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 A.sup.1 is a C.sub.6-C.sub.20 arylene and each of A.sup.2-A.sup.3 is independently selected from a C.sub.6-C.sub.20 aryl, wherein the aryl or arylene may be unsubstituted or substituted with groups comprising C and H or with a further LiO group, provided that the given C count in an aryl or arylene group includes also all substituents present on the said group.

Claims

1. A compound according to formula (I): ##STR00011## wherein A.sup.1 is m- or p-arylene and each of A.sup.2-A.sup.3 is independently selected from a C.sub.6-C.sub.20 aryl, wherein each of the C.sub.6-C.sub.20 aryls or the m- or p-arylene, independently, is unsubstituted or substituted with groups comprising C and H or with a further LiO group, wherein the C.sub.6-C.sub.20 carbons of each of the C.sub.6-C.sub.20 aryls also includes the carbons of all substituents present on each of the C.sub.6-C.sub.20 aryls.

2. The compound according to claim 1, wherein each of A.sup.2-A.sup.3 is independently selected from a C.sub.6-C.sub.10 aryl.

3. The compound according to claim 1, wherein the arylene is m-phenylene.

4. The compound according to claim 1, wherein A.sup.1 is a C.sub.6-C.sub.20 arylene, wherein the C.sub.6-C.sub.20 carbons of the C.sub.6-C.sub.20 arylene also includes the carbons of all substituents present on the C.sub.6-C.sub.20 arylene.

5. The compound according to claim 4, wherein A.sup.1 is a C.sub.6-C.sub.12 arylene.

6. The compound according to claim 1, wherein A.sup.2 and A.sup.3 are phenyl.

7. The compound according to claim 1, wherein the arylene is p-arylene.

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.

ORGANIC ELECTRONIC DEVICES

(4) 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.

(5) 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.

(6) 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).

(7) 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

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

(9) ##STR00004##
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:

(10) ##STR00005##
(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 H.sub.2O.sub.2 (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 250 mL water, the organic phase was dried and evaporated. The crude product was purified via column chromatography (SiO.sub.2, DCM, then DCM/MeOH 99:1). The obtained foamy product was then washed two times with 40 mL acetonitrile.

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

(12) NMR: .sup.31P NMR (CDCl.sub.3, 121.5 MHz): (ppm): 27 (m).sup.1H NMR (500 MHz, CD.sub.2Cl.sub.2) (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).

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

(14) Synthetic Procedure for Preparing the Compounds of Formula (I)

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

1) Synthetic Scheme for the Synthesis of Lithium 2-(diphenylphosphoryl)phenolate (1)

(16) ##STR00006##

1.1) (2-methoxyphenyl)diphenylphosphine Oxide

(17) A solution of 3.36 mL (5.0 g, 26.7 mmol, 1.05 eq.) o-bromoanisole in 20 mL dry THF from SPS was slowly added to a suspension of magnesium turnings (0.98 g, 40.1 mmol, 1.57 eq.) in 20 mL THF, in presence of a catalytic amount of elemental iodine. After the initial temperature rise was over, the reaction mixture was refluxed for 2 h, then let return to room temperature and inert filtered. The filtrate was cooled at 50 C. and a solution of 6 g (25.4 mmol, 1 eq.) of diphenylphosphinyl chloride in 20 mL THF was added drop wise. The suspension was allowed to warm slowly to room temperature and stirred overnight. The mixture was then refluxed for 3 h, and then cooled down to room temperature. The reaction was quenched by the addition of 10 mL methanol. The solvents were evaporated under vacuum, the residue was suspended in 50 mL chloroform and filtered. The filtrate was evaporated to afford (2-methoxyphenyl)diphenylphosphine oxide quantitatively (7.8 g, 25.4 mmol). The crude product was used without further purification.

(18) GC-MS: m/z=308 (96% purity)

1.2) (2-hydroxyphenyl)diphenylphosphine Oxide

(19) A solution of 7.8 g (25.4 mmol, 1 eq.) (2-methoxyphenyl)diphenylphosphine oxide in 20 mL dry DCM was cooled to 5 C. To the reaction mixture, 28 mL (1.1 eq.) of a 1M boron tribromide solution in DCM were slowly added. The cooling bath was removed and the reaction was stirred at room temperature overnight. After quenching with 10 mL methanol, the mixture was neutralized with a saturated aqueous sodium hydrogen carbonate solution. Extraction from this mixture with 50 mL chloroform followed by evaporation and precipitation from chloroform with hexane afforded 4.1 g (13.9 mmol, 55% yield) (2-hydroxyphenyl)diphenylphosphine oxide.

