Organic electronic device

Abstract

The present invention relates to organic electronic devices. The devices can include a first electrode, a second electrode, and a substantially organic layer. The substantially organic layer may include a lithium-containing compound, and may be arranged between the first and the second electrode. Also provided herein are organic light emitting diodes, organic solar cells, and organic field effect transistors that include the lithium-containing compound.

Claims

1. An organic electronic device comprising a first electrode, a second electrode, and a substantially organic layer arranged between the first and the second electrode, wherein the substantially organic layer comprises a compound according to formula (I): ##STR00010## wherein A.sup.1 is a pyridine-diyl, and each of A.sup.2 and A.sup.3 is independently selected from a C.sub.6-C.sub.30 aryl or a C.sub.2-C.sub.30 heteroaryl comprising at least one atom selected from O, S, or N in an aromatic ring.

2. The organic electronic device according to claim 1, wherein each of A.sup.2 and A.sup.3 is independently selected from a C.sub.6-C.sub.10 aryl or a C.sub.2-C.sub.12 heteroaryl.

3. The organic electronic device according to claim 1, wherein A.sup.2 and A.sup.3 are independently selected from phenyl or pyridyl.

4. The organic electronic device according to claim 1, wherein the substantially organic layer comprises an electron transport matrix compound.

5. The organic electronic device according to claim 4, wherein the electron transport matrix compound comprises an imidazole or a PO functional group.

6. The organic electronic device according to claim 4, wherein the compound according to formula (I) and the electron transport matrix compound are present in the substantially organic layer in the form of a homogeneous mixture.

7. The organic electronic device according to claim 1, wherein the device is selected from an organic light emitting diode, an organic solar cell, or an organic field effect transistor.

8. The organic electronic device according to claim 7, wherein the device is the organic light emitting diode, wherein the first electrode is an anode, the second electrode is a cathode, and the device further comprises a light emitting layer arranged between the anode and the cathode, and wherein the substantially organic layer is arranged between the cathode and the light emitting layer.

9. The organic electronic device of claim 1, wherein at least one of A.sup.2 and A.sup.3 is the C.sub.2-C.sub.30 heteroaryl comprising at least one atom selected from O, S, or N in an aromatic ring.

10. A compound according to formula (I): ##STR00011## wherein A.sup.1 is a pyridine-diyl, and each of A.sup.2 and A.sup.3 is independently selected from a C.sub.6-C.sub.30 aryl or a C.sub.2-C.sub.30 heteroaryl comprising at least one atom selected from O, S, or N in an aromatic ring.

11. The compound according to claim 10, wherein each of A.sup.2 and A.sup.3 is independently selected from a C.sub.6-C.sub.10 aryl or a C.sub.2-C.sub.12 heteroaryl.

12. The compound according to claim 10, wherein A.sup.2 and A.sup.3 are independently selected from phenyl or pyridyl.

13. The compound according to claim 10, wherein the compound of formula (I) is selected from a lithium salt of (3-hydroxypyridin-2-yl)diphenylphosphine oxide or (2-hydroxypyridin-3-yl)diphenylphosphine oxide.

14. An electrically doped semiconducting material comprising at least one electron transport matrix compound and at least one compound according to claim 10.

15. The compound of claim 10, wherein at least one of A.sup.2 and A.sup.3 is the C.sub.2-C.sub.30 heteroaryl comprising at least one atom selected from O, S, or N in an aromatic ring.

16. An organic electronic device comprising a first electrode, a second electrode, and a substantially organic layer arranged between the first and the second electrode, wherein the substantially organic layer comprises a compound according to formula (I): ##STR00012## wherein A.sup.1 is a C.sub.6-C.sub.30 arylene or C.sub.6-C.sub.30 heteroarylene, each of A.sup.2 and A.sup.3 is independently selected from a C.sub.6-C.sub.30 aryl or a C.sub.2-C.sub.30 heteroaryl comprising at least one atom selected from O, S, or N in an aromatic ring, and at least one of A.sup.2 and A.sup.3 is the C.sub.2-C.sub.30 heteroaryl comprising at least one atom selected from O, S, or N in an aromatic ring.

