TW201927772A - Photoelectric material containing 4-thiosulfone aryl dibenzofuran and application thereof - Google Patents

Abstract

The present invention relates to a photovoltaic material containing 4-thiosulfone aryl dibenzofuran and application thereof, a specific arrangement of bipolar materials based on 4-thiosulfone aryl dibenzofuran, having the structure of formula (I) a compound in which Ar1, Ar2 is represented by an aryl group or a heteroaryl group or a fused ring aryl group having 5 to 15 ring atoms, R1, R2 represents an alkyl-substituted or unsubstituted acridinyl group, a phenothiazine group, a phenoxazinyl group, a carbazole, an indolocarbazole, a diphenylamine or other aromatic diphenylamine derivative, hydrogen, halogen, C1-C4 alkyl group, and at least one of R1, R2 being a Alkyl substituted or unsubstituted acridinyl group, a phenothiazine group, a phenoxazinyl group, a carbazole, an indolocarbazole, a diphenylamine or other aromatic diphenylamine derivative. The compound of the invention has a higher glass transition temperature than the common host material CBP, and the compound of the invention significantly improves the thermal stability of the host material, and is more in line with the requirements of the organic light-emitting diode for the host material.

Description

Photoelectric material containing 4-thiofluorenylaryl dibenzofuran and application thereof

The invention relates to a novel bipolar host material, belongs to the technical field of organic light-emitting materials, and particularly relates to a photovoltaic material containing 4-thiofluorenylaryl dibenzofuran and application thereof.

Organic light emitting diodes (OLEDs) are considered to be one of the most promising products of the 21st century due to their characteristics of active light emission, fast response speed, low energy consumption, high brightness, wide viewing angle, and flexibility. At present, OLED devices have achieved mass production and are widely used in electronic products such as mobile phones, tablet computers, car meters, and wearable devices. Electrofluorescence and electrophosphorescence are referred to as first and second generation OLEDs, respectively. OLEDs based on fluorescent materials have the characteristics of high stability, but are limited by the laws of quantum statistics. The ratio of singlet excitons and triplet excitons generated by electrical activation is 1: 3, so fluorescent materials The maximum quantum efficiency in electroluminescence is only 25%. The phosphorescent material has the spin-orbit coupling effect of heavy atoms. The phosphorescent material can comprehensively use singlet excitons and triplet excitons to achieve 100% internal quantum efficiency. Studies have shown that due to the relatively long exciton lifetime of transition metal complexes, the presence of triplet exciton accumulation at high current density can cause triplet-triplet annihilation (TTA), triplet-pole extinction (TPA) , Resulting in phenomena such as efficiency roll-off. To overcome this problem, researchers often dope phosphorescent materials into organic host materials, such as doped in bipolar host materials, to better balance the carrier injection. The host material can provide stable charge carriers and sufficiently high triplet energy, which is an important prerequisite for obtaining high-performance phosphorescent devices. It has also been reported that for some compounds with clearly parallel electron-conducting and hole-conducting groups, there is a certain short-range molecular order. Due to their intermolecular π-π interactions, charges can be transferred quickly. In addition, materials with thermally active delayed fluorescent materials have also been used in the body of phosphorescent devices. Because the thermally active delayed fluorescent materials have a small singlet-triplet energy level difference, triplet excitons can pass through the intersystem Crossover to the singlet state, and then transferred to the guest material through Förster resonance energy transfer (FRET), thereby reducing the triplet exciton concentration in the light emitting layer, and its device performance is also improved. Thermally active delayed fluorescent materials have higher singlet energy levels and higher triplet energy levels, have balanced carrier injection and transport capabilities, and have both electron and hole conduction groups, so they are suitable for phosphorescence. The body of the material. For high-efficiency organic light-emitting diodes, it is important to develop host materials with carrier-balanced transport capabilities.

