Electronic device comprising an organic semiconducting material

Abstract

The present invention relates to an electronic device comprising at least one organic semiconducting material according to the following formula (I): wherein R.sub.1-4 are independently selected from H, halogen, CN, substituted or unsubstituted C.sub.1-C.sub.20-alkyl or heteroalkyl, C.sub.6-C.sub.20-aryl or C.sub.5-C.sub.20-heteroaryl, C.sub.1-C.sub.20-alkoxy or C.sub.6-C.sub.20-aryloxy, Ar is selected from substituted or unsubstituted C.sub.6-C.sub.20-aryl or C.sub.5-C.sub.20-heteroaryl, and R5 is selected from substituted or unsubstituted C.sub.6-C.sub.20-aryl or C.sub.5-C.sub.20-heteroaryl, H, F or formula (II). ##STR00001##

Claims

1. An electronic device comprising at least one organic semiconducting material according to formula (I): ##STR00111## wherein R.sub.1-4 are independently selected from H, halogen, CN, C.sub.1-C.sub.20-alkyl, C.sub.1-C.sub.20-heteroalkyl, C.sub.6-C.sub.20-aryl, C.sub.5-C.sub.20-heteroaryl, C.sub.1-C.sub.20-alkoxy, or C.sub.6-C.sub.20-aryloxy, wherein each C.sub.1-C.sub.20-alkyl, C.sub.1-C.sub.20-heteroalkyl, C.sub.6-C.sub.20-aryl, C.sub.5-C.sub.20-heteroaryl, C.sub.1-C.sub.20 alkoxy, or C.sub.6-C.sub.20-aryloxy is unsubstituted or substituted, wherein Ar is selected from, substituted or unsubstituted, C.sub.6-C.sub.20-aryl or C.sub.5-C.sub.20-heteroaryl, and R.sub.5 is selected from substituted or unsubstituted C.sub.6-C.sub.20-aryl, substituted or unsubstituted C.sub.5-C.sub.20-heteroaryl, H, F, or ##STR00112## wherein R.sub.1-4, are as previously defined; wherein the device has a layered structure and at least one layer comprises at least one compound according to formula (I).

2. The electronic device according to claim 1, wherein Ar and R.sub.1-4 are independently selected from C.sub.6-C.sub.20 aryl or C.sub.5-C.sub.20-heteroaryl.

3. The electronic device according to claim 1, wherein R.sub.5 is H or F, and R.sub.5 and Ar are a moiety selected from ##STR00113## ##STR00114##

4. The electronic device according to claim 1, wherein Ar is selected from ##STR00115## ##STR00116##

5. The electronic device according to claim 1, wherein the organic semiconducting material is doped by an n-dopant.

6. The electronic device according to claim 5, wherein the organic semiconducting material is doped by an organic n-dopant having a HOMO energy level which is more positive than 3.3 eV.

7. The electronic device according to claim 1, wherein the device is an electronic, optoelectronic or electroluminescent device having an electronically functionally effective region, wherein the electronically effective region comprises at least one compound according to formula (I).

8. The electronic device according to claim 1, wherein the device is an organic light-emitting diode, a field-effect transistor, a sensor, a photodetector, an organic thin-film transistor, an organic integrated circuit, an organic light-emitting transistor, a light-emitting electrochemical cell, or an organic laser diode.

