Light-emitting device, light-emitting apparatus, electronic device and lighting device

Abstract

Light-emitting device comprising: an EL layer between a pair of electrodes, wherein the EL layer comprises a light-emitting layer, wherein the light-emitting layer comprises an organic compound comprising a naphtho[2',1':4,5]furo[2,3-b]pyrazine skeleton and a phosphorescent substance, where a T1 level of the phosphorescent substance T G lower than or equal to 2.5 eV, where the T G a T1 level is derived from an absorption edge of an absorption spectrum of the phosphorescent substance, where a difference between a T1 level of the organic compound T H and the T1 level of the phosphorescent substance T G a formula (1) is satisfied, and 0.1 eV ≦ TH − TG ≦ 0.4 eV where the T Ha Tl level is derived from an emission edge on a short wavelength side of a phosphorescence spectrum of the organic compound.

Description

Background of the invention 1. Field of the invention

[0001] One embodiment of the present invention relates to a light-emitting device, a light-emitting apparatus, an electronic device and a lighting device. 2. Description of the state of the art

[0002] A light-emitting device (also known as an organic EL device or organic EL element) that incorporates an EL layer between a pair of electrodes utilizes electroluminescence (EL) and exhibits properties such as thinness, lightness, high response speed to input signals, and low power consumption. Therefore, a display incorporating such a light-emitting device has attracted attention as a next-generation flat-panel display.

[0003] In a light-emitting device, a voltage applied between the pair of electrodes causes recombination of electrons and holes injected by the electrodes in the EL layer, which excites a light-emitting substance (an organic compound) contained in the EL layer. Light is emitted when the light-emitting substance returns from the excited state to the ground state. The excited state can be a singlet excitation state (S*) or a triplet excitation state (T*). Light emission from a singlet excitation state is called fluorescence, and light emission from a triplet excitation state is called phosphorescence. The statistical generation ratio of this process in the light-emitting device is assumed to be S*:T* = 1:3.Since the spectrum of light emitted by a light-emitting substance depends on the light-emitting substance itself, light-emitting devices that exhibit different colors can be obtained by using different types of organic compounds as light-emitting substances.

[0004] For example, improvements to the device structure and the development of a material for such light-emitting devices have been actively carried out in order to improve the device properties and reliability (see, for example, patent document 1). [Reference] [Patent Document 1] Japanese Patent Publication JP 2017 - 188 671 A [Patent document 2] US 2019 / 0031673A1 relates to an organic compound comprising a furopyrazine derivative, a light-emitting element, a light-emitting device, an electronic device, and a lighting device. Summary of the invention

[0005] To improve the device characteristics and reliability, it is important to reduce damage resulting from the operation of the device, taking into account the mechanism of energy transfer between a host material and a guest material in a light-emitting layer of a light-emitting device.

[0006] In light of the foregoing, one embodiment of the present invention provides a light-emitting device that not only includes a light-emitting layer in which the efficiency of energy transfer from a host material to a guest material is increased, but also exhibits high reliability. Another embodiment of the present invention provides a light-emitting device that includes a light-emitting layer in which the efficiency of energy transfer from a host material to a guest material is increased. A further embodiment of the present invention provides a light-emitting device with high reliability.

[0007] It should be noted that the description of these problems does not preclude the existence of further problems. One embodiment of the present invention does not necessarily fulfill all of these problems. Further problems will become apparent from the explanation of the description, the drawings, the claims, and the like, and can be derived from them.

[0008] The invention relates to a light-emitting device according to one of the independent claims, a light-emitting arrangement according to claim 7, an electronic device according to claim 8, and a lighting device according to claim 9. Advantageous embodiments are specified in the dependent claims. According to one embodiment of the present invention, a light-emitting layer of a light-emitting device comprises an organic compound with a specific naphthofuropyrazine scaffold as a host material and a light-emitting substance (e.g., a metal-organic complex) whose T1 level (T G ) within a certain range, as guest material, thereby increasing not only the efficiency of energy transfer from the host material to the guest material, but also the reliability.

[0009] One embodiment of the present invention is a light-emitting device comprising an EL layer between a pair of electrodes, wherein the EL layer includes a light-emitting layer. The light-emitting layer contains an organic compound with a naphtho[2',1':4,5]furo[2,3-b]pyrazine skeleton and a phosphorescent substance. The T1 level of the phosphorescent substance (T G ) is less than or equal to 2.5 eV. It should be noted that T G The T1 level is derived from an absorption edge of an absorption spectrum of the phosphorescent substance. A difference between a T1 level of the organic compound T H and the T1 level of the phosphorescent substance T G satisfies a formula (1), and 0.1 eV≦TH−TG≦0.4 eV where the T Ha T1 level is derived from an emission edge on a short wavelength side of a phosphorescence spectrum of the organic compound.

[0010] Another embodiment of the present invention is a light-emitting device comprising an EL layer between a pair of electrodes, wherein the EL layer includes a light-emitting layer. The light-emitting layer contains an organic compound with a naphtho[2',1':4,5]furo[2,3-b]pyrazine framework and a metal-organic complex with a diazine framework. A T1 level of the metal-organic complex T G is less than or equal to 2.5 eV. It should be noted that T G The T1 level is derived from an absorption edge of an absorption spectrum of the phosphorescent substance. A difference between a T1 level of the organic compound T H and the T1 level of the phosphorescent substance TG satisfies a formula (1), and 0.1 eV≦TH−TG≦0.4 eV where the T H a T1 level is derived from an emission edge on a short wavelength side of a phosphorescence spectrum of the organic compound.

[0011] In each of the above structures, the diazine framework is preferably a pyrazine framework or a pyrimidine framework.

[0012] Another embodiment of the present invention is a light-emitting device comprising an EL layer between a pair of electrodes, wherein the EL layer includes a light-emitting layer. The light-emitting layer contains a first organic compound, represented by a general formula (G1), and a phosphorescent substance. The T1 level of the phosphorescent substance (T G ) is less than or equal to 2.5 eV. It should be noted that T Grepresents the T1 level, which is derived from an absorption edge of an absorption spectrum of the phosphorescent substance.

[0013] In the formula, Q represents oxygen or sulfur, A represents a group with a molecular weight of less than or equal to 1000, and R represents 1 to R 6 each independently represents hydrogen, a substituted or unsubstituted alkyl group with 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group with 3 to 7 carbon atoms, or a substituted or unsubstituted aryl group with 6 to 30 carbon atoms.

[0014] In each of the above structures, a difference between the T1 level of the organic compound (T) satisfies H ) and the T1 level of the phosphorescent substance (T G ) the formula (1) shown below. It should be noted that T Ga T1 level derived from an absorption edge of an absorption spectrum of the phosphorescent substance, and that T H a T1 level is derived from an emission edge on a short wavelength side of a phosphorescence spectrum of the organic compound. [Formula 1] 0.1 eV≦TH−TG≦0.4 eV

[0015] In each of the above structures, a difference between the T1 level of the organic compound (T) satisfies H ) and the T1 level of the phosphorescent substance (T G ) preferably the formula (2) shown below. It should be noted that T G a T1 level derived from an absorption edge of an absorption spectrum of the phosphorescent substance, and that T H a T1 level is derived from an emission edge on a short wavelength side of a phosphorescence spectrum of the organic compound. [Formula 2] 0.2 eV≦TH−TG≦0.4 eV

[0016] In addition to a light-emitting device comprising the light-emitting apparatus described above, one embodiment of the present invention in its category comprises an electronic device comprising a light-emitting device or a light-emitting apparatus (in particular, an electronic device comprising a light-emitting device or a light-emitting apparatus and a connection port or an operating button), and a lighting device comprising a light-emitting device or a light-emitting apparatus (in particular, a lighting device comprising a light-emitting device or a light-emitting apparatus and a housing). The light-emitting device in this description accordingly refers to an image display device or a light source (including a lighting device).Additionally, a light-emitting device in its category includes a module in which a light-emitting device is connected to a connector, such as a flexible printed circuit (FPC) or a tape carrier package (TCP), a module in which a printed circuit board is provided at the end of a TCP, and a module in which an integrated circuit (IC) is mounted directly onto a light-emitting device by a chip-on-glass (COG) process.

[0017] One embodiment of the present invention can provide a light-emitting device that not only includes a light-emitting layer in which the efficiency of energy transfer from the host material to the guest material is increased, but also exhibits high reliability.

[0018] Another embodiment of the present invention can provide a light-emitting device, an electronic device, and a display device, each exhibiting high reliability. Another embodiment of the present invention can provide a light-emitting device, an electronic device, and a display device, each exhibiting low power consumption.

[0019] It should be noted that the description of these effects does not preclude the existence of further effects. An embodiment of the present invention need not exhibit all of the effects listed above. Further effects will become apparent from the explanation of the description, the drawings, the claims, and the like, and can be derived from them. A novel light-emitting device with increased reliability can be provided. Brief description of the drawings Fig. 1A and Fig. Figure 1B each represents a structure of a light-emitting device. Fig. 2A to 2C represent light-emitting devices. Fig. 3A and Fig. 3B are a top view or a cross-sectional view depicting a light-emitting device. Fig. 4A represents a portable computer, Fig. 4B represents a portable image display device, Fig. 4C represents a digital camera, Fig. 4D represents a portable information terminal, Fig. 4E represents a portable information terminal, Fig. 4F represents a television set, and Fig. 4G represents a portable information terminal. Fig. 5A to 5C represent an electronic device. Fig. 6A and Fig. 6B represents a vehicle. Fig. 7A and Fig.7B each represent a lighting device. Fig. Figure 8 represents a light-emitting device. Fig. Figure 9 is a diagram showing the luminance-current density characteristics of a light-emitting device 1 and a light-emitting comparison device 2. Fig. Figure 10 is a diagram showing the luminance-voltage characteristics of the light-emitting device 1 and the light-emitting comparison device 2. Fig. Figure 11 is a diagram showing the power efficiency-luminance characteristics of light-emitting device 1 and light-emitting comparison device 2. Fig. Figure 12 is a diagram showing the current-voltage characteristics of the light-emitting device 1 and the light-emitting comparison device 2. Fig.Figure 13 is a diagram showing the emission spectra of the light-emitting device 1 and the light-emitting comparison device 2. Fig. Figure 14 is a diagram showing the reliability of the light-emitting device 1 and the light-emitting comparison device 2. Fig. Figure 15 is a diagram showing the luminance-current density properties of a light-emitting device 3. Fig. Figure 16 is a diagram showing the luminance-voltage properties of the light-emitting device 3. Fig. Figure 17 is a diagram showing the power efficiency-luminance characteristics of the light-emitting device 3. Fig. Figure 18 is a diagram showing the current-voltage characteristics of the light-emitting device 3. Fig. Figure 19 is a diagram showing an emission spectrum of the light-emitting device 3. Fig. 20 is a 1H-NMR diagram of 8mDBtBPNfpr(II). Fig. 21A shows an absorption spectrum of [Ir(dppm)2(acac)] and Fig. Figure 21B is an enlarged view of an absorption edge and its surroundings of the absorption spectrum of [Ir(dppm)2(acac)]. Fig. 22A shows a phosphorescence spectrum of 8mDBtBPNfpr(II) and Fig. 22B is an enlarged view of an emission edge and its surroundings of the phosphorescence spectrum of 8mDBtBPNfpr(II). Fig. 23A shows an absorption spectrum of [Ir(ppy)2(mdppy)] and Fig. Figure 23B is an enlarged view of an absorption edge and its surroundings of the absorption spectrum of [Ir(ppy)2(mdppy)]. Detailed description of the invention

[0020] Embodiments and examples of a light-emitting device of the present invention are described in detail below with reference to the drawings.

[0021] It should be noted that the position, size, area, or the like of each component shown in drawings and the like is, in some cases, not shown precisely for ease of understanding. The disclosed invention is therefore not necessarily limited to the position, size, area, or the like shown in the drawings and the like.

[0022] In explaining the embodiments of the present invention with reference to the drawings in this description and the like, identical components in different drawings are provided with the same reference numeral. (Version 1)

[0023] In this embodiment, light-emitting devices of embodiments of the present invention are based on Fig. 1A and Fig.1B is described. It should be noted that the light-emitting devices each have a structure in which an EL layer is positioned between a pair of electrodes. The EL layer comprises at least one light-emitting layer and may, as required, include functional layers such as a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer.

[0024] The light-emitting layer is a layer that contains both a light-emitting substance (a guest material) and a host material. It should be noted that the light-emitting layer can contain a variety of organic compounds (e.g., a first organic compound and a second organic compound (or a host material and an auxiliary material)) that serve as host materials.

[0025] Light emission from the light-emitting device is obtained when, in the light-emitting layer, energy is transferred from the host material in an excited state generated by recombination of charge carriers (holes and electrons) to the guest material, causing the guest material to emit light. In the light-emitting device described in this embodiment, an organic compound with a specific naphthofuropyrazine framework, preferably with a naphtho[2',1':4,5]furo[2,3-b]pyrazine framework, is used as the host material, and a light-emitting substance (e.g., a metal-organic complex) with a T1 level within a certain range, preferably lower than or equal to 2.5 eV, is used as the guest material. Consequently, the efficiency of energy transfer from the excited host material to the guest material can be increased. <<Struktur von Licht emittierenden Vorrichtungen> >

[0026] Fig. 1A and Fig. Figure 1B represents an example of a light-emitting device that includes an EL layer with a light-emitting layer between a pair of electrodes. In particular, an EL layer 103 is provided between a first electrode 101 and a second electrode 102. In the case where, for example, the first electrode 101 is an anode, the EL layer 103 has a structure in which a hole injection layer 111, a hole transport layer 112, a light-emitting layer 113, an electron transport layer 114, and an electron injection layer 115 are arranged as functional layers in that order.

[0027] Embodiments of the present invention also include light-emitting devices with other structures, such as a light-emitting device that can be operated at low voltage by means of a structure (a tandem structure) in which a plurality of EL layers are provided between a pair of electrodes and a charge-generating layer is provided between the EL layers, and a light-emitting device that has an optical microresonator (microcavity) structure between a pair of electrodes and therefore has improved optical properties. The charge-generating layer has a function for injecting electrons into one of the adjacent EL layers and injecting holes into the other of the EL layers when a voltage is applied between the first electrode 101 and the second electrode 102.

