Compounds comprising a hetero-fluorene group

Abstract

The present invention relates to a compound, and to an organic semiconductor layer comprising this compound, suitable for use as an organic semiconductor layer for electronic devices, and a method of manufacturing the same, wherein the compound comprises a hetero-fluorene group and is represented by formula 1.

##STR00001##

Claims

1. A compound having the formula 1: ##STR00060## wherein X.sup.1, X.sup.2, X.sup.3, X.sup.3, X.sup.4, X.sup.5, X.sup.6, X.sup.7 and X.sup.8 are independently selected from C—H, N, C—R.sup.1, wherein R.sup.1 are independently selected from CN, F, deuterium, substituted or unsubstituted C.sub.6 to C.sub.18 aryl, substituted or unsubstituted C.sub.3 to C.sub.20 heteroaryl, C1-C.sub.16 alkyl, C.sub.1 to C.sub.16 alkoxy, alkenyl, formula 2, nitrile, amino, PY(R.sup.2).sub.2 with Y being O or S, wherein the substituents of the substituted C.sub.6 to C.sub.18 aryl and of the substituted C.sub.3 to C.sub.20 heteroaryl are independently selected from C.sub.1 to C.sub.12 alkyl, perhalogenated C.sub.1 to C.sub.12 alkyl, C.sub.1 to C.sub.12 alkoxy, perhalogenated C.sub.1 to C.sub.12 alkoxy, C.sub.6 to C.sub.18 aryl, perhalogenated C.sub.6 to C.sub.18 aryl, C.sub.3 to C.sub.24 heteroaryl, CN, halogen; wherein at least one of X.sup.1 to X.sup.8 but not more than four of X.sup.1 to X.sup.8 are N, and wherein at least one of R.sup.1 but not more than three of R.sup.1 are formula 2: ##STR00061## wherein L is a direct bond, phenylene or biphenylene, substituted or unsubstituted C.sub.6 to C.sub.18 arylene, substituted or unsubstituted C.sub.3 to C.sub.20 heteroarylene, or C.sub.6 to C.sub.40 alkenyl, wherein the substituents of the substituted C.sub.6 to C.sub.18 arylene and substituted C.sub.3 to C.sub.20 heteroarylene are independently selected from C.sub.6 to C.sub.18 aryl, C.sub.3 to C.sub.20 heteroaryl, D, F, CN, C.sub.1 to C.sub.16 alkyl, C.sub.1 to C.sub.16 alkoxy, nitrile, and —PY(R.sup.2).sub.2 with Y being O or S; wherein G is independently selected from unsubstituted or substituted C.sub.6 to C.sub.40 aryl or C.sub.3 to C.sub.42 heteroaryl, C.sub.6 to C.sub.40 alkenyl, CN, PY(R.sup.2).sub.2 with Y being O or S wherein the substituents of the substituted C.sub.6 to C.sub.18 aryl and of the substituted C.sub.3 to C.sub.20 heteroaryl are independently selected from H, CN, F, deuterium, C.sub.6 to Cis aryl, C.sub.3 to C.sub.20 heteroaryl, C.sub.1 to C.sub.16 alkyl, C.sub.1 to C.sub.16 alkoxy, nitrile, and PY(R.sup.2).sub.2 with Y being O or S; n=0, 1, 2 or 3; Y.sup.1, Y.sup.2Y.sup.3 and Y.sup.4 are C—R.sup.3, wherein R.sup.3 is independently selected from H, CN, F, deuterium, substituted or unsubstituted C.sub.6 to C.sub.18 aryl, substituted or unsubstituted C.sub.3 to C.sub.20 heteroaryl, C1-C.sub.16 alkyl, C.sub.1 to C.sub.16 alkoxy, C6 to C.sub.40 alkenyl, nitrile, amino, PY(R.sup.2).sub.2 with Y being O or S, wherein the substituents of the substituted C.sub.6 to C.sub.18 aryl and of the substituted C.sub.3 to C.sub.20 heteroaryl are independently selected from C.sub.1 to C.sub.12 alkyl, perhalogenated C.sub.1 to C.sub.12 alkyl, C.sub.1 to C.sub.12 alkoxy, perhalogenated C.sub.1 to C.sub.12 alkoxy, C.sub.6 to C.sub.18 aryl, perhalogenated C6 to C.sub.18 aryl, C.sub.3 to C.sub.24 heteroaryl, CN, halogen; or Y.sup.2 and Y.sup.3 are C and connected via a single bond or bridged by formula 3, ##STR00062## wherein W is CH.sub.2, C—(CH.sub.3).sub.2, N—H, N—R.sup.4, O or S, and Y.sup.1 and Y.sup.4 are C—H, wherein R.sup.4 is selected from C.sub.1 to C.sub.6 alkyl, substituted or unsubstituted C.sub.6 to C.sub.18 aryl, substituted or unsubstituted C.sub.2 to C.sub.20 heteroaryl, wherein the substituents of the substituted C.sub.6 to C.sub.18 aryl and substituted C.sub.3 to C.sub.20 heteroaryl are independently selected from C.sub.6 to C.sub.18 aryl, C.sub.3 to C.sub.20 heteroaryl, D, F, CN, C.sub.1 to C.sub.16 alkyl, C.sub.1 to C.sub.16 alkoxy, nitrile, and —PY(R.sup.2).sub.2 with Y being O or S; or Y.sup.1, Y.sup.2 and Y.sup.3 are C, wherein Y.sup.1 and Y.sup.2 are part of an annelated benzene ring and the annelated benzene ring is connected via a single bond to Y.sup.3; and wherein the hetero atom is selected from N, O or S; and wherein R.sup.2 are the same or different and independently selected from the group consisting of C.sub.1 to C.sub.16 alkyl, C.sub.1 to C.sub.16 alkoxy, C.sub.6 to C.sub.26 alkenyl, C.sub.6 to C.sub.18 aryl and C.sub.3 to C.sub.25 heteroaryl.

