JP2019189540A - Organic compound, light emitting element, light emitting device, electronic apparatus, and illumination device - Google Patents

Abstract

To provide a novel organometallic complex, and provide a novel organometallic complex having strong resistance to electrons and holes.SOLUTION: An organometallic complex represented by the formula (100) is characterized in that: a pyridine derivative coordinated to iridium as a central metal has a cyano group at a meta or para position and a phenyl group having a dimethyl group at an ortho position as substituents.SELECTED DRAWING: None

Description

One embodiment of the present invention relates to an organic compound, a light-emitting element, a light-emitting device, an electronic device, and a lighting device. Note that one embodiment of the present invention is not limited thereto. That is, one embodiment of the present invention relates to an object, a method, a manufacturing method, or a driving method. Alternatively, one embodiment of the present invention relates to a process, a machine, a manufacture, or a composition (composition of matter). Specifically, a semiconductor device, a display device, a liquid crystal display device, and the like can be given as examples.

A light-emitting element (also referred to as an organic EL element) in which an EL layer is sandwiched between a pair of electrodes has characteristics such as thin and light weight, high-speed response to input signals, and low power consumption. It is attracting attention as a next-generation flat panel display.

In the light-emitting element, by applying a voltage between a pair of electrodes, electrons and holes injected from each electrode are recombined in the EL layer, and a light-emitting substance (organic compound) contained in the EL layer is in an excited state. Light is emitted when the excited state returns to the ground state. The types of excited states include a singlet excited state (S ^* ) and a triplet excited state (T ^* ). Light emitted from the singlet excited state is fluorescent, and light emitted from the triplet excited state is phosphorescent. being called. In addition, the statistical generation ratio of the light emitting elements is considered to be S ^* : T ^* = 1: 3.

Among the above luminescent substances, compounds that can convert energy in singlet excited state into light emission are called fluorescent compounds (fluorescent materials), and can convert energy in triplet excited state into light emission. Such a compound is called a phosphorescent compound (phosphorescent material).

Therefore, based on the above generation ratio, the theoretical limit of the internal quantum efficiency (ratio of photons generated with respect to injected carriers) in a light emitting device using each of the above light emitting substances is limited when a fluorescent material is used. Is 25%, and is 75% when a phosphorescent material is used.

That is, it is possible to obtain higher efficiency in a light emitting element using a phosphorescent material than in a light emitting element using a fluorescent material. Therefore, various kinds of phosphorescent materials have been actively developed in recent years. In particular, because of its high phosphorescent quantum yield, organometallic complexes having iridium or the like as a central metal have attracted attention (for example, Patent Document 1).

JP 2009-23938 A

As reported in the above-mentioned Patent Document 1, the development of phosphorescent materials exhibiting excellent characteristics is progressing, but the development of new materials exhibiting even better characteristics is desired.

Thus, in one embodiment of the present invention, a novel organometallic complex is provided. In one embodiment of the present invention, a novel organometallic complex with high resistance to electrons and holes is provided. Another embodiment of the present invention provides a novel organometallic complex that can be used for a light-emitting element. Another embodiment of the present invention provides a novel organometallic complex that can be used for an EL layer of a light-emitting element. In one embodiment of the present invention, a highly reliable novel light-emitting element using a novel organometallic complex is provided. In addition, a novel light-emitting device, a novel electronic device, or a novel lighting device is provided. Note that the description of these problems does not disturb the existence of other problems. One embodiment of the present invention does not necessarily have to solve all of these problems. In addition, problems other than these will be apparent from the description of the specification, drawings, claims, etc., and other problems can be extracted from the description of the specifications, drawings, claims, etc. It is.

One embodiment of the present invention is characterized in that the pyridine derivative coordinated to iridium as a central metal has a phenyl group having a cyano group at the meta position or para position and a dimethyl group at the ortho position as a substituent. An organometallic complex represented by General Formula (G1) below.

However, in General Formula (G1), A represents any one of a substituted or unsubstituted aromatic hydrocarbon ring and aromatic heterocycle having 6 to 13 carbon atoms in total. ^Further, any one of R 10 ^{to R 12} represents a CN group. R ⁹ and R ¹³ each represent an alkyl group having 1 to 6 carbon atoms. In addition, other R ^{1 to} R ⁸ , R ^{10 to} R ¹² and R ^{14 to} R ¹⁷ each independently have hydrogen, an alkyl group having 1 to 6 carbon atoms, or a total carbon number of 6 to 12 forming a ring. Or a substituted or unsubstituted aryl group having 3 to 12 carbon atoms in total to form a ring. N = 0, 1, or 2.