At present, the host material widely used in phosphorescent devices is CBP (4,4'-bis (9-carbazolyl) biphenyl), but it requires a higher driving voltage and a lower glass transition temperature (Tg) (Tg = 62 ℃), easy to crystallize. In addition, CBP is a P-type material. The hole mobility is much higher than the electron mobility, which is not conducive to carrier injection and transport balance, and has low luminous efficiency.

Aiming at the problems of high driving voltage required by the existing host (CBP) material, easy glass transition temperature, carrier injection and unbalanced transport, etc., the present invention provides a bipolar material. Benzofuran is the central core, and it is connected in a specific arrangement to groups having a hole conduction effect, such as diphenylamine, carbazole, acridine, and other aromatic diphenylamine derivatives.

A bipolar material containing 4-thiofluorenylaryl dibenzofuran, a compound having a structure of formula (I), (I)

Among them, Ar ₁ and Ar ₂ are aryl or heteroaryl or fused ring aryl having 5 to 15 ring atoms, and R ₁ and R ₂ are alkyl substituted or unsubstituted acridinyl, phenothiazine , Phenoxazinyl, carbazole, indencarbazole, diphenylamine, or other aromatic diphenylamine derivatives, hydrogen, halogen, C1-C4 alkyl, and at least one of R ₁ and R ₂ is alkyl substituted or unsubstituted Substituted acridinyl, phenothiazinyl, phenoxazinyl, carbazole, indencarbazole, diphenylamine or other aromatic diphenylamine derivatives, wherein the heteroatoms in the heteroaromatic group are N, O.

Preferably: wherein Ar ₁ and Ar ₂ are aryl or fused ring aryl having 6 to 14 ring atoms, R ₁ and R ₂ are hydrogen, C1-C4 alkyl substituted or unsubstituted acridinyl, phenothiazine Group, phenoxazinyl, carbazole, indencarbazole, diphenylamine or other aromatic diphenylamine derivatives.

Preferably: wherein, Ar ₁ and Ar ₂ are phenylene, naphthylene, biphenylene, and terphenylene, R _{1 is} independently represented by hydrogen, and R ₂ is a C1-C4 alkyl-substituted or unsubstituted acryl Pyridyl, phenothiazinyl, phenoxazinyl, carbazole, indencarbazole, diphenylamine or other aromatic diphenylamine derivatives.

Preferably, wherein Ar ₁ and Ar ₂ are phenylene and naphthylene, R _{1 is} independently represented by hydrogen, and R ₂ is acridinyl, carbazole, or indencarbazole.

Among them, Ar ₁ is a phenylene group and a naphthylene group, Ar ₂ is a phenylene group, R _{1 is} independently represented as hydrogen, and R ₂ is a carbazole or an indencarbazole. Preferably, the compound of formula (I) is a compound of the following structure: .

An organic electroluminescent device includes a cathode, an anode, and an organic layer. The organic layer is one or more of a hole transporting layer, a hole blocking layer, an electron transporting layer, and a light emitting layer. It should be particularly pointed out that the above-mentioned organic layers can be according to requirements, and these organic layers do not need to exist in each layer.

The compound according to the formula (I) is a material of a light emitting layer.

The total thickness of the organic layer of the electronic device of the present invention is 1-1000 nm, preferably 1-500 nm, and more preferably 5-300 nm.

The organic layer may be formed into a thin film by evaporation or spin coating.

As mentioned above, the compounds of formula (I) of the present invention are as follows, but are not limited to the enumerated structures: .

The method for preparing the above bipolar host material includes the following preparation steps: First, dibenzofuran (a) is formed into a lithium salt under the condition of n-butyl lithium, and then 4,6-diiododibenzofuran ( b), and then substituted or unsubstituted aryl thiophenol (c) to obtain a thioether intermediate (d) by Ullmann reaction; oxidation of the halogenated thioether intermediate to obtain a halogenated thiosulfide compound (e); (e) A palladium-catalyzed Suzuki reaction with a substituted or unsubstituted arylboronic acid / borate (f) and the like to obtain the bipolar host material.

