Dihydrophenazine derivative and organic light-emitting element using same

Abstract

This dihydrophenazine derivative is represented by general formula (1). In formula (1), R's may be the same or different from each other, and each represent a cyano group, or each represent an aromatic ring having 6-24 ring-forming carbon atoms, a heterocyclic ring having 5-24 ring-forming atoms, a substituted or unsubstituted aryl group having 6-60 ring-forming carbon atoms, a substituted or unsubstituted pyridyl group, a substituted or unsubstituted quinolyl group, a substituted or unsubstituted alkyl group having 1-50 carbon atoms, an alkoxy group, a substituted or unsubstituted cycloalkyl group having 3-50 ring-forming carbon atoms, a substituted or unsubstituted aralkyl group having 7-50 carbon atoms, a substituted or unsubstituted aryloxy group having 6-50 ring-forming carbon atoms, an arylthio group, or a substituted or unsubstituted alkoxycarbonyl group having 2-50 carbon atoms.

Description

Dihydrophenazine derivatives and organic light-emitting devices using the same

[0001] The present invention relates to an electron-accepting organic material used as a material for an acceptor layer of a photoelectric conversion layer, and an organic light-emitting device using the same.

[0002] Organic electroluminescent devices (OLEDs, organic electroluminescent diodes) are self-emitting, have high brightness, a wide viewing angle, faster response, and a simple manufacturing process, and are thus widely used in industrial displays. In recent years, with the development and widespread application of electronic products such as mobile phones, personal digital assistants, and notebook computers, the demand for flat display devices that consume less power and occupy less space has been increasing.

[0003] Conventional organic electroluminescent devices generally rely on intrinsic semiconductor materials and have an undoped hole injection layer, and have higher driving voltages and power consumption compared to the same type of liquid crystal display (LCD). In order to reduce the driving voltage and power consumption of organic electroluminescent diodes, OLEDs having a p-i-n structure are known. Specifically, such an OLED has a p-doped hole injection layer.

[0004] Also, p-i-n OLEDs using F4-TCNQ (2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-p-quinodimethane) as a p-dopant and m-MTDATA (4,4',4''-tris(3-methylphenylphenylamino)-triphenylamine) as a host of the p-doped layer are known.

[0005] Patent Document 1 discloses an organic light-emitting device including a first electrode, an organic film, and a second electrode, wherein the organic film contains 2,6-dicyanomethylene-1,3,4,5,7,8-hexafluoronaphthalene and a phenylamine-based compound.

[0006] Japanese Patent Application Laid-Open No. 2011-233898

[0007] However, 2,6-dicyanomethylidene-1,3,4,5,7,8-hexafluoronaphthalene, described in Patent Document 1, had the problem of having low conductivity when used as a dopant material for OLEDs, resulting in insufficient performance.

[0008] In view of the above problems, the present invention aims to provide a dihydrophenazine derivative useful as an acceptor-containing layer for an organic light-emitting device, and an organic light-emitting device using the same.

[0009] To achieve the above objective, the first configuration of the present invention is a dihydrophenazine derivative represented by the following general formula (1). In formula (1), R may be the same or different, and represents a cyano group, or an aromatic ring having 6 to 24 ring-forming atoms, a heterocycle having 5 to 24 ring-forming atoms, a substituted or unsubstituted aryl group having 6 to 60 ring-forming atoms, a substituted or unsubstituted pyridyl group, a substituted or unsubstituted quinolyl group, a substituted or unsubstituted alkyl group having 1 to 50 ring-forming atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring-forming atoms, a substituted or unsubstituted aralkyl group having 7 to 50 ring-forming atoms, a substituted or unsubstituted alkoxy group having 1 to 50 ring-forming atoms, a substituted or unsubstituted aryloxy group having 6 to 50 ring-forming atoms, or a substituted or unsubstituted alkoxycarbonyl group having 2 to 50 ring-forming atoms.

[0010] According to the first configuration of the present invention, by using the compound represented by formula (1) above as the material for the acceptor-containing layer of the organic light-emitting element, the mobility of charge (electrons) can be improved, and the luminescence efficiency of the organic light-emitting element is improved.