Note that in the above structure, A in the general formula (G1) includes any one of a benzene ring, a biphenyl skeleton, a naphthalene ring, a fluorene ring, a carbazole ring, a dibenzothiophene ring, and a dibenzofuran ring. May have a substituent.

Another embodiment of the present invention is an organometallic complex represented by General Formula (G2) below.

However, in General Formula (G2), any one of R ^{10 to} R ¹² represents a CN group. R ⁹ and R ¹³ each represent an alkyl group having 1 to 6 carbon atoms. In addition, R ^{1 to} R ⁸ , R ^{10 to} R ^12, and R ^{14 to} R ²⁰ are independently hydrogen, an alkyl group having 1 to 6 carbon atoms, and a total carbon number forming a ring is 6 carbon atoms. Or a substituted or unsubstituted aryl group having 1 to 12 carbon atoms, or a substituted or unsubstituted heteroaryl group having 3 to 12 carbon atoms in total to form a ring. N = 0, 1, or 2.

Another embodiment of the present invention is an organometallic complex represented by General Formula (G3) below.

However, in General Formula (G3), any one of R ^{10 to} R ¹² represents a CN group. R ⁹ and R ¹³ each represent an alkyl group having 1 to 6 carbon atoms. In addition, other R ^{1 to} R ⁸ , R ^{10 to} R ¹² , R ^{14 to} R ¹⁸ and R ^{20 to} R ²⁴ are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, substituted or unsubstituted. It represents either an aryl group having 6 to 12 carbon atoms or a substituted or unsubstituted heteroaryl group having 3 to 12 carbon atoms. N = 0, 1, or 2.

Another embodiment of the present invention is an organometallic complex represented by any one of Structural Formula (100), Structural Formula (101), Structural Formula (102), and Structural Formula (103).

Another embodiment of the present invention is characterized in that a pyridine derivative coordinated to iridium as a central metal has a phenyl group having a cyano group at the meta position or para position and a dimethyl group at the ortho position as a substituent. And a light-emitting element using an organometallic complex. Note that a light-emitting element having another organic compound in addition to the above organometallic complex is also included in one embodiment of the present invention.

Another embodiment of the present invention is a light-emitting element using the organometallic complex which is one embodiment of the present invention. Note that a light-emitting element formed using the organometallic complex which is one embodiment of the present invention for an EL layer between a pair of electrodes or a light-emitting layer included in the EL layer is also included in one embodiment of the present invention. . In addition to a light-emitting element, a light-emitting device including a transistor, a substrate, and the like is also included in the scope of the invention. Furthermore, in addition to these light-emitting devices, an electronic device or lighting device including a microphone, a camera, an operation button, an external connection portion, a housing, a cover, a support base, a speaker, or the like is also included in the scope of the invention.

The organometallic complex which is one embodiment of the present invention can be used for a light-emitting layer of a light-emitting element in combination with another organic compound. That is, since light emission from the triplet excited state can be obtained from the light emitting layer, the efficiency of the light emitting element can be increased, which is very effective. Therefore, a light-emitting element in which the organometallic complex which is one embodiment of the present invention is combined with another organic compound and used in the light-emitting layer is included in one embodiment of the present invention. In addition to the above, a structure in which a third substance is added to the light-emitting layer may be employed.

One embodiment of the present invention includes a light-emitting device including a light-emitting element, and further includes a lighting device including the light-emitting device. Therefore, the light-emitting device in this specification refers to an image display device or a light source (including a lighting device). Also, a connector such as a flexible printed circuit (FPC) or TCP (Tape Carrier Package) attached to the light emitting device, a module provided with a printed wiring board at the end of the TCP, or a COG (Chip On Glass) attached to the light emitting element. It is assumed that the light emitting device also includes all modules on which IC (integrated circuit) is directly mounted by the method.

One embodiment of the present invention can provide a novel organometallic complex. In one embodiment of the present invention, a novel organometallic complex having high resistance to electrons and holes can be provided. In one embodiment of the present invention, a novel organometallic complex that can be used for a light-emitting element can be provided. In one embodiment of the present invention, a novel organometallic complex that can be used for an EL layer of a light-emitting element can be provided. In addition, a highly reliable novel light-emitting element using the novel organometallic complex which is one embodiment of the present invention can be provided. In addition, a novel light-emitting device, a novel electronic device, or a novel lighting device can be provided. Note that the description of these effects does not disturb the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. It should be noted that the effects other than these are naturally obvious from the description of the specification, drawings, claims, etc., and it is possible to extract the other effects from the descriptions of the specification, drawings, claims, etc. It is.

