An organic electroluminescent element

Abstract

The present invention provides an organic electroluminescent device. The organic electroluminescent device includes a hole injection layer, a hole transport layer, a light-emitting layer, and an electron transport layer stacked in sequence. The host of the light-emitting layer includes compound A or compound B, and the electron transport layer includes compound C: Compound C in the electron transport layer of the organic electroluminescent device has the same fragment as compound A and compound B in the host of the light-emitting layer, so the interfacial effect between the film layers is weakened, which is beneficial to the rapid transport of electrons into the light-emitting layer; Since the host material of the light-emitting layer has bipolar characteristics, the transport capabilities of holes and electrons are further balanced. Therefore, due to the synergistic effects of the above-mentioned substances, the efficiency of the organic electroluminescent device is significantly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electroluminescence, and more particularly to an organic electroluminescent element. Background Art

[0002] Due to its characteristics such as being thin, light, wide viewing angle, high contrast, low power consumption, high response speed, full-color display, and flexibility, organic electroluminescent elements have currently been applied in fields such as smartphones, tablets, and vehicles, and are expanding towards large-size application fields such as televisions.

[0003] An organic electroluminescent element generally includes multiple film layers such as a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer. Holes and electrons are respectively injected from the anode and the cathode, enter the light-emitting layer through the transport layers, and recombine with each other to emit light. The efficiency of the element depends on the recombination probability of holes and electrons. Therefore, controlling the balance of the two carriers is the key. The main means of control are: improving the injection and transportability of holes and electrons, thereby increasing the probability of recombination of holes and electrons; improving the blocking property of holes and electrons, thereby confining the generated excitons in the light-emitting layer to obtain high luminous efficiency; or combining fragments with electron activity and fragments with hole activity to form a bipolar host material, so that electrons and holes can be transported simultaneously, balance the two, reduce exciton quenching, and thus improve the luminous efficiency.

[0004] The molecular structure of the bipolar host material is usually relatively complex, and many factors need to be considered. Simply combining fragments with electron activity and fragments with hole activity does not necessarily result in a good bipolar material. The balance of electron and hole transport capabilities and the stability of the material also need to be considered. Moreover, the material selection on both sides also needs to match it in order to achieve the purpose of optimizing the device performance. Summary of the Invention

[0005] The main object of the present invention is to provide an organic electroluminescent element to solve the problem of low luminous efficiency of the electroluminescent element in the prior art due to the difficulty in balancing holes and electrons.

[0006] To achieve the above object, according to one aspect of the present invention, an organic electroluminescent element is provided. The organic electroluminescent element includes a hole injection layer, a hole transport layer, a light-emitting layer, and an electron transport layer stacked in sequence. The host of the light-emitting layer includes compound A or compound B.

[0007]

[0008] The electron transport layer includes compound C:

[0009]

[0010] Furthermore, the above-mentioned hole injection layer includes any one or more arylamine compounds and any one or more [n]cumulene derivatives doped therein.

[0011] The arylamine compound has the general formula I: wherein, Ar1 to Ar4 each independently represent a substituted or unsubstituted C6-C 30 aryl group, a substituted or unsubstituted C5-C 30 heteroaryl group, and the substituents on both Ar1 and Ar2, and both Ar3 and Ar4 can be combined with each other into a ring via a single bond, a substituted or unsubstituted methylene group, an oxygen atom or a sulfur atom, and n is any integer from 0 to 4;

[0012] The [n]cumulene derivative has the general formula II: wherein, Ar6 is a C6-C 18 aryl group substituted with an electron-withdrawing group, and preferably the electron-withdrawing group is fluorine or cyano.

[0013] Furthermore, in the above general formula I, Ar1 to Ar4 each independently are selected from any one of a substituted or unsubstituted phenyl group, a biphenyl group, a naphthyl group, a fluorenyl group, a phenanthryl group or a carbazolyl group.

[0014] Furthermore, in the above general formula II, Ar6 is selected from a phenyl group or a biphenyl group substituted with at least one cyano group or F atom.

[0015] Furthermore, in the above arylamine compound and [n]cumulene derivative, the doping mass ratio of the [n]cumulene derivative is 2% to 20%.

[0016] Furthermore, the above-mentioned hole transport layer includes a first hole transport layer and a second hole transport layer stacked in sequence away from the hole injection layer, and the first hole transport layer includes any one or more arylamine compounds.

[0017] Furthermore, the above-mentioned second hole transport layer includes any one or more triarylamine compounds represented by the general formula III:

[0018]

[0019] wherein, Ar7, Ar8 and Ar9 each independently represent a substituted or unsubstituted C6-C 30 aryl group, a substituted or unsubstituted C5-C 30 any one of heteroaryl groups.