9. A compound according to formula (I): ##STR00117## wherein R.sub.1-4 are independently selected from H, halogen, CN, C.sub.1-C.sub.20-alkyl, C.sub.1-C.[.12.]..Iadd.20.Iaddend.-heteroalkyl, C.sub.6-C.sub.20-aryl, C.sub.5-C.sub.20-heteroaryl, C.sub.1-C.sub.20-alkoxy, or C.sub.6-C.sub.20aryloxy, wherein each C.sub.1-C.sub.20-alkyl, C.sub.1-C.sub.20-heteroalkyl, C.sub.1-C.sub.20-aryl, C.sub.5-C.sub.20-heteroaryl, C.sub.1-C.sub.20-alkoxy, or C.sub.6-C.sub.20-aryloxy is unsubstituted or substituted, .[.wherein R.sub.5 is H, and Ar is ##STR00118## .]. .Iadd.wherein Ar is selected from unsubstituted C.sub.6-C.sub.20-aryl or C.sub.5-C.sub.20-heteroaryl, and wherein R.sub.5 is selected from F, substituted or unsubstituted C.sub.6-C.sub.20-aryl, substituted or unsubstituted C.sub.5-C.sub.20-heteroaryl in which one or two carbon atoms is substituted by N or S, ##STR00119## wherein R.sub.1-R.sub.4 are as previously defined, ##STR00120## .Iaddend.

.Iadd.10. A compound according to formula (I): ##STR00121## wherein R.sub.1-4 are independently selected from H, halogen, CN, C.sub.1-C.sub.20-alkyl, C.sub.1-C.sub.20-heteroalkyl, C.sub.6-C.sub.20-aryl, C.sub.5-C.sub.20-heteroaryl, C.sub.1-C.sub.20-alkoxy, or C.sub.6-C.sub.20-aryloxy, wherein each C.sub.1-C.sub.20-alkyl, C.sub.1-C.sub.20-heteroalkyl, C.sub.6-C.sub.20-aryl, C.sub.5-C.sub.20-heteroaryl, C.sub.1-C.sub.20-alkoxy, or C.sub.6-C.sub.20-aryloxy is unsubstituted or substituted, wherein Ar is selected from, substituted or unsubstituted, C.sub.6-C.sub.20-aryl or C.sub.5-C.sub.20-heteroaryl, and wherein R.sub.5 is H or F and combines with Ar to a moiety selected from ##STR00122## ##STR00123## .Iaddend.

.Iadd.11. A compound having one of the following structures: ##STR00124## ##STR00125## ##STR00126## ##STR00127## ##STR00128## ##STR00129## ##STR00130## ##STR00131## .Iaddend.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a cross section of a typical exemplary small molecule OLED.

(2) The organic electronic device of the present invention may be an organic light emitting diode. FIG. 1 shows a typical layer structure of an organic light emitting diode. The layers are disposed on a substrate (10) in the following order: anode (11), p-doped hole transport layer (12), electron blocking layer (13), emission layer (14), hole blocking layer (15), n-electron transport layer (16), and cathode (17). Two or more layers can collapse into a smaller number of layers if properties can be combined. Inverted structure and multiple stacked OLEDs are also well known in the field. The emission layer is usually composed by an emitter matrix material and an emitter dopant; this layer can be also composed by several other layers to generate light with a broad spectrum combining several emitters, for example, to generate white light.

EXAMPLES

General Synthesis Method

(3) ##STR00082##

(4) Of course, the R's in the above general synthesis scheme shall stand for R.sub.1-4 according to formula (I). Additionally, Ar shall in this general synthesis scheme be understood to stand for the moiety ArR.sub.5 according to formula (I).

(5) R1-4 are independently introduced in steps 1 and/or 2 of the general synthesis scheme by choosing the proper tetralone derivative (such as 6-fluoro-3,4-dihydro-7-methoxy-1(2H) naphthalenone or 3,4-dihydro-5,8-dimethyl-1(2H)-naphthalenone, or 6,7-dichloro-3,4-dihydro 1(2H)-naphthalenone, or, 3,4-dihydro-6-nitro-1(2H)-naphthalenone, or 3,4-dihydro-7-phenyl-1(2H)-naphthalenone which are all commercial materials.

Example 1

Synthesis of

(6) ##STR00083##

(7) First Step:

(8) Synthesis of 2-benzylidene-3,4-dihydronaphthalen-1(2H)-one (1). All manipulations were carried out in air, without any further purification of commercial solvents/chemicals.