4A and 4B illustrate a structure of a light-emitting element. FIG. 6 illustrates a light-emitting device. FIG. 6 illustrates a light-emitting device. 6A and 6B illustrate electronic devices. 6A and 6B illustrate electronic devices. The figure explaining a motor vehicle. The figure explaining an illuminating device. ¹ H-NMR chart of an organometallic complex represented by Structural Formula (100). The ultraviolet-visible absorption spectrum and emission spectrum in the solution of the organometallic complex shown to Structural formula (100). ¹ H-NMR chart of an organometallic complex represented by Structural Formula (101). An ultraviolet / visible absorption spectrum and an emission spectrum of an organometallic complex represented by the structural formula (101) in a solution. ¹ H-NMR chart of an organometallic complex represented by Structural Formula (102). An ultraviolet / visible absorption spectrum and an emission spectrum of an organometallic complex represented by the structural formula (102) in a solution. ¹ H-NMR chart of an organometallic complex represented by Structural Formula (103). An ultraviolet / visible absorption spectrum and an emission spectrum of an organometallic complex represented by the structural formula (103) in a solution. 3A and 3B illustrate a light-emitting element. FIG. 6 shows current density-luminance characteristics of Light-Emitting Element 1, Light-Emitting Element 2, and Comparative Light-Emitting Element 3. FIG. 10 shows voltage-luminance characteristics of Light-Emitting Element 1, Light-Emitting Element 2, and Comparative Light-Emitting Element 3. FIG. 11 shows luminance-current efficiency characteristics of the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3. FIG. 11 shows voltage-current characteristics of the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3. FIG. 6 shows emission spectra of the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3. FIG. 6 shows reliability of the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3. The figure which shows the result by molecular orbital calculation.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and various changes can be made in form and details without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments below.

Note that the position, size, range, and the like of each component illustrated in the drawings and the like may not represent the actual position, size, range, or the like for easy understanding. Therefore, the disclosed invention is not necessarily limited to the position, size, range, or the like disclosed in the drawings and the like.

Further, in this specification and the like, in describing the structure of the invention with reference to the drawings, the same reference numerals are used in different drawings.

(Embodiment 1)
In this embodiment, an organometallic complex which is one embodiment of the present invention will be described.

In the organometallic complex which is one embodiment of the present invention, a pyridine derivative coordinated to iridium which is a central metal has a phenyl group having a cyano group at a meta position or a para position and a dimethyl group at an ortho position as a substituent. It has a structure represented by the following general formula (G1).

In General Formula (G1), A represents any one of a substituted or unsubstituted aromatic hydrocarbon ring and aromatic heterocycle having 6 to 13 carbon atoms in total. ^Further, any one of R 10 ^{to R 12} represents a CN group. R ⁹ and R ¹³ each represent an alkyl group having 1 to 6 carbon atoms. In addition, other R ^{1 to} R ⁸ , R ^{10 to} R ¹² and R ^{14 to} R ¹⁷ each independently have hydrogen, an alkyl group having 1 to 6 carbon atoms, or a total carbon number of 6 to 12 forming a ring. Or a substituted or unsubstituted aryl group having 3 to 12 carbon atoms in total to form a ring. N = 0, 1, or 2.

Note that A in the general formula (G1) represents any one of an aromatic hydrocarbon ring and an aromatic heterocyclic ring having 6 to 13 carbon atoms in total forming the ring, and the aromatic hydrocarbon ring and the aromatic Specific examples of the heterocyclic ring include a benzene ring, a biphenyl skeleton, a naphthalene ring, a fluorene ring, a carbazole ring, a dibenzothiophene ring, and a dibenzofuran ring. Further, these rings or skeletons may have a substituent.

In addition, an organometallic complex which is another embodiment of the present invention has a structure represented by the following general formula (G2).

In General Formula (G2), any one of R ^{10 to} R ¹² represents a CN group. R ⁹ and R ¹³ each represent an alkyl group having 1 to 6 carbon atoms. In addition, R ^{1 to} R ⁸ , R ^{10 to} R ^12, and R ^{14 to} R ²⁰ are independently hydrogen, an alkyl group having 1 to 6 carbon atoms, and a total carbon number forming a ring is 6 carbon atoms. Or a substituted or unsubstituted aryl group having 1 to 12 carbon atoms, or a substituted or unsubstituted heteroaryl group having 3 to 12 carbon atoms in total to form a ring. N = 0, 1, or 2.

In the organometallic complex represented by the general formula (G1) and the general formula (G2), the substitution is preferably a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a sec-butyl group, an alkyl group having 1 to 6 carbon atoms such as tert-butyl group, n-pentyl group, n-hexyl group, phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 1-naphthyl group, This represents substitution with a substituent such as an aryl group having 6 to 12 carbon atoms such as 2-naphthyl group, 2-biphenyl group, 3-biphenyl group, 4-biphenyl group. Further, these substituents may be bonded to each other to form a ring.

