Organic electronic device

Abstract

The present invention relates to an organic electronic device, comprising a first electrode, a second electrode, and a substantially organic layer comprising a compound according to formula (I) between the first and the second electrode: ##STR00001##
wherein M is a metal ion, each of A.sup.1-A.sup.4 is independently selected from H, substituted or unsubstituted C6-C20 aryl and substituted or unsubstituted C2-C20 heteroaryl and n is valency of the metal ion.

Claims

1. Organic electronic device, comprising a first electrode, a second electrode, and a substantially organic layer comprising a compound according to formula (I) between the first and the second electrode: ##STR00009## wherein M is a metal ion, each of A.sup.1-A.sup.4 is independently selected from H, substituted or unsubstituted C6-C20 aryl and substituted or unsubstituted C2-C20 heteroaryl and n is valency of the metal ion, wherein at least three groups selected from A.sup.1-A.sup.4 are nitrogen containing heteroaryls, and wherein the substantially organic layer further comprises an electron transport material and the electron transport matrix comprises an imidazole or a P═O functional group.

2. Organic electronic device according to claim 1, wherein n is 1 or 2.

3. Organic electronic device according to claim 1, wherein M is an alkaline metal or an alkaline earth metal.

4. Organic electronic device according to claim 1, wherein nitrogen containing heteroaryl is bound to the central boron atom through a B—N bond.

5. Organic electronic device according to claim 4, wherein the heteroaryl is pyrazolyl.

6. Organic electronic device according to claim 1, wherein M is Mg or Li.

7. Organic electronic device according to claim 1, wherein the compound according to formula (I) and the electron transport matrix are present in the substantially organic layer in the form of a homogeneous mixture.

8. Organic electronic device according to claim 1, wherein the device is selected from an organic light emitting diode, organic solar cell and organic field effect transistor.

9. Organic electronic device according to claim 8, wherein the device is an organic light emitting diode with the first electrode being an anode, the second electrode being a cathode, and the device further comprising a light emitting layer between the anode and the cathode and wherein the substantially organic layer is comprised between the cathode and the light emitting layer.

10. Organic electronic device according to claim 9, wherein the light emitting layer comprises a light emitting polymer.

11. A method for improving the charge carrier transport and/or the electron injection in and/or adjacent an electron transport layer of an organic electronic device, the method comprising: disposing a compound according to formula (I), ##STR00010## wherein M is a metal ion, each of A.sup.1-A.sup.4 is independently selected from H, substituted or unsubstituted C6-C20 aryl and substituted or unsubstituted C2-C20 heteroaryl and n is valency of the metal ion, in a substantially organic layer comprised in the organic electronic device, wherein the substantially organic layer further comprises an electron transport matrix material and the electron transport matrix material comprises an imidazole or a P═O functional group.

12. Organic electronic device according to claim 1, wherein the electron transport matrix material comprises the P═O functional group.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates a first embodiment of an inventive organic electronic device;

(2) FIG. 2 illustrates a second embodiment of an inventive organic electronic device;

(3) FIG. 3 shows a third embodiment of an inventive organic electronic device.

(4) Organic Electronic Devices

(5) FIG. 1 illustrates a first embodiment of an inventive organic electronic device in the form of a stack of layers forming an OLED or a solar cell. In FIG. 1, 10 is a substrate, 11 is an anode, 12 is an EML or an absorbing layer, 13 is a EIL (electron injection layer), 14 is a cathode.

(6) The layer 13 can be a pure layer of a compound according to formula (I). At least one of the anode and cathode is at least semi-transparent. Inverted structures are also foreseen (not illustrated), wherein the cathode is on the substrate (cathode closer to the substrate than the anode and the order of the layers 11-14 is reversed). The stack may comprise additional layers, such as ETL, HTL, etc.

(7) FIG. 2 represents a second embodiment of the inventive organic electronic device in the form of a stack of layers forming an OLED or a solar cell. Here, 20 is a substrate, 21 is an anode, 22 is an EML or an absorbing layer, 23 is an ETL, 24 is a cathode. The layer 23 comprises an electron transport matrix material and a compound according to formula (I).

(8) FIG. 3 illustrates a third embodiment of the inventive device in the form of an OTFT, with semi-conductor layer 32, a source electrode 34 and a drain electrode 35. An unpatterned (unpatterned between the source and drain electrodes) injection layer 33 provides charge carrier injection and extraction between the source-drain electrodes and semi-conducting layer. OTFT also comprises a gate insulator 31 (which could be on the same side as the source drain electrodes) and a gate electrode 30, which gate electrode 30 is on the side of the layer 31 which is not in contact with the layer 32. Obviously, the whole stack could be inverted. A substrate may also be provided. Alternatively, insulator layer 31 may be the substrate.

