Fused polycyclic compound and electroluminescent device thereof

Abstract

The invention provides a fused polycyclic compound and an electroluminescent device thereof, belongs to the field of heterocyclic compounds, and particularly relates to the technical field of organic electroluminescent materials. The vibration relaxation of the rigid structure of the condensed polycyclic compound provided by the invention is weakened, the half-peak width of a luminescence peak can be narrowed, meanwhile, carbonyl and sulfuryl are introduced, spin-orbit coupling can be increased, and the reverse intersystem crossing rate can be increased, so that the efficiency roll-off is reduced.

Description

Technical Field

[0001] The invention belongs to the field of heterocyclic compounds, specifically to the technical field of organic electroluminescent materials, and in particular to a condensed polycyclic compound and an electroluminescent device thereof. Background Art

[0002] An organic electroluminescent device (OLED) is a device made by depositing a layer of organic material between two metal electrodes by spin coating or vacuum evaporation. A classic three-layer organic electroluminescent device includes a hole transport layer, a light-emitting layer, and an electron transport layer. The holes generated by the anode are combined with the electrons generated by the cathode through the electron transport layer to form excitons in the light-emitting layer, and then emit light. Organic electroluminescent devices can be adjusted to emit various required lights by changing the material of the light-emitting layer as needed.

[0003] Generally, organic light-emitting materials have a very wide half-width (FWHM) spectrum (usually 70-100nm) due to their high structural flexibility and strong vibration relaxation. However, this will lead to low spectral color purity. In order to meet practical applications, the industry generally uses optical means such as filters or optical microcavities to obtain high color purity, but it inevitably causes energy loss and increases preparation costs. In order to meet the requirements of BT2020, the development of narrow-band luminescent materials has become a research hotspot in the field of OLEDs.

[0004] Rigid planar luminescent materials have the advantage of narrow half-width, but the efficiency roll-off of OLED devices prepared with them is serious. The so-called "efficiency roll-off" phenomenon means that under macroscopic conditions, the power efficiency and current efficiency of organic electroluminescent devices made of luminescent materials will show a sharp downward trend as the current density increases, and in severe cases, the device will directly break down. The microscopic reason for this phenomenon is that the reverse intersystem crossing rate of this type of material is low, resulting in severe exciton quenching. By increasing the spin-orbit coupling, the reverse intersystem crossing rate can be increased, thereby reducing the efficiency roll-off. Summary of the invention

[0005] In order to solve the problems existing in the background technology, the first object of the present invention is to provide a condensed polycyclic compound, the general structural formula of which is shown as follows (I):

[0006] Among them, X and Y are the same or different, selected from , ; The empty substitution sites on the aromatic ring A, the benzene ring B, the aromatic ring C, the aromatic ring D and the aromatic ring E can be independently substituted by any substituent selected from hydrogen, deuterium, cyano, alkyl, aryl and aromatic amine.

[0007] As a preference of the present invention, the aromatic ring A, the aromatic ring C, the aromatic ring D and the aromatic ring E are all benzene rings.

[0008] As a preferred embodiment of the present invention, the general structural formula (I) is represented by formula (1-1) or formula (1-2):

[0009] As a preferred embodiment of the present invention, the specific structure of formula (1-1) is as follows:

[0010] As a preferred embodiment of the present invention, the specific structure of formula (1-2) is as follows:

[0011] Another object of the present invention is to provide an organic electroluminescent device, comprising a first electrode, a second electrode and an organic material layer arranged therebetween, wherein the organic material layer comprises an electron transport layer, a light-emitting layer and a hole blocking layer, and the preparation material of the light-emitting layer comprises the above-mentioned condensed polycyclic compound.

[0012] As a preferred embodiment of the present invention, the organic light emitting device is applied to a flat panel display device, a flexible display device, a monochrome or white flat panel lighting device, and a monochrome or white flexible lighting device.