[0011] Partial cross-sectional view of the organic electroluminescent element 100 according to the first embodiment of the present invention Partial cross-sectional view of the organic electroluminescent element 100 according to the second embodiment of the present invention

[0012] [1. Structure of the Organic Electroluminescent Element] First, the organic electroluminescent element using the dihydrophenazine derivative of the present invention will be described. Figure 1 is a partial cross-sectional view of an organic electroluminescent element (hereinafter simply referred to as an organic light-emitting element) 100 according to the first embodiment of the present invention. The organic light-emitting element 100 comprises a substrate 1, an anode 2, a hole injection layer 3, a hole transport layer 4, a light-emitting layer 5, a donor-containing layer 6, an acceptor-containing layer 7, and a light-transmitting cathode 8.

[0013] <Substrate> The substrate 1 is not particularly limited as long as it can be used for the organic light-emitting element 100. The substrate 1 may be transparent or opaque. Examples of transparent substrates include transparent rigid substrates such as glass like quartz glass or synthetic quartz plates, and transparent flexible substrates such as transparent resin films or optical resin plates. Transparent flexible substrates have advantages such as ease of processing, reduced manufacturing costs, lighter weight, resistance to breakage, and applicability to curved surfaces.

[0014] <Anode> Anode 2 is a hole injection electrode. Materials used as anode 2 include, for example, gold (Au), silver (Ag), cobalt (Co), nickel (Ni), platinum (Pt), carbon (C), indium tin oxide (ITO), and tin oxide (SnO). ２ Examples include fluorine-doped tin oxide (FTO) and zinc oxide (ZnO).

[0015] Furthermore, the material of the anode 2 is appropriately selected considering whether or not the organic light-emitting element 100 emits light from the side facing the substrate 1. If the substrate 1 is a transparent substrate and light is emitted from the side facing the substrate 1, it is preferable that the anode 2 be a transparent electrode. Examples of materials used when the anode 2 is a transparent electrode include indium zinc oxide (IZO), ITO, FTO, ZnO-Al, and Zn-Sn-O.

[0016] The anode 2 may be a single layer. Alternatively, the anode 2 may be composed of multiple layers having different work functions.

[0017] The anode 2 may be formed in a sheet-like manner over the entire surface of the substrate 1, or it may be formed in a pattern-like manner on the substrate 1. The shape of the anode 2 may be flat or uneven. Examples of uneven shapes include textured structures, pyramidal structures, wave-like structures, comb-like structures, and nanopillow structures. The anode 2 may be formed by methods such as sputtering, electron beam deposition, thermal deposition, or chemical deposition.

[0018] <Hole Injection Layer> The hole injection layer 3 is laminated between the anode electrode 2 and the hole transport layer 4. The hole injection layer 3 is provided to facilitate the injection (movement) of holes from the anode 2 (hole injection electrode) to the hole transport layer 4.

[0019] <Hole Transport Layer> The hole transport layer 4 is laminated between the hole injection layer 3 and the light-emitting layer 5. The hole transport layer 4 is provided to facilitate the injection (movement) of holes from the hole injection layer 3 to the light-emitting layer 5. By laminating the hole injection layer 3 and the hole transport layer 4, the hole injection efficiency from the anode 2 to the light-emitting layer 5 is increased, and the luminous efficiency of the organic light-emitting element 100 is improved.

[0020] <Emitting Layer> The emissive layer 5 is laminated between the hole transport layer 4 and the donor-containing layer 6. The emissive layer 5 contains an emissive material that emits light due to the recombination energy of holes injected from the anode 2 and electrons injected from the light-transmitting cathode 8. The emissive layer 5 may use the emissive material alone, or it may contain the emissive material and a host material. In order for the organic light-emitting element 100 to exhibit high luminescence efficiency, it is important to confine the singlet and triplet excitons generated in the emissive material within the emissive material. Therefore, it is preferable to add a host material in addition to the emissive material to the emissive layer 5.

[0021] As the luminescent material, one or more compounds selected from the conventionally known group of compounds can be used. As the host material, an organic compound having at least one of the excitation singlet energy and excitation triplet energy higher than that of the luminescent material can be used. Preferably, the host material is an organic compound that has hole transport ability, electron transport ability, prevents the emission from becoming longer wavelengths, and has a high glass transition temperature. The emission from the luminescent layer 5 originates from the luminescent material contained in the luminescent layer 5. This emission includes both fluorescence emission and delayed fluorescence emission. However, some or partial emission may originate from the host material.