In the organometallic complex represented by the general formula (G1) and the general formula (G2), R ^{1 to} R ¹⁷ in the general formula (G1) or R ^{1 to} R ²⁰ in the general formula (G2). When any of these represents an alkyl group having 1 to 6 carbon atoms, specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, an isobutyl group, and a tert-butyl group. , Pentyl group, isopentyl group, sec-pentyl group, tert-pentyl group, neopentyl group, hexyl group, isohexyl group, sec-hexyl group, tert-hexyl group, neohexyl group, 3-methylpentyl group, 2-methylpentyl group 2-ethylbutyl group, 1,2-dimethylbutyl group, 2,3-dimethylbutyl group and the like.

In the organometallic complex represented by General Formula (G1) and General Formula (G2), R ^{1 to} R ⁸ , R ^{10 to} R ^12, and R ^{14 to} R ¹⁷ in General Formula (G1), or When any of R ^{1 to} R ⁸ , R ^{10 to} R ^12, and R ^{14 to} R ²⁰ in General Formula (G2) represents a substituted or unsubstituted aryl group having 6 to 12 carbon atoms forming a ring Specific examples of are, for example, phenyl group, biphenyl group, naphthyl group, or indenyl group.

In the organometallic complex represented by General Formula (G1) and General Formula (G2), R ^{1 to} R ⁸ , R ^{10 to} R ^12, and R ^{14 to} R ¹⁷ in General Formula (G1), or Specific examples of the substituted or unsubstituted heteroaryl group having 3 to 12 carbon atoms in which any of R ^{1 to} R ⁸ , R ^{10 to} R ¹² and R ^{14 to} R ²⁰ in General Formula (G2) form a ring Examples include triazinyl group, pyrazinyl group, pyrimidinyl group, pyridinyl group, quinolinyl group, isoquinolinyl group, benzothienyl group, benzofuranyl group, indolyl group, dibenzothienyl group, dibenzofuranyl group, carbazolyl group, and the like.

Next, specific structural formulas of the organometallic complex which is one embodiment of the present invention described above are shown below.

Note that the organometallic complexes represented by the structural formulas (100) to (117) are examples of the organometallic complex represented by the general formula (G1), and the organometallic complex which is one embodiment of the present invention Not limited to this.

Next, an example of a method for synthesizing the organometallic complex which is one embodiment of the present invention represented by the following general formula (G1) will be described.

<< Method for Synthesizing Organometallic Complex Represented by General Formula (G1) >>
First, the case where n = 2 in the general formula (G1) will be described.

In the case of n = 2, as one embodiment of the present invention, an organometallic complex represented by the following general formula (G1-1) is obtained.

Note that the organometallic complex represented by the general formula (G1-1) includes a binuclear complex (P1) having a structure crosslinked with a halogen, a general formula (A-1), and a general formula (A-1), as shown in the following synthesis scheme (A-1). It can be obtained by reacting the pyridine compound represented by G0-a) in an inert gas atmosphere.

Note that in the above synthesis scheme (A-1), X represents a halogen atom, and A represents a substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocyclic ring having 6 to 13 carbon atoms in total. Represents either one. ^Further, any one of R 10 ^{to R 12} represents a CN group. R ⁹ and R ¹³ each represent an alkyl group having 1 to 6 carbon atoms. In addition, other R ^{1 to} R ⁸ , R ^{10 to} R ¹² and R ^{14 to} R ¹⁷ each independently have hydrogen, an alkyl group having 1 to 6 carbon atoms, or a total carbon number of 6 to 12 forming a ring. Or a substituted or unsubstituted aryl group having 3 to 12 carbon atoms in total to form a ring.

In addition, the organometallic complex obtained above (general formula (G1-1)) may be further reacted by irradiation with light or heat to obtain isomers such as geometric isomers and optical isomers. . Note that these isomers are also represented by the above general formula (G1-1) and are organometallic complexes which are one embodiment of the present invention.

As another method, after reacting a dinuclear complex (P1) having a structure crosslinked with halogen and a dechlorinating agent such as silver trifluoromethanesulfonate to precipitate silver chloride, Then, the pyridine compound represented by the general formula (G0-a) in the synthesis scheme (A-1) is reacted in an inert gas atmosphere to obtain an organometallic complex (general formula (G1-1)). May be.

Next, the case where n = 3 in the general formula (G1) will be described.

In the case of n = 3, as one embodiment of the present invention, an organometallic complex represented by General Formula (G1-2) below is obtained.