2. The compound according to claim 1, wherein in formula 1: one of X.sup.1, X.sup.2, X.sup.3, X.sup.3, X.sup.4, X.sup.5, X.sup.6, X.sup.7 and X.sup.8 are selected N and at least one are C—R.sup.1 but not more than three are C—R.sup.1, then if X.sup.1 is selected N or if X.sup.8 is selected N, then at least one of R.sup.1 but not more than three of R.sup.1 are formula 2 comprising at least one hetero atom selected from N, O or S.

3. The compound according to claim 1, wherein X.sup.3 is N and at least one of X.sup.1, X.sup.6, X.sup.7 or X.sup.8 is CR.sup.1 with R.sup.1 being formula 2.

4. The compound according to claim 1, wherein L is selected from a direct bond, phenylene, biphenylene, substituted or unsubstituted C.sub.6 to C.sub.12 arylene, or substituted or unsubstituted C.sub.3 to C.sub.11 heteroarylene wherein the hetero atom of the heteroarylene is N, and wherein the substituents of the substituted arylene and of the substituted heteroaryl are independently selected from, C.sub.6 to C.sub.12 aryl, C.sub.3 to C.sub.11 heteroaryl, C.sub.1 to C.sub.5 alkyl, C.sub.1 to C.sub.5 alkoxy, nitrile, and PY(R.sup.2).sub.2 with Y being O or S, wherein the R.sup.2 are independently selected from the group consisting of C.sub.1 to C.sub.3 alkyl, C.sub.1 to C.sub.3 alkoxy, C.sub.6 to C.sub.12 aryl and C.sub.3 to C.sub.11 heteroaryl.

5. The compound according to claim 1, wherein G is selected from the group consisting of triazine, pyrazine, acridine, benzoacridine, dibenzoacridine, phenanthroline, benzimidazole, and carbazole.