EXAMPLES

(9) Compounds used as electron transporting matrices for testing the effects of inventive compounds

(10) ##STR00003##

(11) ETM1 and ETM2 were described in patent application WO2011/154131 (Examples 4 and 6), ETM3 (CAS number 561064-11-7) is commercially available. ETM4 was synthesized from the intermediate (10) described in Example 3 of WO2011/154131 according to following procedure:

(12) ##STR00004##

(13) (10) (4.06 g, 9.35 mmol) was dissolved in 60 mL dry THF under argon. The solution was cooled down to −78° C., n-butyllithium was added dropwise within 25 min (2.5 mol/L, 5.6 mL, 14.0 mmol), and the reaction mixture stirred at that temperature for half an hour. The temperature was then let rise up to −50° C., and diphenylphosphine chloride (2.17 g, 9.82 mmol) was added. The mixture was stirred overnight at room temperature. The reaction was then quenched with methanol (MeOH, 30 mL), and the solvents were evaporated. The solid residue was dissolved in 50 mL dichloromethane (DCM), 8 mL aqueous H2O2 (30% by weight) was then added and the mixture was stirred for 24 hours. The reaction mixture was then washed with 50 mL brine and 2×50 mL water, the organic phase was dried and evaporated. The crude product was purified via column chromatography (SiO2, DCM, then DCM/MeOH 99:1). The obtained foamy product was then washed two times with 40 mL acetonitrile.

(14) Yield: 3.1 g (60%). Pale yellow solid.

(15) NMR: .sup.31P NMR (CDCl.sub.3, 121.5 MHz): δ (ppm): 27 (m) .sup.1H NMR (500 MHz, CD.sub.2Cl.sub.2) δ (ppm): 9.78 (d, 8.03 Hz, 2H), 7.95 (m, 3H), 7.85 (m, 2H), 7.76 (m, 11H), 7.57 (ddd, 1.39 Hz, 9.84 Hz, 7.24 Hz, 2H), 7.50 (m, 6H).

(16) m.p. 250° C. (from differential scanning calorimetry (DSC) peak).

Synthetic Procedure for Preparing Compounds of Formula (I)

(17) All reactions were performed under inert atmosphere. Commercial reactants and reagents were used without further purification. Reaction solvents tetrahydrofuran (THF), acetonitrile (AcN) and dichloromethane (DCM) were dried by a solvent purification system (SPS).

1) Synthetic Scheme for the Synthesis of lithium phenyltri(1H-Pyrazol-1-Yl)borate (1)

(18) ##STR00005##

1.1) Lithium phenyltrihydroborate

(19) A solution of 5.2 g (42.6 mmol, 1 eq.)phenylboronic acid in 30 mL dry diethyl ether was cooled to −5° C. A suspension of lithium aluminium hydride (LAH, 2.75 g, 72.4 mmol, 1.7 eq.) in 40 mL dry diethyl ether was added in portions to the first solution over 40 minutes. Mixture went back to room temperature and was stirred for another hour. Inert filtration of unreacted LAH rests through celite (the celite pad was washed with 2×20 mL dry diethyl ether) afforded, after evaporation of the solvent from the collected filtrate and drying under high vacuum 4.66 g crude solid material (grey powder) for which 1H-NMR in DMSO-d6 confirmed the structure. This crude product was used as such in the next step.

(20) .sup.1H-NMR (DMSO-d.sub.6, 500.13 MHz): δ [ppm]=8.01 (m, 2H, Ar—H), 7.61 (t, J=7 Hz, 2H, Ar—H), 7.45 (t, J=7 Hz, 1H, Ar—H), 1.88 (m, 3H, 4 bands from .sup.11B-.sup.1H coupling).

1.2) Lithium phenyltri(1H-pyrazol-1-yl)borate (1)

(21) In a sealed autoclave was mixed under argon 2.4 g (24.5 mmol, theoretically 1 eq.) 1.1) and 6.66 g (98 mmol, 4 eq.) pyrazole in 100 mL dry toluene. The reaction mixture was heated in the sealed vessel until 250° C. were reached, then maintained at this temperature over night. After returning to room temperature, reaction mixture was filtered and the obtained solid was washed with toluene to eliminate pyrazole rests. Obtained 5.0 g of a grey powder (69% yield). Further purification was achieved by gradient sublimation.

(22) ESI-MS: 289 m/z.

