Compound and an organic semiconducting layer comprising the same
11566033 · 2023-01-31
Assignee
Inventors
Cpc classification
C07F9/5325
CHEMISTRY; METALLURGY
International classification
Abstract
The present invention relates to the compound represented by the general Formula (I): wherein X is selected from the group consisting of O, S and Se; R.sup.1 and R.sup.2 are independently selected from the group consisting of C.sub.1 to C.sub.12 alkyl, C.sub.6 to C.sub.20 aryl and C.sub.5 to C.sub.20 heteroaryl, wherein the respective C.sub.1 to C.sub.12 alkyl may optionally be substituted with C.sub.6-C.sub.20 aryl; L represents a single bond or is selected from the group consisting of C.sub.6 to C.sub.18 arylene or C.sub.2 to C.sub.20 heteroarylene; wherein the rings B, C and D may each be unsubstituted or substituted and B and C are anellated aromatic 6-membered rings; R.sup.3 and R.sup.4 are independently selected from the group consisting of unsubstituted or substituted C.sub.1 to C.sub.12 alkyl, unsubstituted or substituted C.sub.1 to C.sub.12 fluorinated alkyl, unsubstituted or substituted C.sub.6 to C.sub.20 aryl and unsubstituted or substituted C.sub.5 to C.sub.20 heteroaryl; wherein the substituents, if present in B, C, D, R.sup.3 and R.sup.4, are independently selected from the group consisting of C.sub.1-C.sub.20 linear alkyl, C.sub.3-C.sub.20 branched alkyl, C.sub.3-C.sub.20 cyclic alkyl, C.sub.1-C.sub.20 linear alkoxy, C.sub.3-C.sub.20 branched alkoxy, linear fluorinated C.sub.1-C.sub.12 alkyl, linear fluorinated C.sub.1-C.sub.12 alkoxy, C.sub.3-C.sub.12 branched fluorinated cyclic alkyl, C.sub.3-C.sub.12 fluorinated cyclic alkyl, C.sub.3-C.sub.12 fluorinated cyclic alkoxy, CN, C.sub.6-C.sub.20 aryl, C.sub.2-C.sub.20 heteroaryl, OR, SR, (C═O)R, (C═O)NR2, SiR.sub.3, (S═O)R, (S═O).sub.2R, CR═CR.sub.2, Fluorine, NR.sub.2, NO.sub.2; wherein R is 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 R.sup.3 and R.sup.4 may or may not be connected with each other via a single bond, 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 same. ##STR00001##
Claims
1. A compound represented by the general Formula (I): ##STR00037## wherein X is selected from the group consisting of O, S and Se; R.sup.1 and R.sup.2 are independently selected from the group consisting of C.sub.1 to C.sub.12 alkyl, C.sub.6 to C.sub.20 aryl and C.sub.5 to C.sub.20 heteroaryl, wherein the respective C.sub.1 to C.sub.12 alkyl optionally is substituted with C.sub.6-C.sub.20 aryl; L represents a single bond or is selected from the group consisting of C.sub.6 to C.sub.18 arylene or C.sub.2 to C.sub.20 heteroarylene; wherein the rings B, C and D are each unsubstituted or substituted and B and C are anellated aromatic rings; R.sup.3 and R.sup.4 are independently selected from the group consisting of unsubstituted or substituted C.sub.1 to C.sub.12 alkyl, unsubstituted or substituted C.sub.1 to C.sub.12 fluorinated alkyl, unsubstituted or substituted C.sub.6 to C.sub.20 aryl and unsubstituted or substituted C.sub.5 to C.sub.20 heteroaryl; wherein the substituents of B, C, D, R.sup.3 and R.sup.4, are independently selected from the group consisting of C.sub.1-C.sub.20 linear alkyl, C.sub.3-C.sub.20 branched alkyl, C.sub.3-C.sub.20 cyclic alkyl, C.sub.1-C.sub.20 linear alkoxy, C.sub.3-C.sub.20 branched alkoxy, linear fluorinated C.sub.1-C.sub.12 alkyl, linear fluorinated C.sub.1-C.sub.12 alkoxy, C.sub.3-C.sub.12 branched fluorinated cyclic alkyl, C.sub.3-C.sub.12 fluorinated cyclic alkyl, C.sub.3-C.sub.12 fluorinated cyclic alkoxy, CN, C.sub.6-C.sub.20 aryl, C.sub.2-C.sub.20 heteroaryl, OR, SR, (C═O)R, (C═O)NR2, SiR.sub.3, (S═O)R, (S═O).sub.2R, CR═CR.sub.2, Fluorine, NR.sub.2, and NO.sub.2; wherein R is 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 R.sup.3 and R.sup.4 are not connected or connected with each other via a single bond.