(20) HPLC purity: 97% (UV detector at 300 nm)

1.3) Lithium 2-(diphenylphosphoryl)phenolate (1)

(21) To 4.0 g (13.6 mmol, 1 eq.) (2-hydroxyphenyl)diphenylphosphine oxide suspended in 80 mL dry AcN 109 mg (13.6 mmol, 1 eq.) lithium hydride was added under argon stream. The suspension was stirred overnight at room temperature, then filtered and washed with AcN to afford 3.40 g (83% yield) of a grey powder. Further purification was achieved by gradient sublimation.

(22) HPLC: 97% (250 nm), 98% (300 nm)

(23) DSC: melting point: 436 C. (onset)

(24) .sup.1H-NMR (CD.sub.3OD, 500.13 MHz): [ppm]=6.38 (broad s, 1H), 6.65 (m, 1H), 6.77 (broad s, 1H), 7.18 (t, J=8 Hz, 1H), 7.42 (td, J=3 Hz and 8 Hz, 4H), 7.50 (m, 2H), 7.65 (m, 4H).

(25) .sup.13C-NMR (CD.sub.3OD, 125.76 MHz, with PC coupling): [ppm]=114.01 (d, J=11 Hz), 115.80 (d, J=3 Hz), 122.19 (d, J=10 Hz), 129.35 (d, J=12 Hz), 132.69 (d, J=15 Hz), 133.34 (d, J=105 Hz), 134.34 (s), 134.64 (d, J=10 Hz), 135.19 (s), 135.73 (d, J=3 Hz).

(26) .sup.31P-NMR (CD.sub.3OD, 125.76 MHz, without PC coupling): [ppm]=37.28.

2) Synthetic Scheme for the Synthesis of Lithium 3-(diphenylphosphoryl)phenolate (2)

(27) ##STR00007##

2.1) (3-methoxyphenyl)diphenylphosphine Oxide

(28) A solution of 3.36 mL (5.0 g, 26.7 mmol, 1.05 eq.) of 3-bromoanisole in 20 mL dry THF from SPS was slowly added to a suspension of magnesium turnings (0.98 g, 40.1 mmol, 1.57 eq.) in 20 mL THF, in presence of a catalytic amount of elemental iodine. After the initial temperature rise was over, reaction mixture was refluxed 2 h, then let return to room temperature and inert filtered. The filtrate was cooled at 50 C. and a solution of 6 g (25.4 mmol, 1 eq.) diphenylphosphinyl chloride in 20 mL THF was added drop wise. The suspension was allowed to warm slowly to room temperature and stirred overnight. The mixture was then refluxed for 3 h, and then cooled down to room temperature. The reaction was quenched by the addition of 10 mL methanol. The solvents were evaporated under vacuum and the residue was suspended in 50 mL chloroform and filtered. The filtrate was evaporated to afford (3-methoxyphenyl) diphenylphosphine oxide quantitatively (7.8 g, 25.4 mmol). The crude product was used without further purification.

(29) GC-MS: m/z=308 (96%)

2.2) (3-hydroxyphenyl)diphenylphosphine Oxide

(30) A solution of 7.8 g (25.4 mmol, 1 eq.) (3-methoxyphenyl)diphenylphosphine oxide in 20 mL dry DCM was cooled to 5 C. To the reaction mixture were slowly added 28 mL (1.1 eq.) of a 1M solution of boron tribromide in DCM. The cooling bath was removed and the reaction was stirred at room temperature overnight. After quenching with 10 mL methanol, the mixture was neutralized with a saturated aqueous sodium hydrogen carbonate solution. Extraction from this mixture with 50 mL chloroform followed by evaporation and precipitation from chloroform with hexane afforded 4.1 g (13.9 mmol, 55% yield) (3-hydroxyphenyl)diphenylphosphine oxide.

(31) HPLC: 96% (300 nm)

2.3) Lithium 3-(diphenylphosphoryl)phenolate (2)

(32) To a suspension of 4.0 g (13.6 mmol, 1 eq.) of (3-hydroxyphenyl)diphenylphosphine oxide in 80 mL dry can, 109 mg (13.6 mmol, 1 eq.) of lithium hydride was added under argon stream. The suspension was stirred overnight at room temperature, then filtered and the solid product washed with AcN to afford 3.40 g (83% yield) of a grey powder. Further purification was achieved by gradient sublimation.

(33) HPLC: 97% (250 nm), 98% (300 nm)

(34) DSC: melting point: 177 C. (onset)

(35) .sup.1H-NMR (CD.sub.3OD, 500.13 MHz): [ppm]=7.02-7.07 (m, 3H, ArH from phenolic ring), 7.34-7.38 (m, 1H, ArH from phenolic ring), 7.54-7.56 (m, 4H, ArH phenyl rings), 7.61-7.65 (m, 6H, ArH from phenyl rings).