[0013] In the present invention, "alkyl" may include straight-chain alkyl, branched-chain alkyl and cycloalkyl, and the alkyl may have 1-12 carbon atoms; cycloalkyl refers to a cyclic saturated hydrocarbon, including monocyclic and polycyclic structures, and the cycloalkyl may have a small ring, a common ring or a large ring with 3-20 carbon atoms; the cycloalkyl may also be divided into a monocyclic, a bicyclic or a polycyclic ring; the cycloalkyl may also be divided into a spirocyclic ring in which two rings share one carbon atom, a condensed ring in which two rings share two carbon atoms, and a bridged ring in which two rings share more than two carbon atoms, such as a five-membered cycloalkyl, i.e., a cyclopentyl group, a six-membered cycloalkyl, i.e., a cyclohexyl group, a 10-membered polycyclic alkyl group such as an adamantyl group, etc. In addition, the cycloalkyl may be substituted or unsubstituted.

[0014] In the present invention, aryl refers to an optional functional group or substituent derived from an aromatic hydrocarbon ring that does not contain heteroatoms such as B, N, O, S, Se, Si or P. The aryl group may be a monocyclic aryl group or a polycyclic aryl group. In other words, the aryl group may be a monocyclic aryl group, a condensed ring aryl group, two or more monocyclic aryl groups conjugated by a carbon-carbon bond, a monocyclic aryl group or a condensed ring aryl group conjugated by a carbon-carbon bond, or two or more condensed ring aryl groups conjugated by a carbon-carbon bond, such as phenyl, naphthyl, fluorenyl, anthracenyl, phenanthrenyl, biphenyl, terphenyl, quaterphenyl, pentphenyl, hexaphenyl, benzo[9,10]phenanthrenyl, pyrenyl, peryl, benzofluoranthenyl, 9,9-dimethylfluorenyl, 9,9-diphenylfluorenyl, spirobifluorenyl, indenyl, etc. The "aryl" of the present invention may contain 6-30 carbon atoms.

[0015] In the present application, "amino" refers to an amine derivative having the structural characteristics of the formula -N(X), wherein each "X" is independently H, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocyclyl, etc. Non-limiting types of amines include -NH2, -N(alkyl)2, -NH(alkyl), -N(cycloalkyl)2, -NH(cycloalkyl), -N(heterocyclyl), -NH(heterocyclyl), -N(aryl), -NH(aryl), -N(alkyl)(aryl), -N(alkyl)(heterocyclyl), -N(cycloalkyl)(heterocyclyl), -N(aryl)(heteroaryl), -N(alkyl)(heteroaryl), etc.

[0016] The beneficial effects of the present invention are as follows: The rigid structure vibration relaxation of the condensed polycyclic compound provided by the present invention is weakened, which can narrow the half-width of the luminescence peak. At the same time, the introduction of carbonyl and sulfone groups can increase spin-orbit coupling and increase the reverse intersystem crossing rate, thereby reducing efficiency roll-off. DETAILED DESCRIPTION

[0017] The technical scheme of the present invention will be clearly and completely described below in conjunction with the examples. Obviously, the described examples are only part of the embodiments of the present invention, not all of them. Other compounds of the present invention can be obtained by referring to the preparation methods of the following examples, so they are not listed one by one here. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] In the present invention, the preparation methods are conventional methods unless otherwise specified, and the raw materials used are all available from public commercial channels unless otherwise specified.