6. The compound according to claim 1, wherein n is selected from 0, 1 or 2.

7. The compound according to claim 1, wherein the compounds of formula 1 are represented by formula 5 to 8, wherein W is selected from C—(CH.sub.3).sub.2, N—R.sup.4, O or S, and Y.sup.1 to Y.sup.4 are C—R.sup.3: ##STR00063##

8. The compound according to claim 1, wherein the number of aromatic 6 member rings is 5 to 15.

9. The compound according to claim 1, wherein G is selected from the group comprising D1 to D43, wherein G is bonded at anyone of the C atoms of D1 to D43 via a single bond to L: ##STR00064## ##STR00065## ##STR00066## ##STR00067## ##STR00068## ##STR00069## and wherein Z is selected from O, S, Se, SiR.sub.2, CR.sub.2, and NR.sub.2; and wherein Z.sup.1 is selected from O, S, and NR; wherein R is selected from C.sub.1 to C.sub.6 alkyl, C.sub.6 to C.sub.18 aryl, C.sub.2 to C.sub.20 heteroaryl.

10. The compound according to claim 1, wherein L is independently selected from the group comprising F1 to F12: ##STR00070## ##STR00071##

11. The compound according to claim 1, wherein the compounds of formula 1 are selected from G1 to G8: ##STR00072## ##STR00073##

12. An organic semiconductor layer comprising at least one compound of formula 1 according to claim 1, wherein the organic semiconductor layer is a charge transport layer.

13. The organic semiconductor layer according to claim 12, further comprising a dopant or an additive or does not contain a dopant and/or an additive.

14. The organic semiconductor layer according to claim 12, comprising a first component that is the compound of formula 1 and in addition at least one second component that differs from the compound of formula 1.

15. An organic electronic device comprising at least one organic semiconductor layer according to claim 12.

16. The organic electronic device according to claim 15, further comprising at least one anode and at least one cathode.

17. The organic electronic device according to claim 15, wherein the organic electronic device is a lighting device, thin film transistor, a battery, a display device, or a photovoltaic cell.

18. The compound according to claim 1, wherein in formula 1: two of X.sup.1, X.sup.2, X.sup.3, X.sup.3, X.sup.4, X.sup.5, X.sup.6, X.sup.7 and X.sup.8 are selected N and at least one is C—R.sup.1 but not more than three are C—R.sup.1, wherein R.sup.1 is formula 2, then X.sup.3 and X.sup.7 are N, or X.sup.3 and X.sup.5 are N.

19. The compound according to claim 1, wherein in formula 1: one of X.sup.1, X.sup.2, X.sup.3, X.sup.3, X.sup.4, X.sup.5, X.sup.6, X.sup.7 and X.sup.8 are N, namely X.sup.3, X.sup.7 or X.sup.8 is N, and at least one is C—R.sup.1 but not more than three are C—R.sup.1, wherein R.sup.1 is formula 2.

21. The compound according to claim 1, wherein X.sup.7 is N and at least one of X.sup.1, X.sup.2 or X.sup.3 is CR.sup.1 with R.sup.1 being formula 2.

22. The compound according to claim 1, wherein X.sup.8 is N and at least one of X.sup.1, X.sup.2, X.sup.3, X.sup.6 is CR.sup.1 with R.sup.1 being formula 2.

23. The compound according to claim 1, wherein one of X.sup.1, X.sup.2, X.sup.3, X.sup.3, X.sup.4, X.sup.5, X.sup.6, X.sup.7 or X.sup.8 is CR.sup.1 with R.sup.1 being formula 2.

24. The organic semiconductor layer according to claim 14, wherein the at least one second component is selected from the group consisting of a metal, metal salt, a metal complex, and a matrix material that differs from the compound of formula 1.

Description

DESCRIPTION OF THE DRAWINGS

[0445] 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:

[0446] FIG. 1 is a schematic sectional view of an organic light-emitting diode (OLED), according to an exemplary embodiment of the present invention with an emission layer, one electron transport layer and an electron injection layer;

[0447] FIG. 2 is a schematic sectional view of an organic light-emitting diode (OLED), according to an exemplary embodiment of the present invention with an emission layer and two electron transport layers;

[0448] FIG. 3 is a schematic sectional view of an OLED, according to an exemplary embodiment of the present invention with an emission layer and three electron transport layers;

[0449] FIG. 4 is a schematic sectional view of an organic light-emitting diode (OLED), according to an exemplary embodiment of the present invention with an emission layer and one electron transport layer;

[0450] FIG. 5 is a schematic sectional view of an organic light-emitting diode (OLED), according to an exemplary embodiment of the present invention with an emission layer and two electron transport layers;

[0451] FIG. 6 is a schematic sectional view of an OLED, according to an exemplary embodiment of the present invention with an emission layer and three electron transport layers.