[0028] The first electrode 101 and / or the second electrode 102 of the light-emitting device are / are a translucent electrode (e.g., a transparent electrode or a transflective electrode). In the case where the translucent electrode is a transparent electrode, the transparent electrode has a visible light transmittance of 40% or higher. In the case where the translucent electrode is a transflective electrode, the transflective electrode has a visible light reflectance of 20% or higher and 80% or lower, preferably 40% or higher and 70% or lower. These electrodes preferably have a resistivity of 1 × 10⁻⁶ -2 Ωcm or less.

[0029] Furthermore, if, in the light-emitting device of an embodiment of the present invention, either the first electrode 101 or the second electrode 102 is a reflective electrode, the reflectance for visible light of the reflective electrode is higher than or equal to 40% and lower than or equal to 100%, preferably higher than or equal to 70% and lower than or equal to 100%. This electrode preferably has a resistivity of 1 × 10 -2 Ωcm or less. <Erste Elektrode und zweite Elektrode>

[0030] Any of the following materials, in a suitable combination, can be used for the first electrode 101 and the second electrode 102, provided that the electrodes fulfill the functions described above. For example, a metal, an alloy, an electrically conductive compound, a mixture thereof, and the like can be used appropriately. In particular, an In-Sn oxide (also known as ITO), an In-Si-Sn oxide (also known as ITSO), an In-Zn oxide, an In-W-Zn oxide, or the like can be used. Furthermore, it is possible to use a metal, such as…Aluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), gallium (Ga), zinc (Zn), indium (In), tin (Sn), molybdenum (Mo), tantalum (Ta), tungsten (W), palladium (Pd), gold (Au), platinum (Pt), silver (Ag), yttrium (Y), or neodymium (Nd), or an alloy containing a suitable combination of any of these metals, may be used. It is also possible to use an element from Group 1 or an element from Group 2 of the periodic table not described above (e.g., lithium (Li), cesium (Cs), calcium (Ca), or strontium (Sr)), a rare-earth metal such as europium (Eu) or ytterbium (Yb), an alloy containing a suitable combination of any of these elements, graphene, or the like.

[0031] These electrodes can be manufactured using a sputtering process or a vacuum evaporation process. <lochinjektionsschicht>

[0032] The hole injection layer 111 promotes hole injection from the first electrode 101 serving as an anode into the EL layer 103 and contains an organic acceptor material and a material with a high hole injection property.

[0033] The organic acceptor material allows holes to be created in another organic compound whose HOMO level is close to the LUMO level of the organic acceptor material when charge separation is induced between the organic acceptor material and the organic compound. Therefore, a compound with an electron-withdrawing group (a halogen group or a cyano group), such as a quinodimethane derivative, a chloranil derivative, or a hexaazatriphenylene derivative, can be used as the organic acceptor material. Examples of organic acceptor materials include 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), 3,6-difluoro-2,5,7,7,8,8-hexacyanoquinodimethane, chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), 1,3,4,5,7,8-hexafluorotetracyanonaphthoquinodimethane (abbreviation: F6-TCNNQ), 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile and the like.

[0034] It should be noted that among organic acceptor materials, a compound in which electron-withdrawing groups are bonded to a condensed aromatic ring with a multitude of heteroatoms, such as HAT-CN, is particularly preferred because of its thermal stability. A [3]radialene derivative with an electron-withdrawing group (in particular a cyano group or a halogen group, such as a fluorine group) exhibiting high acceptor properties and stable film quality against heat is particularly preferred. Additionally, a [3]radialene derivative exhibiting very high electron-accepting properties is preferred. Specific examples include α,α',α''-1,2,3-Cyclopropanetriylidentris[4-cyan-2,3,5,6-tetrafluorobenzolacetonitrile], α,α',α''-1,2,3-Cyclopropanetriylidentris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzolacetonitrile], α,α',α''-1,2,3-Cyclopropanetriylidentris[2,3,4,5,6-pentafluorobenzolacetonitrile] and the like.

[0035] Examples of materials with high hole injection properties include transition metal oxides, such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide. Other examples are phthalocyanine-based compounds, such as phthalocyanine (abbreviation: H₂Pc) and copper phthalocyanine (abbreviation: CuPc), and the like.

[0036] Other examples include aromatic amine compounds, which are low-molecular-weight compounds, such as... B. 4,4',4''-Tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4''-Tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: MTDATA), 4,4'-Bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), 4,4'-Bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD), 1,3,5-Tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-Bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-Naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1) and the like.

[0037] Other examples include high-molecular-weight compounds (e.g., oligomers, dendrimers, and polymers), such as poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenylamino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide] (abbreviation: PTPDMA), poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviation: poly-TPD), and the like. Alternatively, a high-molecular-weight compound to which an acid has been added can be used, such as poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (abbreviation: PEDOT / PSS) or polyaniline / poly(styrenesulfonic acid) (abbreviation: PAni / PSS).

[0038] Alternatively, a composite material containing a hole transport material and an acceptor material (an electron acceptor material) can be used as a material with high hole injection properties. In this case, the acceptor material extracts electrons from the hole transport material, so that holes are created in the hole injection layer 111, and the holes are injected through the hole transport layer 112 into the light-emitting layer 113. It should be noted that the hole injection layer 111 can be configured as a single-layer structure using a composite material containing a hole transport material and an acceptor material (electron acceptor material), or as a multi-layer structure consisting of a layer containing a hole transport material and a layer containing an acceptor material (electron acceptor material).

[0039] Preferably, a substance with a hole mobility of higher than or equal to 1 × 10 is used as the hole transport material. -6 cm 2 / Vs is used in the case where the square root of the electric field intensity [V / cm] is 600. It should be noted that other substances can be used as long as they have a hole transport property that is higher than their electron transport property.

[0040] Materials with high hole transport properties, such as a π-electron-rich heteroaromatic compound (e.g., a carbazole derivative and a furan derivative) and an aromatic amine (a compound with an aromatic amine skeleton), are preferred as hole transport materials.

[0041] Examples of the aforementioned carbazole derivative (a compound with a carbazole skeleton) include a bicarbazole derivative (e.g., a 3,3'-bicarbazole derivative) and an aromatic amine with a carbazolyl group.

[0042] Specific examples of the bicarbazole derivative (e.g., a 3,3'-bicarbazole derivative) are 3,3'-Bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 9,9'-Bis(1,1'-biphenyl-4-yl)-3,3'-bi-9H-carbazole, 9,9'-Bis(1,1'-biphenyl-3-yl)-3,3'-bi-9H-carbazole, 9-(1,1'-Biphenyl-3-yl)-9'-(1,1'-biphenyl-4-yl)-9H,9'H-3,3'-bicarbazole (abbreviation: mBPCCBP), 9-(2-Naphthyl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP), and the like.

[0043] Specific examples of the aforementioned aromatic amine with a carbazolyl group include 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazol-3-amine (abbreviation: PCBiF), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), 4,4'-diphenyl-4"-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-Naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-Di(1-naphthyl)-4"-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 4-Phenyldiphenyl-(9-phenyl-9H-carbazol-3-yl)amine (abbreviation: PCA1BP), N,N'-Bis(9-phenylcarbazol-3-yl)-N,N'-diphenylbenzene-1,3-diamine (abbreviation: PCA2B), N,N',N''-Triphenyl-N,N',N"-tris(9-phenylcarbazol-3-yl)benzene-1,3,5-triamine (abbreviation: PCA3B), 9,9-Dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF),N-Phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluoren-2-amine (abbreviation: PCBASF), 3-[N-(9-Phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-Bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-Naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1), 3-[N-(4-Diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-Bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA2), 3,6-Bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviation: PCzTPN2), 2-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: PCASF), N-[4-(9H-carbazol-9-yl)phenyl]-N-(4-phenyl)phenylaniline (abbreviation: YGA1BP), N,N'-Bis[4-(carbazol-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F) and 4,4',4"-Tris(carbazol-9-yl)triphenylamine (abbreviation: TCTA).,

[0044] Other examples of the carbazole derivative (the compound with a carbazole skeleton) include 3-[4-(9-phenanthryl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn), 3-[4-(1-naphthyl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB) and 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA).

[0045] Specific examples of the aforementioned furan derivative (the compound with a furan framework) include compounds with a thiophene framework, such as... B. 4,4',4"-(Benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-Diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III) and 4-[4-(9-Phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), 4,4',4"-(Benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-Phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II).

[0046] Specific examples of the aforementioned aromatic amine (the compound with an aromatic amine skeleton) include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), N-(9,9-Dimethyl-9H-fluoren-2-yl)-N-{9,9-dimethyl-2-[N'-phenyl-N'-(9,9-dimethyl-9H-fluoren-2-yl)amino]-9H-fluoren-7-yl}phenylamine (abbreviation: DFLADFL), N-(9,9-Dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine (abbreviation: DPNF), 2-[N-(4-Diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPASF), 2,7-Bis[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPA2SF), 4,4',4"-Tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviation: 1'-TNATA), 4.4',4"-Tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4"-Tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: m-MTDATA), N,N'-Di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-Bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-Bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD) and 1,3,5-Tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B).

[0047] Other examples of hole transport materials are high-molecular-weight compounds, such as poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenylamino)phenyl]phenyl-N-phenylamino}phenyl)methacrylamide] (abbreviation: PTPDMA) and poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviation: poly-TPD).

[0048] It should be noted that the hole transport material is not limited to the above examples and any of the various known materials can be used alone or in combination as the hole transport material.

[0049] An oxide of a metal belonging to one of groups 4 to 8 of the periodic table can be used as the acceptor material for the hole injection layer 111. Specific examples include molybdenum oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, tungsten oxide, manganese oxide, and rhenium oxide. Among these oxides, molybdenum oxide is particularly preferred because it is stable in air, has low hygroscopic properties, and is easy to handle. It is also possible to use any of the aforementioned organic acceptor materials.

[0050] The hole injection layer 111 can be formed by any of the known film formation methods, such as a vacuum evaporation method. <lochtransportschicht>

[0051] The hole transport layer 112 transports holes injected from the first electrode 101 through the hole injection layer 111 to the light-emitting layer 113. The hole transport layer 112 contains a hole transport material. Therefore, the hole transport layer 112 can be formed using a hole transport material, such as the one described above, which can be used for the hole injection layer 111.

[0052] It should be noted that in the light-emitting device of one embodiment of the present invention, the same organic compound as that used for the hole transport layer 112 can be used for the light-emitting layer 113. The use of the same organic compounds for the hole transport layer 112 and the light-emitting layer 113 enables holes to be efficiently transported from the hole transport layer 112 to the light-emitting layer 113. <Licht emittierende Schicht>

[0053] The light-emitting layer 113 of the light-emitting device of an embodiment of the present invention contains the light-emitting substance (guest material) and one or more types of organic compounds (host material) in which the light-emitting substance is dispersed. In particular, the light-emitting layer 113 of the light-emitting device of an embodiment of the present invention preferably contains an organic compound with a specific naphthofuropyrazine framework (more preferably a naphtho[2',1':4,5]furo[2,3-b]pyrazine framework) as the host material and a phosphorescent substance (e.g., a metal-organic complex with a diazine framework (e.g., a pyrazine framework or a pyrimidine framework)), the T1 level of which (by T G The T1 level (derived from an absorption edge of the absorption spectrum of the phosphorescent substance) is shown to be within a specific range (preferably lower than or equal to 2.5 eV) as guest material. Furthermore, a difference (T H -T G ) between the T1 level of the guest material (T G ) and the T1 level of the host material (by T H (shown, which denotes the T1 level derived from the emission edge on the short wavelength side of the phosphorescence spectrum of the organic compound) in the light-emitting layer 113 preferably the formula (1) shown below. This is based on the discovery by the inventors of the present invention that, although the T1 level of the host material (T H ) higher than the T1 level of the host material (T G ) must be at least a certain value to ensure both sufficient efficiency and sufficient service life, the excessively high T1 level (T H ) often reduces the service life. It should be noted that one embodiment of the present invention has a viewpoint that differs from the conventional viewpoint, namely that the T1 level of the host material is preferably as high as possible. From this viewpoint, the T H -T G preferably lower than or equal to 0.3 eV. [Formula 3] 0.1eV≦TH−TG≦0.eV

[0054] The difference between the T1 level of the guest material (T G ) and the T1 level of the host material (by T H shown, which denotes the T1 level derived from the emission edge on the short wavelength side of the phosphorescence spectrum of the organic compound) in the light-emitting layer 113 more preferably satisfies the formula (2) shown below. [Formula 4] 0.2eV≦TB−TG≦0.4eV

[0055] With the light-emitting layer 113 having such a structure, the efficiency of energy transfer from the host material to the guest material can be high and the light-emitting device can be very reliable.

[0056] As the preceding T1 level of the host material (T H The value used is that obtained from the emission edge on the short-wavelength side of the host material's phosphorescence spectrum (onset of the spectrum). The emission edge of a phosphorescence spectrum is the wavelength at the intersection of the horizontal axis and a tangent drawn to the curve on the short-wavelength side at approximately halfway through a peak on the shortest wavelength side. From this value, the T1 level of the host material (T1) can be determined. H ) will be received.

[0057] The above T1 level of the guest material (T G The absorption edge of the absorption spectrum of the guest material can be obtained from this value. The absorption edge of an absorption spectrum is the wavelength at the intersection of the horizontal axis and a tangent drawn to the curve on the longest wavelength side of the absorption spectrum at approximately the midpoint of a peak or shoulder peak on the longest wavelength side. From this value, the T1 level of the guest material (T1) can be determined. G ) will be received.

[0058] The light-emitting substance (guest material) that can be used for the light-emitting layer 113 can be a substance that emits fluorescence (a fluorescent substance), a substance that emits phosphorescence (a phosphorescent substance), a substance that emits thermally activated delayed fluorescence (a thermally activated delayed fluorescent (TADF) material), other light-emitting substances, or the like. It should be noted that, as described above, in one embodiment of the present invention, the light-emitting substance (e.g., an organic complex with a diazine framework (e.g., a pyrazine framework or a pyrimidine framework)) whose T1 level (T G ) is within a certain range (preferably lower than or equal to 2.5 eV), is particularly preferably used. Alternatively, a substance whose emission color is blue, violet, blue-violet, green, yellow-green, yellow, orange, red, or the like may be used in a suitable manner. Alternatively, the light-emitting layer 113 may comprise a plurality of light-emitting layers containing different light-emitting substances to exhibit different emission colors (for example, complementary emission colors may be combined to obtain white light emission). Alternatively, a light-emitting layer may contain a plurality of different light-emitting substances.

