NEW EMITTER MATERIALS AND MATRIX MATERIALS FOR OPTOELECTRONIC AND ELECTRONIC COMPONENTS, IN PARTICULAR ORGANIC LIGHT-EMITTING DIODES (OLEDS)

Abstract

The invention relates to compounds, comprising at least one donor group and at least one acceptor group, in which the transition energy of the lowest excited triplet hack into the ground state both of the corresponding donor molecule and of the corresponding acceptor molecule being at least 2.2 eV, and the use thereof as an emitter or a carrier material in an optoelectronic component.

Claims

1. A compound comprising at least one donor group and at least one acceptor group, in which the vertical transition energy of the lowest excited triplet back to the electronic ground state both for the individual corresponding donor molecule and for the individual corresponding acceptor molecule is at least 2.2 eV, and wherein the dihedral angle between the at least one donor group and the at least one acceptor group is at least 70°.

2. The compound as claimed in claim 1, wherein the at least one donor group and/or acceptor group is a compound of the formula (1) or a compound of the formula (II): ##STR00011## where, in the compounds of the formula (I), R.sup.11-R.sup.18 are each independently selected from the group consisting of hydrogen, C.sub.1-C.sub.20 alkyl, aryl and bromine, or R.sup.11, R.sup.14, R.sup.15 and R.sup.18 are as defined above and R.sup.13 and/or R.sup.16 or R.sup.12 and/or R.sup.17 denotes ##STR00012## which represents the point of attachment to another part of the molecule; Y.sup.1 is selected from the group consisting of N—R.sup.19, P(O)R.sup.19 and P(O)OR.sup.19 and X.sup.1 is selected from the group consisting of P(O)R.sup.19, P(O)OR.sup.19, Si(C.sub.1-C.sub.20 alkyl).sub.2, Si(aryl).sub.2 and SO.sub.2; where R.sup.19 is in each case independently selected from the group consisting of hydrogen, C.sub.1-C.sub.20 alkyl and aryl, or R.sup.19 denotes ##STR00013## which represents the point of attachment to another part of the molecule; and where, in the compounds of the formula (II), R.sup.21-R.sup.28 are each independently selected from the group consisting of hydrogen, C.sub.1-C.sub.20 alkyl, aryl and bromine, or R21, .sub.R24.sub., R25 an.sub.d are as defined above and R.sup.23 and/or R.sup.26 R.sup.28 or R.sup.22 and/or R.sup.27 denotes ##STR00014## which represents the point of attachment to another part of the molecule; Y.sup.2 is selected from the group consisting of P(O)R.sup.29, P(O)OR.sup.29, Si(C.sub.1-C.sub.20 alkyl).sub.2, Si(aryl).sub.2 and SO.sub.2; X.sup.2 is selected from the group consisting of P(O)R.sup.29, P(O)OR.sup.29, Si(C.sub.i-C.sub.20 alkyl).sub.2, Si(aryl).sub.2 and SO.sub.2; where R.sup.29 is in each case independently selected from the group consisting of hydrogen, C.sub.1-C.sub.20 alkyl and aryl, or R.sup.29 denotes ##STR00015## which represents the point of attachment to another part of the molecule.

3. The compound as claimed in claim 2, wherein R.sup.19 and/or R.sup.29 is/are each independently selected from the group consisting of hydrogen, C.sub.1-C.sub.20 alkyl and phenyl, or R.sup.19 and/or R.sup.29 denote(s) ##STR00016## which represents the point of attachment to another part of the molecule.

4. The compound as claimed in claim 1, wherein the compound, in addition to the at least one donor molecule and the at least one acceptor molecule, comprises at least one further donor molecule or acceptor molecule in which the vertical transition energy of the lowest excited triplet is at least 2.2 eV.

5. The compound as claimed in claim 4, wherein the at least one further donor group or acceptor group is a compound of the formula (I) or (11) as defined in claim 3.

6. The compound as claimed in claim 1, wherein the compound is a compound of the formula (III) or a compound of the formula (IV):
A-B-A   (III)
A-B   (IV) wherein, in the compounds of the formula (III) or (IV), components A and B are each either a donor group or an acceptor group, where at least one A or B is, preferably all A and more preferably all A and B are, a compound having a vertical transition energy of the lowest excited triplet back to the electronic ground state of at least 2.2 eV, and wherein the dihedral angle between at least one donor group and at least one acceptor group, preferably between (each) A and B, is at least 70°.