[0022] <Donor-containing layer> The donor-containing layer 6 is laminated between the light-emitting layer 5 and the acceptor-containing layer 7. The donor-containing layer 6 is a layer that extracts electrons from the acceptor-containing layer 7 and injects them into the light-emitting layer 5 (donates electrons). By providing the donor-containing layer 6, the large difference in affinity levels between the light-emitting layer 5 and the acceptor-containing layer 7 can be eliminated, making it easier for the donor-containing layer 5 to receive electrons from the acceptor-containing layer 7.

[0023] <Acceptor-containing layer> The acceptor-containing layer 7 is laminated between the donor-containing layer 6 and the light-transmitting cathode 8. In this embodiment, the acceptor-containing layer 7 is directly laminated to the donor-containing layer 6. That is, the donor-containing layer 6 and the acceptor-containing layer 7 are in contact with each other. The acceptor-containing layer 7 is provided so that electrons can be easily injected (transferred) from the light-transmitting cathode 8 (electron injection electrode) to the donor-containing layer 6. An easily reducible organic compound can be used as the acceptor-containing layer 7. The ease of reduction of a compound can be measured by its reduction potential. In this invention, a compound having a reduction potential of -0.8 V or higher, more preferably -0.3 V or higher, and particularly preferably a compound having a value greater than the reduction potential of tetracyanoquinodimethane (TCNQ) (approximately 0 V), with a saturated calomel (SCE) electrode as the reference electrode, is preferred.

[0024] By providing an acceptor-containing layer 7 between the donor-containing layer 6 and the light-transmitting cathode 8, the acceptors contained in the acceptor-containing layer 7 extract electrons from the contact surface between it and the light-transmitting cathode 8. Since the acceptor-containing layer 7 is electron-transporting, electrons are transported from this contact surface into the acceptor-containing layer 7 in the direction of the donor-containing layer 6. Furthermore, electrons are injected from the donor-containing layer 6 in the direction of the light-emitting layer 5. Meanwhile, holes from the anode 2 are injected into the hole injection layer 3 and the hole transport layer 4, and further injected into the light-emitting layer 5. In the light-emitting layer 5, holes and electrons recombine, generating light emission.

[0025] In the organic light-emitting element 100 of this embodiment, by providing an acceptor-containing layer 7 and a donor-containing layer 6 between the light-transmitting cathode 8 and the light-emitting layer 5, the injection (movement) of electrons from the light-transmitting cathode 8 to the light-emitting layer 5 is facilitated, thereby reducing the driving voltage of the organic light-emitting element 100, increasing efficiency, and extending its lifespan.

[0026] In the organic light-emitting element 100 of this embodiment, the acceptor-containing layer 7 contains a dihydrophenazine derivative represented by the following general formula (1).

[0027]

[0028] In formula (1), R may be the same or different, and represents a cyano group, or an aromatic ring having 6 to 24 ring-forming atoms, a heterocycle having 5 to 24 ring-forming atoms, a substituted or unsubstituted aryl group having 6 to 60 ring-forming atoms, a substituted or unsubstituted pyridyl group, a substituted or unsubstituted quinolyl group, a substituted or unsubstituted alkyl group having 1 to 50 ring-forming atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring-forming atoms, a substituted or unsubstituted aralkyl group having 7 to 50 ring-forming atoms, a substituted or unsubstituted alkoxy group having 1 to 50 ring-forming atoms, a substituted or unsubstituted aryloxy group having 6 to 50 ring-forming atoms, or a substituted or unsubstituted alkoxycarbonyl group having 2 to 50 ring-forming atoms.

[0029] Specific examples of dihydrophenazine derivatives represented by general formula (1) include compounds (1-1) to (1-14) represented by the following chemical formulas.

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044] Compounds (1-1) to (1-6), (1-11) each have one halogen, cyano group, nitro group, or trifluoromethyl group in which the substituent R is an acceptor substituent (electron-withdrawing group). Compounds (1-7) to (1-10), (1-12) to (1-14) each have a plurality of halogen, cyano group, nitro group, or trifluoromethyl group in which the substituent R is an acceptor substituent (electron-withdrawing group). The more electron-withdrawing groups there are as substituents, the greater the electron-withdrawing property of the compound itself, and the better the performance as a dopant.