17. A compound according to formula (I): ##STR00013## wherein A.sup.1 is a C.sub.6-C.sub.30 arylene or C.sub.6-C.sub.30 heteroarylene, each of A.sup.2 and A.sup.3 is independently selected from a C.sub.6-C.sub.30 aryl or a C.sub.2-C.sub.30 heteroaryl comprising at least one atom selected from O, S, or N in an aromatic ring, and at least one of A.sup.2 and A.sup.3 is the C.sub.2-C.sub.30 heteroaryl comprising at least one atom selected from O, S, or N in an aromatic ring.

Description

SHORT SUMMARY OF THE FIGURES

(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) FIGS. 4 and 5 show current-voltage and current-efficiency curves of an inventive device comprising compound D1 in comparison with devices comprising previous art compounds C2 and C3, all in the matrix A1.

(5) FIGS. 6 and 7 show current-voltage and current-efficiency curves of an inventive device comprising compound D1 in comparison with a device comprising previous art compound C2, both in the matrix A2.

(6) FIGS. 8 and 9 show current-voltage and current-efficiency curves of an inventive device comprising compound D1 in comparison with a device comprising previous art compound C3, both in the matrix A3.

ORGANIC ELECTRONIC DEVICES

(7) 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.

(8) 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.

(9) 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).

(10) 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

(11) Following compounds were used as electron transporting matrices for testing the effects of inventive compounds:

(12) ##STR00003##

(13) A1 is described in the application PCT/EP2012/004961 (WO2013/079217, page 51-52), A2 is described in the application WO2011/154131 (Examples 4 and 6), A3 (CAS number 561064-11-7) is commercially available.

(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).

Example 1: Synthesis of lithium 2-(diphenylphosphoryl)pyridin-3-olate (1)

Step 1: diphenyl(pyridin-2-yl)phosphine oxide

(16) ##STR00004##

(17) TABLE-US-00001 2-fluoropyridine 2.50 g, 1.0 eq, 25.8 mmol potassium diphenylphosphide 51.5 mL, 1.0 eq, 25.8 mmol THF 50 mL DCM 80 mL hydrogen peroxide 25 mL hexane 20 mL

(18) Fluoropyridine was dissolved in dry THF. The potassium diphenylphosphide solution was added drop wise during one hour at room temperature. The resulting orange solution was stirred overnight at room temperature. The solvent was removed under reduced pressure and the residue dissolved in dichloromethane. Hydrogen peroxide was added slowly at 0 C. The mixture was stirred overnight at room temperature. The solvent was removed under reduced pressure and the residue treated with hexane. The resulting solid was filtered off, washed with hexane and dried in vacuum.

(19) Yield: 2.2 g (31%), HPLC-MS purity 98.0%.

Step 2: (3-hydroxypyridin-2-yl)diphenylphosphine oxide

(20) ##STR00005##

(21) TABLE-US-00002 diphenyl(pyridin-2-yl)phosphine oxide 2.0 g, 1.0 eq., 7.2 mmol 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2- 4.35 mL, 3.0 eq., 21.5 mmol dioxaborolane Lithium diisopropylamide (LDA) 9.56 mL, 2.0 eq., 14.3 mmol THF 50 mL Chloroform 50 mL Hydrogen peroxide 10 mL DCM 15 mL

(22) The starting material was dissolved in dry THF and cooled to 78 C. The borolane was added and the mixture stirred for 20 min. The LDA solution was added drop wise and the temperature was allowed to rise slowly to room temperature. The reaction was stirred for 3 days at room temperature. The solvent was removed under reduced pressure and the residue was dissolved in chloroform. Hydrogen peroxide was added slowly at 0 C. and the mixture was stirred overnight at room temperature. The mixture was extracted with chloroform and brine. The organic phase was dried over magnesium sulphate and the solvent removed under reduced pressure. The residue was dissolved in DCM and precipitated with hexane. The solid was filtered off, washed with hexane and dried in vacuum.