7. The compound as claimed in claim 6, wherein component A is in each case independently a compound of the formula (I) as defined in claim 3 which is bonded to component B via R.sup.19 in each case.

8. The compound as claimed in claim 7, wherein component B is a compound having a vertical transition energy of the lowest excited triplet back to the electronic ground state of at least 2.2 eV, especially selected from carbazole and carbazole-containing compounds, dihydroacridine, dimethylacridine, phenothiazine and phenoxazine.

9. The compound as claimed in claim 6, wherein component B is a compound of the formula (I) or of the formula (H) as defined in claim 3, each of which is bonded to component(s) A via (a) R.sup.13 and/or R.sup.16 or (b) R.sup.12 and/or R.sup.17 or (c) R.sup.23 and/or R.sup.26 or (d) R.sup.22 and/or R.sup.27.

10. The compound as claimed in claim 9, wherein each component A is independently selected from compounds having a vertical transition energy of the lowest excited triplet back to the electronic ground state of at least 2.2 eV, especially selected from carbazole and carbazole-containing compounds, dihydroacridine, dimethylacridine, phenothiazine and phenoxazine.

11. The compound as claimed in claim6, wherein the compound is selected from the group of compounds of the formulae (1)-(14): ##STR00017## ##STR00018## ##STR00019## ##STR00020##

12. The compound as claimed in claim1, wherein the compound exhibits thermally activatable delayed fluorescence.

13. The use of a compound as claimed in claim1 in an optoelectronic component, for example an organic electroluminescent device (OLED), an organic integrated circuit (O-IC), an organic field-effect transistor (O-FET), an organic thin--film transistor (O-TFT), an organic light-emitting transistor (O-LET), an organic solar cell (O-SC), an organic optical detector, an organic photoreceptor, an organic field-quench device (O-FQD), a light-emitting electrochemical cell (LEC) or an organic laser diode (O-laser) as emitter or matrix material, preferably as emitter.

Description

EXAMPLES

[0111] I.) Synthesis Examples

[0112] Bromination of Phenothiazine:

[0113] 5.0 g (0.025 mol) of phenothiazine were suspended in 200 mL of glacial acetic acid, and the mixture was freed of oxygen by introducing Ar through a cannula for 20 minutes. Then 3.3 mL of Br.sub.2 (0.063 mol) in 200 mL of glacial acetic acid were slowly added dropwise over one hour and the dark-colored mixture was stirred for 16 h. After addition of 6.3 g (0.050 mol) of Na.sub.2SO.sub.3, the reaction mixture solidified. Adding a little water gave rise to a violet mass of high viscosity that turned a lighter color within 3 h. After addition of 4.1 g (0.062 mol) of KOH while cooling with ice, the mixture was poured onto 500 mL of ice-water. The greenish precipitate was filtered off with suction and washed with a little cold 2-propanol. The precipitate was subjected to hot digestion and dissolution five times in 200 mL each time of 2-propanol. Needles precipitated out of 2-propanol in the first fraction, and fine flakes in the subsequent fractions. After the crystals had been filtered off with suction and the mother liquor had been concentrated, 7.54 g (85%) of 3,7-dibromophenothiazine were obtained in the form of green crystals.

[0114] .sup.1H NMR (500 MHz, d-DMSO): δ (ppm) 6.58 (d, J=8.1 Hz, 2H), 7.10-7.15 (m, 4H), 8.84 (s, 1H).

[0115] .sup.13C NMR (125 MHz, d-DMSO): δ 112.7; 116.0; 118.2; 128.1; 130.3; 140.8.

[0116] MS (FAB+) m/z (%): 356.9 (100, M+).

N-Alkylation of 3,7-dibromophenothiazine

[0117] 10 g (0.028 mol) of 3,7-dibromophenothiazine and 5.24 g (0.033 mol) of ethyl iodide were dissolved in 100 mL of DMF. 3.36 g (0.14 mol) of NaH (5.6 g of a 60% dispersion in mineral oil) were added stepwise and the mixture was stirred at room temperature overnight. The reaction mixture was poured into ice-water and filtered. The solids obtained were dissolved in ethyl acetate and the solution was washed with saturated sodium chloride solution and dried over magnesium sulfate. After the solvent had been removed by rotary evaporation under reduced pressure, 9.9 g (92%) of the waxy material 3,7-dibromo-10-ethylphenothiazine were obtained.