[0020] Furthermore, in the above general formula III, Ar7, Ar8 and Ar9 each independently are selected from any one of a biphenyl group, a fluorenyl group, a dibenzofuranyl group, a phenyl-substituted naphthyl group, a phenyl-substituted dibenzofuranyl group or a phenyl-substituted carbazolyl group.

[0021] Furthermore, the host of the above-mentioned light-emitting layer is any one or more phosphorescent red dyes represented by General Formula IV:

[0022]

[0023] Among them, R1, R2, R3, and R4 are each independently selected from substituted or unsubstituted C1-C 10 alkyl, substituted or unsubstituted C6-C 30 aryl, or substituted or unsubstituted C5-C 30 heteroaryl; m and n are each independently any integer from 0 to 4.

[0024] Furthermore, in the above General Formula IV, R1, R2, R3, and R4 are each independently selected from any one of methyl, ethyl, isopropyl, isobutyl, or 3-methylpentyl. m is preferably 1 or 2, and n is preferably 1 or 2.

[0025] Applying the technical solution of the present invention, the compound C in the electron transport layer of the organic electroluminescent device has the same fragment as the compound A and the compound B in the host of the light-emitting layer. Therefore, the interfacial effect between the film layers is weakened, which is beneficial to the rapid transmission of electrons into the light-emitting layer. In addition, since the host material of the light-emitting layer has bipolar characteristics, the transport capabilities of holes and electrons are further balanced. Therefore, due to the mutual synergistic effects of the above-mentioned substances, the efficiency of the organic electroluminescent device is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0027] Figure 1 shows a schematic structural diagram of an OLED device provided according to an embodiment of the present invention;

[0028] The above-mentioned drawings include the following reference numerals:

[0029] 1. Anode layer; 2. Hole injection layer; 3. First hole transport layer; 4. Second hole transport layer; 5. Light-emitting layer; 6. Electron transport layer; 7. Electron injection layer; 8. Cathode layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0031] As analyzed in the background art of the present application, although in theory, a bipolar host material can be formed by combining an electronically active fragment and a hole-active fragment in the prior art, so that electrons and holes can be transported simultaneously to balance the two and reduce exciton quenching, thereby improving the luminescence efficiency. However, in practice, due to the influence of the application environment and the like, not any bipolar host material with the above characteristics can achieve the effect of improving the luminescence efficiency. Based on this, in order to improve the luminescence efficiency of the electroluminescent device, the present application provides an organic electroluminescent device, which includes a hole injection layer, a hole transport layer, a light-emitting layer, and an electron transport layer stacked in sequence. The host of the light-emitting layer includes compound A or compound B.

[0032]

[0033] The electron transport layer includes compound C:

[0034]

[0035] Compound C in the electron transport layer of the organic electroluminescent device of the present application has the same fragment as compound A and compound B in the host of the light-emitting layer, so the interfacial effect between the film layers is weakened, which is beneficial to the rapid transport of electrons into the light-emitting layer; in addition, since the host material of the light-emitting layer has bipolar characteristics, the transport capabilities of holes and electrons are further balanced. Therefore, due to the mutual synergistic effects of the above substances, the efficiency of the organic electroluminescent device is significantly improved.

[0036] In an embodiment of the present application, in order to reduce the interfacial effect between the hole injection layer and the hole transport layer, it is preferred that the hole injection layer includes any one or more arylamine compounds and any one or more annulene derivatives doped therein.

[0037] The arylamine compound has the general formula I: Wherein, Ar1 to Ar4 each independently represent a substituted or unsubstituted C6-C 30 aryl group, a substituted or unsubstituted C5-C 30 heteroaryl group. The substituents on Ar1 and Ar2, and Ar3 and Ar4 can be combined with each other into a ring via a single bond, a substituted or unsubstituted methylene group, an oxygen atom or a sulfur atom. n is any integer from 0 to 4;

[0038] The annulene derivative has the general formula II: Wherein, Ar6 is a C6-C 18 aryl group substituted with an electron-withdrawing group, and preferably the electron-withdrawing group is fluorine or cyano.

[0039] Using the above arylamine compound as the host of the hole injection layer ensures a low interface effect between the hole injection layer and the hole transport layer. At the same time, an axylene derivative is doped to improve the injection and transport ability of holes to the light-emitting layer by using its electron-withdrawing ability, and the recombination probability of holes and electrons is increased.

[0040] In a preferred embodiment, in the above general formula I, Ar1 to Ar4 are each independently selected from any one of substituted or unsubstituted phenyl, biphenyl, naphthyl, fluorenyl, phenyl or carbazolyl. Further, it is preferred that the above arylamine compound is selected from any one or more of the following compounds:

[0041]

[0042] Preferably, in the above general formula II, Ar6 is selected from phenyl or biphenyl substituted with at least one cyano group or F atom. Further, the above axylene derivative can be selected from any one or more of the following compounds:

[0043]

[0044] In order to achieve a balance between the interface effect and the electron transport ability to obtain a more ideal luminous efficiency, it is preferred that in the above arylamine compound and the axylene derivative, the doping mass ratio of the axylene derivative is 2% - 20%, and further preferably the doping mass ratio of the axylene derivative is 2% - 8%.