(36) .sup.13C-NMR (CD.sub.3OD, 125.76 MHz, with PC coupling): [ppm]=119.69 (d, J=11 Hz), 121.02 (d, J=3 Hz), 124.15 (d, J=10 Hz), 130.13 (d, J=12 Hz), 131.48 (d, J=15 Hz), 132.93 (d, J=105 Hz), 133.27 (d, J=10 Hz), 133.89 (d, J=105 Hz), 133.91 (d, J=3 Hz), 159.33 (d, J=15 Hz).

(37) .sup.31P-NMR (CD.sub.3OD, 125.76 MHz, without PC coupling): [ppm]=32.83.

3) Lithium 2,2-(phenylphosphoryl)diphenolate (3)

(38) ##STR00008##

(39) To a solution of 3.58 g (38 mmol, 2.1 eq.) phenol in 80 mL dry THF, 5.4 mL (2.1 eq.) diisopropylamine were added dropwise and the whole mixture was cooled to 0 C. 3.53 g (18 mmol, 1 eq.) dichlorophenyl phosphine oxide were added dropwise at this temperature with a syringe, leading to the formation of a white precipitate. The reaction mixture was stirred vigorously over night at room temperature. Inert filtration of this mixture afforded a clear filtrate that was added to a solution of freshly prepared lithium diisopropylamide (43 mmol, 2.4 eq.) in 100 mL dry THF cooled at 78 C. The reaction mixture was let return to room temperature over night. After evaporation of the solvents, the brown residue was dissolved in 200 mL chloroform, and precipitated by the addition of 300 mL n-hexane. A beige solid was isolated by filtration, which was further purified by a slurry wash in 150 mL AcN to afford after filtration and drying 3.6 g (62% yield) (3) as a light beige solid.

(40) HPLC: 97% (300 nm)

(41) .sup.1H-NMR (CD.sub.3OD, 500.13 MHz): [ppm]=6.50 (t, J=7 Hz, 2H), 6.65 (dd, J=6 Hz and 8 Hz, 2H), 7.16 (dd, J=8 Hz and 14 Hz, 2H), 7.22 (t, J=8 Hz, 2H), 7.40 (td, J=2 Hz and 8 Hz, 2H), 7.48 (td, J=1 Hz and 8 Hz, 1H), 7.56 (dd, J=8 Hz and 13 Hz, 2H).

4) Synthetic scheme for lithium 3-(diphenylphosphoryl)-[1,1-biphenyl]-4-olate (4)

(42) ##STR00009##

4.1) Synthesis of [1,1-biphenyl]-4-yl Diphenylphosphinate

(43) To a solution of 1.0 g (5.9 mmol, 1.1 eq.) of p-phenylphenol in 30 mL dry THF, 0.8 mL (2.1 eq.) diisopropylamine were added dropwise and the whole mixture was cooled to 0 C. 1.26 g (5.3 mmol, 1 eq.) chlorodiphenylphosphine oxide were added dropwise at this temperature with a syringe, leading to the formation of a white precipitate. The reaction mixture was stirred vigorously over night at room temperature. Filtration of this mixture followed by evaporation of the solvents afforded a beige powder. Obtained 960 mg (49% yield) of [1,1-biphenyl]-4-yl diphenylphosphinate.

(44) HPLC: 98.6% (250 nm)

4.2) Synthesis of Lithium 3-(diphenylphosphoryl)-[1,1-biphenyl]-4-olate (4)

(45) A solution of 0.96 g (2.6 mmol, 1.0 eq.) [1,1-biphenyl]-4-yl diphenylphosphinate in 20 mL dry THF was added to a solution of freshly prepared lithium diisopropylamide (2.8 mmol, 1.1 eq.) in 20 mL THF cooled at 78 C. The reaction mixture was let return to room temperature over night. After filtration of the salts and evaporation of the solvents, the brown residue was washed in a few mL of THF to afford after filtration and drying 560 mg (58% yield) of a light beige solid.

(46) HPLC: 94.8% (250 nm)

(47) .sup.1H-NMR (CD.sub.3OD, 500.13 MHz): [ppm]=6.69 (dd, J=6 Hz and 9 Hz, 1H), 7.12 (t, J=7 Hz, 1H), 7.26 (m, 2H), 7.34 (m, 4H), 7.48 (td, J=2 Hz and 8 Hz, 3H), 7.56 (m, 2H), 7.74 (m, 5H).

5) Synthetic Scheme for Lithium 4-(diphenylphosphoryl)phenolate (5)

(48) ##STR00010##

4.1) Synthesis of (4-methoxyphenyl)diphenylphosphine Oxide

(49) A solution of 3.34 mL (26.7 mmol, 1.0 eq.) 4-bromoanisole in 20 mL dry THF was added dropwise to a suspension of 960 mg (40 mmol, 1.5 eq.) magnesium turnings with a catalytic amount of iodine in 20 mL dry THF cooled at 0 C. After the exothermic addition was complete, reaction mixture was further refluxed for 2 h, and then the rests of magnesium were filtered off under inert conditions. To the cooled filtrate (at 50 C.), 5.1 mL (26.7 mmol, 1 eq.) chlorodiphenyl phosphine oxide were added. The reaction mixture was let return to room temperature over night. Gel filtration (SiO2, DCM/MeOH 99:1) afforded 5.66 g (67% yield) of a yellow glassy solid.