[0059] In addition to electron transport materials and hole transport materials, various charge carrier transport materials, such as the TADF material described above, can be used as one or more types of organic compounds (e.g., host materials). The host material can be a hole transport material suitable for the hole transport layer 112 described above, an electron transport material suitable for the electron transport layer 114 described below, or the like. In particular, for example, one or more types of materials appropriately selected from those described in this description or from known materials can be used as hole transport materials, electron transport materials, or the like.

[0060] Examples of fluorescent substances that can be used as guest material in the light-emitting layer 113 are as follows. Other fluorescent substances can also be used.

[0061] The examples include 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-Bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), e4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-Diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), Perylene, 2,5,8,11-Tetra-tert-butylperylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N''-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis[N,N,N'-triphenyl-1,4-phenylenediamine] (abbreviation: DPABPA), N,9-Diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-Diphenyl-2-anthryl)phenyl]-N,N,N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N',N',N',N'',N',N'',N'''-Octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), Coumarin 30, N-(9,10-Diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), N-[9,10-Bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCABPhA), N-(9,10-Diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-Bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,N,N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-Bis(1,1'-biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracene-2-amine (abbreviation: 2YGABPhA), N,N,9-Triphenylanthracene-9-amine (abbreviation: DPhAPhA), Coumarin 545T, N,N'-Diphenylquinacridone (abbreviation: DPQd), Rubren, 5,12-Bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT),2-(2-{2-[4-(Dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-Methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[lj]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-Tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-Diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhAFD), 2-{2-Isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI), 2-{2-tert-Butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2,6-Bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2,6-Bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[lj]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanenitrile (abbreviation: BisDCJTM), N,N'-Diphenyl-N,N'-(1,6-pyrene-diyl)bis[(6-phenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03), 3,10-Bis[N-(9-phenyl-9H-carbazol-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10PCA2Nbf(IV)-02) and 3,10-Bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10FrA2Nbf(IV)-02). Condensed aromatic diamine compounds, typically pyrenediamine compounds, such as... B. 1,6FLPAPrn, 1,6mMemFLPAPrn and 1,6BnfAPrn-03, are particularly preferred because of their high hole-trapping properties, high emission efficiency and high reliability.

[0062] Examples of the phosphorescent substance that can be used as guest material in the light-emitting layer 113 are as follows.

[0063] The examples include an organometallic iridium complex with a 4H-triazole skeleton, such as Tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) (abbreviation: [Ir(mpptz-dmp)3]), Tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz)3]) and Tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPrptz-3b)3]), an organometallic iridium complex with a 1H-triazole skeleton, such as... B. Tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(Mptz1-mp)3]) and Tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me)3]), a metal-organic iridium complex with an imidazole skeleton, such asfac-Tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: [Ir(iPrpmi)3]) and Tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me)3]), and an organometallic iridium complex in which a phenylpyridine derivative with an electron-withdrawing group is a ligand, such as Bis[2-(4',6'-difluorophenyl)pyridinato-N,C. 2' ]iridium(III)tetrakis(1-pyrazolyl)borate (abbreviation: Flr6), Bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2' ]iridium(III)picolinate (abbreviation: Flrpic), Bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C 2' }iridium(III)picolinate (abbreviation: [Ir(CF3ppy)2(pic)]) and Bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2' ]Iridium(III)acetylacetonate (abbreviation: Flr(acac)). These compounds emit blue phosphorescence and exhibit an emission peak at 440 nm to 520 nm.

[0064] Other examples include organometallic iridium complexes with a pyrimidine framework, such as... B. Tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)3]), Tris(4-tert-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)3]), (Acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)2(acac)]), (Acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]), (Acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm)2(acac)]), (Acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm)2(acac)]) and (Acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]), organometallic iridium complexes with a pyrazine framework, such as(Acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac)]) and (Acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]), organometallic iridium complexes with a pyridine skeleton, such as Tris(2-phenylpyridinato-N,C. 2' )iridium(III) (abbreviation: [Ir(ppy)3]), Bis(2-phenylpyridinato-N,C 2' )iridium(III)acetylacetonate (abbreviation: [Ir(ppy)2(acac)]), Bis(benzo[h]quinolinato)iridium(III)acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), Tris(benzo[h]quinolinato)iridium(III) (abbreviation: [Ir(bzq)3]), Tris(2-phenylquinolinato-N,C 2' )iridium(III) (abbreviation: [Ir(pq)3]) and bis(2-phenylquinolinato-N,C 2' Iridium(III) acetylacetonate (abbreviation: [Ir(pq)2(acac)]), and a rare-earth metal complex, such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac)3(Phen)]). These are mainly compounds that emit green phosphorescence and exhibit an emission peak at 500 nm to 600 nm. It should be noted that organometallic iridium complexes with a pyrimidine framework exhibit significantly high reliability and emission efficiency and are therefore particularly preferred.

[0065] Other examples include organometallic iridium complexes with a pyrimidine framework, such as (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(5mdppm)2(dpm)]) and bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]), organometallic iridium complexes with a pyrazine framework, such as... B. (Acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr)2(acac)]), Bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: [Ir(tppr)2(dpm)]) and (Acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]), organometallic iridium complexes with a pyridine skeleton, such as Tris(1-phenylisoquinolinato-N,C 2' )iridium(III) (abbreviation: [Ir(piq)3]) and bis(1-phenylisoquinolinato-N,C 2' Iridium(III) acetylacetonate (abbreviation: [Ir(piq)2(acac)]), platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrinplatin(II) (abbreviation: PtOEP), and rare-earth metal complexes such as tris(1,3-diphenyl-1,3-propanedioneto)(monophenanthroline)europium(III) (abbreviation: [Eu(DBM)3(Phen)]) and tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviation: [Eu(TTA)3(Phen)]). These compounds emit red phosphorescence and exhibit an emission peak at 600 nm to 700 nm. Furthermore, the metal-organic iridium complexes with a pyrazine framework can provide red light emission with advantageous chromaticity.

[0066] In addition to the materials described above, known phosphorescent substances can also be used.

[0067] Examples of the TADF material that can be used as a guest material in the light-emitting layer 113 are as follows.

[0068] Examples of TADF material include a fullerene, a derivative thereof, an acridine, a derivative thereof, and an eosin derivative. Furthermore, a metal-containing porphyrin, such as one containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd), can be specified. Examples of the metal-containing porphyrin include a protoporphyrin tin fluoride complex (SnF2(Proto IX)), a mesoporphyrin tin fluoride complex (SnF2(Meso IX)), a hematoporphyrin tin fluoride complex (SnF2(Hämato IX)), a coproporphyrin tetramethyl ester tin fluoride complex (SnF2(Copro III-4Me)), an octaethylporphyrin tin fluoride complex (SnF2(OEP)), an etioporphyrin tin fluoride complex (SnF2(Etio I)) and an octaethylporphyrin platinum chloride complex (PtCl2OEP), which are represented by the following structural formulas.

[0069] Furthermore, a heterocyclic compound with a π-electron-rich heteroaromatic ring and / or a π-electron-poor heteroaromatic ring, represented by one of the following structural formulas, such as:2-(Biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-Dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), Bis[4-(9,9-dimethyl-9,10-dihydroacridin)phenyl]sulfone (abbreviation: DMAC-DPS), 10-Phenyl-10H,10'H-spiro[acridin-9,9'-anthracene]-10'-one (abbreviation: ACRSA), 4-(9'-Phenyl-3,3'-bi-9H-carbazol-9-yl)benzofuro[3,2-d]pyrimidine (abbreviation: 4PCCzBfpm), 4-[4-(9'-Phenyl-3,3'-bi-9H-carbazol-9-yl)phenyl]benzofuro[3,2-d]pyrimidine (abbreviation: 4PCCzPBfpm) or 9-[3-(4,6-Diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02).

[0070] Such a heterocyclic compound is preferred due to its excellent electron and hole transport properties, as it features a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring. Among frameworks with the π-electron-deficient heteroaromatic ring, a pyridine framework, a diazine framework (a pyrimidine framework, a pyrazine framework, and a pyridazine framework), and a triazine framework are preferred due to their high stability and reliability. In particular, a benzofuropyrimidine framework, a benzothienopyrimidine framework, a benzofuropyrazine framework, and a benzothienopyrazine framework are preferred due to their high acceptor properties and reliability.

[0071] Among frameworks with the π-electron-rich heteroaromatic ring, an acridine framework, a phenoxazine framework, a phenothiazine framework, a furan framework, a thiophene framework, and a pyrrole framework exhibit high stability and reliability; consequently, at least one of these frameworks is preferably included. A dibenzofuran framework is preferred as the furan framework. A dibenzothiophene framework is preferred as the thiophene framework. In particular, an indole framework, a carbazole framework, an indolocarbazole framework, a bicarbazole framework, and a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole framework are preferred as the pyrrole framework.

[0072] It should be noted that a substance in which the π-electron-rich heteroaromatic ring is directly bonded to the π-electron-poor heteroaromatic ring is particularly preferred, since both the electron-donating property of the π-electron-rich heteroaromatic ring and the electron-accepting property of the π-electron-poor heteroaromatic ring are enhanced, and the energy difference between the S1 level and the T1 level becomes small; therefore, thermally activated delayed fluorescence can be obtained with high efficiency. It should also be noted that an aromatic ring to which an electron-withdrawing group, such as a cyano group, is bonded can be used instead of the π-electron-poor heteroaromatic ring. An aromatic amine framework, a phenazine framework, or the like can be used as the π-electron-rich framework.A π-electron-deficient framework can be a xanthene framework, a thioxanthene dioxide framework, an oxadiazole framework, a triazole framework, an imidazole framework, an anthraquinone framework, a boron-containing framework such as phenylborane or boranthrene, an aromatic ring or a heteroaromatic ring with a cyano group or a nitrile group such as benzonitrile or cyanobenzene, a carbonyl framework such as benzophenone, a phosphine oxide framework, a sulfone framework or the like.

[0073] As described above, a π-electron-deficient framework and a π-electron-rich framework can be used instead of the π-electron-deficient heteroaromatic ring and / or the π-electron-rich heteroaromatic ring.

[0074] It should be noted that a TADF material is one that exhibits a small difference between the S1 and T1 levels and possesses a function for converting triplet excitation energy to singlet excitation energy via reverse intersystem crossing. Thus, a TADF material can, using a small amount of thermal energy, convert triplet excitation energy upwards to singlet excitation energy (i.e., reverse intersystem crossing) and efficiently generate a singlet excitation state. Furthermore, the triplet excitation energy can be converted into light emission.

[0075] An exciplex whose excitation state is formed by two types of substances has a very small difference between the S1 level and the T1 level and serves as a TADF material that can convert the triplet excitation energy into the singlet excitation energy.

[0076] A phosphorescence spectrum observed at a low temperature (e.g., 77 K to 10 K) is used in this case to define the T1 level. If the energy level corresponding to a wavelength of the line obtained by extrapolating a tangent to the fluorescence spectrum at one end on the short wavelength side is the S1 level, and the energy level corresponding to a wavelength of the line obtained by extrapolating a tangent to the phosphorescence spectrum at one end on the short wavelength side is the T1 level, then the difference between the S1 level and the T1 level of the TADF material is preferably less than or equal to 0.3 eV, more preferably less than or equal to 0.2 eV.

[0077] When the TADF material is used as a guest material in the light-emitting layer 113, the S1 level and the T1 level of the host material are preferably higher than the S1 level and the T1 level of the TADF material, respectively.

[0078] Any of the following hole transport materials or the electron transport material can be used as the host material of the light-emitting layer 113, as required. In one embodiment of the present invention, the light-emitting layer 113 is preferably formed using an organic compound with a specific naphthofuropyrazine framework (a naphtho[2',1':4,5]furo[2,3-b]pyrazine framework) as the host material and the light-emitting substance whose T1 level is less than or equal to 2.5 eV, or the metal-organic complex having a diazine framework (e.g., a pyrazine framework or a pyrimidine framework) and whose T1 level is less than or equal to 2.5 eV.Under naphthofuropyrazine scaffolds, a naphtho[2',1':4,5]furo[2,3-b]pyrazine scaffold exhibits, in particular, a high T1 level of 2.5 eV or more, which allows the T1 excitation energy to be transferred without deactivation to the light-emitting substance whose T1 level is less than or equal to 2.5 eV. Furthermore, under naphthofuropyrazine scaffolds, a naphtho[2',1':4,5]furo[2,3-b]pyrazine scaffold exhibits, in particular, a phosphorescence spectrum that largely overlaps with an MLCT absorption band of the metal-organic complex with a diazine scaffold (e.g., a pyrazine scaffold or a pyrimidine scaffold). This optimizes energy transfer efficiency and enables stable excitation of such a complex, allowing the light-emitting device to exhibit improved durability and high reliability.

[0079] An organic compound represented below by a general formula (G1) can be used as the above organic compound having a naphthofuropyrazine skeleton (a naphtho[2',1':4,5]furo[2,3-b]pyrazine skeleton).

[0080] In the formula, Q represents oxygen or sulfur, A represents a group with a molecular weight of less than or equal to 1000, and R represents 1 to R 6 each independently represents hydrogen, a substituted or unsubstituted alkyl group with 1 to 6 hydrocarbon atoms, a substituted or unsubstituted cycloalkyl group with 3 to 7 hydrocarbon atoms, or a substituted or unsubstituted aryl group with 6 to 30 hydrocarbon atoms.

[0081] Specific examples of the alkyl group with 1 to 6 carbon atoms in the above general formula (G1) are a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a neopentyl group, a hexyl group, an isohexyl group, a 3-methylpentyl group, a 2-methylpentyl group, a 2-ethylbutyl group, a 1,2-dimethylbutyl group, a 2,3-dimethylbutyl group, an n-heptyl group and the like.

[0082] Specific examples of the cycloalkyl group with 3 to 7 carbon atoms in the above general formula (G1) are a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a 1-methylcyclohexyl group, a 2,6-dimethylcyclohexyl group, a cycloheptyl group, a cyclooctyl group and the like.

[0083] Specific examples of the aryl group with 6 to 30 carbon atoms in the above general formula (G1) are a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a mesityl group, an o-biphenyl group, an m-biphenyl group, a p-biphenyl group, a 1-naphthyl group, a 2-naphthyl group, a fluorenyl group, a 9,9-dimethylfluorenyl group, a spirofluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group and the like.