[0019] Synthesis Examples Example 1: Preparation of Compound 1

[0020] Synthesis of intermediate 1-1: Under nitrogen (N2) atmosphere, raw material 1-1 (9.06 g, 45.54 mmol), raw material 1-2 (6.83 g, 20.7 mmol), cuprous iodide (CuI) (1.73 g, 9.11 mmol), 2,2,6,6-tetramethylheptane-3,5-dione (3.57 g, 18.21 mmol) and cesium carbonate (Cs2CO3) (12.59 g, 91.07 mmol) were dispersed in DMF (70 mL) and refluxed for 8 hours. After cooling to room temperature, the filter cake was obtained by filtration under reduced pressure. The crude product was purified by silica gel column chromatography (dichloromethane (DCM) as eluent) and recrystallized from DCM and methanol to obtain intermediate 1-1 (7.63 g, 78%); Synthesis of intermediate 1-2: Intermediate 1-1 (3.67 g, 7.77 mmol), sulfur (1.28 ml, 40 mmol) and iodine (0.15 g, 0.56 mmol) were dissolved in 1,2-dichlorobenzene (10 ml). The mixture was refluxed at 180 ° C for 20 hours under nitrogen, cooled to room temperature, and filtered under reduced pressure to obtain a filter cake. The crude product was purified by silica gel column chromatography (eluent: petroleum ether / dichloromethane, 6:1) to obtain intermediate 1-2 (2.19 g, 53%); Synthesis of compound 1: m-Chloroperbenzoic acid (mCBPA) (2.32 g, 13.42 mmol) was slowly added to a DCM (10 mL) solution of intermediate 1-2 (0.71 g, 1.34 mmol) and stirred at room temperature overnight. The reaction was quenched with saturated sodium hydroxide solution, the aqueous phase was washed three times with DCM, the organic phases were combined, the organic layer solvent was removed by rotary evaporation, and the crude product was purified by silica gel column chromatography (ethyl acetate / DCM, 2:1), and recrystallized with DCM and methanol to obtain compound 1 (0.73 g, 83%), MS: 660.11.

[0021] Example 2: Preparation of Compound 4

[0022] Synthesis of intermediate 4-1: The synthesis method is the same as that of intermediate 1-1, except that raw material 4-1 is used to replace raw material 1-2; Synthesis of intermediate 4-2: The synthesis method is the same as that of intermediate 1-2, except that intermediate 4-1 is used to replace intermediate 1-1; Synthesis of compound 4: The synthesis method is the same as that of compound 1, except that intermediate 4-2 is used to replace intermediate 1-2, MS: 827.18.

[0023] Example 3: Preparation of Compound 10

[0024] Synthesis of intermediate 10-1: The raw material 1-1 (4.98 g, 25 mmol), the raw material 10-1 (3.80 g, 10 mmol), potassium carbonate (K2CO3) (4.6 g, 33 mmol) were dissolved in anhydrous toluene (20 mL), and a mixture of tris(dibenzylideneacetone)dipalladium [Pd2(dba)3] (0.14 g, 0.15 mmol) and dichloropalladium (DFFP) (0.17 g, 0.3 mmol) was refluxed under a nitrogen (N2) atmosphere for about 48 hours. After cooling to room temperature, the obtained mixture was diluted with chloroform and filtered through a celite pad. The collected organic layer was extracted with water and dried over anhydrous Na2SO4. After filtration and evaporation, the crude product was separated by silica gel column chromatography (eluent: hexane / ethyl acetate = 4:1) to obtain intermediate 10-1 (5.55 g, 49%); Synthesis of Intermediate 10-2: A suspension of Intermediate 10-1 (1.36 g, 2.2 mmol) in ethanol (20 mL), tetrahydrofuran (THF) (20 mL) and an aqueous solution (20 mL) of sodium hydroxide (NaOH) (1.8 g, 44 mmol) was refluxed for about 24 hours. After cooling to room temperature, the resulting mixture was evaporated under reduced pressure to remove THF, and hydrochloric acid (HCl) (6 mol / L) was added thereto until the pH reached 1 to 2 for acidification. The precipitate was filtered and washed with water and hexane and dried under vacuum at about 60°C for more than about 3 hours to obtain a powder, which was dispersed in CH2Cl2 (30 mL), and oxalyl chloride (0.7 mL, 8.0 mmol) and four drops of N,N-dimethylformamide (DMF) were added to the reaction mixture in sequence. After refluxing for about 3 hours, the reaction mixture was cooled to room temperature. Under a positive N2 flow, aluminum chloride (AlCl3) (5.3 g, 40 mmol) was slowly added. After refluxing for about 24 hours, the reaction mixture was cooled to room temperature and quenched with a large amount of water. The precipitate was filtered and washed with water, methanol and hexane. After vacuum drying at about 60°C for about 3 hours, the precipitate was sublimed by vacuum temperature gradient (350°C, 1.0×10 -3 Pa) The crude product was separated to give intermediate 10-2 (0.47 g, 41%); Synthesis of compound 10: The synthesis method is the same as that of compound 1, except that intermediate 10-2 is used to replace intermediate 1-2, MS: 588.19.