(9) ##STR00084##

(10) A 250 mL flask was charged with tetralone (4 g, 27.4 mmol) and benzaldehyde (3.88 g, 36.6 mmol). This was dissolved in warm tetrahydrofuran (15 mL), and to this yellow solution was slowly added a 4 wt % solution of KOH in methanol (125 mL). The reaction was stirred for 4 days at room temperature. The solvent was then removed under reduced pressure, and it was poured into 150 mL of water and extracted with methylene chloride. The organic extract was dried over magnesium sulfate and filtered, and the solvent was removed at reduced pressure to afford 4.1 g (64%) as white powder.

(11) NMR: 1H NMR (500 MHz, CD2Cl2) 8.01 (dd, J=64.7, 65.4, 2H), 7.71-6.92 (m, 8H), 3.39-2.64 (m, 4H).

(12) Second Step:

(13) Synthesis of 7-phenyl-5,6,8,9-tetrahydrodibenzo[c,h]acridine (2). All manipulations were carried out under argon.

(14) ##STR00085##

(15) 1 (2.9 g, 12.4 mmol) and tetralone (1.7 g, 11.6 mmol) are introduced in a flask together with BF3.Et2O (1.8 mL, 14.2 mmol). The mixture is stirred at 100 C. for 4 hours and cooled to room temperature. Et2O was added (15 mL) and the mixture is stirred for an additional hour. The precipitate is filtered and washed with Et2O (15 mL). This powder (1.9 g) is then introduced at 0 C. in a flask together with a ammonia-ethanol solution. The mixture was allowed to stir at room temperature for 6 h, the solid was filtered and washed several times with ethanol. 1.4 g (34% yield) of a white powder was obtained.

(16) Third Step:

(17) Synthesis of 7-phenyldibenzo[c,h]acridine (3). All manipulations were carried out under argon with dry solvents.

(18) ##STR00086##

(19) 2 (1.55 g, 4.31 mmol) was dissolved in 100 mL dioxane and 2,3-dichloro-5,6-dicyanobenzoquinone was added (6.88 g, 30.3 mmol). The mixture was refluxed under argon for 2 days. The reaction mixture was then cooled to room temperature, poured in 300 mL saturated aqueous sodium carbonate solution and stirred at 65 C. for 30 min. The mixture was then cooled to room temperature, the precipitation was filtered and washed with water and methylene chloride. Yield: 1.1 g (72%).

(20) 1H NMR (500 MHz, CD2Cl2) 8.02-7.94 (m, 4H), 7.86 (dd, J=1.2, 7.8, 2H), 7.71 (ddd, J=5.9, 11.0, 25.9, 3H), 7.45 (dd, J=7.3, 8.4, 4H), 7.20 (d, J=8.7, 2H), 7.05 (ddd, J=1.5, 7.0, 8.6, 2H).

Example 2

Synthesis of

(21) ##STR00087##

(22) First Step:

(23) Synthesis of (E)-2-(4-bromobenzylidene)-3,4-dihydronaphthalen-1(2H)-one (4). All manipulations were carried out in air, without any further purification of commercial solvents/chemicals.

(24) ##STR00088##

(25) A 250 mL flask was charged with tetralone (3.22 g, 22 mmol) and 4-bromobenzaldehyde (5.3 g, 28.6 mmol). This was dissolved in warm tetrahydrofuran (12 mL), and to this yellow solution was slowly added a 4 wt % solution of KOH in methanol (100 mL). The reaction was stirred for 4 days at room temperature. The mixture was concentrated and reduced to approx 10% vol. The residue was filtered and washed with MTBE (3*50 mL), dried, to afford a light yellow powder (6.61 g, 96%).

(26) Second Step:

(27) Synthesis of 7-(4-bromophenyl)-5,6,8,9-tetrahydrodibenzo[c,h]acridine (5). All manipulations were carried out under argon.