[0084] The organic compound with the above structure (the naphthofuropyrazine framework (naphtho[2',1':4,5]furo[2,3-b]pyrazine framework)) is used as the host material, and a metal-organic complex with a diazine framework (e.g., a pyrazine framework or a pyrimidine framework) whose T1 level is less than or equal to 2.5 eV is used as the light-emitting substance in the light-emitting layer 113. The difference between the T1 level of the organic compound as host material and the T1 level of the light-emitting substance (guest material) is preferably greater than or equal to 0.2 eV and less than or equal to 0.4 eV. Under naphthofuropyrazine scaffolds, a naphtho[2',1':4,5]furo[2,3-b]pyrazine scaffold in particular has a high T1 level of 2.5 eV or more, which allows the T1 excitation energy to be transferred without deactivation to the light-emitting substance whose T1 level is less than or equal to 2.5 eV.Furthermore, under naphthofuropyrazine frameworks, a naphtho[2',1':4,5]furo[2,3-b]pyrazine framework exhibits, in particular, a phosphorescence spectrum that largely overlaps with an MLCT absorption band of the metal-organic complex with a diazine framework (e.g., a pyrazine framework or a pyrimidine framework). This optimizes the energy transfer efficiency and enables stable excitation of such a complex, allowing the light-emitting device to exhibit improved stability and high reliability. Such a complex can be excited more stably, and the light-emitting device can exhibit improved stability, if the light-emitting layer 113, which contains the metal-organic complex with a diazine framework (e.g.,a pyrazine skeleton or a pyrimidine skeleton) as a light-emitting substance, the difference between the T1 level of the organic compound as host material and the T1 level of the light-emitting substance (guest material) is within a reasonable range, i.e. greater than or equal to 0.2 eV and less than or equal to 0.4 eV.

[0085] Specific examples of the organic compound represented by the above general formula (G1) are shown by the following structural formulas (100) to (123).

[0086] Further hole transport materials that can be used as host material in the light-emitting layer 113 preferably include a substance having a hole mobility of higher than or equal to 1 × 10⁻⁶ 6 cm 2 / Vs is used in the case where the square root of the intensity of the electric field [V / cm] is 600. Examples of the substance are shown below.

[0087] Examples of the substance include compounds with an aromatic amine skeleton, such as:4,4'-Bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-Bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4'-Bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-Phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-Phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-Phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-Diphenyl-4"-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-Naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-Di(1-naphthyl)-4"-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-Dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF) and N-Phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluoren-2-amine (abbreviation: PCBASF), compounds with a carbazole skeleton, such as1,3-Bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-Di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-Bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP) and 3,3'-Bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), compounds with a thiophene skeleton, such as... B. 4,4',4"-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III) and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and compounds with a furan skeleton, such as 4,4',4"-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II).Among the aforementioned materials, the compound with an aromatic amine framework and the compound with a carbazole framework are preferred because these compounds are very reliable and exhibit high hole transport properties, thus contributing to a reduction in operating stress. Furthermore, the organic compounds given as examples of the second organic compound mentioned above can be used.

[0088] Preferably, a substance with an electron mobility of 1 × 10⁻⁵ is used as the electron transport material. -6 cm 2 / Vs in the case where the square root of the intensity of the electric field [V / cm] is 600. It should be noted that any of these electron transport materials described below can also be used for the electron transport layer 114 to be described below.

[0089] Specific examples of the electron transport material include metal complexes such as bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq2), tris(8-quinolinolato)aluminium(III) (abbreviation: Alq3), tris(4-methyl-8-quinolinolato)aluminium(III) (abbreviation: Almq3), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminium(III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO) and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ).

[0090] Other specific examples of the electron transport material include heterocyclic compounds with a polyazole framework, such as 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2"-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI) and 2-[3-(Dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II).

[0091] Other specific examples of the electron transport material are heterocyclic compounds with a diazine framework. The diazine framework includes, for example, dibenzoquinoxaline derivatives, such as 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II) and 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), pyrimidine frameworks, such as...4,6-Bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-Bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4-[3-(Dibenzothiophen-4-yl)phenyl]-8-(naphthalen-2-yl)-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8βN-4mDBtPBfpm), 4,8-Bis[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm), 8-[3'-(Dibenzothiophen-4-yl)(1,1'-biphenyl-3-yl)]naphtho[1',2':4,5]furo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm) and 8-[(2,2'-Binaphthalene)-6-yl]-4-[3-(dibenzothiophen-4-yl)phenyl-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm), and pyrazine derivatives, such as3,8-Bis[3-(dibenzothiophen-4-yl)phenyl]benzofuro[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 9-[(3'-Dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9mDBtBPNfpr), 8-[(3'-Dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[2',1':4,5]furo[2,3-b]pyrazine (abbreviation: 8mDBtBPNfpr(II)) and 12-[(3'-dibenzothiophen-4-yl)biphenyl-3-yl]phenanthro[9',10':4,5]furo[2,3-b]pyrazine (abbreviation: 12mDBtBPPnfpr).

[0092] Other specific examples of the electron transport material include heterocyclic compounds with a pyridine framework, such as 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy) and 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB).

[0093] Among the aforementioned materials, the heterocyclic compound with a diazine framework and the heterocyclic compound with a pyridine framework exhibit high reliability and are therefore preferable. In particular, the heterocyclic compound with a diazine (pyrimidine or pyrazine) framework exhibits high electron transport properties and contributes to a reduction in operating voltage.

[0094] The aforementioned TADF material can also be used as a host material in the light-emitting layer 113. When the TADF material is used as the host material, the triplet excitation energy generated in the TADF material is converted into singlet excitation energy by reverse intersystem crossing and transferred to the emission center substance, thereby increasing the emission efficiency of the light-emitting device. Here, the TADF material acts as an energy donor, and the emission center substance acts as an energy acceptor. Therefore, the use of the TADF material as a host material is effective when a fluorescent substance is used as the guest material. In this case, the S1 level of the TADF material is preferably higher than the S1 level of the fluorescent substance to achieve high emission efficiency.Furthermore, the T1 level of the TADF material is preferably higher than the S1 level of the fluorescent substance. Therefore, the T1 level of the TADF material is preferably higher than the T1 level of the fluorescent substance.

[0095] In addition to the above organic compounds, further examples of the organic compound that can be used for the light-emitting layer 113 are given below with regard to advantageous compatibility with a light-emitting substance (a fluorescent substance or a phosphorescent substance) (some of the following organic compounds have been described above).

[0096] In the case where the light-emitting substance is a fluorescent substance, examples of an organic compound that is preferably used in combination with the fluorescent substance include condensed polycyclic aromatic compounds, such as an anthracene derivative, a tetracene derivative, a phenanthrene derivative, a pyrene derivative, a chrysene derivative and a dibenzo[g,p]chrysene derivative.

[0097] Specific examples of the organic compound, preferably used in combination with the fluorescent substance, include 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3,6-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: DPCzPA), 3-[4-(1-naphthyl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 9,10-diphenylanthracene (abbreviation: DPAnth), N,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: CzA1PA), 4-(10-phenyl-9-anthryl)triphenylamine (abbreviation: DPhPA), YGAPA, PCAPA, N,9-Diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazol-3-amine (abbreviation: PCAPBA), N-(9,10-Diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), 6,12-Dimethoxy-5,11-diphenylchrysene, N,N,N',N',N'',N'',N'',N"',N"'-Octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), 9-[4-(10-Phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-Diphenyl-2-anthryl)phenyl]-benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-Phenyl-10-{4-(9-phenyl-9H-fluoren-9-yl)-biphenyl-4'-yl}-anthracene (abbreviation: FLPPA), 9,10-Bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 9,10-Di(2-naphthyl)anthracene (abbreviation: DNA), 2-tert-Butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 9,9'-Bianthryl (abbreviation: BANT), 9,9'-(Stilben-3,3'-diyl)diphenanthrene (abbreviation: DPNS), 9,9'-(Stilben-4,4'-diyl)diphenanthrene (abbreviation: DPNS2), 1,3,5-Tri(1-pyrenyl)benzene (abbreviation: TPB3), 5,12-Diphenyltetracene and 5,12-Bis(biphenyl-2-yl)tetracene.

[0098] In the case where the light-emitting substance is a phosphorescent substance, an organic compound with a triplet excitation energy (an energy difference between a ground state and a triplet excitation state) higher than that of the light-emitting substance is preferably selected as the organic compound used in combination with the phosphorescent substance. It should be noted that when a plurality of organic compounds (e.g., a first host material and a second host material (or a host material and an auxiliary material)) are used to form an exciplex in combination with a light-emitting substance, the plurality of organic compounds is preferably mixed with a phosphorescent substance.

[0099] In such a structure, light emission can be achieved through exciplex triplet energy transfer (ExTET), which is the transfer of energy from an exciplex to a light-emitting substance. It should be noted that a combination of the many organic compounds that readily form an exciplex is preferably used, and it is particularly preferable to combine a compound that can readily accept holes (hole transport material) and a compound that can readily accept electrons (electron transport material).

[0100] In the case where the light-emitting substance is a phosphorescent substance, examples of an organic compound (a host material or an auxiliary material) that is preferably used in combination with the phosphorescent substance include an aromatic amine, a carbazole derivative, a dibenzothiophene derivative, a dibenzofuran derivative, a zinc- or aluminum-based metal complex, an oxadiazole derivative, a triazole derivative, a benzimidazole derivative, a quinoxaline derivative, a dibenzoquinoxaline derivative, a pyrimidine derivative, a pyrazine derivative, a triazine derivative, a pyridine derivative, a bipyridine derivative, and a phenanthroline derivative.

[0101] Specific examples include 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), triazole derivatives, such as... B. 3-(4-Biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ) and 3-(4-tert-Butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole (abbreviation: p-EtTAZ), 2,2',2"-(1,3,5-Benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(Dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), 4,4'-Bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOS), Bathophenanthroline (abbreviation: Bphen), Bathocuproin (abbreviation: BCP), 2,9-Bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen) and quinoxaline derivatives and dibenzoquinoxaline derivatives, such as2-[3-(Dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(Dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-Carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-Diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(Dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II) and 6-[3-(Dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II).

[0102] Other examples include pyrimidine derivatives, such as 4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II) and 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), triazine derivatives, such as... B. 2-{4-[3-(N-Phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn) and 9-[3-(4,6-Diphenyl-1,3,5-triazine-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), and pyridine derivatives, such as 3,5-Bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy) and 1,3,5-Tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB).

[0103] As another alternative, a high molecular weight compound such as poly(2,5-pyridindiyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py) or poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl)] (abbreviation: PF-BPy) can be used.

[0104] Any of the above materials can be used in combination with a low-molecular-weight material or a high-molecular-weight material. A known method (a vacuum evaporation process, a coating process, a printing process, or the like) can be appropriately used for film formation. <elektronentransportschicht>

[0105] The electron transport layer 114 transports electrons injected from the second electrode 102 into the light-emitting layer 113. It should be noted that the electron injection layer 115, to be described below, can be provided between the electron transport layer 114 and the second electrode 102. The electron transport layer 114 contains an electron transport material. In addition to an electron transport material, the electron transport layer 114 can contain any of the following metals, metal salts, metal oxides, and metal complexes. In particular, a metal complex containing an alkali metal or an alkaline earth metal is preferably used. Any such metal, metal salt, metal oxide, and metal complex is contained in any region of the electron transport layer 114 or in any layer if, for example, the electron transport layer 114 has a multilayer structure.The LUMO level of the electron transport material in the electron transport layer 114 in contact with the light-emitting layer 113 (or a layer in contact with the light-emitting layer in the multilayer structure) is lower than the LUMO level of the host material used in the light-emitting layer 113. The difference between the LUMO level of the electron transport material and the LUMO level of the host material is preferably greater than or equal to 0.15 eV and less than or equal to 0.40 eV, or greater than or equal to 0.20 eV and less than or equal to 0.40 eV, more preferably greater than or equal to 0.20 eV and less than or equal to 0.35 eV.

[0106] The electron transport material used for the electron transport layer 114 is preferably one with a HOMO level higher than or equal to -6.0 eV. The electron mobility of the electron transport material with a HOMO level higher than or equal to -6.0 eV is preferably higher than or equal to 1 × 10⁻⁶ eV when the square root of the electric field intensity [V / cm] is 600. -7 cm 2 / Vs and less than or equal to 1 × 10 -5 cm 2 , more strongly preferred higher than or equal to 1 × 10 -7 cm 2 / Vs and less than or equal to 5 × 10 -5 cm 2 It should be noted that the electron transport material with a HOMO level higher than or equal to -6.0 eV preferably has an anthracene framework, more preferably an anthracene framework as well as a heterocyclic framework.

[0107] Examples of an organic compound used for the electron transport layer 114 include materials with high electron transport properties (electron transport materials), such as... B. an organic compound with a structure in which an aromatic ring is fused to a furan ring of a furodiazine skeleton, a metal complex with a quinoline skeleton, a metal complex with a benzoquinoline skeleton, a metal complex with an oxazole skeleton, a metal complex with a thiazole skeleton, an oxadiazole derivative, a triazole derivative, an imidazole derivative, an oxazole derivative, a thiazole derivative, a phenanthroline derivative, a quinoline derivative with a quinoline ligand, a benzoquinoline derivative, a quinoxaline derivative, a dibenzoquinoxaline derivative, a pyridine derivative, a bipyridine derivative, a pyrimidine derivative and a π-electron-deficient heteroaromatic compound (e.g. a nitrogen-containing heteroaromatic compound).In particular, some of the electron transport materials described above, which can be used as host material in the light-emitting layer 113, or the materials listed above as suitable for use as host material in combination with the fluorescent substance described above, can be used. It should be noted that other substances can also be used, provided they have an electron transport property that is superior to a hole transport property. The electron transport layers 114, 114a, and 114b each function with a single-layer structure; however, if the electron transport layer 114 has a multilayer structure with two or more layers as required, the device properties can be improved.

[0108] Any of the substances listed below can be used as metals, metal salts, metal oxides and metal complexes that can be used for the electron transport layer 114.

[0109] Examples of metals include alkali metals, alkaline earth metals, and rare earth metals. Specific examples are Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, and the like.

[0110] Examples of metal salts are halides and carbonates of the aforementioned metals. Specific examples include LiF, NaF, KF, RbF, CsF, MgF₂, CaF₂, SrF₂, BaF₂, LiCl, NaCl, KCl, RbCl, CsCl, MgCl₂, CaCl₂, SrCl₂, BaCl₂, Li₂CO₃, Cs₂CO₃, and the like.

[0111] Examples of metal oxides are oxides of the aforementioned metals. Specific examples include Li₂O, Na₂O, Cs₂O, MgO, CaO, and the like.

[0112] Metal complexes are preferred that each contain a ligand with an 8-quinoline olate structure and a monovalent metal ion. Examples of ligands with an 8-quinoline olate structure include 8-quinoline olate, methyl-substituted (e.g., 2-methyl-substituted or 5-methyl-substituted) 8-quinoline olate, and the like. It should be noted that the 8-quinoline olate structure refers to a structure in which a proton from an -OH group has been removed from substituted or unsubstituted 8-quinoline.