2. The compound according to claim 1, wherein X is O.
3. The compound according to claim 1, wherein R.sup.1 and R.sup.2 are independently selected from the group consisting of C.sub.1 to C.sub.12 alkyl or wherein R.sup.1 and R.sup.2 are independently selected from the group consisting of C.sub.6 to C.sub.20 aryl.
4. The compound according to claim 1, wherein L represents a single bond or wherein L comprises at least one of a bivalent structure moiety which is selected from the group consisting of phenylene, biphenylene, dibenzofuranylene, anthracenylene, quinolinylene, terphenylenylene, dibenzosilolylene, fluorenylene and naphtylene.
5. The compound according to claim 1, wherein R.sup.3 and R.sup.4 are independently selected from C.sub.6 to C.sub.20 aryl.
6. The compound according to claim 1, wherein Formula (I) comprises one of a spiro[benzo[a]fluorene-11,9′ fluorene], spiro[benzo[b]fluorene-11,9′ fluorene], or spiro[benzo[c]fluorene-7,9′-fluorene] moiety.
7. The compound according to claim 1, represented by one of the following Chemical Formulas A-1 to A-47: ##STR00038## ##STR00039## ##STR00040## ##STR00041## ##STR00042## ##STR00043## ##STR00044## ##STR00045## ##STR00046## ##STR00047## ##STR00048## ##STR00049## ##STR00050##
8. An organic semiconducting layer comprising a compound according to claim 1.
9. The organic semiconducting layer according to claim 8 further comprising an additive selected from a metal, a metal salt, an organic metal complex or a mixture thereof.
10. An organic electronic device comprising the organic semiconducting layer according to claim 8.
11. The organic electronic device according to claim 10, wherein the organic electronic device comprises, between an anode and a cathode and in electrical contact therewith, the organic semiconducting layer and an emission layer, wherein the organic semiconducting layer is arranged between the emission layer and the cathode.
12. The organic electronic device according to claim 11 further comprising, between the cathode and the anode, an electron transport layer, wherein the organic semiconducting layer is arranged between the electron transport layer and the cathode.
13. A display device comprising the organic electronic device according to claim 10.
14. A lighting device comprising the organic electronic device according to claim 10.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) 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:
(2)
(3)
(4)
DETAILED DESCRIPTION
(5) 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.
(6) 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.
(7)
(8) Instead of a single electron transport layer 160, optionally an electron transport layer stack (multiple ETL) can be used.
(9)
(10) Referring to
(11)
(12) Referring to
(13) While not shown in
(14) 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.
(15) The features disclosed in the foregoing description, in the claims and/or in the accompanying drawings may, both separately and in any combination thereof, be material for realizing the invention in diverse forms thereof.
Preparation of the Inventive Compounds
(16) ##STR00024##
(17) ##STR00025##
(18) ##STR00026##
(19) ##STR00027##
(20) ##STR00028##
Synthesis of dimethyl(3-(spiro[benzo[b]fluorene-11,9′-fluoren]-4-yl)phenyl)phosphine oxide (A-20) (Scheme 1b)
(21) Synthesis of 4-bromo-11H-benzo[b]fluoren-11-one was carried out according to the literature (WO 2015033559)
Synthesis of 11-([1,1′-biphenyl]-2-yl)-4-bromo-11H-benzo[b]fluoren-11-ol
(22) ##STR00029##
(23) s-BuLi (1.4M in cyclohexane, 55.3 mL, 77.1 ol, 2.9 eq.) was added dropwise to a solution of 2-bromo-1,1′-biphenyl (18.6 g, 13.8 mL, 79.8 mmol, 3.0 eq.) in dried THF (200 mL) at −80° C. solution was stirred at −80° C. for 1 h and 45 min. A suspension was formed. 4-bromo-11H-benzo[b]fluoren-11-one (8.2 g, 26.6 g, 1.0 eq.) was then added at −80° C. and the mixture was stirred at this temperature. After 40 min, full conversion was observed. MeOH (10 mL) and water was added, and the crude reaction mixture was warm it up to room temperature. Then, it was extracted with ethylacetate. The combined organic phase was washed with brine, dried with Na2CO3 and solvents were removed under vacuum. 30 ml of mixture ethylacetate/hexane 5/95 was added to the solid and heated to reflux for a minute. The white solid was filtered off and washed with small amount of the ethylacetate/hexane 5/95 mixture and then hexanes to obtain 10.3 g (83% yield) of 11-([1,1′-biphenyl]-2-yl)-4-bromo-11H-benzo[b]fluoren-11-ol. APCI-MS: 445 (M-OH).