[0452] Reference will now be made in detail to the exemplary aspects, 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, by referring to the figures.

[0453] Herein, when a first element is referred to as being formed or disposed “on” 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” a second element, no other elements are disposed there between.

[0454] The term “contacting sandwiched” refers to an arrangement of three layers whereby the layer in the middle is in direct contact with the two adjacent layers.

[0455] The organic light emitting diodes according to an embodiment of the present invention may include a hole transport region; an emission layer; and a first electron transport layer comprising the compound according to the invention.

[0456] FIG. 1 is a schematic sectional view of an organic light-emitting diode 100, according to an exemplary embodiment of the present invention. The OLED 100 comprises an emission layer 150, an electron transport layer (ETL) 161 comprising the compound according to the invention, and an electron injection layer 180, whereby the first electron transport layer 161 is disposed directly on the emission layer 150 and the electron injection layer 180 is disposed directly on the first electron transport layer 161.

[0457] FIG. 2 is a schematic sectional view of an organic light-emitting diode 100, according to an exemplary embodiment of the present invention. The OLED 100 comprises an emission layer 150 and an electron transport layer stack (ETL) 160 comprising a first electron transport layer 161, and a second electron transport layer 162 comprising the compound according to the invention, whereby the second electron transport layer 162 is disposed directly on the first electron transport layer 161.

[0458] FIG. 3 is a schematic sectional view of an organic light-emitting diode 100, according to an exemplary embodiment of the present invention. The OLED 100 comprises an emission layer 150 and an electron transport layer stack (ETL) 160 comprising a first electron transport layer 161, a second electron transport layer 162, and a third electron transport layer 163, whereby the second electron transport layer 162 is disposed directly on the first electron transport layer 161 and the third electron transport layer 163 is disposed directly on the first electron transport layer 162. The first and/or the second and/or the third electron transport layer comprise the compound according to the invention.

[0459] FIG. 4 is a schematic sectional view of an organic light-emitting diode 100, according to an exemplary embodiment of the present invention. The OLED 100 comprises a substrate 110, a first anode electrode 120, a hole injection layer (HIL) 130, a hole transport layer (HTL) 140, an emission layer (EML) 150, one first electron transport layer (ETL) 161, an electron injection layer (EIL) 180, and a cathode electrode 190. The first electron transport layer (ETL) 161 comprises the compound according to the invention. The electron transport layer (ETL) 161 is formed directly on the EML 150.

[0460] FIG. 5 is a schematic sectional view of an organic light-emitting diode 100, according to an exemplary embodiment of the present invention. The OLED 100 comprises a substrate 110, a first anode electrode 120, a hole injection layer (HIL) 130, a hole transport layer (HTL) 140, an emission layer (EML) 150, an electron transport layer stack (ETL) 160, an electron injection layer (EIL) 180, and a cathode electrode 190. The electron transport layer (ETL) 160 comprises a first electron transport layer 161 and a second electron transport layer 162, wherein the first electron transport layer is arranged near to the anode (120) and the second electron transport layer is arranged near to the cathode (190). The first and/or the second electron transport layer comprise the compound according to the invention.

[0461] FIG. 6 is a schematic sectional view of an organic light-emitting diode 100, according to an exemplary embodiment of the present invention. The OLED 100 comprises a substrate 110, a first anode electrode 120, a hole injection layer (HIL) 130, a hole transport layer (HTL) 140, an emission layer (EML) 150, an electron transport layer stack (ETL) 160, an electron injection layer (EIL) 180, and a second cathode electrode 190. The electron transport layer stack (ETL) 160 comprises a first electron transport layer 161, a second electron transport layer 162 and a third electron transport layer 163. The first electron transport layer 161 is formed directly on the emission layer (EML) 150. The first, second and/or third electron transport layer comprise the compound according to the invention.

[0462] Hereinafter, the embodiments are illustrated in more detail with reference to examples. However, the present disclosure is not limited to the following examples. Reference will now be made in detail to the exemplary aspects.