(23) Yield: 1.4 g (67%), GCMS purity 100%, structure confirmed by .sup.1H-NMR, (ppm)=11.48 (s, 1H, OH), 8.25 (d X from ABX system, J=4.5 Hz, 1H), 7.90 (dd, J=12 Hz and 7.5 Hz, 4H), 7.58 (br t, J=7 Hz, 2H), 7.50 (td, J=7.5 Hz and 3 Hz, 4H), 7.30 (ddd, B from ABX system, 1H), 7.24 (br dd, A from ABX system, 1H).

Step 3: lithium 2-(diphenylphosphoryl)pyridin-3-olate (1)

(24) ##STR00006##

(25) TABLE-US-00003 (3-hydroxypyridin-2-yl)- 1.0 g, 1.0 eq., 3.4 mmol diphenylphosphine oxide Lithium tert-butoxide 0.27 g, 1.0 eq., 3.4 mmol Acetonitrile 40 mL

(26) The starting material was suspended in dry acetonitrile. The lithium tert-butoxide was added at room temperature and the mixture was heated at reflux for 13 hours. The solid was filtered off, washed with acetonitrile and dried in vacuum.

(27) Yield: 0.865 g (87%), TGA-DSC: m.p. 442 C.

(28) Analytical data (after sublimation):

(29) TGA-DSC: m.p. 445 C.

(30) Elemental analysis: 67.6% C-content (theory 67.79%), 4.48% H-content (theory 4.35%), 4.64% N-content (theory 4.65%)

Example 2: lithium 7-(diphenylphosphoryl)quinolin-8-olate (2)

(31) ##STR00007##

Step 1: synthesis of quinolin-8-yl diphenylphosphinate

(32) 10 g 8-hydroxyquinoline were dissolved in 170 mL dry THF. 17.9 g (1.1 eq.) diphenylphosphoryl chloride and 7.7 g (1.1 eq.) diisopropylamine were added at room temperature. After stirring overnight, the reaction mixture was filtered, then evaporated to dryness and treated with 40 mL hexane. 23.5 g white solid were obtained (98% yield), GCMS gives 100% purity.

Step 2: synthesis of lithium 7-(diphenylphosphoryl)quinolin-8-olate (2)

(33) 7 g quinolin-8-yl diphenylphosphinate from the previous step were dissolved in 120 mL dry THF under argon. The clear solution was cooled to 80 C. 14.9 mL (1.1 eq.) of 1.5 M lithium diisopropylamide solution in cyclohexane were added dropwise as to the starting compound. The reaction mixture was allowed to return to room temperature overnight and further stirred for one entire week. Then, an addition of 100 mL n-hexane afforded a precipitate that was isolated by filtration and further purified by a hot slurry wash in 120 mL acetonitrile. 2.43 g (34% yield) of a beige solid were obtained and further purified through gradient sublimation.

Example 3: lithium 2-(diphenylphosphoryl)quinolin-3-olate (3)

(34) ##STR00008##

Step 1: synthesis of diphenyl(quinolin-2-yl)phosphine oxide

(35) 4 g 2-chloroquinoline (1 eq.) were dissolved in 50 mL dry THF under argon. To this solution, 48.9 mL (1 eq.) of commercial 0.5 M solution of potassium diphenylphosphite in THF were added at room temperature over 90 minutes. After stirring overnight at room temperature, the solution was evaporated to dryness and the residue suspended in 80 mL dichloromethane and treated with 20 mL of 30 wt. % hydrogen peroxide aqueous solution. After 3 h stirring at room temperature, the organic phase was washed twice with 30 mL brine and twice with 30 mL distilled water, dried over magnesium sulfate, filtered and evaporated. The residue was precipitated from dichloromethane/hexane to obtain 4.62 g (57% yield) of a pale yellow solid. HPLC showed 99.2% purity.