[0025] Example 4: Preparation of Compound 16

[0026] Synthesis of intermediate 16-1: The synthesis method is the same as that of intermediate 10-1, except that raw material 16-1 is used to replace raw material 1-1; Synthesis of intermediate 16-2: The synthesis method is the same as that of intermediate 10-2, except that intermediate 16-1 is used to replace intermediate 10-1; Synthesis of compound 16: The synthesis method is the same as that of compound 1, except that intermediate 1-2 is replaced by intermediate 16-2, MS: 892.29.

[0027] Device Embodiment The application effects of the compounds of the present invention in organic electroluminescent devices are described in detail below through device examples and comparative examples to verify the technical progress and beneficial effects of the compounds of the present invention in this field.

[0028] All layers are formed by evaporation deposition in a vacuum atmosphere. The structure of the device from bottom to top is: First electrode: 50 nm indium tin oxide (ITO); Hole injection layer: 10 nm of dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10,11-hexa (HAT-CN); First hole transport layer: 40 nm of 1,1-bis[(di-4-methylphenylamino)phenyl]cyclohexane (TAPC); Second hole transport layer: 10 nm 9-phenyl-9H-3,9'-bicarbazole (CCP); Light-emitting layer: 20 nm thick, of which the dopant accounts for 3%, and the main compound is (9-phenyl-9H-carbazole-3,6-diyl)bis(diphenylphosphine oxide) (PPCz); First electron transport layer: 10 nm of dibenzo[b,d]furan-2,8-diylbis(diphenylphosphine oxide) (PPF); Second electron transport layer: 50 nm of 4,6-bis(3,5-di(pyridin-3-yl)phenyl)-2-methylpyrimidine (B3PyMPM); Electron injection layer: 1 nm 8-hydroxyquinoline lithium (Liq); Second electrode: 100 nm of Al.

[0029] The compounds selected in the device examples and comparative examples are used as dopants for the light-emitting layer, and their structures and the structures of the guest compounds used in the devices are shown below: .

[0030] The evaluation results are shown in Table 1 below. In the device evaluation, EQE was measured and shown. 100cdm-2 (%), EQE max (%), maximum emission wavelength λ max (nm), roll-off ratio of external quantum efficiency (EQE) (%) = (EQE max -EQE 100cdm -2 ) / EQE max .

[0031] Table 1

[0032] As can be seen from Table 1, when the compounds in the present invention are used as dopants, compared with the comparative compounds, the efficiency roll-off can be greatly reduced while maintaining blue light emission. The reason is that the compounds in the present invention introduce carbonyl and sulfone groups, which can increase spin-orbit coupling and increase the reverse intersystem crossing rate, thereby reducing the efficiency roll-off.

Claims

1. A condensed polycyclic compound, characterized in that: The general structural formula is shown below (I): ; Among them, X and Y are the same or different, selected from , ; The empty substitution sites on the aromatic ring A, the benzene ring B, the aromatic ring C, the aromatic ring D and the aromatic ring E can be independently substituted by any substituent selected from hydrogen, deuterium, alkyl, cyano, amine and aryl.

2. The fused polycyclic compound according to claim 1, characterized in that: The aromatic ring A, aromatic ring C, aromatic ring D and aromatic ring E are all benzene rings.

3. The fused polycyclic compound according to claim 1, characterized in that: The general structural formula (I) is represented by formula (1-1) or formula (1-2): .

4. The fused polycyclic compound according to claim 3, characterized in that: The specific structure of formula (1-1) is as follows: 。 5. The fused polycyclic compound according to claim 3, characterized in that: The specific structure of formula (1-2) is as follows: 。 6. An organic electroluminescent device, characterized in that: The invention comprises a first electrode, a second electrode and an organic material layer arranged therebetween, wherein the organic material layer comprises an electron transport layer, a light-emitting layer and a hole blocking layer, and the preparation material of the light-emitting layer comprises the condensed polycyclic compound according to any one of claims 1 to 5.

7. The organic electroluminescent device according to claim 6, characterized in that: The organic light emitting device is applied to a flat panel display device, a flexible display device, a monochrome or white flat panel lighting device, and a monochrome or white flexible lighting device.

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