Note that the organometallic complex represented by the general formula (G1-2) includes a binuclear complex (P2) having a structure crosslinked with a halogen, a general formula (B-1), and a general formula (B-1), as shown in the following synthesis scheme (B-1). It can be obtained by reacting the pyridine compound represented by G0-a) in an inert gas atmosphere.

Note that in the above synthesis scheme (B-1), X represents a halogen atom, and A represents a substituted or unsubstituted aromatic hydrocarbon ring and aromatic heterocyclic ring having 6 to 13 carbon atoms in total. Represents either one. ^Further, any one of R 10 ^{to R 12} represents a CN group. R ⁹ and R ¹³ each represent an alkyl group having 1 to 6 carbon atoms. In addition, other R ^{1 to} R ⁸ , R ^{10 to} R ¹² and R ^{14 to} R ¹⁷ each independently have hydrogen, an alkyl group having 1 to 6 carbon atoms, or a total carbon number of 6 to 12 forming a ring. Or a substituted or unsubstituted aryl group having 3 to 12 carbon atoms in total to form a ring.

In addition, the organometallic complex (general formula (G1-2)) obtained above may be further reacted by irradiation with light or heat to obtain isomers such as geometric isomers and optical isomers. . Note that these isomers are also represented by the above general formula (G1-2) and are organometallic complexes which are one embodiment of the present invention.

As another method, after reacting a dinuclear complex (P2) having a halogen-crosslinked structure with a dechlorinating agent such as silver trifluoromethanesulfonate to precipitate silver chloride, The pyridine compound represented by the general formula (G0-b) in the above synthesis scheme (B-1) is reacted in an inert gas atmosphere to obtain an organometallic complex (general formula (G1-2)). May be.

Next, the case where n = 1 in the general formula (G1) will be described.

In the case of n = 1, as one embodiment of the present invention, an organometallic complex represented by the following general formula (G1-3) is obtained.

Note that the organometallic complex represented by the general formula (G1-3) includes a dinuclear complex (P2) having a structure crosslinked with a halogen, a general formula (C1), and a general formula (C-1), as shown in the following synthesis scheme (C-1). It can be obtained by reacting the pyridine compound represented by G0-b) in an inert gas atmosphere.

Note that in the above synthesis scheme (C-1), X represents a halogen atom, and A represents a substituted or unsubstituted aromatic hydrocarbon ring and aromatic heterocyclic ring having 6 to 13 carbon atoms in total. Represents either one. ^Further, any one of R 10 ^{to R 12} represents a CN group. R ⁹ and R ¹³ each represent an alkyl group having 1 to 6 carbon atoms. In addition, other R ^{1 to} R ⁸ , R ^{10 to} R ¹² and R ^{14 to} R ¹⁷ each independently have hydrogen, an alkyl group having 1 to 6 carbon atoms, or a total carbon number of 6 to 12 forming a ring. Or a substituted or unsubstituted aryl group having 3 to 12 carbon atoms in total to form a ring.

In addition, the organometallic complex obtained above (general formula (G1-3)) may be further reacted by irradiation with light or heat to obtain isomers such as geometric isomers and optical isomers. . Note that these isomers are also represented by the above general formula (G1-3) and are organometallic complexes which are one embodiment of the present invention.

As another method, after reacting a dinuclear complex (P2) having a halogen-crosslinked structure with a dechlorinating agent such as silver trifluoromethanesulfonate to precipitate silver chloride, Then, the pyridine compound represented by the general formula (G0-b) in the synthesis scheme (C-1) is reacted in an inert gas atmosphere to obtain an organometallic complex (general formula (G1-3)). May be.

As described above, the method for synthesizing the organometallic complex represented by the general formula (G1) has been described as the organometallic complex which is one embodiment of the present invention; however, the present invention is not limited thereto, and other synthesizing methods. May also be synthesized.

The organometallic complex which is one embodiment of the present invention is an organometallic complex having strong resistance to electrons and holes. This is because the organometallic complex which is one embodiment of the present invention has a phenyl group orthometalated with iridium, a phenyl group having a CN group as a substituent, and a phenyl group having a CN group as a substituent This is due to the structure having a dimethyl group as a dialkyl group at the ortho position. The organometallic complex which is one embodiment of the present invention has a phenyl group ortho-metalated with iridium and a phenyl group having a CN group as a substituent, thereby stabilizing the HOMO and LUMO of the complex. Therefore, the resistance of the complex to electrons and holes can be increased. On the other hand, a phenyl group having a strong electron-attracting group such as a CN group as a substituent is considered to be unstable in radical cation. Decomposition is suppressed. That is, by having a dialkyl group at the ortho position of the phenyl group having the CN group as a substituent, the phenyl group having the CN group as a substituent and the phenyl group orthometalated with iridium are not flat. , It can be said that HOMO spread to a phenyl group having a CN group as a substituent is suppressed, and a hole is difficult to enter. Therefore, it can be said that the organometallic complex which is one embodiment of the present invention is an organometallic complex having high resistance to electrons and holes.