General Synthetic Scheme of Key Intermediates

[0463] ##STR00046##

Synthesis of C5.1: 7′-chlorospiro[fluorene-9,5′-indeno[1,2-c]pyridine]

[0464] ##STR00047##

[0465] To an anhydrous THE solution (360 ml) containing 2-bromo-1,1′-biphenyl (16.8 g, 72.2 mmol) at −90° C. under inert atmosphere and stirring, n-butyl lithium (30.4 mL, 75.8 mmol, 2.5 M in hexanes) was added slowly, during 30 minutes. After 1h 30 min, a solution of 7-chloro-5H-indeno[1,2-c]pyridin-5-one (14.8 g, 68.6 mmol) in anhydrous THE (400 mL) and under inert atmosphere was added slowly, during an hour. The reaction mixture was allowed to warm to room temperature overnight, and then was quenched by addition of water (200 mL). The product was extracted with dichloromethane (2×250 mL), the organic phase was washed with water (2×250 mL) and NaCl.sub.(aq) (50 mL), dried over anhydrous MgSO4, and the solvent was partially evaporated. Precipitation was favored by addition of toluene. The resulting suspension was stirred at room temperature and the precipitate was collected by suction filtration to yield 20.5 g of 5-([1,1′-biphenyl]-2-yl)-7-chloro-5H-indeno[1,2-c]pyridin-5-ol. This intermediate compound was stirred in a mixture of sulfuric acid (5.5 mL) and acetic acid (550 mL) at 120° C. overnight. After cooling down to room temperature, the solution was added slowly to water (500 mL). Additional water (1500 mL) was added and the resulting precipitate was isolated by suction filtration and washed with water (500 mL) to yield 20.6 g (81%) of a beige solid after drying.

Synthesis of C5.2: 7′-chlorospiro[fluorene-9,5′-indeno[1,2-b]pyridine]

[0466] ##STR00048##

[0467] 2-Bromo-1,1′-biphenyl (30.0 g, 129.0 mmol) was dissolved in toluene (150 ml). The solvent was evaporated to remove water by azeotropic distillation using a rotary evaporator. After evaporation of the solvent, the starting material was kept for 1h at 1 mbar and 55° C. A 500 mL 4-necked round-bottom flask (equipped with reflux condenser, thermometer, valve and septum) was dried and kept under nitrogen. The flask was charged with magnesium (3.2 g, 135.1 mmol) and THE (150 ml, dry) was added. In a different dried flask and under nitrogen atmosphere, the pre-dried 2-bromo-1,1′-biphenyl (30 g, 129 mmol) was dissolved in THE (75 mL, dry) and then added to the Magnesium suspension via a syringe. After 1 hour, the reaction mixture was heated up to reflux for 4 hours. Then it was cooled down to room temperature and the Grignard was added on to a solution of 7-chloro-5H-indeno[1,2-b]pyridin-5-one (27.8 g, 129.0 mmol) in THE (230 mL, dry) under nitrogen atmosphere. The mixture was refluxed overnight. After cooling down to room temperature, water was added and the product was extracted with dichloromethane. The organic phase was washed with water until pH neutral and dried over anhydrous MgSO.sub.4. Solvent was partially evaporated and the resulting suspension was stirred at room temperature. The precipitate was collected by suction filtration and stirred in dichloromethane (140 mL) for two hours. The precipitate was collected by suction filtration and dried to yield 24.9 g of 5-([1,1′-biphenyl]-2-yl)-7-chloro-5H-indeno[1,2-b]pyridin-5-ol.

[0468] This intermediate compound was stirred in a mixture of sulfuric acid (5.3 mL) and acetic acid (666 mL) at 120° C. overnight. After cooling down to room temperature, the solution was added slowly to water (500 mL). Additional water (2000 mL) was added and the resulting precipitate was isolated by suction filtration and washed with water (500 mL) to yield 22.6 g (50%) of a solid after drying.