Experiments show that the compound of the present invention has a higher glass transition temperature than the commonly used host material CBP, and the present invention significantly improves the thermal stability of the host material. The organic electroluminescent device prepared by using the bipolar host material of the invention has high stability, has better application prospects, and meets the requirements of the organic light emitting diode for the host material.

The present invention is described in further detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

Example 1

(1) The synthetic route of 4,6-diiododibenzofuran (b) is shown below: The specific synthesis steps are as follows: Dibenzofuran (8.41 g, 50 mmol) is weighed into a three-necked flask, protected by nitrogen, added to dry ether (150 mL), and the flask is placed in a -78 ° C low temperature reactor, and slowly dropped Add n-butyllithium (2.2 M, 68 mL, 150 mmol). After the addition is complete, the reaction system is slowly warmed to room temperature and stirring is continued for 10 h. The temperature was lowered to -78 ° C, and a tetrahydrofuran solution (38 g, 150 mmol) of I2 was slowly added dropwise. After the dropwise addition was completed, the mixture was stirred at room temperature for 4 h. After the reaction, 10% NaHSO3 solution (100 mL) was added, and the layers were extracted. The inorganic phase was extracted with dichloromethane (3 * 50 mL). The organic phase was collected, dried over anhydrous MgSO ₄ and the solution was dried to obtain a crude product. Beat and dry with suction filtration to obtain 14 g of white solid. Yield: 67%.

(2) The synthetic route of 4-iodo-6-bis (phenylthio) dibenzo [b, d] furan (d1) is shown below: The specific synthetic steps are: Weigh 4,6-diiododibenzofuran (b) (4.2 g, 10 mmol), thiophenol (0.55 g, 5 mmol), CuI (0.48 g, 2.5 mmol), phenanthrene Porphyrin (0.9 g, 5 mmol) and potassium carbonate (4.8 g, 35 mmol) were placed in a 100 mL three-necked flask and replaced with nitrogen three times. Dry DMSO was added, and the temperature was raised to 130 ° C for 16 hours. After the reaction was completed, 150 mL of water was added and extracted with dichloromethane (3 * 50 mL). The organic layers were combined and dried over anhydrous magnesium sulfate. Sand core funnel was filtered, the solvent was spin-dried, and n-hexane was used as the eluent for silica gel column chromatography to obtain 1.8 g of a white solid. Yield: 44.8%.

(3) The synthetic route of 4-iodo-6- (phenylfluorenyl) dibenzo [b, d] furan (e1) is shown below: The specific synthetic steps are: Weigh 4-iodo-6- (phenylthio) dibenzo [ b , d ] furan ( d1 ) (1 g, 2.49 mmol) in a flask, dissolve dichloromethane, and place the reaction system in In an ice bath, 2.2 equivalents of m-chloroperoxybenzoic acid were slowly added and reacted at room temperature for 24 hours. After the reaction, 50 mL of 5% NaHSO ₃ solution was added, and extracted with dichloromethane (3 * 50 mL). The organic layers were combined, washed with Na ₂ CO ₃ solution, dried over anhydrous magnesium sulfate, and subjected to silica gel column chromatography. 0.7 g of a white solid. Yield: 64.8%.

(4) The synthetic route of 9- [3- (6- (phenylfluorenyl) dibenzo [b, d] furan-4-yl) phenyl] -9H-carbazole (1) is shown below: The specific synthetic steps are: Weigh 4-iodo-6- (phenylfluorenyl) dibenzo [ b , d ] furan ( e1 ) (0.6 g, 1.38 mmol), 3- (9 H -carbazole) -9- -Phenylphenylboronic acid ( f1 ) (0.4 g, 1.38 mmol), tetrakis (triphenylphosphine) palladium (0.08 g, 0.07 mmol), potassium carbonate (0.48 g, 3.45 mmol) in a 50 mL flask, add 10 mL Dioxane, 2 mL of purified water, was replaced by nitrogen extraction, and heated to 100 ° C for 10 h. After the reaction was completed, 20 mL of water was added, and extracted with dichloromethane (3 * 20 mL). Dichloromethane: n-hexane = 2: 1 was used as the eluent. Silica gel column chromatography separated 0.66 g of a white solid. Yield: 86.9%. Product identification information is as follows: ¹ H NMR (400MHz, CDCl ₃ ) δ = 8.45 (d, J = 8.0 Hz, 2 H), 8.08 (s, 1 H), 8.03 (d, J = 8.0 Hz, 2 H), 7.89-7.66 (m, 8 H), 7.53-7.46 (m, 6 H), 7.45-7.36 (m, 4 H) ppm. Ms (ESI: Mz 550) (M + 1)