(50) GCMS: 100% m/z 308 [M].sup.+

4.2) Synthesis of (4-hydroxyphenyl)diphenylphosphine Oxide

(51) 40.9 mL (2.1 eq.) of 1.6M boron tribromide solution in dichloromethane were added dropwise to a solution of 5.6 g (18.2 mmol, 1.0 eq.) (4-methoxyphenyl)-diphenyl-phosphine oxide in 50 mL dry DCM cooled at 0 C. The reaction mixture was heated at 40 C. over night, and then quenched by a few drops of MeOHl. After one hour, the mixture was washed with an aqueous 1M sodium hydrogen carbonate solution and extracted with chloroform. The organic layer was thoroughly washed with water until the water layer was pH-neutral, and then evaporated to dryness. The residue was further slurry washed with 30 mL DCM to afford 1.23 g (23% yield) of a beige solid

(52) GCMS: 100% m/z 294 [M].sup.+

4.3) Synthesis of Lithium 4-(diphenylphosphoryl)phenolate (5)

(53) 1.23 g (42 mmol, 1 eq.) (4-hydroxyphenyl)diphenylphosphine oxide was dissolved at 40 C. in 45 mL dry DCM, then let return to room temperature. 29 mg (42 mmol, 1 eq.) lithium hydride were added to the mixture, that was again heated to 40 C. for 15 minutes, then let return to room temperature over night. After evaporation of the solvents, the residue was slurry washed with 20 mL hexane to afford 1.16 g (93%) of a light beige solid.

(54) HPLC: 100% (300 nm)

(55) .sup.1H-NMR (THF-d8, 500.13 MHz): [ppm]=6.82 (dd, J=2 Hz and 9 Hz, 2H), 7.40-7.51 (m, 8H), 7.63-7.67 (m, 4H).

(56) Alternative Procedure for the Compound (I)

(57) Oxidation of (2-hydroxyphenyl) Diphenylphosphine:

(58) 32.25 g (116 mmol) (2-Hydroxyphenyl) diphenylphosphine were dissolved in 480 ml of dichloromethane and 17.8 ml of 30% aqueous hydrogen peroxide solution were added dropwise. The resulting suspension was stirred for 1.5 days at room temperature. The precipitate was filtered and washed with 30 ml of dichloromethane.

(59) After drying 27.82 g (82% yield) of HPLC-pure (2-hydroxyphenyl) diphenylphosphine oxide were obtained.

(60) Deprotonation of (2-hydroxyphenyl) Diphenylphosphine Oxide:

(61) 27.82 g (94.6 mmol) of (2-hydroxyphenyl) diphenylphosphine oxide were suspended in 1.4 l of dichloromethane. 0.833 g (104.1 mmol) of lithium hydride was added and the suspension was stirred for 1.5 days before removing the solvent under reduced pressure. The crude product was stirred with 300 ml of chloroform over night and the solid was filtered, washed with chloroform and dried in vacuum. 26.46 g (93% yield) were sublimed in high vacuum for further purification.

Device Examples

Comparative Example 1

(62) 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) (matrix dopant ratio of 97:3 wt %) was deposited with a thickness of 20 nm. A 36 nm layer of the compound according 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.

(63) 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.

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

Comparative Example 2

(65) 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.

(66) 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

(67) 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 according to Formula (I) and ETM1 with a weight ratio of 1:1.

(68) This device showed a slightly increased voltage of 4.3 V at a current density of 10 mA/cm2, an extremely enhanced luminance of 532 cd/m2 at a current density of 10 mA/cm2 with a current efficiency of 5.3 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.

(69) OLEDs with other ETMs and the compound according to Formula (I) showed similar performance improvements OLEDs with other ETMs and the compound according to Formula (I) showed similar performance improvements, as shows the Table 1:

(70) TABLE-US-00001 ETL Voltage (V) CIE CIE QEff (%) at compound matrix at 10 mA/cm.sup.2 1931 x 1931 y 10 mA/cm.sup.2 1 3 4.0 0.14 0.09 6.0 1 2 4.6 0.14 0.09 5.5 2 3 7.3 0.14 0.09 2.7 2 2 8.3 0.14 0.10 5.0 LiQ 3 4.3 0.13 0.11 5.1 LiQ 2 4.9 0.13 0.10 3.8

(71) 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.

(72) 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.