(23) .sup.1H-NMR (CD.sub.3OD, 500.13 MHz): δ [ppm]=6.15 (t, J=2 Hz, 2H), 6.95 (m, 2H), 7.09 (d, J=2 Hz, 3H), 7.11 (m, 3H), 7.54 (s, 3H).

2) Tri(1H-pyrazol-1-yl)hydroborate Complexes

(24) ##STR00006##

(25) Synthesis of these complexes was achieved by following the procedures reported by S. Trofimenko in the following reference: Journal of the American Chemical Society, 89 (13), 3170-3177. Complexes of Zinc, Magnesium, and Calcium were synthesized.

2.1) Zinc (II) tri(1H-pyrazol-1-yl)hydroborate (2)

(26) The above cited synthetic procedure was applied to the synthesis of this material.

(27) Characterization: white powder

(28) EI-MS: 489 m/z [M-H].sup.+1

(29) Elem. An. C: 43.99% (calc. 43.99%); H: 4.20% (calc. 4.10%); N: 34.16% (calc. 34.20%).

2.2) Magnesium (II) tri(1H-pyrazol-1-yl)hydroborate (3)

(30) The above cited synthetic procedure was applied to the synthesis of this material.

(31) Characterization: white powder

(32) EI-MS: 449 m/z [M-H].sup.+1 (from unsublimed material)

2.3) Calcium (II) tri(1H-pyrazol-1-yl)hydroborate (4)

(33) The above cited synthetic procedure was applied to the synthesis of this material.

(34) Characterization: white powder

(35) EI-MS: 465 m/z [M-H].sup.+1

2.4) Lithium tri(1H-pyrazol-1-yl)hydroborate (5)

(36) ##STR00007##

(37) The above cited synthetic procedure was also applied to the synthesis of the lithium salt.

(38) Characterization: white powder

(39) EI-MS: 219 m/z [M-H].sup.+1

(40) Elem. An. C: 49.06% (calc. 49.14%); H: 5.01% (calc. 4.58%); N: 38.20% (calc. 38.21%).

3) Magnesium tetra(1H-pyrazol-1-yl)borate (6)

(41) ##STR00008##

(42) To a solution of 2.04 g (5.5 mmol, 1 eq.) of sodium tetra(1H-pyrazol-1-yl)borate in 100 mL water was added carefully a solution of magnesium chloride (262 mg, 2.8 mmol, 1 eq.) in 5 mL water followed by the addition of 40 mL of water. Mixture was stirred for 4 h, then filtered and the residue was washed with 300 mL of water in portions and dried in air, then under vacuum, to afford (6): 1.28 g (79%)

(43) Characterization: white powder

(44) EI-MS: 582 m/z [M-H].sup.+1 (unsublimed sample)

(45) DSC (purity): 99.0% (m.p. 355° C.).

4) Lithiumium tetra(1H-pyrazol-1-yl)borate (7)

(46) 42.0 g (617 mmol) 1H-pyrazole and 3.23 g (147 mmol) lithium borohydride were mixed in an autoclave reactor and heated for 16 h at 250° C. After cooling to room temperature, the white solid was suspended in 120 ml toluene and stirred for an hour. After filtration, washing with toluene and drying in vacuo 28.93 g (69%) material was obtained. The material was purified by gradient sublimation. The C, H, N content (50.22%, 4.3%, 39, 17%) estimated by microanalysis fitted well the theoretical values (50.40%, 4.2%, 39.20%).

5) Sublimation Data

(47) Table 1 shows that exemplary compounds of formula (I) are sufficiently stable to be applicable in processing of electronic devices by means of vacuum thermal evaporation (VTE) and their deposition as a layer on a proper solid substrate or by their co-deposition with an appropriate matrix compound to form a semiconducting material comprising both matrix as well as formula (I) compounds.

(48) TABLE-US-00001 TABLE 1 Melting Decomposition Sublimation Sublimation Com- Point temperature temperature yield pound (° C.) (° C.) (° C.) (%) 1 345 365 300 66 2 284 >300 175 73 3 281 >300 205 71 (unsublimed) (unsublimed) 4 280 367 210 46 5 268 332 198 80 6 355 >360 267 76

Device Examples

Comparative Example 1

(49) A first blue emitting device was made by depositing a anode of 100 nm thick Ag on a glass substrate. A 40 nm doped layer of HTM2 (matrix to dopant weight ratio of 97:3) was subsequently deposited as hole injection and transport layer, followed by an 92 nm undoped layer of HTM2. Subsequently, an blue fluorescent emitting layer of ABH113 (Sun Fine Chemicals) doped with NUBD370 (Sun Fine Chemicals) (97:3 wt %) was deposited with a thickness of 20 nm. A 36 nm layer of the compound ETM1 was deposited on the emitting layer as ETL. A 1 nm thick layer of lithium quinolate (LiQ) followed the ETM1 layer. Subsequently a layer of Mg:Ag (90:10 wt %) with a thickness of 12 nm was deposited as transparent cathode followed by 60 nm of HTM2 as cap layer.