Example 2

(1) The synthetic route of 4-iodo-6- (naphthalene-2-thio) dibenzo [b, d] furan (d2) is shown below: The specific synthetic steps are: Weigh 4,6-diiododibenzofuran (b) (4.2 g, 10 mmol), 2-naphthylthiophenol (0.8 g, 5 mmol), CuI (0.48 g, 2.5 mmol), Phenanthroline (0.9 g, 5 mmol) and potassium carbonate (4.8 g, 35 mmol) were placed in a 100 mL three-necked flask, and nitrogen was changed three times. Dry DMSO was added, and the temperature was raised to 130 ° C for 16 hours. After the reaction was completed, 150 mL of water was added and extracted with dichloromethane (3 * 50 mL). The organic layers were combined and dried over anhydrous magnesium sulfate. Sand core funnel was filtered, the solvent was spin-dried, and n-hexane was used as the eluent for silica gel column chromatography to obtain 2.1 g of a white solid. Yield: 46.5%.

(2) The synthetic route of 4-iodo-6- (naphthalene-2-fluorenyl) dibenzo [b, d] furan (e2) is shown below: The specific synthetic steps are: Weigh 4-iodo-6- (naphthalene-2-thio) dibenzo [ b , d ] furan ( d2 ) (2 g, 4.42 mmol) in a flask, dissolve dichloromethane, and react The system was placed in an ice bath, and 2.2 equivalents of m-chloroperoxybenzoic acid was slowly added, and reacted at room temperature for 24 hours. After the reaction, 50 mL of 5% NaHSO ₃ solution was added, and extracted with dichloromethane (3 * 50 mL). The organic layers were combined, washed with Na ₂ CO ₃ solution, dried over anhydrous magnesium sulfate, and subjected to silica gel column chromatography. 2 g of white solid. Yield: 93.5%.

(3) Synthesis of 9- [4- (6- (naphthalene-2-fluorenyl) dibenzo [b, d] furan-4-yl) phenyl] -9H-carbazole (2) Show: The specific synthetic steps are: Weigh 4-iodo-6- (naphthalene-2-fluorenyl) dibenzo [b, d] furan (e2) (1.2 g, 2.76 mmol), 4- (9H-carbazole)- 9-yl-phenylboronic acid (f2) (0.8 g, 2.76 mmol), tetrakis (triphenylphosphine) palladium (0.16 g, 0.14 mmol), potassium carbonate (1 g, 6.9 mmol), in a 50 mL flask, add 20 mL of dioxane and 4 mL of purified water were replaced with nitrogen for protection under evacuation, and the temperature was raised to 100 ° C for 10 h. After the reaction was completed, 20 mL of water was added and extracted with dichloromethane (3 * 20 mL). Dichloromethane: n-hexane = 2: 1 was used as the eluent. Silica gel column chromatography gave 1.3 g of a white solid. Yield: 86.1%. Product identification information is as follows: ¹ H NMR (400MHz, CDCl ₃ ) δ = 8.78 (s, 1 H), 8.20 (d, J = 8.0 Hz, 1 H), 8.06 (d, J = 8.0 Hz, 1 H), 7.96-7.92 (m, 7 H), 7.76-7.53 (m, 6 H), 7.46-28 (m, 9 H) ppm. Ms (ESI: Mz 550) (M + 1)