Synthesis of C′5.2: 7′-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)spiro[fluorene-9,5′-indeno[1,2-b]pyridine]

[0469] ##STR00049##

Compound C5.2 (8.0 g, 12.7 mmol), bis(pinacolato)diboron (6.9 g, 27.2 mmol), and potassium acetate (6.7 g, 68.2 mmol) were loaded in a three-neck flask and brought under argon atmosphere, whereupon DMF (100 mL) was added. 2-Dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl (X-Phos, 330 mg, 0.68 mmol) and tris(dibenzylideneacetone)-dipalladium(0) (310 mg, 0.34 mmol) were subsequently added, followed by DMF (130 mL), and the mixture reacted at 110° C. overnight. The mixture was allowed to cool to room temperature and the solvent removed under reduced pressure. The solid residue was dissolved in chloroform (800 mL) and the organic layer washed with water (4×300 mL) until pH neutral. The organic phase was dried over MgSO.sub.4, and then filtered over a pad of silica, and the solvent removed under reduced pressure. The solid residue was dissolved in dichloromethane (120 mL), and then the solvent was partially removed under reduced pressure. Methanol was added (220 mL) and the resulting precipitate recovered by suction filtration. The solid was then re-dissolved in dichloromethane, and precipitated using hexane. The resulting precipitate was recovered by suction filtration, washed with methanol (3×10 mL), and dried under vacuum to yield 6.8 g (67%) of a white solid. m/z=444 ([M+H].sup.+).
General Synthetic Scheme of Final Compound from Key Intermediates

##STR00050##

Synthesis of Final Compounds

[0470] ##STR00051##

7′-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)spiro[fluorene-9,5′-indeno[1,2-c]pyridine]-Compound A-1

[0471] A flask was flushed with nitrogen and charged with 7′-chlorospiro[fluorene-9,5′-indeno[1,2-c]pyridine] (9.0 g, 25.6 mmol), 2,4-diphenyl-6-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-1,3,5-triazine (11.3 g, 25.6 mmol), chloro(crotyl)(2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl)palladium(II) (310 mg, 0.51 mmol), potassium phosphate (13.9 g, 64.0 mmol). A mixture of deaerated THF/water (4:1, 160 mL) was added and the reaction mixture was heated to 50° C. under a nitrogen atmosphere overnight. After cooling down to room temperature, the resulting precipitate was isolated by suction filtration and washed with water (3×100 mL). The crude product was then dissolved in toluene and filtered through a silica gel pad. After rinsing with additional toluene (2 L) and chlorobenzene (1 L), the target compound was eluted with dichloromethane/ethylacetate 4/1 (2 L). The filtrate was concentrated under reduced pressure to a minimal volume and n-hexane (200 mL) was added. The resulting suspension was stirred at room temperature and the precipitate was collected by suction filtration to yield 10.5 g (66%) of a solid after drying. Final purification was achieved by sublimation. m/z=625 ([M+H].sup.+).

##STR00052##

7′-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)spiro[fluorene-9,5′-indeno[1,2-b]pyridine]-Compound A-3

[0472] A flask was flushed with nitrogen and charged with 7′-chlorospiro[fluorene-9,5′-indeno[1,2-b]pyridine] (6.0 g, 17.0 mmol), 2,4-diphenyl-6-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-1,3,5-triazine (7.4 g, 17.0 mmol), chloro(crotyl)(2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl)palladium(II) (206 mg, 2.0 mol %), potassium phosphate (7.2 g, 34.0 mmol). A mixture of deaerated THF/water (8:1, 112 mL) was added and the reaction mixture was heated to 50° C. under a nitrogen atmosphere overnight. After cooling down to room temperature, the resulting precipitate was isolated by suction filtration and washed with water (3×100 mL). The crude product was then dissolved in toluene and purified by column chromatography, using as eluent first toluene and then toluene/methanol 100/1. The filtrate was concentrated under reduced pressure to a minimal volume and n-hexane (70 mL) was added. The resulting suspension was stirred at room temperature and the precipitate was collected by suction filtration. Finally, it was recrystallized in chlorobenzene to yield 8.0 g (76%) of a solid after drying. Final purification was achieved by sublimation. m/z=625 ([M+H].sup.+).

