is improved to 7.49 cd/A, the lifetime is comparable at 41 hours. The voltage rise over time is substantially improved from over 1 Vin comparative example 6 to 0.044 V in example 9.

[0911] In comparative example 7, the hole injection layer comprises compound F7 and HIL matrix compound F1. The doping concentration is reduced to 5 vol.-%. Compared to comparative example 6, the operating voltage is worse at 4 V, the efficiency is improved to 7.67 cd/A, the lifetime is worse at 37 hours. The voltage rise over time is still very high at 1.212 V.

[0912] In example 10, the hole injection layer comprises radialene compound C5 and IL matrix compound F1. Example 10 differs from comparative example 7 in the radialene compound. The operating voltage is improved to 3.68 V and the lifetime is improved to 44 hours. The voltage rise over time is substantially improved from over 1 in comparative example 7 to 0.031V in example 10.

[0913] In comparative example 8, the hole injection layer comprises compound F7 and HIL matrix compound F1. The doping concentration is reduced to 2 vol.-%. Compared to comparative example 7, the operating voltage is worse at 44.22 V, the efficiency is reduced to 7.01 cd/A, the lifetime is worse at 26 hours. The voltage rise over time is still high at 1.035 V.

[0914] In example 11, the hole injection layer comprises radialene compound C12 and HIL matrix compound F1. Example 11 differs from comparative example 8 in the radialene compound. The operating voltage is improved to 3.65V, the efficiency is improved to 8.65 cd/A and the lifetime is improved to 47 hours. The voltage rise over time is substantially improved from over 1 in comparative example 8 to 0.017V in example 11.

[0915] In example 12, the hole injection layer comprises radialene compound C195 and HIL matrix compound F1. Example 12 differs from comparative example 8 in the radialene compound. The operating voltage is improved to 3.66 V, the efficiency is improved further to 8.65 cd/A and the lifetime is improved to 55 hours. The voltage rise over time is substantially improved from over 1 in comparative example 3 to 0.020 V in example 12.

[0916] In comparative example 9, the hole injection layer comprises compound F7 and HIL matrix compound F2. The doping concentration is increased to 14 vol.-%. Compared to comparative example 6, the operating voltage is worse at 4 V, the efficiency is reduced to 6.64 cd/A, the lifetime is improved to 79 hours. The voltage rise over time is still very high at 1.230 V.

[0917] In example 13, the hole injection layer comprises radialene compound C40 and IL matrix compound F2. Example 13 differs from comparative example 9 in the radialene compound. The operating voltage is improved to 3.44 V, the efficiency is improved to 7.05 cd/A, the lifetime is improved to 74 hours. The voltage rise over time is substantially improved from over 1V in comparative example 9 to 0.024 V in example 13.

[0918] In example 14, the hole injection layer comprises radialene compound C5 and HIL matrix compound F2. Example 14 differs from comparative example 9 in the radialene compound and in the doping concentration. The operating voltage is improved to 3.44 V, the efficiency is improved to 6.87 cd/A and the lifetime is improved to 75 hours. The voltage rise over time is substantially improved from over 1V in comparative example 9 to 0.025 V in example 14.

[0919] In example 15, the hole injection layer comprises radialene compound C12 and HIL matrix compound F2. Example 15 differs from comparative example 9 in the radialene compound and in the doping concentration. The operating voltage is improved to 3.45 V, the efficiency is improved to 7.34 cd/A and the lifetime is improved to 80 hours. The voltage rise over time is substantially improved from over 1 in comparative example 9 to 0.022 V in example 15.

[0920] In example 16, the hole injection layer comprises radialene compound C195 and HIL matrix compound F2. Example 16 differs from comparative example 9 in the radialene compound and in the doping concentration. The operating voltage is improved to 3.48 V, the efficiency is improved to 7.05 cd/A and the lifetime is improved to 85 hours. The voltage rise over time is substantially improved from over 1 in comparative example 9 to 0.029 V in example 16.

[0921] A reduction in operating voltage may be beneficial for reduced power consumption and improved battery life, in particular in mobile devices.

[0922] An increase in cd/A efficiency may be beneficial for reduced power consumption and improved battery life, in particular in mobile devices.

[0923] An improvement in voltage stability over time may be beneficial for long-term stability of organic electronic devices.