[0045] By using the compound represented by the above formula (1) as the dopant material (electron-accepting material) constituting the hole injection layer 3, the mobility of charges (electrons) can be improved as shown in the examples described later, and the luminous efficiency of the organic light-emitting device 100 is improved. Further, the compound represented by the above formula (1) has excellent thermal stability and a low deposition temperature, so that the organic light-emitting device 100 can be easily manufactured and the reliability is also improved.

[0046] The dihydrophenazine derivative represented by general formula (1) may form the acceptor-containing layer 7 by itself. That is, the acceptor-containing layer may be formed solely of the dihydrophenazine derivative represented by general formula (1). Alternatively, the dihydrophenazine derivative represented by general formula (1) may be added as a dopant material to the hole transport material forming the acceptor-containing layer 7. That is, the acceptor-containing layer may contain a hole transport material and the dihydrophenazine derivative represented by general formula (1) as a dopant material.

[0047] Examples of hole transport materials used in the acceptor-containing layer include compounds having triarylamine units, spirobifluorene compounds, pentacene compounds, oligothiophene compounds, oligophenyl compounds, oligophenylene vinyl compounds, oligofluorene compounds, porphyrin complexes, or metal phthalocyanine complexes. Two or more of these compounds may be used in combination.

[0048] When the acceptor-containing layer includes a hole transport material and a dihydrophenazine derivative represented by general formula (1) as a dopant material, the molar ratio of the hole transport material to the dihydrophenazine derivative is 10,000:1 to 1:10,000. In particular, a molar ratio of 10:1 to 1:100 is preferred.

[0049] <Light-Transmitting Cathode> The light-transmitting cathode 8 is an electron injection electrode laminated on the acceptor-containing layer 7. The light-transmitting cathode 8 is provided opposite the anode 2. In this embodiment, the light-transmitting cathode 8 is directly laminated on the acceptor-containing layer 7. That is, the acceptor-containing layer 7 and the light-transmitting cathode 8 are in contact with each other. The light-transmitting cathode 8 is not particularly limited as long as it is conductive. The material of the light-transmitting cathode 8 is appropriately selected, for example, taking into consideration the material of the acceptor-containing layer 7.

[0050] Examples of materials used as the material for the light-transmitting cathode 8 include indium tin oxide (ITO), tin oxide (SnO2), fluorine-doped tin oxide (FTO), and zinc oxide (ZnO).

[0051] The light-transmitting cathode 8 may be a single layer. Alternatively, the light-transmitting cathode 8 may be composed of multiple layers having different work functions. The light-transmitting cathode 8 may be formed in a sheet shape over the entire surface of the acceptor-containing layer 7, or it may be formed in a pattern shape on the acceptor-containing layer 7.

[0052] <Other Components> The organic light-emitting element 100 may further comprise other components in addition to the substrate 1, anode 2, hole injection layer 3, hole transport layer 4, light-emitting layer 5, donor-containing layer 6, acceptor-containing layer 7, and light-transmitting cathode 8 described above, as needed. Examples of other components include a protective sheet layer, a filler layer, a barrier layer, a protective hard coat layer, a strength support layer, an anti-fouling layer, a high light reflectivity layer, an ultraviolet blocking layer, an infrared blocking layer, and a sealing layer. Furthermore, adhesive layers may be laminated between each layer of the organic light-emitting element 100, as needed.

[0053] The organic light-emitting element 100 of this embodiment is not limited to the configuration shown in Figure 1. For example, the hole injection layer 3 and the hole transport layer 4 are arbitrary layers and can be omitted, and an electron transport layer or the like can be laminated between the light-emitting layer 5 and the donor-containing layer 6. The hole injection layer 3, the hole transport layer 4, the light-emitting layer 5, the electron transport layer, etc. correspond to the organic thin film layers in the organic light-emitting element 100 of this embodiment.