[0118] .sup.1H NMR (500 MHz, DMSO) δ 1.24 (t, J=6.9 Hz, 3H), 3.85 (q, J=6.9 Hz, 2H), 6.93 (d, J=8.6 Hz, 2H), 7.32-7.36 (m, 4H).

[0119] .sup.13C NMR (125 MHz, d-DMSO): δ 12.3; 41.33; 114; 117.2; 124.8; 128.9; 130.4; 143.4.

Oxidation of 3,7-dibromo-10-ethylphenothiazine to 3,7-dibromo-10-ethylphenothiazine 5,5-dioxide

[0120] 2 g (7.8 mmol) of 3,7-dibromo-10-ethylphenothiazine were dissolved in 40 mL of dichloromethane, and 5.4 g (31.3 mmol) of 3-chloroperbenzoic acid were added stepwise. The reaction mixture was stirred at room temperature overnight. The precipitated white solids were washed with dichloromethane. The filtrate and the wash solution were concentrated to dryness under reduced pressure. The white crystalline solids obtained were washed with methanol in order to remove the remaining 3-chloroperbenzoic acid. After drying, 1.25 g (38%) of the white crystalline material 3,7-dibromo-10-ethylphenothiazine 5,5-dioxide were obtained.

[0121] .sup.1H NMR (500 MHz, DMSO) δ (ppm) 8.14 (d, J=2.4 Hz, 2H), 7.64 (dd, J=9 Hz, J=2.4 Hz, 2H), 7.19 (t, J=4.6 Hz, 2H), 4.16 (q, J=7.1 Hz, 2H), 1.47 (t, J=7.1 Hz, 3H).

[0122] .sup.13C NMR (125 MHz, d-DMSO): δ (ppm) 12.41; 43.49; 114.41; 117.59; 125.15; 126.28; 136.28; 139.19.

[0123] MS (ESI) m/z : 356.9 ([M.sup.+]+1).

[0124] Synthesis of the Nonoxidized Phenothiazine Trimer

[0125] Into a two-neck flask containing 3,7-dibromo-10-ethylphenothiazine (2.51 g, 6.55 mmol), phenothiazine (2.87 g, 14.42 mmol), Pd.sub.2(dba).sub.3 (0.18 g, 0.197 mmol) and sodium tert-butoxide (0.53 g, 5.5 mmol) were introduced a solution of tri-tert-butylphosphine in o-xylene [1 M] (0.32 mL) and 40 mL of 1,4-dioxane under an argon atmosphere. The mixture was stirred at 95° C. for 12 hours. After cooling, the solvent was removed and the remaining solids were dispersed in an ultrasound waterbath and filtered. The precipitated material obtained was washed with methanol and diethyl ether. The solids obtained were purified via column chromatography with dichloromethane as eluent. 2.84 g (69%) of yellowish crystals were obtained.

[0126] .sup.1H NMR (500 MHz, DMSO) δ 1.43 (t, J=6.9 Hz, 3H), 4.07 (q, J=6.8 Hz, 2H), 5.76 (s, 2H), 6.26 (d, J=8.2 Hz, 2H), 6.85 (t, J=7.4 Hz, 4H), 6.96 (t, J=7.2 Hz, 4H), 7.05 (d, J=7.5 Hz, 4H), 7.32-7.23 (m, 6H).

[0127] .sup.13C NMR (125 MHz, d-DMSO): δ 12.4; 54.9; 115; 117.3; 119.1; 122.7; 124.6; 126.6; 127.4; 128.9; 130.0; 133.4; 134.7; 143.6.

[0128] MS (ESI) m/z : 622 ([M.sup.+]+1).

[0129] Synthesis of the Phenothiazine Dioxide Trimer 2 g (3.22 mmol) of the above-described phenothiazine trimer dissolved in 50 mL of N-methyl-2-pyrrolidone (NMP) and 11.1 g (64 mmol) of 3-chloroperbenzoic acid were introduced stepwise into the reaction vessel. The reaction mixture was stirred at 90° C. overnight. The white precipitate of the product formed in the reaction was filtered and washed in methanol and acetone. After drying, 1.67 g (73%) of white crystalline phenothiazine dioxide trimer were obtained.

