Organic Light Emitting Diode and Device Comprising the Same

Abstract

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

Claims

1. Organic light emitting diode comprising a non-transparent substrate, an anode, a cathode, an emission layer, an electron injection layer and an electron transport layer stack; wherein the electron transport layer stack is arranged between the emission layer and the electron injection layer; the electron transport layer stack comprises a first electron transport layer and a second electron transport layer; the first electron transport layer comprises a compound of Formula (I) $\begin{array}{cc}{\left({\text{Ar}}^1-{\text{A}}_{\text{c}}\right)}_{\text{a}}-{\text{X}}_{\text{b}}& \text{­­­(I)}\end{array}$ 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 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; 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 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; 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 C.sub.6 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 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; 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 ≥ o D and ≤ 4 D; the second electron transport layer comprises a compound of Formula (II) $\begin{array}{cc}{\left({\text{Ar}}^2\right)}_{\text{m}}-{\left({\text{Z}}_{\text{k}}-\text{G}\right)}_{\text{n}}& \text{­­­(II)}\end{array}$ 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 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; wherein each C.sub.6 to C.sub.12 aryl substituent on Ar.sub.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 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; - 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 ≥ 1D and ≤ 7D; the first electron transport layer and the second electron transport layer are free of an electrical dopant; .

2. 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, tetraphenylsilylor a group having the formula (IIa) ##STR00333## 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 heterorayl.

3. 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.

4. 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.

5. Organic light emitting diode according to preceding 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.

6. 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.

7. 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.

8. 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 ##STR00334## ##STR00335## ##STR00336## ##STR00337## ##STR00338## ##STR00339## ##STR00340## ##STR00341## ##STR00342## ##STR00343## ##STR00344## ##STR00345## ##STR00346## ##STR00347## ##STR00348## ##STR00349## ##STR00350## ##STR00351## ##STR00352## ##STR00353## ##STR00354## ##STR00355## ##STR00356## ##STR00357## ##STR00358## ##STR00359## ##STR00360## ##STR00361## ##STR00362## ##STR00363## ##STR00364## ##STR00365## ##STR00366## ##STR00367## ##STR00368## ##STR00369## ##STR00370## ##STR00371## ##STR00372## ##STR00373## ##STR00374## ##STR00375## ##STR00376## ##STR00377## ##STR00378## ##STR00379## ##STR00380## ##STR00381## ##STR00382## ##STR00383## ##STR00384## ##STR00385## ##STR00386## ##STR00387## ##STR00388## ##STR00389## ##STR00390## ##STR00391## ##STR00392## ##STR00393## ##STR00394## ##STR00395## ##STR00396## ##STR00397## ##STR00398## ##STR00399## ##STR00400## ##STR00401## ##STR00402## ##STR00403## ##STR00404## ##STR00405## ##STR00406## ##STR00407## ##STR00408## ##STR00409## ##STR00410## ##STR00411## ##STR00412## ##STR00413## ##STR00414## ##STR00415## ##STR00416## ##STR00417## ##STR00418## ##STR00419## ##STR00420## ##STR00421## ##STR00422## ##STR00423## ##STR00424## ##STR00425## ##STR00426## ##STR00427## ##STR00428## ##STR00429## ##STR00430## ##STR00431## ##STR00432## ##STR00433## ##STR00434## ##STR00435## ##STR00436## ##STR00437## .

9. Organic light emitting diode according to claim 1, wherein the compound of Formula (II) is selected from B-1 to B-26 ##STR00438## ##STR00439## ##STR00440## ##STR00441## ##STR00442## ##STR00443## ##STR00444## ##STR00445## ##STR00446## ##STR00447## ##STR00448## ##STR00449## ##STR00450## ##STR00451## ##STR00452## ##STR00453## ##STR00454## ##STR00455## ##STR00456## ##STR00457## ##STR00458## ##STR00459## ##STR00460## ##STR00461## ##STR00462## ##STR00463## .

10. 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.

11. Organic light emitting diode according to claim 10, wherein the compound (III) comprises 1 to 5 heteroaromatic rings.

12. Organic light emitting diode according to claim 10, 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.

13. 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.

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

15. Organic light emitting diode according to preceding claim 1, wherein the electron injection layer comprises a metal, alternatively an alkali metal, a metal salt alternatively an alkaline earth metal salt and/or rare earth metal salt, or an organic alkali metal complex, alternatively an alkali metal complex, alternatively LiF, LiCl, LiBr, LiI, LiQ, a metal borate, or mixtures thereof.