[0054] The configuration of the organic light-emitting element 100 of the present invention has been described above using the organic light-emitting element 100 of the first embodiment shown in Figure 1 as an example. However, the present invention is not limited to the configuration of the organic light-emitting element 100 of the first embodiment. For example, a stacked type multi-photon emission element (MPE element) may be used in which two or more light-emitting units are sandwiched between an anode 2 and a light-transmitting cathode 8, and a charge generation layer is stacked between the light-emitting units.

[0055] Figure 2 is a schematic cross-sectional view of an organic light-emitting element 100 according to a second embodiment of the present invention. The organic light-emitting element 100 of this embodiment comprises, in this order, an anode 2, a first light-emitting unit 10, a charge generation layer 11, a second light-emitting unit 12, a donor-containing layer 6, an acceptor-containing layer 7, and a light-transmitting cathode 8 on a substrate 1. The two light-emitting units 10 and 12 each have a single-layer or multilayer structure having at least a light-emitting layer. For example, it is preferable that the light-emitting units 10 and 12 have a multilayer film structure in which a hole transport layer, a light-emitting layer, and an electron transport layer are stacked from the anode 2 side.

[0056] The organic light-emitting element 100 has the same configuration as the organic light-emitting element 100 of the first embodiment shown in Figure 1, except that it has two light-emitting units. In other words, the organic light-emitting element 100 of the first embodiment has an element configuration having one light-emitting unit consisting of a hole injection layer 3, a hole transport layer 4, and a light-emitting layer 5.

[0057] The charge generation layer 11 includes a p-type charge generation layer and an n-type charge generation layer. The p-type charge generation layer contains a dihydrophenazine derivative represented by general formula (1).

[0058] In this embodiment, for example, by changing the material of the light-emitting layer constituting each light-emitting unit 10, 12 to produce different light-emitting colors, an organic light-emitting element 100 that emits white light can be obtained.

[0059] The organic light-emitting element 100 of this embodiment is not limited to the configuration shown in Figure 2. For example, in each light-emitting unit 10, 12 of the organic light-emitting element 100 of this embodiment, the donor-containing layer and acceptor-containing layer described above may be laminated between the light-emitting layer and the charge-generating layer. Specifically, the first light-emitting unit 10 may have a configuration in which a hole transport layer, a light-emitting layer, a donor-containing layer, and an acceptor-containing layer are laminated from the anode 2 side.

[0060] Furthermore, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. For example, in the above embodiments, an example was described in which the dihydrophenazine derivative of the present invention was used in the acceptor-containing layer 7 of the organic light-emitting element 100, but it can also be used, for example, as the acceptor layer of an organic solar cell. The effects of the present invention will be described in more detail below with reference to examples.

[0061] [Synthesis Example of Dihydrophenazine Derivative (1-1)] Under a nitrogen atmosphere, at 0°C, 30 mL of anhydrous tetrahydrofuran solution containing 0.66 g (10 mmol) of malononitrile (compound B) was added dropwise to a solution of 0.40 g (10 mmol) of 60% sodium hydride and stirred for 1 hour. 1.0 g (3 mmol) of octafluorophenazine (compound A) was added dropwise to the reaction mixture and stirred under reflux at 80°C for 8 hours. After returning to room temperature, the reaction mixture was poured into water, acidified with hydrochloric acid, and the precipitated solid was filtered off. The solid was washed with water and diethyl ether to obtain 0.312 g of intermediate product (b-1) (yield 25%). The synthesis scheme is shown below.

[0062]

[0063] Under a nitrogen atmosphere, 0.30 g (0.72 mmol) of intermediate product (b-1) was dissolved in 20 mL of anhydrous acetonitrile. After cooling the solution to 0°C, 16 g (4 mmol) of 2% bromine water was added dropwise, and the mixture was stirred for 1 hour while returning to room temperature. The reaction mixture was poured into water, the precipitated solid was filtered off, washed twice with water and twice with ether, and dried to obtain 0.119 g of compound (1-1) (yield 40%). The synthesis scheme is shown below.

[0064]

[0065] [Synthesis Examples of Dihydrophenazine Derivatives (1-2) to (1-10)] Dihydrophenazine derivatives (1-2) to (1-10) were synthesized in the same manner as in Example 1, except that compound (B) was changed. Table 1 shows the yields of compound (B) used in the synthesis, intermediate products (b-1) to (b-10), and dihydrophenazine derivatives (1-1) to (1-10).