[0045] In an embodiment of the present application, the above hole transport layer includes a first hole transport layer and a second hole transport layer stacked in sequence away from the hole injection layer, and the first hole transport layer includes an arylamine compound. Since both the above first hole transport layer and the hole injection layer have an arylamine compound, the interface effect between them is weak. In order to further reduce the interface effect, it is preferred that the arylamine compounds of the two are the same.

[0046] In an embodiment, the above second hole transport layer includes any one or more triarylamine compounds represented by the general formula III:

[0047]

[0048] Among them, Ar7, Ar8 and Ar9 each independently represent any one of substituted or unsubstituted C6-C 30 aryl, substituted or unsubstituted C5-C 30 heteroaryl. This triarylamine compound enables the second hole transport layer to assist in the further transport of holes on the one hand, and on the other hand, can confine electrons in the light-emitting layer to improve the luminous efficiency.

[0049] Further, preferably in the above general formula III, Ar7, Ar8 and Ar9 are each independently selected from any one of biphenyl, fluorene, dibenzofuran, phenyl-substituted naphthyl, phenyl-substituted dibenzofuran or phenyl-substituted carbazolyl. Preferably, any one or more of the following compounds can be selected as the above triarylamine compound:

[0050]

[0051]

[0052] In order to further improve the luminescence efficiency and stability, preferably, the guest of the above luminescent layer is any one or more phosphorescent red dyes represented by the general formula IV:

[0053]

[0054] Among them, R1, R2, R3, and R4 are each independently selected from substituted or unsubstituted C1-C 10 alkyl, substituted or unsubstituted C6-C 30 aryl, or substituted or unsubstituted C5-C 30 heteroaryl; m and n are each independently any integer from 0 to 4. The phosphorescent red dye having the above structure can cooperate with the host material in the luminescent layer to achieve a better electron and hole recombination effect.

[0055] Preferably, in the above general formula IV, R1, R2, R3, and R4 are each independently selected from any one of methyl, ethyl, isopropyl, isobutyl or 3-methylpentyl, m is preferably 1 or 2, and n is preferably 1 or 2. Further, preferably, the above phosphorescent red dye is selected from any one or more of the following compounds:

[0056]

[0057] Hereinafter, the beneficial effects of the present application will be further described in conjunction with examples and comparative examples.

[0058] Synthesis Example

[0059] 1.1 Synthesis of Intermediate M1

[0060]

[0061] 2,4-dichloroquinoline (29.7 g, 150 mmol), 3-phenylcarbazole (36.9 g, 157.5 mmol), and toluene (500 mL) were added to a 1 L four-necked flask. Stirring was started and nitrogen was passed through to remove oxygen for 15 minutes. After heating to 50 °C until the solid was completely dissolved, bis(dibenzylideneacetone)palladium(0) (2.05 g, 2.25 mmol) and 1,1'-bis(diphenylphosphino)ferrocene (4.98 g, 9 mmol) were added to the four-necked flask. After reacting for 15 minutes, sodium tert-butoxide (21.6 g, 225 mmol) was further added to the four-necked flask, and then the mixture was heated to 110 °C and refluxed for 5 hours. After the reaction was complete, it was cooled to room temperature and filtered through a silica gel pad. The solvent in the obtained filtrate was removed by vacuum evaporation to obtain a crude product containing intermediate M1. The crude product was recrystallized with a mixed solvent of tetrahydrofuran-ethanol to obtain 48 g of intermediate M1. This intermediate M1 was a pale white solid powder with a yield of 79%. The purity was 98.5%.

[0062] 1.2 Synthesis of Compound A

[0063]

[0064] Intermediate M1 (20 g, 49.4 mmol), bis(pinacolato)diboron (18.8 g, 74.1 mmol), potassium acetate (9.8 g, 99 mmol), and 1,4-dioxane (200 mL) were added to a 500 mL four-necked flask. Stirring was started and nitrogen was passed through to remove oxygen for 15 minutes. After heating to 50 °C and maintaining the temperature for 15 minutes, palladium(II) acetate (350 mg, 1.49 mmol) and tricyclohexylphosphine tetrafluoroborate (1.1 g, 3 mmol) were added to the four-necked flask. Then the mixture was heated to 100 °C and refluxed for 4 hours. After the reaction was complete, it was filtered through a silica gel pad while it was still hot. The solvent in the obtained filtrate was removed by vacuum evaporation to obtain a crude product containing intermediate M2. The crude product was recrystallized with ethanol to obtain 16.13 g of intermediate M2. This intermediate M2 was a pale yellow solid powder with a yield of 65%. The purity was 95.4%.