Further, by using the organometallic complex which is one embodiment of the present invention, a highly reliable light-emitting element, light-emitting device, electronic device, or lighting device can be realized.

Note that in this embodiment, the organometallic complex which is one embodiment of the present invention is described; however, one embodiment of the present invention is not limited thereto. In other words, the invention can be combined with various aspects of the invention shown in other embodiments.

(Embodiment 2)
In this embodiment, a light-emitting element which is one embodiment of the present invention will be described. Note that for the light-emitting element described in this embodiment, an organometallic complex which is one embodiment of the present invention can be used.

≪Basic structure of light emitting element≫
FIG. 1A illustrates a light-emitting element in which an EL layer is sandwiched between a pair of electrodes. Specifically, an EL layer 103 including a light-emitting layer is sandwiched between the first electrode 101 and the second electrode 102.

In FIG. 1B, a plurality of (two layers in FIG. 1B) EL layers (103a and 103b) are provided between a pair of electrodes, and the charge generation layer 104 is sandwiched between the EL layers. 1 illustrates a light-emitting element having a stacked structure (tandem structure). Such a light-emitting element having a tandem structure can realize a light-emitting device that can be driven at a low voltage and has low power consumption.

Note that when a voltage is applied to the first electrode 101 and the second electrode 102, the charge generation layer 104 injects electrons into one EL layer (103a or 103b) and the other EL layer (103b or 103a). ) Has a function of injecting holes. Therefore, in FIG. 1B, when a voltage is applied to the first electrode 101 so that the potential is higher than that of the second electrode 102, electrons are injected from the charge generation layer 104 into the EL layer 103a, and the EL layer 103b. Holes are injected into the.

The charge generation layer 104 preferably has a property of transmitting visible light from the viewpoint of light extraction efficiency (specifically, the visible light transmittance of the charge generation layer 104 is 40% or more). In addition, the charge generation layer 104 functions even when it has lower conductivity than the first electrode 101 or the second electrode 102.

FIG. 1C illustrates a stacked structure of the EL layer 103. In FIG. 1C, when the first electrode 101 functions as an anode, the EL layer 103 is formed over the first electrode 101 with a hole injection layer 111, a hole transport layer 112, The light emitting layer 113, the electron transport layer 114, and the electron injection layer 115 are sequentially stacked. In the case of having a plurality of EL layers as in the tandem structure illustrated in FIG. 1B, each EL layer is sequentially stacked as described above from the anode side. Note that when the first electrode 101 is a cathode and the second electrode 102 is an anode, the stacking order is reversed.

Each of the light-emitting layers 113 included in the EL layers (103, 103a, and 103b) includes a light-emitting substance and a plurality of substances as appropriate in combination, so that fluorescent light emission or phosphorescence light emission having a desired light emission color can be obtained. be able to. Alternatively, the light-emitting layer 113 may have a stacked structure with different emission colors. Note that in this case, different materials may be used for the light-emitting substance and other substances used for the stacked light-emitting layers. Alternatively, different light emission colors may be obtained from the plurality of EL layers (103a and 103b) illustrated in FIG. In this case as well, the light-emitting substance and other substances used for each light-emitting layer may be different materials.

The light-emitting element which is one embodiment of the present invention may have a structure in which light emission obtained from the EL layers (103, 103a, and 103b) is resonated between both electrodes to increase the light emission obtained. For example, in FIG. 1C, the first electrode 101 is a reflective electrode and the second electrode 102 is a semi-transmissive / semi-reflective electrode to form a micro optical resonator (microcavity) structure, and an EL layer. The light emission obtained from 103 can be increased.

Note that in the case where the first electrode 101 of the light-emitting element is a reflective electrode having a stacked structure of a reflective conductive material and a light-transmitting conductive material (transparent conductive film), a film of the transparent conductive film Optical adjustment can be performed by controlling the thickness. Specifically, the distance between the first electrode 101 and the second electrode 102 is near mλ / 2 (where m is a natural number) with respect to the wavelength λ of light obtained from the light-emitting layer 113. It is preferable to adjust as follows.