Synthesis of 4-bromospiro[benzo[b]fluorene-11,9′-fluorene]
(24) ##STR00030##
(25) Trifluoromethansulfonic acid (0.2 mL, 2.2 mmol, 0.1 eq.) was added to a solution of 11-([1,1′-biphenyl]-2-yl)-4-bromo-11H-benzo[b]fluoren-11-ol (10.3 g, 22.2 mmol, 1.0 eq.) in anhydrous dichloromethane (30 mL), s and the mixture was stirred at room temperature for 1.5 h. The suspension was cooled to 0° C. and the solid filtered and washed with a mixture of dichloromethane/hexane=5/95 to obtain 8.9 g (89% yield) of 4-bromospiro[benzo[b]fluorene-11,9′-fluorene]. APCI-MS: 445 (M+H).
Synthesis of dimethyl(3-(spiro[benzo[b]fluorene-11,9′-fluoren]-4-yl)phenyl)phosphine oxide (A-20)
(26) ##STR00031##
(27) 4-bromospiro[benzo[b]fluorene-11,9′-fluorene] (10 g, 22.5 mmol, 1.0 eq.), dimethyl(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)phosphine oxide (6.9 g, 24.7 mmol, 1.1 eq.) and potassium carbonate (6.2 g, 44.9 mmol, 2.0 eq.) were placed in a flask der a nitrogen stream. Dioxane (90 mL) and water (22 ere added and the mixture was degassed with nitrogen. Then, tetrakis(triphenylphosphine)palladium(0) (519 mg, 0.4 mmol, 0.02 eq.) was added under a nitrogen stream. The reaction mixture was stirred under nitrogen overnight at 90° C. The reaction mixture was cooled down and solvent was removed under vacuum. The crude residue was dissolved in dichloromethane (30 mL), then toluene was added (130 mL) and the solvents were removed under vacuum (till 50 mL). The precipitated was filtered, dissolved in chloroform and filtered over florisil using chloroform as eluent. Chloroform was partially removed under vacuum, then toluene was added and the solvents were removed under vacuum (till 50 mL). Solid was filtered to obtain 4.7 g (40% yield) of dimethyl(3-(spiro[benzo[b]fluorene-11,9′-fluoren]-4-yl)phenyl)phosphine oxide. MS (ESI): 519 (M+H), 541 (M+Na).
Synthesis of diphenyl(3-(spiro[benzo[b]fluorene-11,9′-fluoren]-4-yl)phenyl)phosphine oxide (A-47) (Scheme 1a)
(28) ##STR00032##
(29) Synthesis of diphenyl(3-(spiro[benzo[b]fluorene-11,9′-fluoren]-4-yl)phenyl)phosphine oxide was performed according to the procedure described for dimethyl(3-(spiro[benzo[b]fluorene-11,9′-fluoren]-4-yl)phenyl)phosphine oxide (A-20) using diphenyl(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)phosphine oxide.
(30) 4-bromospiro[benzo[b]fluorene-11,9′-fluorene] (15.0 g, 33.7 mmol, 1.0 eq.), diphenyl(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)phosphine oxide (13.6 g, 33.7 mmol, 1.0 eq.) and potassium carbonate (13.9 g, 67.4 mmol, 2.0 eq.) were placed in a flask under a nitrogen stream. Dioxane (135 mL) and water (51 mL) were added and the mixture was degassed with nitrogen. Then, tetrakis(triphenylphosphine)palladium(0) (1.16 g, 1 mmol, 0.03 eq.) was added under a nitrogen stream. The reaction mixture was stirred under nitrogen overnight at 90° C. The reaction mixture was cooled down and solvent was removed under vacuum. The crude residue was dissolved in dichloromethane (200 mL) and washed with deionized water (3×100 ml). Organic phase was dried over MgSO4 and concentrated to ca. 100 ml. To this residue 150 ml of n-hexane was added and the mixture was stirred overnight. Formed solid was filtered-off and recrystallized from toluene (250 ml). Isolated solid was recrystallized from chlorobenzene (100 ml) to obtain 12 g (55%) of diphenyl(3-(spiro[benzo[b]fluorene-11,9′-fluoren]-4-yl)phenyl)phosphine oxide MS (ESI): 643 (M+H), 665 (M+Na).