(28) ##STR00089##

(29) 4 (6.54 g, 20.9 mmol) and tetralone (2.93 g, 20.0 mmol) are introduced in a flask together with BF3.Et2O (3 mL, 23.7 mmol). The mixture is stirred at 100 C. for 4 hours and cooled to room temperature. Et2O was added (25 mL) and the mixture is stirred for an additional hour. The precipitate is filtered and washed with Et.sub.2O (20 mL). This powder (3.8 g) is then introduced at 0 C. in a flask together with an ammonia-ethanol solution. The mixture was allowed to stir at room temperature for 5 h, the precipitate was filtered and washed several times with ethanol.

(30) 2.98 g (34% yield) of a white powder was obtained.

(31) Third Step:

(32) Synthesis of 7-(4-bromophenyl)dibenzo[c,h]acridine (6). All manipulations were carried out under argon with dry solvents.

(33) ##STR00090##

(34) 2 (2.98 g, 6.80 mmol) was dissolved in 190 mL dioxane and 2,3-dichloro-5,6-dicyanobenzoquinone was added (10.9 g, 48 mmol). The mixture was refluxed under argon for 2 days. The reaction mixture was then cooled to room temperature, poured in 600 mL saturated aqueous sodium carbonate solution and stirred at 65 C. for 30 min. The mixture was then cooled to room temperature, the precipitation was filtered and washed with water and dichloromethane.

(35) Yield: 2 g (68%). .sup.1H NMR (500 MHz, CD.sub.2Cl.sub.2) (ppm): 9.80 (d, J=8.0, 2H), 8.00-7.68 (m, 10H), 7.53 (d, J=9.2, 2H), 7.45-7.34 (m, 2H).

(36) Fourth Step:

(37) Synthesis of 4,4-bis(dibenzo[c,h]acridin-7-yl)-1,1:4,1-terphenyl (7). All manipulations were carried out in air, without any further purification of commercial solvents/chemicals.

(38) ##STR00091##

(39) 6 (700 mg, 1.61 mmol), 1,4-phenylenediboronic acid (146 mg, 0.88 mmol), Palladium tetrakis triphenylphoshine (186 mg, 0.16 mmol) and potassium carbonate (1.34 g, 9.66 mmol) were introduced in a flask together with 17 mL toluene, 8.8 mL ethanol and 2.6 mL distilled water. This mixture is stirred at 80 C. during 24 hours before being filtered. The solid is then washed with hexane, water and some mL of chloroform before being dried.

(40) Yield: 200 mg (20%).

Example 3

Synthesis of

(41) ##STR00092##

(42) First Step:

(43) Synthesis of (E)-2-(3-bromobenzylidene)-3,4-dihydronaphthalen-1(2H)-one (8). All manipulations were carried out in air, without any further purification of commercial solvents/chemicals.

(44) ##STR00093##

(45) A 250 mL flask was charged with tetralone (5.2 g, 35.6 mmol) and 3-bromobenzaldehyde (8.51 g, 56 mmol). This was dissolved in warm tetrahydrofuran (20 mL), and to this yellow solution was slowly added a 4 wt % solution of KOH in methanol (160 mL). The reaction was stirred for 4 days at room temperature. The mixture was concentrated and reduced to approx 10% vol. The residue was filtered and washed with MTBE (3*50 mL), dried, to afford a light yellow powder (10.3 g, 92%).

(46) NMR: 1H NMR (500 MHz, CD2Cl2) 8.01 (dd, J=64.7, 65.4, 2H), 7.71-6.92 (m, 8H), 3.39-2.64 (m, 4H).

(47) Second Step:

(48) Synthesis of 7-(3-bromophenyl)-5,6,8,9-tetrahydrodibenzo[c,h]acridine (9). All manipulations were carried out under argon.

(49) ##STR00094##

(50) 4 (10.2 g, 32.6 mmol) and tetralone (4.52 g, 30.9 mmol) are introduced in a flask together with BF3.Et2O (4.7 mL, 37.1 mmol). The mixture is stirred at 100 C. for 4 hours and cooled to room temperature. Et.sub.2O was added (70 mL) and the mixture is stirred for an additional hour. The precipitate is filtered and washed with Et.sub.2O (20 mL). This powder (5.6 g) is then introduced at 0 C. in a flask together with an ammonia-ethanol solution. The mixture was allowed to stir at room temperature for 5 h, the solid was filtered and washed several times with ethanol.