[0065] Intermediate M2 (4.96 g, 10 mmol), 2-chloro-4,6-diphenyl-1,3,5-triazine (2.94 g, 11 mmol), ethylene glycol dimethyl ether (50 mL), and aqueous potassium carbonate solution (1 M, 20 mL, 20 mmol) were added to a 250 mL four-necked flask. Stirring was started and nitrogen was passed through to remove oxygen for 15 minutes. After heating to 50 °C and reacting for 15 minutes, tetrakis(triphenylphosphine)palladium (350 mg, 1.49 mmol) was added to the four-necked flask, and the mixture was heated to 85 °C and refluxed for 4 hours. After the reaction was complete, the mixture was cooled to room temperature and filtered to obtain the crude product containing Compound A. The crude product was subjected to Soxhlet extraction with tetrahydrofuran and then filtered. The obtained filter cake was washed with a mixed solvent of tetrahydrofuran-ethanol (1:4) to obtain 3.4 g of Compound A. This Compound A was an orange solid powder with a yield of 56.5% and a purity of 97.5%. The Compound A was further purified by vacuum sublimation twice to a purity of 99.97%.

[0066] The structural characterization results of Compound A are as follows:

[0067] 1 H NMR (400 MHz, CDC13) δ 9.16 (d, J = 8.2 Hz, 1H), 8.79 (d, J = 8.1 Hz, 5H), 8.36 (s, 2H), 8.21 (dd, J = 16.2, 8.2 Hz, 3H), 7.99 - 7.84 (m, 1H), 7.76 (d, J = 7.4 Hz, 4H), 7.70 - 7.45 (m, 9H), 7.40 (dd, J = 13.8, 7.0 Hz, 2H).

[0068] 1.3 Synthesis of Compound B

[0069]

[0070] Intermediate M1 (4.04 g, 10 mmol), 2,3-dimethylquinoxaline-6-boronic acid pinacol ester (3.12 g, 11 mmol), ethylene glycol dimethyl ether (50 mL), and aqueous potassium carbonate solution (1 M, 20 mL, 20 mmol) were added to a 250 mL four-necked flask. Stirring was started and nitrogen was passed through to remove oxygen for 15 minutes. After heating to 50 °C and reacting for 15 minutes, tetrakis(triphenylphosphine)palladium (350 mg, 1.49 mmol) was added to the four-necked flask, and the mixture was heated to 85 °C and refluxed for 4 hours. After the reaction was complete, the mixture was filtered while hot through silica gel. The filtrate was concentrated under vacuum to remove the solvent, and the resulting crude product containing Compound B was obtained. The crude product was recrystallized from ethanol to obtain 4.52 g of Compound B. Compound B was a pale yellow solid powder with a yield of 86% and a purity of 99.3%. Compound B was further purified by vacuum sublimation twice to a purity of 99.98%.

[0071] The structural characterization results of Compound B are as follows:

[0072] 1 1H NMR (400 MHz, CDCl3) δ 8.32 (dd, J = 22.8, 4.7 Hz, 3H), 8.25 - 8.08 (m, 4H), 8.01 (d, J = 8.3 Hz, 1H), 7.97 - 7.88 (m, 2H), 7.88 - 7.80 (m, 1H), 7.74 (d, J = 8.1 Hz, 3H), 7.57 (t, J = 7.2 Hz, 1H), 7.50 (dd, J = 14.7, 7.2 Hz, 3H), 7.37 (q, J = 7.2 Hz, 2H), 2.81 (d, J = 4.2 Hz, 6H).

[0073] Synthesis of Compound C

[0074]

[0075] In a 500 mL three-necked flask, 4-bromo-o-phenylenediamine (20 g, 0.106 mol), 2,3-butanedione (9.66 g, 0.112 mol) and toluene (200 mL) were added, and the mixture was heated under reflux for 3 hours. After the reaction was completed, it was cooled to room temperature, filtered through silica gel, and the solvent in the filtrate was removed by vacuum evaporation to obtain a crude product. The crude product was dissolved in n-hexane, decolorized and recrystallized to obtain 18.0 g of intermediate M3. This intermediate M3 was a pale white solid powder with a yield of 71% and a purity of 99.95%.

[0076] In a three-necked flask, intermediate M3 (10 g, 0.042 mol), 2-[3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (18.36 g, 0.042 mol), potassium carbonate (11.65 g, 0.084 mol), tetrakis(triphenylphosphine)palladium (0.49 g), toluene (150 mL), ethanol (45 mL) and water (30 mL) were added, and the mixture was heated under reflux for 8 hours under nitrogen protection. After the reaction was completed, it was cooled to room temperature, extracted with toluene and water, and the organic layer was filtered through silica gel. The solvent in the filtrate was removed by vacuum evaporation to obtain a crude product. The crude product was dissolved in toluene, decolorized and recrystallized to obtain 13.3 g of Compound C. Compound C was a white solid powder with a yield of 68% and a purity of 99.93%. Compound C was purified by vacuum sublimation twice to a purity of 99.96%.