[0924] In summary, a substantial improvement in performance of organic light emitting diodes has been obtained, in particular the voltage rise over time has been obtained.

TABLE-US-00011 TABLE 5 Performance of blue fluorescent OLEDs according to invention and comparative examples 1 to 9 Composition Percentage of Cd/A U (50-1 radialene Tested tested ETL efficiency LT at hour) compound HIL ETL matrix V at 15 at 15 30 at 30 Radialene in HIL matrix matrix compound mA/cm.sup.2 mA/cm.sup.2 mA/cm.sup.2 mA/cm.sup.2 compound [vol.-%] compound compound [wt.-%] [V] [cd/A] [h] [V] Comparative F.sub.7 8 F.sub.1 E.sub.2 100 3.89 7.53 25 1.161 example 1 Example 1 C.sub.40 8 F.sub.1 E.sub.2 100 3.66 7.49 34 0.042 Comparative F.sub.7 5 F.sub.1 E.sub.2 100 3.95 7.62 20 1.090 example 2 Example 2 C.sub.5 5 F.sub.1 E.sub.2 100 3.66 7.62 38 0.029 Comparative F.sub.7 2 F.sub.1 E.sub.2 100 4.24 6.89 12 1.285 example 3 Example 3 C.sub.12 2 F.sub.1 E.sub.2 100 3.62 8.62 40 0.015 Example 4 C.sub.195 2 F.sub.1 E.sub.2 100 3.63 8.78 45 0.017 Comparative F.sub.7 14 F.sub.2 E.sub.2 100 3.96 6.65 48 1.781 example 4 Example 5 C.sub.40 14 F.sub.2 E.sub.2 100 3.4  7.21 67 0.009 Example 6 C.sub.5 8 F.sub.2 E.sub.2 100 3.41 7.05 66 0.025 Example 7 C.sub.12 4 F.sub.2 E.sub.2 100 3.41 7.48 74 0.023 Example 8 C.sub.195 4 F.sub.2 E.sub.2 100 3.42 7.29 76 0.028 Comparative F.sub.7 8 F.sub.1 E.sub.1:E.sub.3 70:30 3.93 7.41 42 1.245 example 6 Example 9 C.sub.40 8 F.sub.1 E.sub.1:E.sub.3 70:30 3.68 7.49 41 0.044 Comparative F.sub.7 5 F.sub.1 E.sub.1:E.sub.3 70:30 4.00 7.67 37 1.212 example 7 Example C.sub.5 5 F.sub.1 E.sub.1:E.sub.3 70:30 3.68 7.40 44 0.031 10 Comparative F.sub.7 2 F.sub.1 E.sub.1:E.sub.3 70:30 4.22 7.01 26 1.035 example 8 Example C.sub.12 2 F.sub.1 E.sub.1:E.sub.3 70:30 3.65 8.65 47 0.017 11 Example C.sub.195 2 F.sub.1 E.sub.1:E.sub.3 70:30 3.66 8.65 55 0.020 12 Comparative F.sub.7 14 F.sub.2 E.sub.1:E.sub.3 70:30 4.00 6.64 79 1.230 example 9 Example C.sub.40 14 F.sub.2 E.sub.1:E.sub.3 70:30 3.44 7.05 74 0.024 13 Example C.sub.5 8 F.sub.2 E.sub.1:E.sub.3 70:30 3.44 6.87 75 0.025 14 Example C.sub.12 4 F.sub.2 E.sub.1:E.sub.3 70:30 3.45 7-34 80 0.022 15 Example C.sub.195 4 F.sub.2 E.sub.1:E.sub.3 70:30 3.48 7-05 85 0.029 16

[0925] The particular combinations of elements and features in the above detailed embodiments are exemplary only; the interchanging and substitution of these teachings with other teachings in this and the patents/applications incorporated by reference are also expressly contemplated.

[0926] As those skilled in the art will recognize, variations, modifications, and other implementations of what is described herein can occur to those of ordinary skill in the art without departing from the spirit and the scope of the invention as claimed. Accordingly, the foregoing description is by way of example only and is not intended as limiting. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. The invention's scope is defined in the following claims and the equivalents thereto. Furthermore, reference signs used in the description and claims do not limit the scope of the invention as claimed.