[0113] Examples of the aforementioned metal complexes with alkali metals or alkaline earth metals are 8-(quinoline olate)lithium (abbreviation: Liq), which is a lithium complex containing a ligand with an 8-quinoline olate structure; 8-(quinoline olate)sodium (abbreviation: Naq), which is a sodium complex containing a ligand with an 8-quinoline olate structure; 8-(quinoline olate)potassium (abbreviation: Kq), which is a potassium complex containing a ligand with an 8-quinoline olate structure; 8-(quinoline olate)magnesium (abbreviation: Mgq2), which is a magnesium complex containing a ligand with an 8-quinoline olate structure; and (8-quinoline olate)zinc (abbreviation: Znq2), which is a zinc complex containing a ligand with an 8-quinoline olate structure. likewise. <elektroneninjektionsschicht>

[0114] The electron injection layer 115 is a layer for increasing the efficiency of electron injection from the second electrode (cathode) 102 and is preferably formed using a material whose LUMO level is a small difference (0.5 eV or less) from the work function of a material of the cathode 102. Therefore, the electron injection layer 115 can be formed using an alkali metal, an alkaline earth metal, or a compound thereof, such as... B. Lithium, Cesium, Lithium Fluoride (LiF), Cesium Fluoride (CsF), Calcium Fluoride (CaF2), 8-Hydroxyquinolinateolithium (abbreviation: Liq), 2-(2-Pyridyl)phenolateolithium (abbreviation: LiPP), 2-(2-Pyridyl)-3-pyridinolatolithium (abbreviation: LiPPy), 4-Phenyl-2-(2-pyridyl)phenolateolithium (abbreviation: LiPPP), Lithium Oxide (LiO) x ) or cesium carbonate. A rare earth metal compound, such as erbium fluoride (ErF3), can also be used.

[0115] If the charge-generating layer 104 is located between two EL layers 103a and 103b, as in the light-emitting device in Fig. Given 1B, a structure can be obtained in which a multitude of EL layers are arranged one above the other between the pair of electrodes (the structure is also called a tandem structure). It should be noted that the functions and materials of the hole injection layer 111, the hole transport layer 112, the light-emitting layer 113, the electron transport layer 114, and the electron injection layer 115, which are described in Fig. 1A are represented in the same way as those of hole injection layers 111a and 111b, hole transport layers 112a and 112b, light-emitting layers 113a and 113b, electron transport layers 114a and 114b and electron injection layers 115a and 115b, which are shown in Fig. 1B will be shown. <ladungserzeugungsschicht>

[0116] In the light-emitting device in Fig. In 1B, the charge-generating layer 104 has a function for injecting electrons into the EL layer 103a on the side of the first electrode (anode) 101 and for injecting holes into the EL layer 103b on the side of the second electrode (cathode) 102 when a voltage is applied between the first electrode (anode) 101 and the second electrode (cathode) 102. The charge-generating layer 104 can be either a p-type layer, in which an electron acceptor is added to a hole transport material, or an n-type layer, in which an electron donor is added to an electron transport material. Alternatively, both of these structures can be stacked on top of each other. Alternatively, the p-type layer can be combined with an electron conduction layer and / or an electron injection buffer layer, which are described below.It should be noted that forming the charge-generating layer 104 using any of the above materials can suppress an increase in operating voltage caused by the layer arrangement of the EL layers.

[0117] In the case where the charge-generating layer 104 is a p-type layer to which an electron acceptor is added to a hole-transporting material, any of the materials described for this embodiment can be used as the hole-transporting material. Examples of suitable electron acceptors include 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, and the like. Further examples include oxides of metals from groups 4 to 8 of the periodic table. Specific examples are vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide.

[0118] In the case where the charge-generating layer 104 is an n-type layer to which an electron donor is added to an electron transport material, any of the materials described in this embodiment can be used as the electron transport material. An alkali metal, an alkaline earth metal, a rare earth metal, metals belonging to groups 2 and 13 of the periodic table, or an oxide or carbonate thereof can be used as the electron donor. In particular, lithium (Li), cesium (Cs), magnesium (Mg), calcium (Ca), ytterbium (Yb), indium (In), lithium oxide, cesium carbonate, or the like are preferably used. An organic compound, such as tetrathianaphthacene, can be used as the electron donor.

[0119] When the electron conduction layer, preferably combined with the p-type layer as described above, is placed between the electron injection buffer layer and the p-type layer, the electron conduction layer serves to prevent interaction between the electron injection buffer layer and the p-type layer and to facilitate the smooth transfer of electrons. The electron conduction layer contains at least one electron transport material, and the LUMO level of the electron transport material is preferably between the LUMO level of the electron-accepting substance in the p-type layer and the LUMO level of a substance in the electron injection buffer layer.As a specific energy level value, the LUMO level of the electron transport material in the electron conduction layer is preferably higher than or equal to -5.0 eV, more preferably higher than or equal to -5.0 eV and lower than or equal to -3.0 eV. It should be noted that the electron transport material in the electron conduction layer is preferably a phthalocyanine-based material or a metal complex comprising a metal-oxygen bond and an aromatic ligand.

[0120] For the electron injection buffer layer, a substance with high electron injection properties can be used. For example, an alkali metal, an alkaline earth metal, a rare earth metal, or a compound thereof (an alkali metal compound (including an oxide, such as lithium oxide, a halide, and a carbonate, such as lithium carbonate and cesium carbonate), an alkaline earth metal compound (including an oxide, a halide, and a carbonate), or a rare earth metal compound (including an oxide, a halide, and a carbonate)) can be used.

[0121] In cases where the electron injection buffer layer contains the electron transport material and an electron-donating substance, an organic compound such as tetrathianaphthacene (abbreviated TTN), nickelocene, or decamethylnickelocene can be used as the electron-donating substance, as can an alkali metal, an alkaline earth metal, a rare earth metal, or a compound thereof (an alkali metal compound (including an oxide, such as lithium oxide, a halide, and a carbonate, such as lithium carbonate and cesium carbonate), an alkaline earth metal compound (including an oxide, a halide, and a carbonate), or a rare earth metal compound (including an oxide, a halide, and a carbonate)). A material similar to the electron transport layer material described above can be used as the electron transport material.

[0122] Although Fig. 1B represents the structure in which two EL layers 103 are arranged on top of each other, three or more EL layers can be arranged on top of each other, with charge generation layers provided between each pair of adjacent EL layers.

[0123] The charge generation layer described above can be used instead of the electron injection layer described above. In this case, the electron injection buffer layer, the electron conduction layer, and the p-type layer are preferably arranged in this order, starting from the anode side. <substrat>

[0124] The light-emitting device described in this embodiment can be formed on any number of different substrates. It should be noted that the type of substrate is not limited to any particular kind. Examples of substrates include semiconductor substrates (e.g., a single-crystal substrate and a silicon substrate), a SOL substrate, a glass substrate, a quartz substrate, a plastic substrate, a metal substrate, a stainless steel substrate, a substrate containing a stainless steel foil, a tungsten substrate, a substrate containing a tungsten foil, a flexible substrate, a mounting film, paper containing a fiber material, and a base material film.

[0125] Examples of the glass substrate include barium borosilicate glass, aluminum borosilicate glass, and soda-lime glass. Examples of the flexible substrate, affixing film, and base material film include plastics, typically polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyethersulfone (PES); a synthetic resin, such as an acrylic resin, polypropylene, polyester, polyvinyl fluoride, polyvinyl chloride, polyamide, polyimide, an aramid resin, an epoxy resin, an evaporation-deposited inorganic film, and paper.

[0126] For the manufacture of the light-emitting device of this embodiment, a vacuum process, such as an evaporation process, or a solution process, such as a rotational coating process or an inkjet process, can be used. If an evaporation process is used, a physical vapor deposition (PVD) process, such as a sputtering process, an ion plating process, an ion beam evaporation process, a molecular beam evaporation process, or a vacuum evaporation process, a chemical vapor deposition (CVD) process, or the like can be employed.In particular, the functional layers contained in the EL layers (the hole injection layers 111, 111a and 111b, the hole transport layers 112, 112a and 112b, the light-emitting layers 113, 113a and 113b, the electron transport layers 114, 114a and 114b and the electron injection layers 115, 115a and 115b) as well as the charge generation layer 104 of the light-emitting device can be coated by an evaporation process (e.g. a vacuum evaporation process), a coating process (e.g. a dip coating process, a nozzle coating process, a rod coating process, a rotary coating process or a spray coating process), a printing process (e.g. an inkjet process, screen printing (stencil printing), offset printing (planographic printing), flexographic printing (relief printing), gravure printing, microcontact printing or nanoembossing lithography) or such training will be provided.

[0127] It should be noted that materials that can be used for the functional layers contained in the EL layers 103, 103a and 103b (the hole injection layers 111, 111a and 111b, the hole transport layers 112, 112a and 112b, the light-emitting layers 113, 113a and 113b, the electron transport layers 114, 114a and 114b and the electron injection layers 115, 115a and 115b) as well as the charge generation layer 104 of the light-emitting device described in this embodiment are not limited to the materials listed above, and other materials can be used in combination, as long as the functions of the layers are ensured. For example, a high molecular weight compound (e.g.An oligomer, a dendrimer, or a polymer), a medium-molecular-weight compound (a compound between a low-molecular-weight compound and a high-molecular-weight compound with a molecular weight of 400 to 4000), or an inorganic compound (e.g., a quantum dot material) can be used. The quantum dot material can be a gelatinous quantum dot material, an alloyed quantum dot material, a core-shell quantum dot material, a core-quantum quantum dot material, or the like.

[0128] The structures described in this embodiment can be used in appropriate combination with any of the structures described in the other embodiments. (Version 2)

[0129] This embodiment describes a light-emitting device of an embodiment of the present invention. It should be noted that a light-emitting device which is in Fig. Figure 2A shows a light-emitting active matrix device in which transistors (FETs) 202 are electrically connected to light-emitting devices 203R, 203G, 203B, and 203W via a first substrate 201. The light-emitting devices 203R, 203G, 203B, and 203W include a common EL layer 204 and each has a microcavity structure in which the optical path length between electrodes is adapted according to the emission color of the light-emitting device. The light-emitting device is a top-emission light-emitting device in which light is emitted from the EL layer 204 through color filters 206R, 206G, and 206B formed on a second substrate 205.

[0130] At the in Fig. In the light-emitting device shown in Figure 2A, a first electrode 207 is configured to serve as a reflective electrode. A second electrode 208 is configured to serve as a transflective electrode, exhibiting both semi-transparent and semi-reflective properties for light (visible light or infrared light). It should be noted that, as needed, reference may be made to the description of one of the other embodiments with regard to the electrode materials for the first electrode 207 and the second electrode 208.

[0131] In the case where, for example, Fig. 2A where the light-emitting device 203R serves as a red light-emitting device, the light-emitting device 203G serves as a green light-emitting device, the light-emitting device 203B serves as a blue light-emitting device, and the light-emitting device 203W serves as a white light-emitting device, is, as in Fig. Figure 2B shows that a distance between the first electrode 207 and the second electrode 208 in the light-emitting device 203R is adjusted to obtain an optical path length of 200R, a distance between the first electrode 207 and the second electrode 208 in the light-emitting device 203G is adjusted to obtain an optical path length of 200G, and a distance between the first electrode 207 and the second electrode 208 in the light-emitting device 203B is adjusted to obtain an optical path length of 200B. It should be noted that the optical adjustment can be carried out such that, as shown in Fig. Figure 2B shows that in the light-emitting device 203R a conductive layer 210R is arranged over the first electrode 207 and in the light-emitting device 203G a conductive layer 210G is arranged over the first electrode 207.

[0132] The second substrate 205 is equipped with the color filters 206R, 206G, and 206B. It should be noted that each color filter transmits visible light within a specific wavelength range and blocks visible light within a specific wavelength range. Therefore, as in Fig. Figure 2A shows the color filter 206R, which transmits only light in the red wavelength range, positioned so that it overlaps the light-emitting device 203R, thus enabling red light emission from the light-emitting device 203R. Similarly, the color filter 206G, which transmits only light in the green wavelength range, is positioned so that it overlaps the light-emitting device 203G, thus enabling green light emission from the light-emitting device 203G. Finally, the color filter 206B, which transmits only light in the blue wavelength range, is positioned so that it overlaps the light-emitting device 203B, thus enabling blue light emission from the light-emitting device 203B. It should be noted that the light-emitting device 203W can emit white light without any color filters.It should be noted that a black layer (black matrix) 209 can be provided at one end section of each color filter. The color filters 206R, 206G, and 206B and the black layer 209 can be covered with a cover layer formed using a transparent material.

[0133] Although the light-emitting device in Fig. 2A has a structure in which light is extracted from the side of the second substrate 205 (top-emission structure), as shown in Fig. As shown in Figure 2C, a structure is used in which light is extracted from the side of the first substrate 201, above which the FETs 202 are formed (bottom-emission structure). In the case of a light-emitting bottom-emission device, the first electrode 207 is configured as a transflective electrode and the second electrode 208 is configured as a reflective electrode. The first substrate 201 is a substrate that has at least a certain light transmittance. As shown in Fig. As shown in Figure 2C, color filters 206R', 206G' and 206B' are provided closer to the first substrate 201 than the light-emitting devices 203R, 203G and 203B.

[0134] In Fig. 2A The light-emitting devices are the red light-emitting device, the green light-emitting device, the blue light-emitting device, and the white light-emitting device; however, the light-emitting devices of an embodiment of the present invention are not limited to the foregoing, and a yellow light-emitting device or an orange light-emitting device may be used. It should be noted that with regard to the materials used for the EL layers (a light-emitting layer, a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, a charge generation layer, and the like), reference may be made, as needed, to the description of one of the other embodiments in order to fabricate each of the light-emitting devices.In this case, a color filter must be selected appropriately according to the emission color of the light-emitting device.

[0135] The above structure can be used to manufacture a light-emitting device that includes light-emitting devices exhibiting a variety of emission colors.

[0136] The structures described in this embodiment can be used in appropriate combination with any of the structures described in the other embodiments. (Version 3)

[0137] This embodiment describes a light-emitting device of an embodiment of the present invention.