Further, in order to amplify desired light (wavelength: λ) obtained from the light emitting layer 113, an optical distance from the first electrode 101 to a region (light emitting region) where desired light of the light emitting layer is obtained, and a second The optical distance from the electrode 102 of the light emitting layer 113 to the region (light emitting region) from which desired light can be obtained is adjusted to be in the vicinity of (2m ′ + 1) λ / 4 (where m ′ is a natural number). Is preferred. Note that the light emitting region herein refers to a recombination region between holes and electrons in the light emitting layer 113.

By performing such optical adjustment, the spectrum of specific monochromatic light obtained from the light emitting layer 113 can be narrowed, and light emission with good color purity can be obtained.

However, in the above case, the optical distance between the first electrode 101 and the second electrode 102 is strictly the total thickness from the reflective region of the first electrode 101 to the reflective region of the second electrode 102. it can. However, since it is difficult to precisely determine the reflection region in the first electrode 101 or the second electrode 102, it is assumed that any position of the first electrode 101 and the second electrode 102 is the reflection region. The above-mentioned effect can be sufficiently obtained. Strictly speaking, the optical distance between the first electrode 101 and the light emitting layer from which desired light can be obtained is the optical distance between the reflective region in the first electrode 101 and the light emitting region in the light emitting layer from which desired light is obtained. It can be said that it is a distance. However, since it is difficult to strictly determine the reflection region in the first electrode 101 and the light-emitting region in the light-emitting layer from which desired light can be obtained, any position of the first electrode 101 can be set as the reflection region, the desired region. It is assumed that the above-described effects can be sufficiently obtained by assuming an arbitrary position of the light emitting layer from which light is obtained as the light emitting region.

In the case where the light-emitting element illustrated in FIG. 1C has a microcavity structure, light with different wavelengths (monochromatic light) can be extracted even if the EL layer is common. Accordingly, it is not necessary to perform separate coloring (for example, RGB) for obtaining different emission colors, and high definition can be achieved. A combination with a colored layer (color filter) is also possible. In addition, since it is possible to increase the light emission intensity in the front direction of the specific wavelength, it is possible to reduce power consumption.

Note that in the above light-emitting element which is one embodiment of the present invention, at least one of the first electrode 101 and the second electrode 102 includes a light-transmitting electrode (a transparent electrode, a semi-transmissive / semi-reflective electrode, or the like). To do. When the light-transmitting electrode is a transparent electrode, the transparent electrode has a visible light transmittance of 40% or more. In the case of a semi-transmissive / semi-reflective electrode, the visible light reflectance of the semi-transmissive / semi-reflective electrode is 20% to 80%, preferably 40% to 70%. These electrodes preferably have a resistivity of 1 × 10 ⁻² Ωcm or less.

In the light-emitting element which is one embodiment of the present invention described above, when one of the first electrode 101 and the second electrode 102 is a reflective electrode (reflective electrode), the reflective electrode is visible. The light reflectance is 40% to 100%, preferably 70% to 100%. The electrode preferably has a resistivity of 1 × 10 ⁻² Ωcm or less.

<< Specific structure and manufacturing method of light-emitting element >>
Next, a specific structure and a manufacturing method of the light-emitting element which is one embodiment of the present invention will be described. Note that in FIGS. 1A to 1D, when the reference numerals are common, the description is also common.

<First electrode and second electrode>
As materials for forming the first electrode 101 and the second electrode 102, the following materials can be used in appropriate combination as long as the functions of both electrodes in the element structure described above can be satisfied. For example, a metal, an alloy, an electrically conductive compound, a mixture thereof, and the like can be used as appropriate. Specifically, an In—Sn oxide (also referred to as ITO), an In—Si—Sn oxide (also referred to as ITSO), an In—Zn oxide, and an In—W—Zn oxide can be given. In addition, 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 ), A metal such as neodymium (Nd), and an alloy containing an appropriate combination thereof. In addition, elements belonging to Group 1 or Group 2 of the periodic table of elements not exemplified above (for example, lithium (Li), cesium (Cs), calcium (Ca), strontium (Sr)), europium (Eu), ytterbium Rare earth metals such as (Yb), alloys containing these in appropriate combinations, other graphene, and the like can be used.

In the light-emitting element illustrated in FIG. 1, in the case where the EL layer 103 having a stacked structure as illustrated in FIG. 1C is provided and the first electrode 101 is an anode, the positive electrode of the EL layer 103 is formed over the first electrode 101. A hole injection layer 111 and a hole transport layer 112 are sequentially stacked by a vacuum deposition method. In addition, as illustrated in FIG. 1D, when a plurality of EL layers (103a and 103b) having a stacked structure are stacked with the charge generation layer 104 interposed therebetween and the first electrode 101 is an anode, the first electrode In addition to sequentially stacking the hole injection layer 111a and the hole transport layer 112a of the EL layer 103a on the substrate 101 by the vacuum deposition method, the EL layer 103a and the charge generation layer 104 are sequentially stacked and then generated. Similarly, the hole injection layer 111b and the hole transport layer 112b of the EL layer 103b are sequentially stacked over the layer 104.