[0066] *F-NMR 282MHz, d6-DMSO, C ６ F ６　 -164.9ppm Compound (1-1) -136.3 (m, 2F), -138.7 (m, 2F), -139.7 (m, 2F) Compound (1-9) -135.8 (m, 2F), -136.3 (m, 2F), -138.7 (m, 2F), -139.7 (m, 2F), -140.4 (m, 4F) Compound (1-10) -135.9 (m, 4F), -136.3 (m, 2F), -138.7 (m, 2F), -139.7 (m, 2F), -152.7 (m, 2F), -163.7 (m, 4F)

[0067] [Synthesis Example of Dihydrophenazine Derivatives (1-11)] Under a nitrogen atmosphere, at 0°C, 30 mL of anhydrous tetrahydrofuran solution containing 0.33 g (5 mmol) of malononitrile (compound B) was added dropwise to 0.20 g (5 mmol) of anhydrous tetrahydrofuran solution containing 60% sodium hydride and the mixture was stirred for 1 hour. 1.0 g (3 mmol) of octafluorophenazine (compound A) was added dropwise to the reaction mixture and the mixture was heated to 80°C and stirred under reflux for 8 hours. After returning to room temperature, the reaction mixture was poured into water, acidified with hydrochloric acid, and the precipitated solid was filtered off. The solid was washed with water and diethyl ether to obtain 0.167 g of intermediate product (c-11) (yield 15%). The synthesis scheme is shown below.

[0068]

[0069] Under a nitrogen atmosphere, at 0°C, 30 mL of anhydrous tetrahydrofuran solution containing 0.71 g (5 mmol) of 4-cyanobenzylnitrile (compound C) was added dropwise to 0.20 g (5 mmol) of anhydrous tetrahydrofuran solution containing 60% sodium hydride, and the mixture was stirred for 1 hour. 1.11 g (3 mmol) of intermediate product (c-11) was added dropwise to the reaction mixture, and the mixture was heated to 80°C and stirred under reflux for 8 hours. After returning to room temperature, the reaction mixture was poured into water, acidified with hydrochloric acid, and the precipitated solid was filtered off. The solid was washed with water and diethyl ether to obtain 0.222 g of intermediate product (b-11) (yield 15%). The synthesis scheme is shown below.

[0070] Under a nitrogen atmosphere, 0.282 g (0.72 mmol) of the intermediate product (b-11) was dissolved in 20 mL of anhydrous acetonitrile. After cooling the solution to 0°C, 16 g (4 mmol) of 2% bromine water was added dropwise, and the mixture was stirred for 1 hour while returning to room temperature. The reaction mixture was poured into water, the precipitated solid was filtered off, washed twice with water and twice with ether, and dried to obtain 0.106 g of compound (1-11) (yield 30%, F-NMR 282 MHz; -136.3 (m, 2F), -138.7 (m, 2F), -139.7 (m, 2F) d6-DMSO, C ６ F ６　 (-164.9 ppm). The synthesis scheme is shown below.

[0071]

[0072] [Synthesis Examples of Dihydrophenazine Derivatives (1-12) to (1-14)] Dihydrophenazine derivatives (1-12) to (1-14) were synthesized in the same manner as in Example 3, except for changing compound (C). Table 2 shows the yields of compound (C), intermediate products (b-11) to (b-14), and dihydrophenazine derivatives (1-11) to (1-14) used in the synthesis.

[0073]

[0074] [Examples of manufacturing organic electroluminescent elements using dihydrophenazine derivatives as dopant materials] Compound HT-1 (a compound described in Science 338, Vol 338, Issue 6107 pp. 643-647) as a host material and a mixed layer (luminescent layer) of compounds (1-1) to (1-14) obtained in Examples 1 and 2 as dopant materials were laminated on a glass substrate by mixed thermal evaporation in a high vacuum chamber to obtain Inventions 1 to 6. In addition, a mixed layer (luminescent layer) of 2,6-dicyanomethylidene-1,3,4,5,7,8-hexafluoronaphthalene (compound HI, a compound described in Patent Document 1) and HT-1 was laminated on a glass substrate to obtain a comparative example.