##STR00053##

7′-(4-(dibenzo[b,d]furan-3-yl)-6-phenyl-1,3,5-triazin-2-yl)spiro[fluorene-9,5′-indeno[1,2-b]pyridine]—Compound A-2

[0473] A flask was charged with a solution of 7′-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)spiro[fluorene-9,5′-indeno[1,2-b]pyridine] (6.7 g, 15.2 mmol) in THE (120 mL), and an aqueous solution (20 mL) of potassium carbonate (4.2 g, 30.4 mmol). The resulting mixture was deaerated by bubbling through N.sub.2 gas. [1,1′-Bis(diphenylphosphino)ferrocene]dichloropalladium(II) (220 mg, 3.0 mmol) was then added in a counter flow of N.sub.2, and the reaction mixture was reacted at 75° C. for 1 day. The resulting mixture was then allowed to cool to room temperature, further cooled by means of an ice bath, and the resulting precipitate isolated by suction filtration. The crude product was dissolved in hot chlorobenzene (900 mL), and the resulting solution filtered over a silica gel pad. After rinsing with additional hot chlorobenzene (2200 mL), followed by a mixture of hexane (1%, vol.) in chlorobenzene, the organic solvent was removed under reduced pressure. The solid residue was triturated in hot chlorobenzene, and the resulting precipitate was collected by suction filtration, to yield 7.4 g (76%) of a white solid after drying. Final purification was achieved by sublimation. m/z=639 ([M+H].sup.+).

##STR00054##

7′-(3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)spiro[fluorene-9,5′-indeno[1,2-c]pyridine]-Compound A-4

[0474] A flask was charged with deaerated solutions of 7′-chlorospiro[fluorene-9,5′-indeno[1,2-c]pyridine] (5.5 g, 15.6 mmol) and 2,4-diphenyl-6-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-1,3,5-triazine (6.8 g, 15.6 mmol) in THE (100 mL), and an aqueous solution (40 mL) of potassium phosphate (8.3 g, 39.0 mmol). Chloro(crotyl)(2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl)palladium(II) (190 mg, 2.0 mol %) was subsequently added in a counter flow of N.sub.2, and the reaction mixture was reacted at 60° C. overnight. The mixture was allowed to cool to room temperature, the resulting precipitate was isolated by suction filtration, washed with a minimal amount of THF, water (400 mL) until neutral pH, and methanol. The crude product was dissolved in hot chlorobenzene (400 mL), and the resulting solution filtered over a silica gel pad. After rinsing with additional hot chlorobenzene (2500 mL), the resulting solution was concentrated under reduced pressure and the residue triturated overnight at room temperature. The resulted precipitate was recovered by suction filtration, washed with chlorobenzene (100 mL) and hexane, and dried under vacuum to afford 6.7 g (69%) of a white solid. Final purification was achieved by sublimation, m/z=625 ([M+H].sup.+).

[0475] US 2015171340. LiQ is commercially available (CAS 25387-93-3). Metal borates may be synthesized as described in WO2013079676A1.

General Procedure for Fabrication of OLEDs

[0476] For top emission devices, Examples 1 to 4 and comparative example 1, a glass substrate was cut to a size of 150 mm×150 mm×0.7 mm, was ultrasonically cleaned with a 2% aquatic 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.

[0477] 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).

[0478] Afterwards the emission layer was formed on the EBL by co-deposition of HOST-1 and EMITTER-1.

[0479] Then, the ET-1 was vacuum deposited onto the emission layer to form the hole blocking layer (HBL). Then, the electron transport layer was formed on the hole blocking layer by co-depositing a compound of formula (I) and LiQ for examples-1 to -3. For the comparative example the electron transport layer was formed on the hole blocking layer by co-depositing the compound comparative-1 and LiQ.

[0480] Then, the electron injection layer is formed on the electron transporting layer by deposing Yb.

[0481] Ag:Mg is then evaporated at a rate of 0.01 to 1 Å/s at 10-7 mbar to form a cathode.

[0482] A cap layer of HT-1 is formed on the cathode.

[0483] 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 ( . . . ):

Layer Stack Details

[0484] Ag [100 nm]/HT-1:D-1 (92:8) [10 nm]/HT-1 [118 nm]/HT-2 [5 nm]/H09:BD200 (97:3) [20 nm]/ET-1 [5 nm]/Compound of formula (I): LiQ (1:1) [31 nm]/Yb [2 nm]/Ag:Mg (90:10) [13 nm]/HT-1 [70 nm].