Example 3

(1) 7,7-dimethyl-5- (3- (6-naphthalene-2-fluorenyl) dibenzo [b, d] furan-4-yl) phenyl) -5,7-dihydro The synthetic route of indeno [2,1-b] carbazole (9) is shown below: The specific synthetic steps are: Weigh 4-iodo-6- (phenylfluorenyl) dibenzo [b, d] furan (e2) (1.21 g, 2.5 mmol), f3 (1.21 g, 2.5 mmol), four (three Phenylphosphine) palladium (0.14 g, 0.12 mmol), potassium carbonate (0.86 g, 6.25 mmol), in a 50 mL flask, add 20 mL of dioxane, 4 mL of purified water, and replace it with nitrogen to evacuate and elevate the temperature. Reaction to 100 ° C for 10 h. After the reaction was completed, 20 mL of water was added, and extracted with dichloromethane (3 * 20 mL). Silica gel column chromatography was used to separate 1.32 g of a white solid. Yield: 73.7%. Product identification information is as follows: Ms (ESI: Mz 716) (M + 1)

Example 4 The glass transition temperature test: Under nitrogen, a heating and cooling rate of 20 ^o C / min by differential scanning calorimetry (DSC) test compound 9 glass transition temperature. The glass transition temperature measured T _g of compound 9 98.9 ^o C (FIG. 1). The glass transition temperature of CBP reported in the literature is only 62 ^o C. It can be seen that the compound in the present invention has a higher glass transition temperature than the commonly used host material CBP, and the present invention significantly improves the thermal stability of the host material.

Example 5

The structure of the organic electroluminescent device is ITO / HATCN (5 nm) / TAPC (50 nm) / Compound 9: Ir (ppy) :( 4 wt%, 20 nm) / TmPyPb (50 nm) / LiF (1 nm) / AL (100 nm)

The device preparation method is described as follows: See Figure 2. First, the transparent conductive ITO glass substrate (including 10 and 20) is processed according to the following steps: washed with detergent solution, deionized water, ethanol, acetone, and deionized water before Oxygen plasma treatment for 30 seconds. Then, 5 nm thick HATCN was evaporated as a hole injection layer 30 on ITO. Then, a 50 nm thick TAPC was evaporated as a hole transport layer 40 on the hole injection layer. Then, 20 nm thick compound 9 : Ir (ppy) :( 4 wt%) was evaporated on the hole transport layer as the light emitting layer 50. Then, a 50 nm-thick TmPyPb was evaporated on the light emitting layer as the electron transporting layer 60. Then, 1 nm-thick LiF was evaporated on the electron transport layer as the electron injection layer 70. Finally, 100 nm thick aluminum was evaporated on the electron injection layer as the device cathode 80.

Comparative example

The structure of the electroluminescent device is ITO / HATCN (5 nm) / TAPC (50 nm) / CBP: Ir (ppy) :( 4 wt%, 20 nm) / TmPyPb (50 nm) / LiF (1 nm) The method of / AL (100 nm) is the same as that of Example 4, except that a commercially available compound CBP is used as a host material to produce an electroluminescent organic semiconductor diode device for comparison.

Experiments show that the electroluminescent device prepared using the bipolar host material of the present invention has a voltage of 7.8 V, a brightness of 6849 cd / m ² , a current efficiency of 34.25 cd / A, and a power efficiency of 13.83 at a current density of 20 mA / cm ^2. lm / W, the external quantum efficiency EQE is 10.12%; and the electroluminescent device prepared using a commercially available host CBP at the same current density, voltage is 7.71 V, brightness is 5845 cd / m ² , current efficiency is 29.23 cd / A, power The efficiency is 11.91 lm / W, and the external quantum efficiency EQE is 8.5%. Therefore, using the bipolar host material of the present invention, a current efficiency of 17% and an external quantum efficiency of 19% higher than that of a device prepared by CBP can be obtained, a higher device stability can be obtained, and the organic light emitting diode is more suitable for the host. Material requirements.