(31) General Procedure for Fabrication of Organic Electronic Devices
(32) In general organic electronic devices may be organic light-emitting diodes (OLEDs), organic photovoltaic cells (OSCs), organic field-effect transistors (OFETs) or organic light emitting transistors (OLETs). Organic electronic light-emitting devices such as OLED and OLET may be part of a lighting device.
(33) Any functional layer in the organic electronic device may comprise a compound of Formula (I) or may consist of a compound of formula 1.
(34) An OLED may be composed of individual functional layers to form a top-emission OLED which emits light through the top electrode. Herein, the sequence of the individual functional layers may be as follows wherein contact interfaces between the individual layers are shown as “/”: non-transparent anode layer (bottom electrode)/hole injection layer/hole transport layer/electron blocking layer/emission layer/hole blocking layer/electron transport layer/electron injection layer/transparent cathode layer (top electrode). Each layer may in itself be constituted by several sub-layers.
(35) An OLED may be composed of individual functional layers to form a bottom-emission OLED which emits light through the bottom electrode. Herein, the sequence of the individual functional layers may be as follows wherein contact interfaces between the individual layers are shown as “/”: transparent anode layer (bottom electrode)/hole injection layer/hole transport layer/electron blocking layer/emission layer/hole blocking layer/electron transport layer/electron injection layer/non-transparent cathode layer (top electrode). Each layer may in itself be constituted by several sub-layers.
(36) Top-emission OLED devices were prepared to demonstrate the technical benefit utilizing the compounds of Formula (I) in an organic electronic device.
(37) Fabrication of Top Emission OLED Devices
(38) For all top emission devices, inventive examples 1 and 2 and comparative example 1, 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, to prepare a first electrode. 100 nm Ag were deposited at a pressure of 10.sup.−5 to 10.sup.−7 mbar to form the anode. Then, 92 vol.-% N-([1,1′-biphenyl]-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amine (CAS 1242056-42-3) with 8 vol.-% 4,4′,4″-((1E,1′E,1″E)-cyclopropane-1,2,3-triylidenetris(cyanomethanylylidene))tris(2,3,5,6-tetrafluorobenzonitrile) was vacuum deposited on the Ag electrode, to form a HIL having a thickness of 10 nm. Then, N-([1,1′-biphenyl]-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amine (CAS 1242056-42-3) was vacuum deposited on the HIL, to form a HTL having a thickness of 118 nm. 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.
(39) Subsequently, the emission layer was deposited. In comparative examples 1 and 2, and in examples 1, 2, 4, 5 and 6, 97 vol.-% 2-(10-phenyl-9-anthracenyl)-benzo[b]naphtho[2,3-d]furan (CAS 1627916-48-6) as EML host mid 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. In example 3, 97 vol.-% H09 (Fluorescent-blue host material) 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.
(40) Then, for comparative example 1 and examples 2, 3 and 6 the hole blocking layer is formed with a thickness of 5 nm by depositing 2,4-diphenyl-6-(4′,5′,6′-triphenyl-[1,1 ′:2′,1″:3″,1″′:3′″,1″″-quinquephenyl]-3″″-yl)-1,3,5-triazine (CAS 2032364-64-8) on the emission layer. For example 4, the hole blocking layer is formed with a thickness of 5 nm by depositing a 7:3 vol.-% mixture of 9-([1,1′-biphenyl]-3-yl)-9′-([1,1′-biphenyl]-4-yl)-9H,9′H-3,3′-bicarbazole and 2,4-diphenyl-6-(3′-(triphenylen-2-yl)-[1,1′-biphenyl]-3-yl)-1,3,5-triazine on the emission layer. For comparative example 2 and example 1 and 5 no hole blocking layer was deposited.
(41) Then, the electron transporting layer is formed on the hole blocking layer with a thickness of 31 nm. The electron transport layer comprises compounds of Formula (I) (or a comparative compound) as matrix compounds and an additive, compositions according to Table 2 and Table 3.
(42) Then, the electron injection layer is formed on the electron transporting layer by deposing Yb with a thickness of 2 nm. Ag is 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. A cap layer of N-([1,1′-biphenyl]-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amine (CAS 1242056-42-3) is formed on the cathode with a thickness of 75 nm.