[0130] .sup.1H NMR (300 MHz, CDCl.sub.3) δ 1.71 (t, J=7 Hz, 3H), 4.46 (q, J=7 Hz, 2H), 6.62 (d, J=8.4 Hz, 4H), 7.28-7.20 (m, 4H), 7.38 (ddd, J=8.7, 7.3, 1.6 Hz, 4H), 7.76-7.62 (m, 4H), 8.14 (dd, J=7.9, 1.5 Hz, 4H), 8.23 (d, J=2.4 Hz, 2H).

[0131] .sup.13C NMR (75 MHz, d-DMSO): δ 17.7; 49.4; 117.0; 119.4; 122.7; 123.4; 123.7; 126.5; 133.0; 133.2; 135.9; 140.6; 140.8.

[0132] MS (ESI) m/z : 718 ([M.sup.α]+1).

[0133] Synthesis of the partially oxidized phenothiazine-phenothiazinealkyl dioxide-phenothiazine trimer 3,7-Dibromo-10-ethylphenothiazine 5,5-dioxide (2 g, 4.8 mmol), phenothiazine (2.1 g, 10.5 mmol), Pd.sub.2(dba).sub.3 (0.132 mg, 0.144 mmol) and sodium tert-butoxide (1.06 g, 11 mmol) were added to a solution of tri-tert-butylphosphine [1 M] (0.24 mL) and 45 mL of dioxane under an argon atmosphere. The mixture was stirred at 95° C. for 24 hours. The reaction mixture was cooled and added to water. After an ultrasound treatment, the white precipitate was filtered and washed with methanol. This material was purified by column chromatography in trichloromethane as eluent. After drying, 1.62 g (52%) of a white powder were obtained.

[0134] .sup.1H NMR (500 MHz, DMSO) δ (ppm) 8.01 (d, J=9.2 Hz, 2H), 7.96 (d, J=2.6 Hz, 2H), 7.88 (dd, J=9.1, 2.6 Hz, 2H), 7.15 (dd, J=7.6, 1.5 Hz, 4H), 7.03-6.99 (m, 4H), 6.93 (td, J=7.5, 1.2 Hz, 4H), 6.31 (dd, J=8.2, 1.1 Hz, 4H), 4.53 (q, J=6.9 Hz, 2H), 1.55 (t, J=7.0 Hz, 3H).

[0135] .sup.13C NMR (125 MHz, d-DMSO): δ (ppm) 12.22; 43.14; 116.93; 120.09; 120.68; 123.22; 123.37; 124.18; 127.04; 127.55; 134.7; 135.75; 139.13; 143.34.

[0136] MS (ESI) m/z : 654 ([M.sup.+]+1).

Methyl 2-aminobenzoate

[0137] In a round-bottom flask, 2-(phenylamino)benzoic acid (20 g, 0.146 mol) was dissolved in methanol and stirred in an ice bath for 10 minutes. At 0° C., SOCl.sub.2 (42 mL, 0.584 mol) was cautiously added dropwise and the mixture was stirred under reflux (90° C.) for 12 hours. Thereafter, the reaction mixture was washed with distilled water and the product was extracted with ethyl acetate. The organic phase was dried with MgSO.sub.4 and concentrated on a rotary evaporator. The product was purified by column chromatography with ethyl acetate. The yield was 17.5 g of a partly crystalline substance.

[0138] .sup.1H NMR (300 MHz, CDCl.sub.3) δ (ppm): 7.79-7.75 (m, 1H), 7.21-7.14 (m, 1H), 6.59-6.52 (m, 2H), 5.64 (s, 1H), 3.78 (s, 3H).

[0139] FT-IR (ATR), v (cm.sup.−1): 3481, 3371, 1691, 1615, 1578, 1455, 1435, 1294, 1245, 750.