[0077] The structural characterization results of Compound C are as follows:

[0078] 1H NMR (400 MHz, CDCl3) δ 9.13 (s, 1H), 8.83 - 8.79 (m, 5H), 8.36 (d, J = 1.6 Hz, 1H), 8.14 - 8.07 (m, 2H), 7.97 (d, J = 8 Hz, 1H), 7.71 (t, J = 7.8 Hz, 1H), 7.63 - 7.57 (m, 6H), 2.79 (d, J = 2.8 Hz, 6H).

[0079] 2. Performance Characterization

[0080] Characterize the physical and chemical properties of Compound A, Compound B, and Compound C. Use a Shimadzu UV-2600 ultraviolet spectrophotometer to measure the absorption wavelength of the material. The solvent is THF, and the material concentration is about 10 ppm. Measure E g = 1240 / UV onset ; Then use a Vertex.C.EIS electrochemical workstation. The working electrode used is a glassy carbon electrode, the reference electrode is a saturated calomel electrode - saturated potassium chloride solution, the counter electrode is a platinum wire electrode, the solvent is 50% dichloromethane + 50% acetonitrile (the material concentration is about 5×10 -4 mol / L), the electrolyte is 0.1 M tetrabutylammonium hexafluorophosphate, and the standard substance is ferrocene. After purging with nitrogen for 10 minutes at room temperature, start the measurement. The scanning condition is rate = 0.1 V / s, and measure the redox potential of the material. Finally, convert it to the LUMO and HOMO energy levels. The characterization results are shown in Table 1.

[0081] Table 1

[0082]

[0083] 3. Preparation of Organic Electroluminescent Devices

[0084] The following uses specific examples and comparative examples to detail the actual effects of the organic electroluminescent devices prepared with the material combinations adopted in the present invention.

[0085] Device Example 1

[0086] Refer to Figure 1 the shown structure and use a Sunic sp1710 evaporation machine to manufacture an OLED device. The specific steps are as follows: Ultrasonically wash a glass substrate (Corning glass 40 mm * 40 mm * 0.7 mm) coated with 135 nm of ITO (indium tin oxide, as the anode layer 1) with isopropyl alcohol and pure water for 5 minutes respectively, then clean it with ultraviolet ozone, and then transfer the glass substrate to a vacuum deposition chamber; Co-dope Compound 1-1 and Compound 2-2 (the doping mass ratio of Compound 2-2 is 4%) on the transparent ITO electrode in a vacuum (about 10 -7Thermal deposition is carried out at 20 Torr to form a hole injection layer 2 with a thickness of 20 nm; then, 60 nm of compound 1-1 is vacuum deposited on the hole injection layer as the first hole transport layer 3; then, 10 nm of compound 3-3 is vacuum deposited to form the second hole transport layer 4; then, 25 nm of compound A doped with 4% by mass of compound 4-1 is vacuum deposited as the light-emitting layer 5; then, 30 nm of compound C doped with 50% LiQ (lithium 8-hydroxyquinoline) is vacuum deposited to form the electron transport layer 6; finally, 2 nm of ytterbium metal (Yb, as the electron injection layer 7) and a magnesium-silver alloy with a doping ratio of 10:1 are sequentially deposited to form the cathode layer 8; finally, the device is transferred from the deposition chamber to a glove box and then encapsulated with a UV-curable epoxy resin and a glass cover plate containing a moisture absorbent.

[0087] In the above manufacturing steps, the deposition rates of the organic material, ytterbium metal, and magnesium metal are maintained at 0.1 nm / s, 0.05 nm / s, and 0.2 nm / s, respectively.

[0088]

[0089] The device structure is represented as: ITO (135 nm) / compound 1-1: 4% compound 2-2 (20 nm) / compound 1-1 (60 nm) / compound 3-3 (10 nm) / compound A: 4% compound 4-1 (25 nm) / compound C: LiQ (5:5, 30 nm) / Yb (2 nm) / Mg:Ag (10:1, 150 nm).

[0090] Device Example 2

[0091] The experiment is carried out in the same manner as in Example 1, except that: compound 1-3 is used instead of compound 1-1, compound 2-4 is used instead of compound 2-2, compound 3-6 is used instead of compound 3-3, and compound 4-4 is used instead of compound 4-1.

[0092] The device structure is represented as: ITO (135 nm) / compound 1-3: 4% compound 2-4 (20 nm) / compound 1-3 (60 nm) / compound 3-6 (10 nm) / compound A: 4% compound 4-4 (25 nm) / compound C: LiQ (5:5, 30 nm) / Yb (2 nm) / Mg:Ag (10:1, 150 nm).