(51) 4.5 g (33% yield) of a white powder was obtained.

(52) Third Step:

(53) Synthesis of 7-(3-bromophenyl)dibenzo[c,h]acridine (10). All manipulations were carried out under argon and with dry solvents.

(54) ##STR00095##

(55) 2 (4.49 g, 10.2 mmol) was dissolved in 220 mL dioxane and 2,3-dichloro-5,6-dicyanobenzoquinone was added (14.3 g, 63 mmol). The mixture was refluxed under argon for 2 days. The reaction mixture was then cooled to room temperature, poured in 700 mL saturated aqueous sodium carbonate solution and stirred at 65 C. for 30 min. The mixture was then cooled to room temperature; the precipitation was filtered and washed with water and dichloromethane.

(56) Yield: 3.3 g (74%).

(57) .sup.1H NMR (500 MHz, CD.sub.2Cl.sub.2) (ppm): 9.80 (d, J=8.1, 2H), 8.01-7.63 (m, 11H), 7.61-7.40 (m, 4H).

(58) Fourth Step:

(59) Synthesis of 7-(3-(pyren-1-yl)phenyl)dibenzo[c,h]acridine (11). All manipulations were carried under argon.

(60) ##STR00096##

(61) 10 (700 mg, 1.61 mmol), pyren-1-ylboronic acid (434 mg, 1.76 mmol), Palladium tetrakis triphenylphoshine (186 mg, 0.16 mmol) and potassium carbonate (1.34 g, 9.66 mmol) were introduced in a flask together with 17 mL toluene, 8.8 mL ethanol and 2.6 mL distilled water. This mixture is stirred at 80 C. during 24 hours before being filtered. The solid is then washed with hexane, water and some mL of chloroform before being dried.

(62) Yield: 392 mg (44%).

Example 4

Synthesis of

(63) ##STR00097##

(64) Fourth Step:

(65) Synthesis of (4-(dibenzo[c,h]acridin-7-yl)phenyl)diphenylphosphine oxide (15). All manipulations were carried under argon.

(66) ##STR00098##

(67) 6 (2.84 g, 5.11 mmol) was solved in 40 mL THF. The solution was cooled down to 78 C. and n-BuLi was added drop wise within 20 min (2.5 Mol/L, 3.5 mL, 8.68 mmol), and then stirred at that temperature for 1 hour. The temperature is then let rise up to 50 C., and diphenylphosphine chloride (1.13 g, 5.11 mmol) was added and the mixture was stirred overnight at Room temperature. The reaction was then quenched with Methanol (25 mL), and the solvents were evaporated. The residue was solved in 40 mL dichloromethane and Water peroxide is then added (8 mL H.sub.2O.sub.2 aq.) and stirred overnight. The reaction is then washed several times with 50 mL Brine, the organic phase was then dried and evaporated. The crude product is purified via column chromatography (SiO.sub.2, Dichloromethane, then DCM/MeOH 97:3). The obtained foamy product is then washed with 200 mL MTBE.

(68) Yield: 1.6 g (43%)

(69) HPLC: >97%

(70) NMR: 31P NMR (CDCl.sub.3, 121.5 MHz): (ppm): 29 (m).

Example 5

(71) ##STR00099##

(72) Fourth Step:

(73) Synthesis of 7-(4-(1-phenyl-1H-benzo[d]imidazol-2-yl)-[1,1-biphenyl]-4-yl)dibenzo[c,h]acridine (16). All manipulations were carried under argon.