[0138] The use of the device structure of the light-emitting device of one embodiment of the present invention enables the fabrication of a light-emitting active matrix device or a light-emitting passive matrix device. It should be noted that a light-emitting active matrix device has a structure comprising a combination of a light-emitting device and a transistor (FET). Therefore, a light-emitting passive matrix device and a light-emitting active matrix device are each embodiments of the present invention. It should be noted that any of the light-emitting devices described in the other embodiments can be used for the light-emitting device described in this embodiment.

[0139] In this embodiment, a light-emitting active matrix device is used based on Fig. 3A and Fig. 3B described.

[0140] Fig. 3A is a top view showing the light-emitting device, and Fig. 3B is a cross-sectional view taken along the catenary AA' in Fig. 3A was taken from the substrate. The light-emitting active matrix device includes a pixel section 302, a driver circuit section (source line driver circuit) 303, and driver circuit sections (gate line driver circuits) 304a and 304b, which are provided above a first substrate 301. The pixel section 302 and the driver circuit sections 303, 304a, and 304b are sealed with a sealant 305 between the first substrate 301 and a second substrate 306.

[0141] A connecting line 307 is provided above the first substrate 301. The connecting line 307 is electrically connected to an FPC 308, which is an external input terminal. It should be noted that the FPC 308 transmits a signal (e.g., a video signal, a clock signal, a start signal, or a reset signal) or a potential from outside to the driver circuit sections 303, 304a, and 304b. The FPC 308 may be provided with a printed circuit board (PWB). It should be noted that the light-emitting device provided with an FPC or a PWB is included in the category of a light-emitting device.

[0142] Fig. Figure 3B represents a cross-sectional structure of the light-emitting device.

[0143] Pixel section 302 contains a plurality of pixels, each containing a switching FET 311, a current-controlling FET 312, and a first electrode 313 electrically connected to FET 312. It should be noted that the number of FETs contained in each pixel is not particularly limited and can be adjusted as appropriate.

[0144] For example, FETs 309, 310, 311, and 312 can be used as staggered transistors or inverted staggered transistors without any particular restrictions. A top-gate transistor, a bottom-gate transistor, or the like can be used.

[0145] It should be noted that there is no particular restriction regarding the crystallinity of a semiconductor that can be used for FETs 309, 310, 311, and 312; an amorphous semiconductor or a semiconductor with crystallinity (a microcrystalline semiconductor, a polycrystalline semiconductor, a single-crystal semiconductor, or a semiconductor that partially contains crystalline regions) can be used. Preferably, a semiconductor with crystallinity is used, in which case a deterioration of the transistor properties can be prevented.

[0146] The semiconductor can be, for example, an element from group 14, a compound semiconductor, an oxide semiconductor, an organic semiconductor, or the like. Typical examples include a semiconductor containing silicon, a semiconductor containing gallium arsenide, or an oxide semiconductor containing indium.

[0147] The driver circuit section 303 includes the FETs 309 and 310. The driver circuit section 303 can be implemented with a circuit containing transistors of the same conduction type (either n-channel or p-channel transistors), or with a CMOS circuit containing one n-channel transistor and one p-channel transistor. Alternatively, a driver circuit can be provided externally.

[0148] An end section of the first electrode 313 is covered with an insulator 314. The insulator 314 can be formed using an organic compound, such as a negative photosensitive resin or a positive photosensitive resin (acrylic resin), or an inorganic compound, such as silicon dioxide, silicon oxynitride, or silicon nitride. The insulator 314 preferably has a curved surface with a suitable curvature at its upper or lower end section. In this case, an advantageous covering can be obtained with a film formed over the insulator 314.

[0149] An EL layer 315 and a second electrode 316 are arranged above the first electrode 313. The EL layer 315 comprises a light-emitting layer, a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, a charge generation layer, and the like.

[0150] The structure and materials described in one of the other embodiments can be used for the components of a light-emitting device 317 described in this embodiment. Although not shown, the second electrode 316 is electrically connected to the FPC 308, which is an external input terminal.

[0151] Although the cross-sectional view in Fig. Where 3B represents only a single light-emitting device 317, a plurality of light-emitting devices are arranged in a matrix in pixel section 302. Light-emitting devices emitting light of three types of colors (R, G, and B) are selectively formed in pixel section 302, thereby obtaining a light-emitting device capable of displaying a full-color image. In addition to the light-emitting devices emitting light of three types of colors (R, G, and B), light-emitting devices emitting, for example, white (W), yellow (Y), magenta (M), cyan (C), and the like can be formed. For example, the light-emitting devices emitting light of some of the aforementioned colors are used in combination with the light-emitting devices emitting light of three types of colors (R, G, and B), thereby producing effects such as…An improvement in color purity and a reduction in power consumption can be achieved. Alternatively, a light-emitting device capable of displaying a full-color image can be created by combining it with color filters. Red (R), green (G), blue (B), cyan (C), magenta (M), and yellow (Y) color filters, and the like, can be used as color filters.

[0152] When the second substrate 306 and the first substrate 301 are joined together with the sealant 305, the FETs 309, 310, 311, and 312 and the light-emitting device 317 are positioned above the first substrate 301 in a space 318 enclosed by the first substrate 301, the second substrate 306, and the sealant 305. It should be noted that the space 318 can be filled with an inert gas (e.g., nitrogen or argon) or an organic substance (including the sealant 305).

[0153] An epoxy resin, a glass frit, or the like can be used for the sealant 305. Preferably, a material with minimal moisture and oxygen permeability is used for the sealant 305. A substrate that can be used as the first substrate 301 can be used as the second substrate 306 in a similar manner. Therefore, any of the various substrates described in the other embodiments can be used appropriately. A glass substrate, a quartz substrate, or a plastic substrate made of fiber-reinforced plastic (FRP), polyvinyl fluoride (PVF), polyester, an acrylic resin, or the like can be used as the substrate. In the case where a glass frit is used for the sealant, the first substrate 301 and the second substrate 306 are preferably glass substrates with regard to adhesion.

[0154] In this way, the light-emitting active matrix device can be obtained.

[0155] In cases where the light-emitting active matrix device is deployed over a flexible substrate, the FETs and the light-emitting device can be formed directly over the flexible substrate; alternatively, the FETs and the light-emitting device can be formed over a substrate provided with a separating layer and then separated by applying heat, force, laser light, or the like to the separating layer to transfer them to a flexible substrate. The separating layer can be, for example, a layer arrangement comprising inorganic films, such as a tungsten film and a silicon oxide film, or an organic resin film made of polyimide or the like.Examples of flexible substrates include, in addition to a substrate on which a transistor can be formed, a paper substrate, a cellophane substrate, an aramid film substrate, a polyimide film substrate, a fabric substrate (including a natural fiber (silk, cotton, or hemp), a synthetic fiber (nylon, polyurethane, or polyester), a regenerated fiber (acetate, cupro, viscose, or regenerated polyester), or the like), a leather substrate, and a rubber substrate. Using any of these substrates, an increase in durability, an increase in heat resistance, a reduction in weight, and a reduction in thickness can be achieved.

[0156] The light-emitting device contained in the active matrix light-emitting unit can emit pulsed light (e.g., at a frequency of kHz or MHz) so that the light can be used for display purposes. The light-emitting device, designed using one of the aforementioned organic compounds, exhibits excellent frequency characteristics; therefore, the operating time of the light-emitting device can be reduced, leading to a decrease in power consumption. Furthermore, a reduction in operating time prevents heat generation, thus reducing the rate of deterioration of the light-emitting device.

[0157] The structures described in this embodiment can be used in appropriate combination with any of the structures described in the other embodiments. (Version 4)

[0158] In this embodiment, examples of various electronic devices and a vehicle are described, which are manufactured using the light-emitting device of an embodiment of the present invention or a light-emitting device that includes the light-emitting device of an embodiment of the present invention. It should be noted that the light-emitting device can be used primarily in a display section of the electronic device described in this embodiment.

[0159] Electronic devices that are in Fig. 4A to 4E may include a housing 7000, a display section 7001, a loudspeaker 7003, an LED lamp 7004, operating buttons 7005 (including a power switch or an operating switch), a connection terminal 7006, a sensor 7007 (a sensor with a function for measuring or detecting force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, electrical power, radiation, flow rate, humidity, gradient, vibration, odor or infrared beam), a microphone 7008 and the like.

[0160] Fig. 4A represents a portable computer which, in addition to the above components, may include a 7009 switch, a 7010 infrared connector, and the like.

[0161] Fig. 4B represents a portable image display device (e.g. a DVD player) which is equipped with a storage medium and may, in addition to the components mentioned above, include a second display section 7002, a storage medium read section 7011 and the like.

[0162] Fig. 4C represents a digital camera which has a television reception function and may, in addition to the above components, include an antenna 7014, a release button 7015, an image reception section 7016 and the like.

[0163] Fig. 4D represents a portable information terminal. The portable information terminal has a function for displaying information on three or more surfaces of the display section 7001. Here, information 7052, information 7053, and information 7054 are displayed on different surfaces. For example, a user of the portable information terminal can check information 7053, which is displayed in such a way that it can be viewed from above the portable information terminal, with the portable information terminal kept in a breast pocket of their clothing. Thus, for example, the user can see the display without removing the portable information terminal from the pocket and can decide whether to answer the call.

[0164] Fig. 4E represents a portable information terminal (e.g., a smartphone) and may include the display section 7001, the control button 7005, and the like within the housing 7000. It should be noted that the portable information terminal may include a speaker 9003, a connection port 7006, a sensor 9007, or the like. The portable information terminal can display text and image data on its various surfaces. Here, three icons 7050 are shown. Additionally, information 7051, represented by dashed rectangles, may be displayed on another surface of the display section 7001. Examples of the information 7051 include notification of the arrival of an email, SNS message, or call; the subject and sender of an email, SNS message, or the like; the date; the time; the remaining battery power; and the signal strength of an antenna.The icon 7050 or similar can be displayed in the place where the information 7051 is displayed.

[0165] Fig. 4F represents a large television set (also called a TV or television receiver) and may include the housing 7000, the display section 7001, and the like. The housing 7000 is also shown here supported by a stand 7018. The television set can be operated with a separate remote control 7111 or the like. The display section 7001 may include a touch sensor. The television set can be operated by touching the display section 7001 with a finger or the like. The remote control 7111 may be equipped with a display section for showing information output by the remote control 7111. The television channels and volume can be controlled, and images displayed on the display section 7001 can be controlled, using buttons or a touchscreen on the remote control 7111.

[0166] The in Fig. The electronic devices shown in 4A to 4F may have various functions, such as a function to display various information (a still image, a moving image, a text image, and the like) on the display section, a touchscreen function, a function to display a calendar, the date, the time, and the like, a function to control processing by means of various types of software (programs), a wireless communication function, a function to connect to various computer networks by means of a wireless communication function, a function to transmit and receive various data by means of a wireless communication function, a function to read a program or data that is / are stored in a storage medium and to display the program or data on the display section, and the like.Furthermore, the electronic device, which includes a multitude of display sections, may have the following functions: a function for displaying image data mainly on one display section while text data is mainly displayed on another display section; a function for displaying a three-dimensional image by displaying images on a multitude of display sections, taking into account parallax or the like.Furthermore, the electronic device, which includes an image reception section, may have the following functions: a function for capturing a still image, a function for capturing a moving image, a function for automatically or manually correcting a captured image, a function for saving a captured image to a storage medium (an external storage medium or a storage medium built into the camera), a function for displaying a captured image on the display section, or the like. It should be noted that functions that are intended for the [missing information] are not included. Fig. The electronic devices shown in 4A to 4F can be provided, are not limited to those described above, and the electronic devices can have various functions.

[0167] Fig. 4G is a wristwatch-like portable information terminal, which can be used, for example, as a smartwatch. The wristwatch-like portable information terminal includes the housing 7000, the display section 7001, control buttons 7022 and 7023, a connection port 7024, a band 7025, a microphone 7026, a sensor 7029, a speaker 7030, and the like. The display surface of the display section 7001 is curved, and images can be displayed on this curved surface. Furthermore, two-way communication is possible between the portable information terminal and, for example, a headset suitable for wireless communication, thus enabling hands-free operation using the portable information terminal. It should be noted that the connection port 7024 allows for two-way data transmission with another information terminal as well as charging.Wireless power supply can also be used during the charging process.

[0168] The display section 7001, which is mounted in the housing 7000 serving as a bezel, includes a non-rectangular display area. The display section 7001 can display an icon 7027, which shows the time, another icon 7028, and the like. The display section 7001 can be a touchscreen (an input / output device) that includes a touch sensor (an input device).

[0169] The smartwatch, which is in Fig. 4G, as displayed, can have various functions, such as a function to display various information (e.g., a still image, a moving image, and a text image) on the display section, a touchscreen function, a function to display a calendar, date, time, and the like, a function to control processing using various types of software (programs), a wireless communication function, a function to connect to various computer networks using a wireless communication function, a function to transmit and receive various data using a wireless communication function, and a function to read a program or data that is / are stored in a storage medium and to display the program or data on the display section.

[0170] The housing 7000 can contain a loudspeaker, a sensor (a sensor with a function to measure or detect force, displacement, position, speed, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, electrical power, radiation, flow rate, humidity, gradient, vibration, odor or infrared rays), a microphone and the like.

[0171] It should be noted that the light-emitting device of an embodiment of the present invention can be used in the display section of any of the electronic devices described in this embodiment, so that a long-life electronic device can be obtained.

[0172] Another electronic device incorporating the light-emitting device is a foldable portable information terminal, which is located in Fig. 5A to 5C are shown. Fig. 5A represents a portable information terminal 9310, which is unfolded. Fig. Figure 5B depicts the portable information terminal 9310 during unfolding or folding. Fig. Figure 5C depicts the 9310 portable information terminal in its folded state. The 9310 portable information terminal is highly portable when folded. When unfolded, the 9310 portable information terminal offers excellent searchability due to its large, seamless display area.

[0173] A display section 9311 is supported by three housings 9315 connected to each other by hinges 9313. It should be noted that the display section 9311 can be a touchscreen (an input / output device) that includes a touch sensor (an input device). The shape of the portable information terminal 9310 can be reversibly changed from an open state to a folded state by bending the display section 9311 at a junction between two housings 9315 using the hinges 9313. The light-emitting device of an embodiment of the present invention can be used for the display section 9311. Furthermore, a long-life electronic device can be obtained. A display area 9312 in the display section 9311 is a display area positioned on a side face of the folded portable information terminal 9310.The display area 9312 can show information icons, shortcuts to frequently used applications or programs, and the like, and allows for easy confirmation of information as well as starting applications and the like.