(50) This device showed a voltage of 4.2 V at a current density of 10 mA/cm2, a luminance of 122 cd/m2 at a current density of 10 mA/cm2 with a current efficiency of 1.2 cd/A at the same current density.

(51) In the whole stack HTM2 can be replaced by HTM1 with similar results.

Comparative Example 2

(52) A similar device was produced as in Comparative Example 1, with the difference that the ETL was deposited as a 36 nm thick layer of a mixture between the ETM1 and LiQ with a weight ratio of 1:1.

(53) This device showed a voltage of 4.0 V at a current density of 10 mA/cm2, a luminance of 260 cd/m2 at a current density of 10 mA/cm2 with a current efficiency of 2.6 cd/A at the same current density.

Inventive Example 1

(54) A similar device was produced as in Comparative Example 1, with the difference that the ETL was deposited as a 36 nm thick layer of a mixture between the compound (7) and ETM1 with a weight ratio of 1:1.

(55) This device showed a slightly increased voltage of 4.37 V at a current density of 10 mA/cm2, an extremely enhanced luminance of 663 cd/m2 at a current density of 10 mA/cm2 with a current efficiency of 6.6 cd/A at the same current density. These values are remarkable good for a blue emitting OLED. Given the high performance, it is possible to operate an OLED with same or higher light intensity than the OLEDs of the comparative examples at a lower voltage.

Comparative Example 3

(56) A similar device was produced as in Comparative Example 1, with the difference that the ETL was deposited as a 36 nm thick layer of a mixture between the ETM2 and LiQ with a weight ratio of 1:1.

(57) This device showed a voltage of 4.7 V at a current density of 10 mA/cm2, a luminance of 452 cd/m2 at a current density of 10 mA/cm2 with a current efficiency of 4.5 cd/A at the same current density.

Inventive Example 2

(58) A similar device was produced as in Comparative Example 3, with the difference that the ETL was deposited as a 36 nm thick layer of a mixture between the ETM2 and the compound (7) with a weight ratio of 1:1.

(59) This device showed a voltage of 4.3 V at a current density of 10 mA/cm2, a luminance of 673 cd/m2 at a current density of 10 mA/cm2 with a current efficiency of 6.7 cd/A at the same current density.

(60) The only difference from this inventive example to the comparative example 3 is the compound according to Formula (I). With this replacement, the device had a surprising enhancement of all key figures, operating at a lower voltage, with higher considerable performance. The lifetime of the device was more than 50 h at to 97% of the initial luminance at a current density of 10 mA/cm2, which is considerable more than of the comparative example 2 with 37 h.

(61) OLEDs with other ETMs and the compound according to Formula (I) showed similar performance improvements, as shows the Table 2:

(62) TABLE-US-00002 Voltage QEff (%) ETL (V) at 10 CIE CIE at 10 compound matrix mA/cm.sup.2 1931 x 1931 y mA/cm.sup.2 (1) 3 4.9 0.145 0.120 5.8 (1) 4 4.0 0.165 0.105 8.5 (2) 3 4.8 0.198 0.095 4.7 (3) 3 4.7 0.138 0.096 5.6 (5) 3 3.6 0.136 0.104 7.0 (5) 2 4.4 0.138 0.092 6.7 (6) 3 4.1 0.137 0.096 6.1 (6) 2 5.5 0.139 0.105 5.8 (7) 3 4.3 0.134 0.098 5.2 (7) 2 4.1 0.137 0.108 6.1 (7) 4 3.8 0.162 0.110 6.3 LiQ 3 4.3 0.132 0.108 5.1 LiQ 2 4.9 0.128 0.096 3.8 LiQ 4 4.7 0.142 0.104 4.7

(63) These results show that the inventive devices comprising compounds of formula (I) are not only useful alternatives to the devices using known LiQ as an electron-injecting additive. Use of compounds of formula (I) significantly broadens the offer of electron transport improving additives, allowing improving and optimizing device performance beyond limits known in the art.

(64) The features disclosed in the foregoing description, the claims and in the drawings may both separately and in any combination thereof, be material for realising the invention in diverse forms thereof.