(74) ##STR00100##

(75) 6 (2.1 g, 4.8 mmol), 1-phenyl-2-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-1H-benzo[d]imidazole (3.8 g, 9.6 mmol), Palladium tetrakis triphenylphoshine (830 mg) and 17 mL of a 1M potassium carbonate solution in water were introduced in a flask together with 35 mL degassed toluene. This mixture is stirred at 80 C. during 36 hours before being let cooled to room temperature and filtered. The solid is then dissolved in dichloromethane (600 mL) and filter over a Celite pad. The volatiles are removed by rotary evaporation and the solid is then dried overnight in a vacuum oven.

(76) Yield: 1.2 g (40%)

(77) HPLC>98%.

Example 6

(78) ##STR00101## ##STR00102##

(79) 6 (3 g, 6.9 mmol), 1-phenyl-2-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-1H-benzo[d]imidazole (3.3 g, 10.36 mmol), Palladium tetrakis triphenylphoshine (1.2 g) and 30 mL of a 1M potassium carbonate solution in water were introduced in a flask together with 100 mL toluene. This mixture is stirred at 95 C. during 48 hours before being let cooled to room temperature and filtered with a paper filter. The solid is then washed with toluene, and the obtain grey solid is dissolved in 500 ml of hot (150 C.) xylene, this suspension is filtered over a celite pad and the volatiles are then removed by rotary evaporation. The obtained solid is then dried in a vacuum oven. Yield: 2.4 g (65%).

(80) HPLC: >98%

Example 7

Synthesis of

(81) ##STR00103##

(82) First Step:

(83) Synthesis of (E)-2-(4-methoxybenzylidene)-3,4-dihydronaphthalen-1(2H)-one (15). All manipulations were carried out in air, without any further purification of commercial solvents/chemicals.

(84) ##STR00104##

(85) A mixture of p-methoxybenzaldehyde (10.00 g, 73.4 mmol, 1.3 eq) and 1-tetralone (8.24 g, 56.4 mmol, 1 eq) was dissolved in tetrahydrofurane (30 mL) and a methanolic solution of potassium hydroxide (4% solution, 250 mL, 7.9 g KOH, 141 mmol, 2.5 eq) was added dropwise over a 15 minutes period to the stirred solution. The mixture was stirred at ambient temperature for three days and the formed precipitate was separated by filtration and purified by washing with MTBE. After drying in vacuo a pale yellow solid (8.57 g, 60% yield, GC-MS purity 99%) was obtained. The filtrate was reduced to a quarter of its volume and a second fraction (3.7 g, 26% yield, GC-MS purity 100%) could be isolated after filtration and washing with a low amount of methanol and a higher amount of MTBE. The over-all yield was 86% and the product was directly used in the next step without any further purification.

(86) Second Step:

(87) Synthesis of 7-(4-methoxyphenyl)-5,6,8,9-tetrahydrodibenzo[c,h]xanthen-14-ium tetra-fluoroborate (16). All manipulations were carried out under argon.

(88) ##STR00105##

(89) In an inert argon atmosphere (diethyloxonio)trifluoroborate (7.83 g, 7.0 mL, 55.2 mmol, 1.2 eq) was added dropwise to a stirred mixture of (E)-2-(4-methoxybenzylidene)-3,4-dihydronaphthalen-1(2H)-one (15) (12.20 g, 46.2 mmol, 1 eq) and 1-tetralone (6.73 g, 46.0 mmol, 1 eq). After complete addition the mixture was heated at 100 C. for 5 hours and then cooled to room temperature. Diethylether (50 mL) was added andafter stirring over a 30 minutes periodthe product was isolated by filtration and purified by washing with diethylether. After drying in vacuo an ochre solid was obtained. The product was used in the next step without any further purification.

(90) Yield: 6.66 g (30%)

(91) Third Step:

(92) Synthesis of 7-(4-methoxyphenyl)-5,6,8,9-tetrahydrodibenzo[c,h]acridine (17). All manipulations were carried out in air, without any further purification of commercial solvents/chemicals.