16. Organic light emitting diode according to claim 1, wherein the compound of (II) is not comprised in the electron injection layer.

17. 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

[0573] 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:

[0574] FIG. 1 is a schematic sectional view of an organic light-emitting diode (OLED), according to an exemplary embodiment of the present invention;

[0575] FIG. 2 is a schematic sectional view of an OLED, according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION

[0576] 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.

[0577] 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.

[0578] 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 non-transparent 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.

[0579] 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.

[0580] Referring to FIG. 2, the OLED 100 includes a non-transparent 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, 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.

[0581] While not shown in FIG. 1 and FIG. 2 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.

[0582] 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

Dipole Moment

[0583] The dipole moment |.Math.| of a molecule containing N atoms is given by:

[00005]$\stackrel{.fwdarw.}{\mu }={\displaystyle \underset{i}{\overset{N}{.Math.}}{q}_i{\stackrel{.fwdarw.}{r}}_{\mathrm{.Math.}}}$

[00006]$\left|\stackrel{.fwdarw.}{\mu }\right|=\sqrt{{\mu }_x^2+{\mu }_y^2+{\mu }_z^2}$

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

[0584] The dipole moment is determined by a semi-empirical molecular orbital method.

[0585] 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

[0586] 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.

Measurement of OLED Performance

[0587] 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 0.1 V 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.

[0588] 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.

[0589] 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.

[0590] 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.

[00007]$\text{Δ}\text{U=}\left[\text{U}\left(50\text{h}\right)\text{-U}\left(0\text{h}\right)\right]$

[0591] The smaller the value of ΔU the better is the operating voltage stability.

General Procedure for Fabrication of OLEDs

[0592] For the top emission OLED devices a substrate with dimensions of 150 mm × 150 mm × 0.7 mm was ultrasonically cleaned with a 2% aqueous solution of Deconex FPD 211 for 7 minutes and then with pure water for 5 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.

[0593] 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).

[0594] Afterwards the emission layer was formed on the EBL by co-deposition of HOST-1 and EMITTER-1.

[0595] Then, the compound of Formula (I) was vacuum deposited onto the emission layer to form the first electron transport layer. Then, the second electron transport layer was formed on the first electron transport layer by depositing a compound of Formula (II) for examples OLED-1 to OLED-12. For the comparative OLED example the second electron transport layer was formed on the first electron transport layer by depositing the compound C-3.

[0596] For examples OLED-13 to OLED-20 the second electron transport layer was formed on the first electron transport layer by depositing a pre-mix compound of Formula (II) and compound (III).

[0597] Then, the electron injection layer is formed as a double layer on the second electron transport layer by depositing first LiQ and subsequently Yb.

[0598] Ag:Mg is then evaporated at a rate of 0.01 to 1 Å/s at 10-7 mbar to form a cathode.

[0599] A cap layer of HT-3 is formed on the cathode.

[0600] 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% given in round brackets (...): [0601] Layer stack details used in the OLED device examples of Table 6: [0602] Ag [100 nm] / HT-1:NDP-9 (wt% 92:8) [10 nm] / HT-1 [130 nm] / HT-2 [5 nm] / H09:BD200 (wt% 97:3) [20 nm] / Compound of Formula (I) [5 nm] / Compound of Formula (II) or C-3 [30 nm] / LiQ [1 nm] / Yb [2 nm] / Ag:Mg (wt% 90:10) [13 nm] / HT-3 [75 nm] [0603] Layer stack details used in the OLED device examples of Table 7: [0604] Ag [100 nm] / HT-1:NDP-9 (wt% 92:8) [10 nm] / HT-1 [130 nm] / HT-2 [5 nm] / H09:BD200 (wt% 97:3) [20 nm] / Compound of Formula (I) [5 nm] / Compound of Formula (II): Compound of Formula (III) (wt% 30:70) [30 nm] / LiQ [mm] / Yb [2 nm] / Ag:Mg (wt% 90:10) [13 nm] / HT-3 [75 nm]