Figure 1 shows the DSC curve of compound 9. FIG. 2 is a device structure diagram of the present invention, where 10 represents a glass substrate, 20 represents an anode, 30 represents a hole injection layer, 40 represents a hole transport layer, 50 represents a light emitting layer, 60 represents an electron transport, and 70 Represented by the electron injection layer, 80 represents the cathode.

Claims (12)

A bipolar material containing 4-thiofluorenylaryl dibenzofuran, a compound having the structure of formula (I), (I) wherein Ar ₁ and Ar ₂ are aryl or heteroaryl or fused ring aryl having 5 to 15 ring atoms, and R ₁ and R ₂ are alkyl substituted or unsubstituted acridinyl, Phenothiazinyl, phenoxazinyl, carbazole, indencarbazole, diphenylamine or other aromatic diphenylamine derivatives, hydrogen, halogen, C1-C4 alkyl, and at least one of R ₁ and R ₂ is alkyl Substituted or unsubstituted acridinyl, phenothiazinyl, phenoxazinyl, carbazole, indencarbazole, diphenylamine or other aromatic diphenylamine derivatives, wherein the hetero atom in the heteroaryl group is N, O . The bipolar material according to item 1 of the scope of patent application, wherein Ar ₁ and Ar ₂ are aryl or fused ring aryl having 6 to 14 ring atoms, R ₁ and R ₂ are hydrogen and C1-C4 alkane Group substituted or unsubstituted acridinyl, phenothiazinyl, phenoxazinyl, carbazole, indencarbazole, diphenylamine or other aromatic diphenylamine derivatives. The bipolar material according to item 2 of the scope of the patent application, wherein Ar ₁ and Ar ₂ are a phenylene group, a naphthylene group, a biphenylene group, and a terphenylene group, R _{1 is} independently represented as hydrogen, and R ₂ is C1-C4 alkyl substituted or unsubstituted acridinyl, phenothiazinyl, phenoxazinyl, carbazole, indencarbazole, diphenylamine or other aromatic diphenylamine derivatives. The bipolar material according to item 3 of the scope of patent application, wherein Ar ₁ and Ar ₂ are phenylene and naphthylene, R _{1 is} independently represented as hydrogen, and R ₂ is acridinyl, carbazole, or indene And carbazole. The bipolar material according to item 4 of the scope of patent application, wherein Ar ₁ is a phenylene group, a naphthylene group, Ar ₂ is a phenylene group, R _{1 is} independently represented as hydrogen, and R ₂ is a carbazole or indene And carbazole. As for the bipolar material described in the first patent application scope, the formula (I) is one of the following structures: . According to the bipolar material described in item 6 of the patent application scope, the formula (I) is one of the following structures: . According to the bipolar material described in item 7 of the scope of patent application, the formula (I) has the following structure: . A method for preparing a bipolar material according to any one of claims 1 to 8 of the scope of patent application, which is prepared by the following method: First, dibenzofuran (a) is formed into a lithium salt under the condition of n-butyllithium , And then iodinated to obtain 4,6-diiododibenzofuran (b), and then with substituted or unsubstituted arylthiophenol or heteroarylthiophenol or fused ring arylthiophenol (c) by Ullmann reaction The thioether intermediate (d); the iodine thioether intermediate is oxidized to give the iodothiophosphonium compound (e); finally the thiophosphonium compound (e) and the substituted or unsubstituted arylboronic acid / borate or heteroarylboronic acid / Borate or fused ring arylboronic acid / borate (f) through Suzuki reaction catalyzed by palladium to obtain the bipolar material, the reaction formula is as follows: . An organic electroluminescent device includes a cathode, an anode, and an organic layer. The organic layer is one or more of a hole transport layer, a hole blocking layer, an electron transport layer, and a light emitting layer. The material of the organic layer is such as The bipolar material according to any one of claims 1 to 8 of the patent application scope. According to the organic electroluminescence device described in item 10 of the scope of the patent application, the total thickness of the organic layer is 1-1000 nm, and the organic layer can be formed into a thin film by evaporation or spin coating. Application of a bipolar material according to any one of claims 1 to 8 in an organic electroluminescent device.