Methyl 2-(phenylamino)benzoate

[0140] Methyl 2-aminobenzoate (15 g, 0.101 mol), bromobenzene (15.6 g, 0.101 mol), Pd(OAc).sub.2, (0.45 g, 2.02 mmol), K.sub.2O0.sub.3 (27 g, 0.202 mol), BINAP (1.25 g, 2.02 mmol) and 50 mL of toluene were introduced into a two-neck round-bottom flask under argon. The mixture was stirred at 70° C. overnight. After cooling, the inorganic residues were filtered off and the solvent was concentrated by evaporation. The product was purified by column chromatography with hexane/ethyl acetate (10/1) and then dried. The yield was 10.42 g (46%) of a white powder.

[0141] .sup.1H NMR (500 MHz, CDC1.sub.3) δ (ppm) 9.5 (s, 1H), 7.98 (dd, J=8 Hz, J=1.3 Hz, 1H), 7.38-7.24 (m, 6H), 7.10 (t, J=7.3 Hz, 1H), 6.74 (ddd, J=8.1, 6.9, 1.3 Hz, 1H), 3.91 (s, 3H).

[0142] FT-IR (ATR), v (cm.sup.−1): 3319, 2949, 1686, 1591, 1515, 1453, 1258, 747.

2-(2-Anilinophenyl)propan-2-ol

[0143] Methyl 2-(phenylamino)benzoate (5.89 g, 0.026 mol) in 100 mL of pure THF were introduced into a baked-out Schlenk flask under nitrogen and cooled down to 0° C. Also added dropwise were 40 mL (0.12 mol) of a 3M MeMgBr solution in diethyl ether, and the mixture was stirred in a nitrogen atmosphere under reflux for 15 hours. Subsequently, the reaction mixture was mixed with saturated ammonium chloride solution, and the organic phase was removed, washed with aqueous sodium chloride solution, dried over MgSO.sub.4 and concentrated on a rotary evaporator under reduced pressure. The product obtained was utilized for the subsequent synthesis steps, without additional purification.

[0144] FT-IR (ATR), v (cm.sup.−1): 3351, 2976, 1589, 1513, 1496, 1454, 1311, 745.

9,9-Dimethyl-10H-acridine

[0145] 6 mL of concentrated sulfuric acid were added to the oily substance obtained beforehand, and the mixture was subsequently stirred at room temperature under nitrogen for one hour. After dilution with water (200 mL), aqueous ammonia (10% (v/v)) was added up to pH 7. This mixture was poured onto water (50 mL) and extracted with ethyl acetate (150 mL). The cleaned organic phase was further washed with saturated sodium carbonate, sodium chloride solution and water, dried with MgSO.sub.4 and concentrated on a rotary evaporator under reduced pressure. The remaining residue was purified by column chromatography with chloroform/isohexane (1/1). The yield was 3.13 g of yellowish crystals.

[0146] .sup.1H NMR (500 MHz, CDC1.sub.3) δ (ppm) 7.38-7.24 (m, 6H), 7.10 (t, J=7.3 Hz, 1H), 6.74 (ddd, J=8.1, 6.9, 1.3 Hz, 1 H), 1.6 (s, 3H).

[0147] 3,7-Bis(9,9-dimethylacridin-10-yl)-10-ethylphenothiazine 3,7-Dibromo-10-ethylphenothiazine (0.997 g, 2.6 mmol), 9,9-dimethyl-10H-acridine (1.09 g, 5.21 mmol), Pd.sub.2(dba).sub.3 (0.071 g, 0.078 mmol), sodium t-butoxide (0.575 g) were added to a two-neck round-bottom flask. The flask was filled with argon, and a 1M solution of tri-t-butylphosphine in o-xylene (0.12 mL) and 20 mL of dioxane were added. The mixture was subsequently stirred at 95° C. for 24 hours. After cooling, the solvent was removed and the solid substance remaining was carefully dispersed in water in an ultrasound bath and filtered off. The precipitate obtained was further washed with methanol and diethyl ether. The solid product thus obtained was then purified via column chromatography with dichloromethane. The yield was 0.7 g (42%) of yellowish crystals.

[0148] MS (ESI) m/z : 642 ([M.sup.+]+1).