(43) 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.
(44) To assess the performance of the inventive examples compared to the existing art, the light output of the top emission OLEDs is measured under ambient conditions (20° C.). Current voltage measurements are performed using a Keithley 2400 sourcemeter, and recorded in V. At 10 mA/cm.sup.2 for top emission devices, a spectrometer CAS140 CT from Instrument Systems, which has been calibrated by Deutsche Akkreditierungsstelle (DAkkS), is used for measurement of CIE coordinates and brightness in Candela. The current efficiency Ceff is determined at 10 mA/cm.sup.2 in cd/A.
(45) 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 from Instrument Systems, which has been 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.
(46) In top emission devices, the emission is forward directed, non-Lambertian and also highly dependent on the micro-cavity. Therefore, the external quantum efficiency (EQE) and power efficiency in 1 m/W will be higher compared to bottom emission devices.
(47) Compounds Used
(48) TABLE-US-00001 IUPAC name Reference N-([1,1′-biphenyl]-4-yl)-9,9-dimethyl-N-(4-(9-phenyl- US2016322581 9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amine (CAS 1242056-42-3) 4,4′,4″-((1E,1′E,1″E)-cyclopropane-1,2,3- US2008265216 triylidenetris(cyanomethanylylidene))tris(2,3,5,6- tetrafluorobenzonitrile) N,N-bis(4-(dibenzo[b,d]furan-4-yl)phenyl)-[1,1′:4′,1″- JP2014096418 terphenyl]-4-amine (CAS 1198399-61-9) 2-(10-phenyl-9-anthracenyl)-benzo[b]naphtho[2,3- EP2924029 d]furan (CAS 1627916-48-6) (Fluorescent-blue host material) H09 (Fluorescent-blue host material) Commercially available from Sun Fine Chemicals, Inc, S. Korea BD200 (Fluorescent-blue emitter material) Commercially available from Sun Fine Chemicals, Inc, S. Korea 2,4-diphenyl-6-(4′,5′,6′-triphenyl-[1,1′:2′, WO 2016171358 1″:3″,1′″:3′″,1″″-quinquephenyl]-3″″-yl)-1,3,5-triazine (CAS 2032364-64-8) 9-([1,1′-biphenyl]-3-yl)-9′-(1,1′-biphenyl]-4-yl)- — 9H,9′H-3,3′-bicarbazole 2,4-diphenyl-6-(3′-(triphenylen-2-yl)-[1,1′-biphenyl]- WO 2015115744 3-yl)-1,3,5-triazine 8-Hydroxyquinolinolato-lithium (CAS 850918-68-2) = WO2013079217 LiQ = Additive-1 Lithium tetra(1H-pyrazol-1-yl)borate (CAS 14728-62- US20140332789 2) = Additive-2 Ytterbium (Yb) (CAS 7440-64-4) = Additive-3 US2016322568
(49) Melting Point
(50) The melting point (Tm) 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).
(51) Glass Transition Temperature
(52) The glass transition temperature (Tg) is measured under nitrogen and using a heating rate of 10 K per min in a Mettler Toledo DSC 822e differential scanning calorimeter as described in DIN EN ISO 11357, published in March 2010.
(53) Rate Onset Temperature
(54) The rate onset temperature (T.sub.RO) for transfer into the gas phase 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 (vacuum thermal evaporation) source temperature is determined through a thermocouple in direct contact with the compound in the VTE source.
(55) The VTE source is heated at a constant rate of 15 K/min at a pressure of 10.sup.−7 to 10.sup.−8 mbar in the vacuum chamber and the temperature inside the source measured with a thermocouple. Evaporation of the compound is detected with a QCM detector which detects deposition of the compound on the quartz crystal of the detector. The deposition rate on the quartz crystal is measured in Angstrom per second. To determine the rate onset temperature, the deposition rate on a logarithmic scale is plotted against the VTE source temperature. The rate onset is the temperature at which noticeable deposition on the QCM detector occurs (defined as a rate of 0.02 Å/s. 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. 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.
(56) Technical Effect of the Invention
(57) Material Property
(58) The Tg of compounds of Formula (I) (Table 2) are increased versus the comparative compounds of existing art (Table 1). The values are in a range suitable for use in or organic electronic devices. High Tg values of materials used in organic electronics are generally preferred for device durability and robustness.
(59) Top Emission OLED Devices
(60) Surprisingly, the cd/A current efficiencies were increased using compounds of Formula (I) mixed with an additive as an electron transport layer (Table 2).