[0174] Fig. 6A and Fig. 6B represents a vehicle that incorporates the light-emitting device. The light-emitting device may be installed in the vehicle and, in particular, may be in headlights 5101 (including rear headlights), a wheel cover 5102, part of a door 5103 or the whole of a door 5103, or the like, on the outside of the vehicle. Fig. The light-emitting device may also be contained in a display section 5104, a steering wheel 5105, a gearshift lever 5106, a seat 5107, an interior rearview mirror 5108, a windscreen 5109, or the like, on the inside of the vehicle shown in Figure 6A. Fig. 6B depicted vehicle or contained in part of a glass window.

[0175] In the manner described above, electronic devices and vehicles can be obtained using the light-emitting device of an embodiment of the present invention. In this case, a long-life electronic device can be obtained. It should be noted that the light-emitting device for electronic devices and vehicles can be used in various fields, without being limited to the electronic devices described in this embodiment.

[0176] The structures described in this embodiment can be used in appropriate combination with any of the structures described in the other embodiments. (Version 5)

[0177] In this embodiment, the structure of a lighting device, which is manufactured using the light-emitting device of an embodiment of the present invention or the light-emitting device which is part of the light-emitting device, is based on Fig. 7A and Fig. 7B described.

[0178] Fig. 7A and Fig. Figure 7B shows examples of cross-sectional views of lighting devices. Fig. 7A represents a bottom-emission lighting device in which light is extracted from the side of the substrate, and Fig. 7B represents a top-emission lighting device in which light is extracted from the side of the sealing substrate.

[0179] A lighting device 4000, which is in Fig. Figure 7A shows a light-emitting device 4002 above a substrate 4001. The lighting device 4000 also includes a substrate 4003 with an unevenness on the outside of the substrate 4001. The light-emitting device 4002 includes a first electrode 4004, an EL layer 4005, and a second electrode 4006.

[0180] The first electrode 4004 is electrically connected to an electrode 4007, and the second electrode 4006 is electrically connected to an electrode 4008. An auxiliary conductor 4009, electrically connected to the first electrode 4004, can also be provided. It should be noted that an insulating layer 4010 is formed over the auxiliary conductor 4009.

[0181] The substrate 4001 and a sealing substrate 4011 are joined together by a sealing agent 4012. A desiccant 4013 is preferably provided between the sealing substrate 4011 and the light-emitting device 4002. The substrate 4003 has the following properties: Fig. 7A shows an unevenness which can increase the extraction efficiency of the light emitted by the light-emitting device 4002.

[0182] A lighting device 4200, which is in Fig. Figure 7B shows a light-emitting device 4202 above a substrate 4201. The light-emitting device 4202 includes a first electrode 4204, an EL layer 4205 and a second electrode 4206.

[0183] The first electrode 4204 is electrically connected to an electrode 4207, and the second electrode 4206 is electrically connected to an electrode 4208. An auxiliary line 4209, electrically connected to the second electrode 4206, can be provided. An insulating layer 4210 can be provided under the auxiliary line 4209.

[0184] The substrate 4201 and a sealing substrate 4211 with unevenness are joined together with a sealant 4212. A barrier film 4213 and a planarizing film 4214 can be provided between the sealing substrate 4211 and the light-emitting device 4202. The sealing substrate 4211 has the following properties: Fig. 7B shows an unevenness which can increase the extraction efficiency of the light emitted by the light-emitting device 4202.

[0185] Examples of such lighting devices include ceiling lights for interior lighting. Examples of ceiling lights include directly mounted lights and recessed lights. Such lighting devices are manufactured using a combination of the light-emitting device and a housing or cover.

[0186] Another example: Such lighting devices can be used for floor lighting, illuminating a floor and thus improving floor safety. Floor lighting can be effectively used, for example, in a bedroom, on stairs, or in a hallway. In this case, the size or shape of the floor lighting can be adapted to the area or structure of a room. The floor lighting can be a stationary lighting device, constructed using a combination of the light-emitting unit and a support.

[0187] Such lighting devices can also be used for a leaf-shaped lighting fixture (leaf-shaped lighting). The leaf-shaped lighting, which is mounted on a wall, is space-saving and can therefore be used for a wide variety of purposes. Furthermore, the surface area of ​​the leaf-shaped lighting can be easily enlarged. The leaf-shaped lighting can also be used on a wall or housing with a curved surface.

[0188] In addition to the above examples, if the light-emitting device of an embodiment of the present invention, or the light-emitting device that is part of the light-emitting device, is used as part of a piece of furniture in a room, a lighting device that serves as that piece of furniture can be obtained.

[0189] As described above, various lighting devices incorporating the light-emitting device can be obtained. It should be noted that these lighting devices are also embodiments of the present invention.

[0190] It should be noted that the structures described in this embodiment can be used in combination with one of the structures described in the other embodiments, as required. [Example 1]

[0191] In this example, a light-emitting device 1 was manufactured as a light-emitting device of an embodiment of the present invention. Its device structure, manufacturing process, and properties are described. A comparison light-emitting device 2 was manufactured, and the device properties of the two devices were compared. It should be noted that Fig. Figure 8 shows a device structure of the light-emitting devices used in this example, and Table 1 shows specific structures. The chemical formulas of materials used in this example are shown below. [Table 1] first electrode Hole injection layer Hole transport layer Light-emitting layer electron transport layer Electron injection layer second electrode 901 911 912 913 914 915 903 Light-emitting device 1 ITSO (70 nm) DBT3P-II:MoOx (2:1.60 nm) PCBBiF (20 nm) * 8mDBtBPNfpr(II)(25 nm) NBphen(15nm) LiF(1 nm) Al(200 nm) Light-emitting comparator 2 ITSO (70 nm) DBT3P-II:MoOx (2:1.60 nm) PCBBiF (20 nm) ** 12mDBtBPPnfpr(25 nm) NBphen(15nm) LiF(1 nm) Al(200 nm) * 8mDBtBPNfpr(II):PCBBiF:[Ir(dppm)2(acac)] (0.75:0.25:0.075; 40 nm)** 12mDBtBPPnfpr:PCBBiF:[Ir(dppm)2(acac)] (0.75:0.25:0.075; 40 nm) <<Herstellung der Licht emittierenden Vorrichtungen> >

[0192] Each of the light-emitting devices described in this example, as shown in Fig. Figure 8 shows a hole injection layer 911, a hole transport layer 912, a light emitting layer 913, an electron transport layer 914 and an electron injection layer 915 arranged in this order over a first electrode 901 formed over a substrate 900, and a second electrode 903 is arranged over the electron injection layer 915.

[0193] First, the first electrode 901 was formed over the substrate 900. The electrode area was set to 4 mm². 2 (2 mm × 2 mm). A glass substrate was used as substrate 900. The first electrode 901 was formed by a sputtering process using indium tin oxide containing silicon oxide (ITSO) with a thickness of 70 nm.

[0194] For pretreatment, one surface of the substrate was washed with water, baked for one hour at 200 °C, and then subjected to a 370-second UV-ozone treatment. Afterward, the substrate was transferred to a vacuum evaporation unit where the pressure was reduced to approximately 1 × 10⁻⁶ -4 The Pa had been reduced and was heated for 30 minutes in a vacuum at 170 °C in a heating chamber of the vacuum evaporation device, and then the substrate was cooled for about 30 minutes.

[0195] Next, the hole injection layer 911 was formed over the first electrode 901. After the pressure in the vacuum evaporation device was increased to 1 × 10 -4 After Pa had been reduced, the hole injection layer 911 was formed by co-evaporation to have a mass ratio of 1,3,5-tri(dibenzothiophen-4-yl)benzene (abbreviation: DBT3P-II) to molybdenum oxide of 2:1 and a thickness of 60 nm.

[0196] Subsequently, the hole transport layer 912 was formed over the hole injection layer 911. The hole transport layer 912 was formed by evaporation of N-(1,1'-Biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF) to a thickness of 20 nm.

[0197] Next, the light-emitting layer 913 was formed above the hole transport layer 912.

[0198] The light-emitting layer 913 of the light-emitting device 1 was formed by co-evaporation of bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]) as a guest material (phosphorescent material) in addition to 8-[(3'-Dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[2',1':4,5]furo[2,3-b]pyrazine (abbreviation: 8mDBtBPNfpr(II)) and PCBBiF to have a weight ratio of 8mDBtBPNfpr(II):PCBBiF:[Ir(dppm)2(acac)] = 0.75:0.25:0.075. The thickness was set to 40 nm. The light-emitting layer 913 of the light-emitting comparison device 2 was formed by co-evaporation of [Ir(dppm)2(acac)] as a guest material (phosphorescent material) in addition to 12-[(3'-Dibenzothiophen-4-yl)biphenyl-3-yl]phenanthro[9',10':4,5]furo[2,3-b]pyrazine (abbreviation: 12mDBtBPPnfpr) and PCBBiF to have a weight ratio of 12mDBtBPPnfpr:PCBBiF:[Ir(dppm)2(acac)] = 0.75:0.25:0.075. The thickness was set to 40 nm.

[0199] Next, the electron transport layer 914 was formed above the light-emitting layer 913.

[0200] The electron transport layer 914 of the light-emitting device 1 was formed as follows: 8mDBtBPNfpr(II) and 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen) were successively deposited by evaporation to thicknesses of 25 nm and 15 nm, respectively. The electron transport layer 914 of the light-emitting comparison device 2 was formed as follows: 12mDBtBPPnfpr and Bphen were successively deposited by evaporation to thicknesses of 25 nm and 15 nm, respectively.

[0201] Subsequently, the electron injection layer 915 was formed over the electron transport layer 914. The electron injection layer 915 was formed by evaporating lithium fluoride (LiF) to a thickness of 1 nm.

[0202] Subsequently, the second electrode 903 was formed above the electron injection layer 915. The second electrode 903 was formed by an evaporation process using aluminum with a thickness of 200 nm. In this example, the second electrode 903 serves as the cathode.

[0203] By the preceding steps, the light-emitting devices, each comprising an EL layer 902 between the pair of electrodes, were formed over the substrate 900. It should be noted that the hole injection layer 911, the hole transport layer 912, the light-emitting layer 913, the electron transport layer 914, and the electron injection layer 915 described above are functional layers that constitute the EL layer of an embodiment of the present invention. Furthermore, in all evaporation steps of the preceding manufacturing process, evaporation was carried out by a resistance heating process.

[0204] Each of the light-emitting devices, manufactured as described above, was sealed using another substrate (not shown) such that the substrate (not shown), to which a UV-curing sealant had been applied, was fixed to substrate 900 in a glove box containing a nitrogen atmosphere, and the substrates were bonded together in such a way that the sealant was applied to enclose the light-emitting device over substrate 900. During the sealing process, the sealant was cured with 365 nm UV light at 6 J / cm². 2 It was irradiated to solidify, and the sealant was heated at 80°C for one hour to stabilize it. <<Betriebseigenschaften der Licht emittierenden Vorrichtungen> >

[0205] The operating characteristics of the manufactured light-emitting devices were measured. It should be noted that the measurement was carried out at room temperature (in an atmosphere maintained at 25 °C). The current density-luminance characteristics are presented as results of the operating characteristics of the light-emitting devices. Fig. Figure 9 shows the voltage-luminance properties in Fig. Figure 10 shows the luminance-power efficiency characteristics. Fig. 11 shown and the voltage-current characteristics are described in Fig. 12 shown.

[0206] Table 2 shows the initial values ​​of the main properties of the light-emitting devices at approximately 1000 cd / m². 2 . [Table 2] Voltage (V) Current (mA) Current density (mA / cm³) 2 ) Chromaticity(x, y) Luminance (cd / m²) 2 ) Power efficiency (cd / A) Energy efficiency (Im / W) external quantum yield (%) Light-emitting device 1 2,9 0,058 1,5 (0,56;0,44) 1200 80 86 31 Light-emitting comparator 2 3,0 0,044 1,1 (0,56;0,44) 670 61 64 26

[0207] The results above reveal that, as in the initial properties in Fig. 9, Fig. 10, Fig. 11 to Fig. As shown in Figure 12 or Table 2, the light-emitting device 1 described in this example has a higher emission efficiency than the light-emitting comparison device 2.

[0208] Fig. Figure 13 shows emission spectra at the time when a current with a current density of 0.1 mA / cm² is applied to the light-emitting device 1 and the light-emitting comparison device 2. 2 was supplied. As in Fig. As shown in Figure 13, the emission spectrum of the light-emitting device 1 and the light-emitting comparison device 2 exhibits a peak at approximately 589 nm, which is presumably due to light emission from [Ir(dppm)2(acac)] contained in the light-emitting layer 913.

[0209] Next, reliability tests were performed on the light-emitting device 1 and the light-emitting comparison device 2. Fig. Figure 14 shows the results of the reliability tests. Fig. Figure 14 shows the vertical axis representing the normalized luminance (%) with an initial luminance of 100%, and the horizontal axis representing the operating time (h) of the devices. Reliability tests were performed using operational tests with a constant luminance of 1000 cd / cm². 2 carried out. The results in Fig. Figure 14 shows that the light-emitting device 1 has a higher reliability than the light-emitting comparison device 2.

[0210] Here it shows Fig. 21A an absorption spectrum of [Ir(dppm)2(acac)], which was used as a guest material (phosphorescent substance), in a dichloromethane solution, and Fig. Figure 21B shows an enlarged view of an absorption edge and its surroundings in the absorption spectrum. Fig. Figure 21B illustrates that the T1 level (by T G The T1 level of [Ir(dppm)2(acac)], which is derived from an absorption edge of the absorption spectrum of a phosphorescent substance, is 2.22 eV (= 559 nm). Therefore, in the light-emitting layer 913 of the light-emitting device described in this example, 18mDBtBPNfpr(II) was used as an organic compound with a naphtho[2',1':4,5]furo[2,3-b]pyrazine framework, and [Ir(dppm)2(acac)], whose T1 level is 2.22 eV (calculated from the measured absorption spectrum of the dichloromethane solution), was used as a phosphorescent substance whose T1 level is less than or equal to 2.5 eV.In the light-emitting layer 913 of the light-emitting comparison device 2, 12mDBtBPPnfpr was used as an organic compound without a naphtho[2',1':4,5]furo[2,3-b]pyrazine framework, and [Ir(dppm)2(acac)] was used as the light-emitting substance as in the light-emitting device 1.

[0211] As described above, the light-emitting device 1 of this example exhibits not only higher emission efficiency than initial properties, but also higher reliability than the light-emitting comparison device 2. This is due to an increase in the efficiency of the energy transfer of 8mDBtBPNfpr(II) in an excitation state on [Ir(dppm)2(acac)] in the light-emitting layer 913 of the light-emitting device 1 with a structure of an embodiment of the present invention.