[0093] Device Example 3

[0094] The experiment was conducted in the same manner as in Example 1, except that: Compound 1-8 was used instead of Compound 1-1, Compound 2-6 was used instead of Compound 2-2, Compound 3-8 was used instead of Compound 3-3, and Compound 4-6 was used instead of Compound 4-1.

[0095] The element structure is represented as: ITO(135nm) / Compound 1-8: 4% Compound 2-6(20nm) / Compound 1-8(60nm) / Compound 3-8(10nm) / Compound A: 4% Compound 4-6(25nm) / Compound C:LiQ(5:5,30nm) / Yb(2nm) / Mg:Ag(10:1,150nm).

[0096] Device Example 4

[0097] The experiment was conducted in the same manner as in Example 1, except that: Compound 1-10 was used instead of Compound 1-1, Compound 2-8 was used instead of Compound 2-2, Compound 3-12 was used instead of Compound 3-3, and Compound 4-10 was used instead of Compound 4-1.

[0098] The element structure is represented as: ITO(135nm) / Compound 1-10: 4% Compound 2-8(20nm) / Compound 1-10(60nm) / Compound 3-12(10nm) / Compound A: 4% Compound 4-10(25nm) / Compound C:LiQ(5:5,30nm) / Yb(2nm) / Mg:Ag(10:1,150nm).

[0099] Device Example 5

[0100] The experiment was conducted in the same manner as in Example 1, except that: Compound 2-7 was used instead of Compound 2-2, and Compound 4-6 was used instead of Compound 4-1.

[0101] The element structure is represented as: ITO(135nm) / Compound 1-1: 4% Compound 2-7(20nm) / Compound 1-1(60nm) / Compound 3-3(10nm) / Compound A: 4% Compound 4-6(25nm) / Compound C:LiQ(5:5,30nm) / Yb(2nm) / Mg:Ag(10:1,150nm).

[0102] Device Example 6

[0103] The experiment was conducted in the same manner as in Example 1, except that: Compound 2-9 was used instead of Compound 2-2, and Compound 4-12 was used instead of Compound 4-1.

[0104] The component structure is represented as: ITO(135nm) / Compound 1-1: 4% Compound 2-9(20nm) / Compound 1-1(60nm) / Compound 3-3(10nm) / Compound A: 4% Compound 4-12(25nm) / Compound C: LiQ(5:5, 30nm) / Yb(2nm) / Mg:Ag(10:1, 150nm).

[0105] Device Example 7

[0106] The experiment was conducted in the same manner as in Example 1, except that: Compound B was used instead of Compound A.

[0107] The component structure is represented as: ITO(135nm) / Compound 1-1: 4% Compound 2-2(20nm) / Compound 1-1(60nm) / Compound 3-3(10nm) / Compound B: 4% Compound 4-1(25nm) / Compound C: LiQ(5:5, 30nm) / Yb(2nm) / Mg:Ag(10:1, 150nm).

[0108] Device Example 8

[0109] The experiment was conducted in the same manner as in Example 1, except that: Compound B was used instead of Compound A, Compound 1-3 was used instead of Compound 1-1, Compound 2-4 was used instead of Compound 2-2, and Compound 4-4 was used instead of Compound 4-1.

[0110] The component structure is represented as: ITO(135nm) / Compound 1-3: 4% Compound 2-4(20nm) / Compound 1-3(60nm) / Compound 3-3(10nm) / Compound B: 4% Compound 4-4(25nm) / Compound C: LiQ(5:5, 30nm) / Yb(2nm) / Mg:Ag(10:1, 150nm).

[0111] Device Example 9

[0112] The experiment was conducted in the same manner as in Example 1, except that: Compound B was used instead of Compound A, Compound 1-8 was used instead of Compound 1-1, Compound 2-6 was used instead of Compound 2-2, and Compound 4-6 was used instead of Compound 4-1.

[0113] The component structure is represented as: ITO(135nm) / Compound 1-8: 4% Compound 2-6(20nm) / Compound 1-8(60nm) / Compound 3-3(10nm) / Compound B: 4% Compound 4-6(25nm) / Compound C: LiQ(5:5, 30nm) / Yb(2nm) / Mg:Ag(10:1, 150nm).

[0114] Device Example 10

[0115] The experiment was carried out in the same manner as in Example 1, except that: Compound B was used instead of Compound A, Compound 1-10 was used instead of Compound 1-1, Compound 2-8 was used instead of Compound 2-2, and Compound 4-10 was used instead of Compound 4-1.

[0116] The element structure is represented as: ITO(135nm) / Compound 1-10:4% Compound 2-8(20nm) / Compound 1-10(60nm) / Compound 3-3(10nm) / Compound B:4% Compound 4-10(25nm) / Compound C:LiQ(5:5,30nm) / Yb(2nm) / Mg:Ag(10:1,150nm).