3,7-Bis(9,9-dimethylacridin-10-yl)-10-ethylphenothiazine 5,5-dioxide

[0149] 3,7-Dibromo-10-ethylphenothiazine 5,5-dioxide (1.36 g, 3.25 mmol), 9,9-dimethyl-10H-acridine (1.5 g, 7.17 mmol), Pd.sub.2(dba).sub.3 (0.09 g, 0.097 mmol) and sodium t-butoxide (0.72 g, 7.45 mmol) were added to a two-neck round-bottom flask. The flask was filled with argon, and then a 1M solution of tri-t-butylphosphine in o-xylene (0.16 mL) and 40 mL of dioxane were added. The mixture was then stirred at 95° C. for 12 hours. After cooling, the solvent was removed and the solid substance remaining was carefully dispersed in water in an ultrasound bath and filtered off. The precipitate obtained was then further washed with methanol and acetone. The crude product was dried and gave a yield of 1.44 g (66%) of white crystals.

[0150] .sup.1H NMR (500 MHz, DMF) δ (ppm) 8.25 (d, J=9.0 Hz, 2H), 8.07 (d, J=2.4 Hz, 2H), 7.94 (dd, J=9.0, 2.4 Hz, 2H), 7.58 (d, J=8.5 Hz, 4H), 7.09 7.03 (m, 4H), 6.99 (t, J=7.5 Hz, 4H), 6.30 (d, J=7.2 Hz, 4H), 4.74 (q, J=7.3 Hz, 2H), 0.87 (t, J=7 Hz, 3H).

[0151] II.) Spectroscopic Studies

[0152] As an example of phosphorescence spectra, FIG. 1 shows the phosphorescence spectra of the three substances phenothiazine 5,5-dioxide (PTO, recorded at a temperature of T =293 K), phenothiazine (PT, at T =80 K), and 9,9-dimethyl-9,10-dihydroacridine (DMAC, at T =80 K), recorded on thin polystyrene films, each of which contains 2% of these materials. Compared to solutions in less polar solvents, these phosphorescence spectra are already somewhat red-shifted. The vertical transition energies E.sub.vert(T.sub.1.fwdarw.S.sub.0) as defined herein are respectively 2,25 eV (PTO), 2.21 eV (PT), and 2.21 eV (DMAC). The tangent shown for PT at half the height of the flank at short wavelengths gives an interpolated minimum of the spectrum at 466 nm or 2,86 eV.

[0153] In the case of line shapes similar to those in FIG. 1, the threshold of 2.2 eV for the vertical transition energy E.sub.vert(T.sub.1.fwdarw.S.sub.0) thus corresponds to the onset of phosphorescence on the upper energetic flank at about 2,65 eV, or at a higher energy by 0.45 eV. Other possible definitions of the phosphorescence energy such as the maximum of the wavelength-dependent intensity l(A) or the maximum of the energy-dependent intensity I(E) lead to energy values between E.sub.vert and the edge of onset at high energy (short wavelength).

[0154] The spectra of selected examples from the substance class as defined herein are shown in FIGS. 2 to 5.

[0155] FIG. 2 shows the prompt and delayed fluorescence of a trimer composed of a central phenothiazine 5,5-dioxide (PTO), and two phenothiazine (PT) groups, abbreviated to PT-PTO-PT, embedded in a concentration of 2% in a thin film of polystyrene. Excitation here was effected by means of a short light pulse of duration 120 ps, at a wavelength of 335 nm. The prompt fluorescence was integrated from a delay of 2.25 ns onward over a period of 1.7 ns, and the delayed fluorescence from a delay of 1 μs onward over a period of 80 μs.

[0156] FIG. 3 shows the prompt and delayed fluorescence of a trimer composed of a central phenothiazine 5,5-dioxide, and two dimethylacridine (DMAC) groups, abbreviated to DMAC-PTO-DMAC, embedded in a concentration of 2% in a thin film of polystyrene. Excitation conditions and time windows as for FIG. 2.

[0157] FIG. 4 shows the evolution against time of the fluorescence intensity of the PT-PTO-PT trimer, embedded in a concentration of 2% in a thin film of polystyrene. The different dynamics over time of the prompt and delayed fluorescence demonstrate the involvement of time-delayed thermally activated fluorescence (TADF). Excitation conditions as for FIG. 2.

[0158] FIG. 5 shows the evolution against time of the fluorescence intensity of the DMAC-PTO-DMAC trimer, embedded in a concentration of 2% in a thin film of polystyrene. The different dynamics over time of the prompt and delayed fluorescence demonstrate the involvement of time-delayed thermally activated fluorescence (TADF). Excitation conditions as for FIG. 2.