[0212] Fig. 22A shows a phosphorescence spectrum of 8mDBtBPNfpr(II), which is an organic compound with a naphtho[2',1':4,5]furo[2,3-b]pyrazine skeleton. Fig. Figure 22B is a magnified view of an emission edge and its surroundings. The phosphorescence spectrum was measured by time-resolved spectroscopy using a mechanical shutter. A PL microscope (LabRAM HR-PL, manufactured by HORIBA, Ltd.) was used, and the measurement temperature was 10 K. Fig. 22B is the T1 level (through T H (shown, which denotes the T1 level, derived from an emission edge on the short wavelength side of the phosphorescence spectrum of the organic compound that is the host material) of 8mDBtBPNfpr(II) as host material 2.52 eV (= 492 nm). Therefore, the T H -T G in the light-emitting device 1 0.30 eV, and the following condition, represented by formula (1) of embodiment 1, is satisfied: 0.1 eV ≤ T H - T G ≤ 0.4 eV. [Example 2]

[0213] In this example, a light-emitting device 3 was manufactured as a light-emitting device of an embodiment of the present invention, and the measurement results of its properties are described.

[0214] The apparatus structure of the light-emitting device 3, which was manufactured in this example, is similar to that which was developed in Example 1 based on Fig. Section 8 has been described. Table 3 shows the specific layer structures of the device structure. The chemical formulas of the materials used in this example are as follows. [Table 3] first electrode Hole injection layer Hole transport layer Light-emitting layer electron transport layer Electron injection layer second electrode 901 911 912 913 914 915 903 Light-emitting device 3 ITSO (70nm) DBT3P-II:MoOx (2:1.45 nm) PCBBi1BP(20 nm) * 8mDBtBPNfpr(II)(20 nm) NBphen(10nm) LiF(1 nm) Al(200nm) * 8mDBtBPNfpr(II):PCCP:[Ir(ppy)2(mdppy)] (0.5:0.5:0.1; 40 nm)

[0215] It should be noted that 4,4'-diphenyl-4"-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP) was used for the hole transport layer 912. For the light-emitting layer 913, [2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium (abbreviation: Ir(ppy)2(mdppy)) was used as a guest material (phosphorescent material) in addition to 8-[(3'-dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[2',1':4,5]furo[2,3-b]pyrazine (abbreviation: 8mDBtBPNfpr(II)) and 3,3'-bis(9-phenyl-9H-carbazole) (Abbreviation: PCCP) is used. < <Betriebseigenschaften der Licht emittierenden Vorrichtung 3»

[0216] The operating characteristics of the manufactured light-emitting device 3 were measured at room temperature. It should be noted that the measurement was carried out at room temperature (in an atmosphere maintained at 25 °C).

[0217] Fig. 15, Fig. 16, Fig. 17 and Fig. Figure 18 shows the current density-luminance properties, the voltage-luminance properties, the luminance-current efficiency properties and the voltage-current properties of the light-emitting device 3.

[0218] Table 4 shows the initial values ​​of the main properties of the light-emitting device at approximately 1000 cd / m². 2 . [Table 4] Voltage (V) Current (mA) Current density (mA / cm³) 2 ) Chromaticity(x, y) Luminance (cd / m²) 2 ) Power efficiency (cd / A) Power efficiency (in watts / watt) external quantum yield (%) Light-emitting device 3 3,3 0,054 1,3 (0,34; 0,62) 1000 76 73 21

[0219] Fig. Figure 19 shows the emission spectra at the time when the light-emitting device 3 is supplied with a current with a current density of 2.5 mA / cm². 2 was supplied. As in Fig. As shown in Figure 19, the emission spectrum of the light-emitting device has a peak at about 524 nm, which is presumably due to the light emission of [Ir(ppy)2(mdppy)] contained in the light-emitting layer 913.

[0220] Here it shows Fig. 23A an absorption spectrum of [Ir(ppy)2(mdppy)], which was used as a guest material (phosphorescent substance), in a dichloromethane solution, and Fig. Figure 23B shows an enlarged view of an absorption edge and its surroundings in the absorption spectrum. Fig. Figure 23B illustrates that the T1 level (by T G The T1 level, which is derived from an absorption edge of the absorption spectrum of a phosphorescent substance, is represented by [Ir(ppy)2(mdppy)], which is a phosphorescent substance, and is 2.44 eV (= 509 nm). Therefore, in the light-emitting layer 913 of the light-emitting device described in this example, 3 8mDBtBPNfpr(II) was used as an organic compound with a naphtho[2',1':4,5]furo[2,3-b]pyrazine framework, and [Ir(ppy)2(mdppy)] was used as the light-emitting substance whose T1 level is less than or equal to 2.5 eV. Therefore, the high emission efficiency of the light-emitting device 3 of this example is due to an increase in the efficiency of the energy transfer of 8mDBtBPNfpr(II) in an excitation state on [Ir(ppy)2(mdppy)] in the light-emitting layer 913 of the light-emitting device 3 with a structure of an embodiment of the present invention. (Regeneration synthesis example 1)

[0221] A method for synthesizing 8-[(3'-Dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[2',1':4,5]furo[2,3-b]pyrazine (abbreviation: 8mDBtBPNfpr(II)), which is the organic compound used in Examples 1 and 2, is described. The structural formula of 8mDBtBPNfpr(II) is shown below. <Schritt 1: Synthese von 5-Chlor-3-(1-methoxynaphthalen-2-yl)pyrazin-2-amin>

[0222] First, 0.92 g of 3-bromo-5-chloropyrazine-2-amine, 0.96 g of 1-methoxynaphthalene-2-boronic acid, 11 ml of a 2 M aqueous sodium carbonate solution, and 22 ml of toluene were placed in a three-necked flask equipped with a reflux tube, and the air in the flask was replaced with nitrogen. The mixture in the flask was degassed by stirring under reduced pressure, and then 0.10 g of tetrakis(triphenylphosphine)palladium(0) (abbreviation: Pd(PPh3)4) was added. The mixture was stirred at 110 °C for 15 hours to initiate a reaction.

[0223] After a predetermined time, extraction with toluene was carried out. Subsequently, purification was performed by silica gel column chromatography using a mobile phase (toluene:ethyl acetate = 30:1) to obtain a pyrazine derivative, which was the target compound (0.97 g of a yellowish-white solid in a yield of 77%). The synthesis scheme of step 1 is shown below in (a-1). <Schritt 2: Synthese von 8-Chlornaphtho[1',2':4,5]furo[2,3-b]pyrazin>

[0224] Next, 0.96 g of 5-chloro-3-(1-methoxynaphthalen-2-yl)pyrazine-2-amine, obtained in step 1, 17 ml of anhydrous tetrahydrofuran, and 17 ml of acetic acid were added to a three-necked flask, and the air in the flask was replaced with nitrogen. After the flask had been cooled to -10 °C, 1.2 ml of tert-butyl nitrite were added dropwise, and the mixture was stirred at -10 °C for 1 hour and at 0 °C for 3.5 hours. After a predetermined time, 200 ml of water were added to the resulting suspension, and suction filtration was carried out, giving a pyrazine derivative, which was the target compound (0.69 g of a yellowish-white solid in 81% yield). The synthesis scheme of step 2 is shown below in (a-2). <Schritt 3: Synthese von 8-(3-Chlorphenyl)naphtho[2',1':4,5]furo[2,3-b]pyrazin>

[0225] Into a three-necked flask, 1.24 g of 8-chloronaphtho[2',1':4,5]furo[2,3-b]pyrazine, obtained in step 2, 0.81 g of 3-chlorophenylboronic acid, 7.0 mL of a 2 M aqueous potassium carbonate solution, 47 mL of toluene, and 4.7 mL of ethanol were added, and the air in the flask was replaced with nitrogen. The mixture in the flask was degassed by stirring under reduced pressure, and then 0.15 g of palladium(II) acetate (abbreviation: Pd(OAc)₂) and 0.56 g of triphenylphosphine were added. The mixture was stirred at 90 °C for 11 hours to initiate a reaction.

[0226] After a predetermined time, extraction with toluene was carried out. Subsequently, purification by silica gel column chromatography using toluene as the mobile phase was performed, yielding a pyrazine derivative, which was the target compound (1.13 g of a yellowish-white solid in a yield of 68%). The synthesis scheme of step 3 is shown below in (a-3). <Schritt 4: Synthese von 8mDBtBPNfpr(II)>

[0227] Into a three-necked flask, 1.12 g of 8-(3-chlorophenyl)naphtho[2',1':4,5]furo[2,3-b]pyrazine, obtained in step 3, 1.69 g of 3-(4-dibenzothiophene)phenylboronic acid, 3.14 g of tripotassium phosphate, 0.91 g of tert-butyl alcohol, and 27 ml of diethylene glycol dimethyl ether (abbreviated as Diglyme) were added, and the air in the flask was replaced with nitrogen. The mixture in the flask was degassed by stirring under reduced pressure, and then 37 mg of palladium(II) acetate (abbreviated as Pd(OAc)2) and 0.12 g of di(1-adamantyl)-n-butylphosphine (abbreviated as CataCXium A) were added. The mixture was stirred at 140 °C for 40.5 hours to induce a reaction.

[0228] After a predetermined time, the resulting suspension was subjected to suction filtration and washed with water and ethanol. The resulting solid was dissolved in toluene, and the mixture was filtered through a filter aid containing Celite, aluminum oxide, and Celite in that order. Recrystallization was carried out from toluene to obtain the target compound (0.99 g of a yellowish-white solid in a yield of 54%).

[0229] 0.99 g of the obtained yellowish-white solid were purified by sublimation using a train sublimation process. The solid was heated under sublimation purification conditions of 2.7 Pa pressure and 10.5 ml / min argon flow rate at 310 °C. After sublimation purification, 0.81 g of a yellowish-white solid, which was the target compound, were obtained with a recovery rate of 82%. The synthesis scheme of step 4 is shown below in (a-4).

[0230] It should be noted that the results of the analysis of the yellowish-white solid obtained in step 4 by nuclear magnetic resonance spectroscopy (1H-NMR) are shown below. 1 H-NMR diagram is shown in Fig. 20 shown. These results reveal that 8mDBtBPNfpr(II), the organic compound, was obtained in this reference synthesis example.

[0231] 1 H-NMR. δ (CDCl3): 7,47-7,49 (m, 2H), 7,60-7,62 (m, 2H), 7,66-7,88 (m, 8H), 7,91 (d, 1H), 8,05 (d, 1H), 8,13-8,14 (m, 2H), 8,20-8,23 (m, 2H), 8,29 (d, 1H), 8,48 (s, 1H), 8,55 (d, 1H), 8,91 (s, 1H).< / substrat> < / ladungserzeugungsschicht> < / elektroneninjektionsschicht> < / elektronentransportschicht> < / lochtransportschicht> < / lochinjektionsschicht>

Claims

Light-emitting device comprising: an EL layer between a pair of electrodes, wherein the EL layer comprises a light-emitting layer, wherein the light-emitting layer comprises an organic compound comprising a naphtho[2',1':4,5]furo[2,3-b]pyrazine skeleton, and a phosphorescent substance, wherein a T1 level of the phosphorescent substance TG is less than or equal to 2.5 eV, wherein the TG is a T1 level derived from an absorption edge of an absorption spectrum of the phosphorescent substance, wherein a difference between a T1 level of the organic compound TH and the T1 level of the phosphorescent substance TG satisfies formula (1), and 0.1 eV ≤ TH − TG ≤ 0.4 eV where the T H a Tl level is derived from an emission edge on a short wavelength side of a phosphorescence spectrum of the organic compound. Light-emitting device comprising: an EL layer between a pair of electrodes, wherein the EL layer comprises a light-emitting layer, the light-emitting layer comprising: an organic compound comprising a naphtho[2',1':4,5]furo[2,3-b]pyrazine framework; and a metal-organic complex comprising a diazine framework, wherein a T1 level of the metal-organic complex TG is less than or equal to 2.5 eV, wherein the TG is a T1 level derived from an absorption edge of an absorption spectrum of the metal-organic complex, wherein a difference between a T1 level of the organic compound TH and the T1 level of the metal-organic complex TG satisfies formula (1), and 0.1 eV ≤ TH − TG ≤ 0.4 eV where the T H a T1 level is derived from an emission edge on a short wavelength side of a phosphorescence spectrum of the organic compound. Light-emitting device according to claim 2, wherein the diazine framework is a pyrazine framework or a pyrimidine framework. Light-emitting device according to claim 2, wherein the difference between the T1 level of the organic compound TH and the T1 level of the metal-organic complex TG satisfies formula (2), 0.2 eV ≤ TH − TG ≤ 0.4 eV Light-emitting device comprising: an EL layer between a pair of electrodes, wherein the EL layer comprises a light-emitting layer, wherein the light-emitting layer comprises an organic compound represented by a general formula (G1) and a phosphorescent substance, wherein a T1 level of the phosphorescent substance TG is less than or equal to 2.5 eV, wherein the TG is a T1 level derived from an absorption edge of an absorption spectrum of the phosphorescent substance, where: Q represents oxygen or sulfur; A represents a group with a molecular weight of less than or equal to 1000; and R 1 to R 6 each independently represent hydrogen, a substituted or unsubstituted alkyl group with 1 to 6 hydrocarbon atoms, a substituted or unsubstituted cycloalkyl group with 3 to 7 hydrocarbon atoms, or a substituted or unsubstituted aryl group with 6 to 30 hydrocarbon atoms, where a difference between a T1 level of the organic compound T H and the T1 level of the phosphorescent substance T G a formula (1) is satisfied, and 0.1 eV ≤ TH − TG ≤ 0.4 eV where the T H a T1 level is derived from an emission edge on a short wavelength side of a phosphorescence spectrum of the organic compound. Light-emitting device according to claim 1 or 5, wherein the difference between the T1 level of the organic compound TH and the T1 level of the phosphorescent substance TG satisfies formula (2), 0.1 eV ≤ TH − TG ≤ 0.4 eV Light-emitting device comprising: the light-emitting device according to any one of claims 1, 2 and 5; and a flexible printed circuit. Electronic device comprising: the light-emitting device according to claim 7; and a microphone and / or a camera and / or a control button and / or an external connection port and / or a loudspeaker. Lighting device comprising: the light-emitting device according to any one of claims 1, 2 and 5; and a housing and / or a cover.

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