[0117] Device Example 11

[0118] The experiment was carried out in the same manner as in Example 1, except that: Compound B was used instead of Compound A, Compound 2-7 was used instead of Compound 2-2, and Compound 4-6 was used instead of Compound 4-1.

[0119] The element structure is represented as: ITO(135nm) / Compound 1-1:4% Compound 2-7(20nm) / Compound 1-1(60nm) / Compound 3-3(10nm) / Compound B:4% Compound 4-6(25nm) / Compound C:LiQ(5:5,30nm) / Yb(2nm) / Mg:Ag(10:1,150nm).

[0120] Device Example 12

[0121] The experiment was carried out in the same manner as in Example 1, except that: Compound B was used instead of Compound A, Compound 2-9 was used instead of Compound 2-2, and Compound 4-12 was used instead of Compound 4-1.

[0122] The element structure is represented as: ITO(135nm) / Compound 1-1:4% Compound 2-9(20nm) / Compound 1-1(60nm) / Compound 3-3(10nm) / Compound B:4% Compound 4-12(25nm) / Compound C:LiQ(5:5,30nm) / Yb(2nm) / Mg:Ag(10:1,150nm).

[0123] Device Example 13

[0124] The experiment was carried out in the same manner as in Example 1, except that when forming the hole injection layer, the doping mass ratio of Compound 2-2 was 2%.

[0125] The element structure is represented as: ITO(135nm) / Compound 1-1: 2% Compound 2-2(20nm) / Compound 1-1(60nm) / Compound 3-3(10nm) / Compound A: 4% Compound 4-1(25nm) / Compound C: LiQ(5:5, 30nm) / Yb(2nm) / Mg:Ag(10:1, 150nm).

[0126] Device Example 14

[0127] The experiment was carried out in the same manner as in Example 1, except that when forming the hole injection layer, the doping mass ratio of Compound 2-2 was 6%.

[0128] The element structure is represented as: ITO(135nm) / Compound 1-1: 6% Compound 2-2(20nm) / Compound 1-1(60nm) / Compound 3-3(10nm) / Compound A: 4% Compound 4-1(25nm) / Compound C: LiQ(5:5, 30nm) / Yb(2nm) / Mg:Ag(10:1, 150nm).

[0129] Device Example 15

[0130] The experiment was carried out in the same manner as in Example 1, except that when forming the hole injection layer, the doping mass ratio of Compound 2-2 was 8%.

[0131] The element structure is represented as: ITO(135nm) / Compound 1-1: 8% Compound 2-2(20nm) / Compound 1-1(60nm) / Compound 3-3(10nm) / Compound A: 4% Compound 4-1(25nm) / Compound C: LiQ(5:5, 30nm) / Yb(2nm) / Mg:Ag(10:1, 150nm).

[0132] Device Example 16

[0133] The experiment was carried out in the same manner as in Example 1, except that when forming the hole injection layer, Compound 2-2 was not used.

[0134] The element structure is represented as: ITO(135nm) / Compound 1-1(20nm) / Compound 1-1(60nm) / Compound 3-3(10nm) / Compound A: 4% Compound 4-1(25nm) / Compound C: LiQ(5:5, 30nm) / Yb(2nm) / Mg:Ag(10:1, 150nm).

[0135] Device Comparative Example 1

[0136] The experiment was conducted in the same manner as in Example 1, except that: Compound 2-7 was used instead of Compound 2-2, Compound 4-6 was used instead of Compound 4-1, and Compound ETA was used instead of Compound C.

[0137] The device structure is represented as: ITO(135nm) / Compound 1-1: 4% Compound 2-7(20nm) / Compound 1-1(60nm) / Compound 3-3(10nm) / Compound A: 4% Compound 4-6(25nm) / ETA:LiQ(5:5,30nm) / Yb(2nm) / Mg:Ag(10:1,150nm).

[0138] Device Comparative Example 2

[0139] The experiment was conducted in the same manner as in Device Comparative Example 1, except that: Compound B was used instead of Compound A.

[0140] The device structure is represented as: ITO(135nm) / Compound 1-1: 4% Compound 2-7(20nm) / Compound 1-1(60nm) / Compound 3-3(10nm) / Compound B: 4% Compound 4-6(25nm) / ETA:LiQ(5:5,30nm) / Yb(2nm) / Mg:Ag(10:1,150nm).

[0141] The luminance, luminous efficiency, and EQE (external quantum efficiency) of the device were measured using the Suzhou FushiDA FS-100GA4, and all measurements were performed at room temperature in air. The specific performance data of the device at a current density of 10 mA / cm 2 for the operating voltage (V), current efficiency (C.E.), external quantum efficiency (EQE), and color coordinates (CIEx, CIEy) are shown in Table 2.