TABLE-US-00006 List of compounds used IUPAC name Reference HT-1 N-([1,1′-biphenyl]-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9′-spirobi[fluoren]-2-amine [CAS 1364603-07-5] WO2012034627 HT-2 N-([1,1′-biphenyl]-4-yl)-9,9-diphenyl-N-(4-(triphenylsilyl)phenyl)-9H-fluoren-2-amine [CAS 1613079-70-1] WO2014088047 D-1 4,4′,4″-((1E,1′E,1″E)-cyclopropane-1,2,3-triylidenetris(cyanomethanylylidene))tris(2,3,5,6-tetrafluorobenzonitrile) [CAS 1224447-88-4] US2008265216 HOST-1 H09 (Fluorescent-blue host material) Commercially available from Sun Fine Chemicals, Inc, S. Korea EMITTER-1 BD200 (Fluorescent-blue emitter material) Commercially available from Sun Fine Chemicals, Inc, S. Korea LiQ 8-Hydroxyquinolinolato-lithium [CAS 850918-68-2] WO2013079217 HT-3 N-([1,1′-biphenyl]-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amine US2016322581 CAS 1242056-42-3 C-3 2-([1,1′-biphenyl]-3-yl)-4-phenyl-6-(3-(10-phenylanthracen-9-yl)phenyl)-1,3,5-triazine Table 4

TABLE-US-00007 Performance of an organic electroluminescent device comprising the compound of Formula (I) in the first electron transport layer and the compound of Formula (II) or the comparative compound C-.sub.3 in the second electron transport layer OLED device example Compound Formula (I) Compound Formula (II) or C-3 EIL Relative Operating voltage at 10 mA/cm.sup.2 (% vs Comparative) Relative cd/A efficiency at 10 mA/cm.sup.2 (% vs Comparative) Compara -tive OLED A-2 C-3 LiQ 100,00 100,00 OLED-1 A-3 B-11 LiQ 57,79 128,97 OLED-2 A-1 B-11 LiQ 58,13 124,17 OLED-3 A-2 B-11 LiQ 57,27 130,81 OLED-4 A-2 B-1 LiQ 56,06 125,09 OLED-5 A-2 B-10 LiQ 58,30 134,87 OLED-6 A-2 B-11 LiQ 57,27 130,81 OLED-7 A-2 B-19 LiQ 55,88 135,06 OLED-8 A-2 B-2 LiQ 56,92 118,45 OLED-9 A-2 B-23 LiQ 55,02 113,10 OLED-10 A-2 B-4 LiQ 62,28 116,79 OLED-11 A-2 B-5 LiQ 55,19 135,61 OLED-12 A-2 B-6 LiQ 61,07 121,40

TABLE-US-00008 Performance of an organic electroluminescent device comprising the compound of Formula (I) in the first electron transport layer and a mixture of compound of Formula (II) and compound of Formula (III) in the second electron transport layer OLED device example CompoundFormula (I) Compound Formula (II) Compound Formula (III) Mix ratio Compound Formula (II): Compound (III) EIL Relative Operating voltage at 10 mA/cm.sup.2 (% vs Comparative) Relative cd/A efficiency at 10 mA/cm.sup.2 (% vs Comparative) OLED-13 A-2 B-17 C-3 30:70 LiQ 57,79 130,63 OLED-14 A-2 B-17 C-5 30:70 LiQ 57,44 137,45 OLED-15 A-2 B-2 C-3 30:70 LiQ 56,92 132,29 OLED-16 A-2 B-2 C-6 30:70 LiQ 56,57 133,03 OLED-17 A-2 B-3 C-5 30:70 LiQ 57,09 142,07 OLED-18 A-2 B-3 C-6 30:70 LiQ 57,96 135,06 OLED-19 A-2 B-4 C-3 30:70 LiQ 57,96 126,94 OLED-20 A-2 B-6 C-3 30:70 LiQ 60,90 134,13 OLED-21 A-9 B-17 C-3 20:80 LiQ 56,06 146,13 OLED-22 A-10 B-17 C-3 20:80 LiQ 56,75 143,91 OLED-23 A-11 B-17 C-3 20:80 LiQ 57,61 136,90 OLED-24 A-13 B-17 C-3 20:80 LiQ 56,57 134,50 OLED-25 A-14 B-17 C-3 20:80 LiQ 56,23 136,72 OLED-26 A-15 B-17 C-3 20:80 LiQ 57,61 130,81 OLED-27 A-16 B-17 C-3 20:80 LiQ 57,44 130,07

[0605] Examples 15, 16, 19 and 20 show that the cd/A efficiency is further increased at comparable or lower voltage if a compound (III) is used in the second electron transport layer.

[0606] 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.