(61) Surprisingly, the lifetime LT97 of top emission OLED devices is increased when using compounds of Formula (I) mixed with an additive as an electron transport layer (Table 3).
(62) Three different of additives were tested, as specified in the overview of compounds used.
(63) In summary, improved LT97 lifetime of top emission OLED devices and increased cd/A efficiency may be achieved when the electron transporting organic semiconductor layer comprises a compound of Formula (I). High performance may be achieved for a range of additives.
(64) Table 4 shows the LUMO energy levels and the molecular dipole moments of compounds of Formula (I).
(65) Table 1: Structural formulae, glass transition temperatures, melting temperatures, rate onset temperatures of comparative and inventive compounds.
(66) TABLE-US-00002 TABLE 1 Tg Tm T.sub.RO Name Formula [° C.] [° C.] [° C.] Comparative Compound 1 Comparative-1
(67) TABLE-US-00003 TABLE 2 Performance data of top emission OLED devices comprising an electron transport layer, which comprise the compounds of Formula (I) a comparative compound as matrix compound, and an additive. OLEDs comprising compounds of Formula (I) show increased cd/A efficiencie Ceff. cd/A vol.-% efficiency vol.-% of alkali Total Ceff at 10 Matrix matrix metal Thickness CIE mA/cm.sup.2 compound compound additive compound ETL/nm 1931 y (cd/A) Comparative Comparative-1 50 Additive-1 50 31 0.046 7.6 Example 1 (LiQ) Example 1 A-20 50 Additive-1 50 31 0.042 8.0 (LiQ) Example 2 A-20 50 Additive-1 50 31 0.043 7.8 (LiQ) Example 3 A-20 95 Additive-3 5 31 0.047 8.2 (Yb)
(68) TABLE-US-00004 TABLE 3 Lifetime LT97 of an organic electroluminescent devices comprising an electron transport layer which comprises the compounds of Formula (I) or a comparative compound as matrix compound, and an additive. OLEDs comprising compounds of Formula (I) show increased Lifetime LT97. Concentration Thickness of matrix Concentration electron Lifetime Matrix compound of additive transport LT97 compound (vol.-%) Additive (vol.-%) layer (nm) CIEy (hours) Comparative Comparative-2 50 Additive-1 50 31 0.049 145 example 2 (LiQ) Example 4 A-20 70 Additive-2 30 31 0.045 285 Example 5 A-20 50 Additive-1 50 31 0.042 248 (LiQ) Example 6 A-20 50 Additive-1 50 31 0.043 164 (LiQ)
(69) TABLE-US-00005 TABLE 4 Calculated LUMO Levels and Dipole Moments for molecules of Formula (I). Compound Name LUMO (eV) Dipole Moment (Debye) A-1 −1.26 3.78 A-2 −1.27 4.17 A-3 −1.27 4.45 A-4 −1.31 4.41 A-5 −1.31 4.03 A-6 −1.32 4.53 A-7 −1.34 4.41 A-8 −1.34 4.35 A-9 −1.35 4.15 A-10 −1.35 4.42 A-11 −1.35 4.45 A-12 −1.36 4.33 A-13 −1.37 4.23 A-14 −1.38 4.55 A-15 −1-39 4.43 A-16 −1-39 4.07 A-17 −1.39 4.17 A-18 −1.40 4.00 A-19 −1.41 4.19 A-20 −1.43 4.41 A-21 −1.44 4.20 A-22 −1.45 4.19 A-23 −1.46 4.23 A-24 −1.48 4.25 A-25 −1.49 4.22 A-26 −1.53 4.06 A-27 −1.55 4-40 A-28 −1.55 4.17 A-29 −1.56 4.11 A-30 −1.56 4.47 A-31 −1.56 4.39 A-32 −1.56 4.31 A-33 −1.56 4.16 A-34 −1.57 4.28 A-35 −1.57 4.25 A-36 −1.57 4.38 A-37 −1.49 4.70 A-38 −1.56 4.74 A-39 −1.34 3.98 A-40 −1.39 4.14 A-41 −1.32 3.69 A-42 −1.43 4.36 A-43 −1.75 4.28 A-44 −1.63 5.73 A-45 −1.39 4.28 A-46 −1.37 4.27 A-47 −1.26 3.75
(70) While 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.
(71) The features disclosed in the foregoing description and in the claims may, both separately or in any combination, be material for realizing the invention in diverse forms thereof.