[0142] Table 2

[0143]

[0144]

[0145] As can be seen from the table, the above embodiments of the present invention achieve the following technical effects: Compared with Device Comparative Example 1, the device efficiency of Device Embodiments 1 to 6 is improved. Similarly, compared with Device Comparative Example 2, the device efficiency of Device Embodiments 7 to 12 is further improved, and the improvement is more obvious compared with the device using Compound A as the host. This is because the LUMO energy level difference between Compounds B and C is smaller (0.03 eV), while the LUMO energy level difference between Compounds A and C is 0.41 eV. Therefore, in Device Embodiment 2, electrons are more easily injected into the light-emitting layer, and thus more easily combine with holes, further improving the light-emitting efficiency.

[0146] As can be seen from the above description, the above embodiments of the present invention achieve the following technical effects:

[0147] Compound C in the electron transport layer of the organic electroluminescent element of the present application has the same fragment as Compounds A and B in the host of the light-emitting layer, so the interfacial effect between the film layers is weakened, which is beneficial to the rapid transport of electrons into the light-emitting layer; in addition, due to the bipolar characteristics of the host material of the light-emitting layer, the transport capabilities of holes and electrons are further balanced. Therefore, due to the mutual synergistic effects of the above substances, the efficiency of the organic electroluminescent element is significantly improved.

[0148] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An organic electroluminescent element, the organic electroluminescent element comprising a hole injection layer, a hole transport layer, a light-emitting layer, and an electron transport layer stacked in sequence, characterized in that, The host of the light-emitting layer comprises compound A or compound B. The electron transport layer comprises compound C.

2. The organic electroluminescent element according to claim 1, wherein The hole injection layer comprises any one or more arylamine compounds and any one or more annulene derivatives doped therein. The arylamine compound has the general formula I: wherein Ar1 to Ar4 each independently represent a substituted or unsubstituted C6-C 30 aryl, a substituted or unsubstituted C5-C 30 heteroaryl, and the substituents on both Ar1 and Ar2, and both Ar3 and Ar4 can be combined with each other via a single bond, a substituted or unsubstituted methylene group, an oxygen atom or a sulfur atom to form a ring, and n is any integer from 0 to 4; The axisene derivative has the general formula II: wherein Ar6 is an aryl group containing a C6-C substituted by an electron-withdrawing group 18 aryl.

3. The organic electroluminescent element according to claim 2, wherein, The electron-withdrawing group is fluorine or cyano.

4. The organic electroluminescent element according to claim 2 or 3, characterized in that, In general formula I, Ar1 to Ar4 are each independently selected from any one of substituted or unsubstituted phenyl, biphenyl, naphthyl, fluorenyl or carbazolyl.

5. The organic electroluminescent element according to claim 2 or 3, characterized in that, In general formula II, Ar6 is selected from phenyl or biphenyl substituted with at least one cyano or F atom.

6. The organic electroluminescent element according to claim 2 or 3, characterized in that, Among the various arylamine compounds and the annulene derivatives, the doping mass ratio of the annulene derivatives is 2% to 20%.

7. The organic electroluminescent element according to claim 2 or 3, characterized in that, The hole transport layer comprises a first hole transport layer and a second hole transport layer stacked in sequence away from the hole injection layer, and the first hole transport layer comprises any one or more of the arylamine compounds.

8. The organic electroluminescent element according to claim 7, wherein, The second hole transport layer comprises any one or more triarylamine compounds represented by general formula III. Among them, Ar7, Ar8 and Ar9 each independently represent a substituted or unsubstituted C6-C 30 aryl, a substituted or unsubstituted C5-C 30 heteroaryl, any one of them.

9. The organic electroluminescent element according to claim 6, characterized in that, In general formula III, Ar7, Ar8 and Ar9 are each independently selected from any one of biphenyl, fluorenyl, dibenzofuranyl, phenyl-substituted naphthyl, phenyl-substituted dibenzofuranyl or phenyl-substituted carbazolyl.

10. The organic electroluminescent element according to claim 1, wherein, The guest of the light-emitting layer is any one or more phosphorescent red dyes represented by general formula IV. Among them, R1, R2, R3, and R4 are each independently selected from substituted or unsubstituted C1-C 10 alkyl, substituted or unsubstituted C6-C 30 aryl, or substituted or unsubstituted C5-C 30 heteroaryl; m and n are each independently any integer from 0 to 4.

11. The organic electroluminescent element according to claim 10, characterized in that, In general formula IV, R1, R2, R3 and R4 are each independently selected from any one of methyl, ethyl, isopropyl, isobutyl or 3-methylpentyl.

12. The organic electroluminescent element according to claim 11, characterized in that, m is 1 or 2, and n is 1 or 2.

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