TABLE-US-00001 TABLE 1 List of compounds used IUPAC name Reference HT-1 N-([1,1′-biphenyl]-4-yl)-9,9-dimethyl- US2016322581 N-(4-(9-phenyl-9H-carbazol-3- yl)phenyl)-9H-fluoren-2-amine [CAS 1242056-42-3] HT-2 N,N-bis(4-(dibenzo[b,d]furan-4-yl) JP2014096418 phenyl)-[1,1′:4′,1″-terphenyl]-4-amine [CAS 1198399-61-9] D-1 4,4′,4″-((1E,1′E,1″E)-cyclopropane- US2008265216 1,2,3-triylidenetris (cyanomethanylylidene)) tris(2,3,5,6-tetrafluorobenzonitrile) [CAS 1224447-88-4] HOST-1 H09 (Fluorescent-blue host material) Commercially available from Sun Fine Chemicals, Inc, S. Korea EMITTER-1 BD200 (Fluorescent-blue emitter Commercially material) available from Sun Fine Chemicals, Inc, S. Korea ET-1 2,4-diphenyl-6-(4′,5′,6′-triphenyl- WO2016171358 [1,1′:2′,1″:3″,1″′:3″′,1″″- quinquephenyl]-3″″-yl)-1,3,5-triazine [CAS 2032364-64-8] Comparative- 2,4-diphenyl-6-(3′-(9-phenyl-9H- US0170250349 1 fluoren-9-yl)-[1,1′-biphenyl]-4-yl)- 1,3,5-triazine [CAS 2129116-80-7] LiQ 8-Hydroxyquinolinolato-lithium WO2013079217 [CAS 850918-68-2]

[0485] 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 (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.

[0486] Lifetime LT of the device is measured at ambient conditions (20° C.) and 30 mA/cm.sup.2, using a Keithley 2400 source meter, and recorded in hours.

[0487] 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.

[0488] Properties of compounds A-1, A-2, A-3 and A-4 of formula (I) and of comparative-1 compound are shown in table 2 below.

TABLE-US-00002 TABLE 2 Properties of compounds of formula (I) and of comparative compound Comparative-1 mp Tg T.sub.RO [° C.] [° C.] [° C.] Comparative-1 [00055] 303 123 268 A-1 [00056] 299 155 240 A-2 [00057] 382 159 272 A-3 [00058] 298 154 252 A-4 [00059] 356 145 264

[0489] Dipole moment, HOMO and LUMO levels of comparative-1 and compounds A-1 to A-4, simulated by DFT (B3LYP_Gaussian/6-31G*, gas phase) are shown in table 3 below.

TABLE-US-00003 TABLE 3 Dipole moment, HOMO and LUMO levels of comapartive-1 and compounds A1 to A4, simulated by DFT (B3LYP_ Gaussian/6-31G*, gas phase) Dipole moment HOMO LUMO [Debye] [eV] [eV] Comparative-1 0.58 −5.81 −1.85 A-1 2.49 −5.82 −1.97 A-2 1.54 −5.83 −2.01 A-3 2.15 −5.74 −1.93 A-4 2.60 −5.81 −1.83

[0490] The Performance data of an organic electroluminescent device comprising an organic semiconductor layer comprising compounds of formula 1, namely A-1 to A-3 as matrix material and an LiQ alkali organic complex in the electron transport layer are shown in table 4 below.

TABLE-US-00004 TABLE 4 Performance data of organic electroluminescent device comprising an organic semiconductor layer comprising compound of formula 1 as matrix material and an alkali organic complex in the electron transport layer OLED Matrix n- Operating voltage at LT97 at 30 device examples material additive 10 mA/cm.sup.2 (V) mA/cm.sup.2 (hours) Comparative example Comparative-1 LiQ 3.65 32 Example-1 A-1 LiQ 3.65 56 Example-2 A-2 LiQ 3.64 76 Example-3 A-3 LiQ 3.50 70

[0491] In summary, improved lifetime may be achieved when the organic semiconductor layer comprises a compound of formula 1, for example A-1 to A-3 and an organic metal complex, such as LiQ, compared with the prior art compound (comparative-1).

[0492] While this 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.