(93) ##STR00106##

(94) 16 (6.63 g, 13.9 mmol, 1 eq) was suspended in ethanol (175 mL, denaturated with 1% methylethyl ketone). Under vigorously stirring an ammonia solution (32% aqueous solution, 18.3 g NH.sub.3, 1.075 mol, 77 eq) was added dropwise and the mixture was stirred at ambient temperature for 171/2 hours to obtain a lavender suspension. The product was isolated by filtration and purified by successive washing with ethanol (250 mL). A lavender solid (91% yield) could be obtained. The compound was directly used in the next step without any further purification.

(95) Yield: 4.93 g (91%)

(96) HPLC: 91% (and 5% of a constitution isomer)

(97) Fourth Step:

(98) Synthesis of 7-(4-methoxyphenyl)dibenzo[c,h]acridine (18). All manipulations were carried out under argon.

(99) ##STR00107##

(100) In an inert argon atmosphere 17 (4.93 g, 12.7 mmol, 1 eq) was dissolved in abs. 1,4-dioxane (300 mL, dried over sodium) under vigorously stirring at 80 C. 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ, 17.25 g, 76 mmol, 6 eq) was added in portions over a 5 minutes period and the DDQ-vessel was flushed with abs. dioxane (20 mL). The almost black mixture was stirred at 80 C. for two days maintaining the inert atmosphere. After cooling to room temperature the reaction mixture was carefully added to 500 mL of an aqueous saturated sodium carbonate solution and the reaction vessel was flushed with saturated Na.sub.2CO.sub.3 solution (250 mL) and water (200 mL). After stirring of the mixture at 65 C. for 75 minutes the precipitate was allowed to settle down and the product was isolated by filtration and purified by multiple slurry of the solid in water (overall ca. 1000 mL). After drying of the crude product in vacuo at 40 C. overnight the solid was suspended in methylene chloride (20 mL), stirred for 45 minutes, isolated by filtration and washed with DCM (220 mL) and dried overnight. 3.53 g of an ochre solid (72% yield) could be obtained in a 99.5% HPLC purity. Further purification of the material was possible by gradient sublimation (initial amount: 1.00 g, sublimation yield: 67%).

(101) Fifth Step:

(102) Synthesis of 4-(dibenzo[c,h]acridin-7-yl)phenol (19). All manipulations were carried out under argon.

(103) ##STR00108##

(104) In a pressure vessel a mixture of 18 (1.00 g, 2.6 mmol, 1 eq) and pyridiniumhydrochloride (1.75 g, 15.1 mmol, 5.8 eq) was heated to 210 C. under an inert atmosphere and vigorously stirred at this temperature over a three days period. The mixture was allowed to cool down to room temperature. The solidified melt was dissolved in chloroform (50 mL) and water (50 mL) and treated in an ultrasonic bath for 5 minutes. The layers were separated and the aqueous layer was extracted with chloroform (350 mL). Afterwards, the combined organic layers were washed with a saturated aqueous sodium hydrogencarbonate solution (550 mL) followed by water (350 mL) and dried over magnesium sulphate. Evaporation of the solvent at 40 C. led to an old rose coloured solid. The product was directly used in the next step without any further purification.

(105) Yield: 810 mg (84%)

(106) HPLC: 98%

(107) Sixth Step:

(108) Synthesis of 7-(4-((6-(1,1-di(pyridin-2-yl)ethyl)pyridin-2-yl)oxy)phenyl)dibenzo-[c,h]acridine (21). All manipulations were carried out under argon.

(109) ##STR00109##

(110) In an inert argon atmosphere a mixture of 19 (700 mg, 1.9 mmol, 1 eq), potassium carbonate (1.31 g, 9.5 mmol, 5 eq) and 20 (531 mg, 1.9 mmol, 1 eq) was placed into a pressure vessel. The vessel was sealed and the mixture was heated to 200 C. under vigorously stirring. After five days reaction at this temperature the mixture was allowed to cool down and then poured into ice/water (300 mL). The pressure vessel was flushed with water (250 mL) and the solution was extracted with dichloromethane (3100 mL) until the organic layer remained almost colourless. Afterwards, the combined organic layers were washed with water (3500 mL) followed by 2 N aqueous hydrogen chloride solution (2100 mL) and water (300 mL) again. After drying over magnesium sulphate the solvent was removed in vacuo at 40 C. The product was precipitated from the remaining solution by addition of water (1.000 mL), stirring over 10 minutes and isolated by filtration, washing with water (500 mL) and drying overnight at 40 C. in a vacuum dry box. An ochre solid (0.94 g, 78% yield, HPLC purity 99.2%) could be obtained.