[0075]

[0076] The doping concentration was 5 mol%, and the thin film thickness was 50 nm. The glass substrate had two ITO (indium tin oxide) strips as electrodes for the thin film. These two ITO strips were spaced 1 mm apart. The conductivity of the mixed layer was measured from the current-voltage characteristics of the thin film. The results are shown in Table 3.

[0077]

[0078] As is clear from Table 3, Inventions 1 to 6, which used compounds (1-1) to (1-14) as dopant materials, showed higher conductivity compared to the comparative example using compound HI as the dopant material. In particular, Inventions 1, 10, and 12-14, which used compounds (1-1), (1-10), and (1-12) to (1-14), showed high conductivity of 2.5E-06 [S / cm] or higher. From these results, it was confirmed that the OLED properties were improved by using dihydrophenazine derivatives as dopant materials.

[0079] The present invention is applicable to dihydrophenazine derivatives used as hole transport layer materials, and to organic light-emitting devices using the same. By utilizing the present invention, it is possible to provide dihydrophenazine derivatives with excellent thermal stability and low deposition temperatures that are useful as hole transport layers, and organic light-emitting devices using the same.

Claims

1. A dihydrophenazine derivative represented by the following general formula (1). (In formula (1), R may be the same or different, and represents a cyano group, or an aromatic ring having 6 to 24 ring-forming atoms, or a heterocycle having 5 to 24 ring-forming atoms, and is a substituted or unsubstituted aryl group having 6 to 60 ring-forming atoms, a substituted or unsubstituted pyridyl group, a substituted or unsubstituted quinolyl group, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring-forming atoms, a substituted or unsubstituted aralkyl group having 7 to 50 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 50 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 50 ring-forming atoms, a substituted or unsubstituted arylthio group having 6 to 50 ring-forming atoms, or a substituted or unsubstituted alkoxycarbonyl group having 2 to 50 carbon atoms.) 2. In the dihydrophenazine derivative according to claim 1, R in the general formula (1) has one or more acceptor substituents.

3. In the dihydrophenazine derivative according to claim 2, R in the general formula (1) has at least one of a halogen, a cyano group, and a nitro group as the acceptor substituent.

4. An organic electroluminescent element comprising: a substrate; an anode laminated on the substrate; one or more organic thin film layers including a light-emitting layer laminated on the anode; a donor-containing layer laminated on the organic thin film layer; an acceptor-containing layer laminated on the donor-containing layer; and a light-transmitting cathode laminated on the acceptor-containing layer, wherein the donor-containing layer and the acceptor-containing layer are in contact with each other, and the acceptor-containing layer and the light-transmitting cathode are in contact with each other, and the acceptor-containing layer contains the dihydrophenazine derivative described in claim 1.

5. In the organic electroluminescent element according to claim 4, the acceptor-containing layer is formed solely of a dihydrophenazine derivative represented by the general formula (1).

6. In the organic electroluminescent element according to claim 4, the acceptor-containing layer comprises, as a hole transport material, one or more selected from compounds having triarylamine units, spirobifluorene compounds, pentacene compounds, oligothiophene compounds, oligophenyl compounds, oligophenylene vinyl compounds, oligofluorene compounds, porphyrin complexes, or metal phthalocyanine complexes, and as a dopant material, a dihydrophenazine derivative represented by the general formula (1), wherein the molar ratio of the hole transport material to the dopant material is 10,000:1 to 1:10,000.

7. In the organic electroluminescent element according to claim 6, the molar ratio of the hole transport material to the dopant material is 10:1 to 1:

100.

8. In the organic electroluminescent element according to claim 4, one or more organic thin film layers, including the light-emitting layer, constitute two or more light-emitting units stacked via a charge-generating layer.

9. In the organic electroluminescent element according to claim 8, the charge generation layer comprises a p-type charge generation layer and an n-type charge generation layer, wherein the p-type charge generation layer comprises a dihydrophenazine derivative represented by the general formula (1).

10. In the organic electroluminescent element according to claim 8, at least one material constituting the light-emitting layer of the light-emitting unit is different from the material constituting the light-emitting layer of the other light-emitting unit.

11. In the organic electroluminescent element according to claim 4, the light-emitting layer emits white light.

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