Step 2: synthesis of (3-hydroxyquinolin-2-yl)diphenylphosphine oxide

(36) 4.5 g (1 eq.) diphenyl(quinolin-2-yl)phosphine oxide were dissolved in 50 mL dry TI-IF under argon. The solution was cooled at 80 C., and 8.4 mL (3 eq.) 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (neat) were added with a syringe. After 20 minute stirring at 80 C., 18.3 mL (2 eq.) of 1.5 M lithium diisopropylamide solution in cyclohexane were added dropwise. The reaction mixture was let return to room temperature over the weekend, then evaporated to dryness and redissolved in 60 mL dichloromethane. The suspension was treated with 10 mL 30% aqueous hydrogen peroxide over 24 h. After washing with 30 mL brine and 50 mL distilled water, the organic phase was dried over magnesium sulfate, filtered and evaporated. The residue was dissolved in 30 mL dichloromethane and washed twice with 30 mL of saturated ammonium chloride solution, then with 2 mL 1M hydrochloric acid for acidifying the aqueous phase before drying and evaporating. The evaporation residue was slurry washed in 30 mL acetonitrile to afford 2.8 g (60% yield) of a bright yellow solid. GCMS showed 96% purity.

Step 3: synthesis of lithium 2-(diphenylphosphoryl)quinolin-3-olate (3)

(37) 2.7 g (1 eq.) (3-hydroxyquinolin-2-yl)diphenylphosphine oxide were suspended in 40 mL dry acetonitrile. 0.63 g (1 eq.) lithium tert-butoxide were added in one portion as a solid. The suspension turned yellow. After 4 h under reflux, the suspension was cooled to room temperature and the solid isolated, washed with a minimal amount acetonitrile and dried. Obtained 2.44 g (89% yield) of a beige solid, which was further purified by gradient sublimation.

Example 4: lithium 3-(diphenylphosphoryl)pyridin-2-olate (4)

(38) ##STR00009##

Step 1: synthesis of diphenyl(pyridin-3-yl)phosphine oxide

(39) 110 mL of a 0.5 M potassium diphenylphosphite solution in THF were diluted with 110 mL dry THF under argon. 8 g 3-fluoropyridine were added dropwise at 0 C. to this solution during 30 minutes. The mixture was stirred overnight at room temperature, then evaporated to dryness and redissolved in 150 mL dichloromethane. The mixture was treated with 17 mL 30% aqueous hydrogen peroxide overnight. The organic phase was then washed twice with 30 mL brine and three times with 40 mL distilled water, then dried over magnesium sulfate, filtered and evaporated. The resulting oil was precipitated by addition 30 mL hexane and an ultrasound treatment. Isolated 12.1 g of a white solid (79% yield), GCMS showed 100% purity.

Step 2: synthesis of (2-hydroxypyridin-3-yl)diphenylphosphine oxide

(40) 5 g diphenyl(pyridin-3-yl)phosphine oxide were dissolved in 100 mL dry THF under argon and the solution was cooled to 80 C. 10.9 mL (3 eq.) 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (neat) were added with a syringe. After 25 minute stirring at 80 C., 23.8 mL (2 eq.) of 1.5 M lithium diisopropylamide solution in cyclohexane were added dropwise. The reaction mixture was let return to room temperature over five days, then evaporated to dryness and redissolved in 200 mL dichloromethane. The suspension was treated by 10 mL 30 wt. % aqueous hydrogen peroxide over 24 h. After washing twice with 30 mL brine and three times with 30 mL distilled water, the organic phase was dried over magnesium sulfate, filtered and evaporated. The residue was slurry washed with 50 mL hexane. Obtained 3.8 g (72% yield) of a pale yellow solid. Used without further purification.

Step 3: synthesis of lithium 3-(diphenylphosphoryl)pyridin-2-olate (4)

(41) 3.6 g (2-hydroxypyridin-3-yl)diphenylphosphine oxide were suspended in 150 mL acetonitrile. After addition 0.98 g (1 eq.) lithium tert-butoxide, the mixture was heated overnight under reflux. After return to room temperature, the formed precipitate was isolated and washed with a minimal amount acetonitrile. Obtained 3.3 g (90%) of a white solid that was further purified by gradient sublimation.

DEVICE EXAMPLES

(42) Lithium 2-(diphenylphosphoryl)phenolate (C2), described in an earlier application PCT/EP/2012/074127, and the well-known lithium 8-hydroxyquinolinolate (LiQ, C3) were used as comparative electrical n-dopants; lithium 2-(diphenylphosphoryl)pyridin-3-olate (1), referred to as D1, lithium 2-(diphenylphosphoryl)quinolin-3-olate (3), referred to as D5, and lithium 3-(diphenylphosphoryl)pyridin-2-olate (4), referred to as D6, were used as inventive n-dopants.