(111) Further purification of the material was performed by gradient sublimation (initial amount: 0.93 g, sublimation yield: 43%).

Example of Conductive Layers

(112) The conductivity of a doped layer consisting of material of structure 1 in table 1 doped with 5% of W(hpp).sub.4 (tetrakis(1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidinato)ditungsten (II)) was measured at room temperature and was 1.3910 S/cm.

(113) The conductivity of a doped layer consisting of material of structure 18 in table 1 doped with 5% of W(hpp).sub.4 was measured at room temperature and was 310.sup.7 S/cm.

(114) The conductivity of a doped layer consisting of material of structure 3 in table 1 doped with 5% of W(hpp).sub.4 was measured at room temperature and was 1.210.sup.5 S/cm.

(115) The conductivity of a doped layer consisting of material of structure 2 in table 1 doped with 5% of W(hpp).sub.4 was measured at room temperature and was 9.9510.sup.6 S/cm.

Example of an OLED

(116) The compounds from examples 1-3 were successfully employed as electron transport materials in OLEDs. An exemplary device structure is given below.

(117) Device 1

(118) An OLED was fabricated with the following procedure: A glass substrate coated with ITO (90 nm thick, pre-patterned) was cleaned in organic solvents in conventional ultra-sound. Afterwards the substrate was treated with ozone plasma for 5 minutes. After the cleaning, the substrate was transferred to vacuum. The organic layers were deposited in high vacuum (base pressure lower than 10.sup.3 Pa) by conventional VTE (Vacuum thermal evaporation). The deposited area was defined by a shadow mask, keeping some area of the ITO surface free so that an electrical contact for the measurements could (later on) be established. The organic layer sequence over the ITO layer is: 50 nm thick NPD layer doped with F4TCNQ; 10 nm thick non-doped NPD layer, 20 nm blue emitter host layer doped with a fluorescent emitter; 10 nm ETL (structure 4), 60 nm ETL (structure 4) doped with W(hpp).sub.4 (5% in weight). A 100 nm aluminum layer was deposited as cathode. The OLED reached 1000 cd/m.sup.2 at 3.59 V.

Comparative Example

(119) Using the following material (14-(naphthalen-2-yl)dibenzo[a,j]acridine (structure 1b),

(120) ##STR00110##
which structure is close to the claimed material as an ETL the following performances were obtained:

(121) Device 2

(122) An OLED was fabricated with the following procedure: A glass substrate coated with ITO (90 nm thick, pre-patterned) was cleaned in organic solvents in conventional ultra-sound. Afterwards the substrate was treated with ozone plasma for 5 minutes. After the cleaning, the substrate was transferred to vacuum. The organic layers were deposited in high vacuum (base pressure lower than 10.sup.3 Pa) by conventional VTE (Vacuum thermal evaporation). The deposited area was defined by a shadow mask, keeping some area of the ITO surface free so that an electrical contact for the measurements could (later on) be established. The organic layer sequence over the ITO layer is: 50 nm thick NPD layer doped with F4TCNQ; 10 nm thick non-doped NPD layer, 20 nm blue emitter host layer doped with a fluorescent emitter; 10 nm ETL (structure 1b), 60 nm ETL (structure 1b) doped with W(hpp).sub.4 (5% in weight). A 100 nm aluminum layer was deposited as cathode. The OLED reached 1000 cd/m.sup.2 at 4.25 V.

(123) Compounds of structure 1-33 successfully passed sublimation, and device tests, showing a low operating voltage in OLEDs, high power efficiency, and long lifetime.

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