Example 1

(43) A blue emitting device was made on a commercially available glass substrate with deposited indium tin oxide (ITO) 90 nm thick layer as an anode. A 10 nm layer of HTM3 doped with 2,2,2-(cyclopropane-1,2,3-triylidene)tris(2-(p-cyanotetrafluorophenyl)acetonitrile) (PD2) (matrix to dopant weight ratio of 92:8) was subsequently deposited as hole injection and transport layer, followed by a 120 nm undoped layer of HTM3. Subsequently, a blue fluorescent emitting layer of ABH113 (Sun Fine Chemicals) doped with NUBD370 (Sun Fine Chemicals) as an emitter (matrix dopant ratio of 97:3 wt. %) was deposited with a thickness of 20 nm. A 36 nm thick ETL having a composition given in the Table 1 was deposited on the emitting layer. A 1 nm thick layer of lithium quinolate (LiQ) followed the ETL, followed by 100 nm thick aluminium layer as a cathode.

(44) The results are shown in the Table 1.

(45) TABLE-US-00004 TABLE 1 Current Voltage at efficiency 10 mA/cm.sup.2 at 10 mA/cm.sup.2 CIE CIE ETL [V] [cd/A] 1931 x 1931 y A1:D1 (60:40 wt. %) 4.4 6.4 0.14 0.10 A1:C2 (60:40 wt. %) 4.3 5.3 0.14 0.09 A1:C3 (60:40 wt. %) 4.6 4.9 0.14 0.10 A2:D1 (50:50 wt. %) 4.9 5.6 0.14 0.10 A2:C2 (50:50 wt. %) 4.7 5.5 0.14 0.09 A3:D1 (50:50 wt. %) 4.6 5.5 0.14 0.11 A3:C3 (50:50 wt. %) 4.5 4.9 0.14 0.11 A1:D5 (60:40 wt. %) 4.4 6.6 0.14 0.11 A1:D6 (60:40 wt. %) 4.5 5.6 0.14 0.11

Advantages of the Invention

(46) Surprisingly, an increase of the OLED efficiency and a decrease of the operating voltage were observed in experimental devices comprising the inventive semiconducting materials.

(47) Inventive devices comprising compounds of formula (I) as ETL additives perform better than devices using known LiQ (C3) and at least equally well as devices comprising compound C2 with a similar structure without a heteroatom. Inventive compounds of formula (I) thus significantly broaden the offer of additives for improving electron transport and/or electron injection in organic electronic devices and allow further improving and optimizing performance of organic electronic devices beyond limits known in the art.

(48) 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.

ABBREVIATIONS USED THROUGHOUT THE APPLICATION

(49) OLED organic light emitting device

(50) OTFT organic thin film transistor

(51) EL electroluminescence, electroluminescent

(52) ETL electron transport layer

(53) ETM electron transport material

(54) HTL hole transport layer

(55) EBL electron blocking layer

(56) HBL hole blocking layer

(57) LEL light emitting layer

(58) EIL electron injecting layer

(59) HIL hole injecting layer

(60) VTE vacuum thermal evaporation

(61) HOMO highest occupied molecular orbital

(62) LUMO lowest unoccupied molecular orbital

(63) .sup.1H-NMR proton magnetic resonance

(64) EI-MS electron impact mass spectroscopy

(65) GCMS gas chromatography (combined with) mass spectroscopy

(66) HPLC-MS high performance liquid chromatography-mass spectroscopy

(67) BPhen bathophenanthroline

(68) Alq3 aluminium tris(8-hydroxyquinolinolate)

(69) LiQ lithium 8-hydroxyquinolinolate

(70) THF tetrahydrofuran

(71) DCM dichloromethane

(72) eq. Equivalent

(73) wt. % weight percent

(74) mol. molar (e.g. percent)

(75) TGA-DSC thermogravimetric analysis-differential scanning calorimetry

(76) TCO transparent conductive oxide

(77) RFID radio-frequency identification