<Hole injection layer and hole transport layer>
The hole injection layer (111, 111a, 111b) is a layer for injecting holes from the first electrode 101 serving as an anode or the charge generation layer (104) into the EL layers (103, 103a, 103b). , A layer containing a material having a high hole injection property.

Examples of the material having a high hole injection property include transition metal oxides such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide. In addition, phthalocyanine compounds such as phthalocyanine (abbreviation: H ₂ Pc) and copper phthalocyanine (abbreviation: CuPC) can be used.

Further, 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 An aromatic amine compound such as -naphthyl) -N- (9-phenylcarbazol-3-yl) amino] -9-phenylcarbazole (abbreviation: PCzPCN1), or the like can be used.

In addition, poly (N-vinylcarbazole) (abbreviation: PVK), poly (4-vinyltriphenylamine) (abbreviation: PVTPA), poly [N- (4), which are high molecular compounds (oligomers, dendrimers, polymers, and the like). -{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) or the like can be used. Alternatively, a polymer system to which an acid such as poly (3,4-ethylenedioxythiophene) / poly (styrenesulfonic acid) (abbreviation: PEDOT / PSS), polyaniline / poly (styrenesulfonic acid) (PAni / PSS) is added A compound etc. can also be used.

As a material having a high hole-injecting property, a composite material including a hole-transporting material and an acceptor material (electron-accepting material) can also be used. In this case, electrons are extracted from the hole transporting material by the acceptor material, and holes are generated in the hole injection layer (111, 111a, 111b), via the hole transporting layer (112, 112a, 112b). Holes are injected into the light emitting layer (113, 113a, 113b). Note that the hole injection layer (111, 111a, 111b) may be formed as a single layer made of a composite material including a hole transporting material and an acceptor material (electron accepting material). The material and the acceptor material (electron-accepting material) may be stacked in separate layers.

The hole transport layer (112, 112a, 112b) is configured to transfer holes injected from the first electrode 101 or the charge generation layer 104 by the hole injection layer (111, 111a, 111b) to the light emitting layer (113, 113a, 113b). Note that the hole transport layers (112, 112a, 112b) are layers containing a hole transport material. As the hole transporting material used for the hole transport layer (112, 112a, 112b), a material having a HOMO level that is the same as or close to the HOMO level of the hole injection layer (111, 111a, 111b) should be used. Is preferred.

As an acceptor material used for the hole-injection layer (111, 111a, 111b), an oxide of a metal belonging to Groups 4 to 8 in the periodic table can be used. Specific examples include molybdenum oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, tungsten oxide, manganese oxide, and rhenium oxide. Among these, molybdenum oxide is especially preferable because it is stable in the air, has a low hygroscopic property, and is easy to handle. In addition, organic acceptors such as quinodimethane derivatives, chloranil derivatives, and hexaazatriphenylene derivatives can be used. Specifically, 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F ₄ -TCNQ), chloranil, 2,3,6,7,10,11 -Hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN) or the like can be used. In particular, a compound in which an electron withdrawing group is bonded to a condensed aromatic ring having a plurality of heteroatoms such as HAT-CN is preferable because it is thermally stable. [3] Radialene derivatives having an electron-withdrawing group (particularly a halogen group such as a fluoro group or a cyano group) are preferable because of their very high electron-accepting properties. Specifically, α, α ′, α ″ − 1,2,3-cyclopropanetriylidenetris [4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α, α ′, α ″ -1,2,3-cyclopropanetriylidenetris [2,6-dichloro-3,5-difluoro-4- (trifluoromethyl) benzeneacetonitrile], α, α ′, α ″ -1,2,3-cyclopropanetriylidentris [2,3,4 , 5,6-pentafluorobenzeneacetonitrile] and the like.

As a hole transporting material used for the hole injection layer (111, 111a, 111b) and the hole transport layer (112, 112a, 112b), a substance having a hole mobility of 10 ⁻⁶ cm ² / Vs or more is used. preferable. Note that other than these substances, any substance that has a property of transporting more holes than electrons can be used.

As the hole transporting material, a material having a high hole transporting property such as a π-electron rich heteroaromatic compound (for example, a compound having a carbazole skeleton or a compound having a furan skeleton) or a compound having an aromatic amine skeleton is preferable.

Specific examples of the hole transporting material 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- (9,9f-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: DFALDFL), N- (9,9-dimethyl-2-diphenylamino-9H-fluorene- 7-yl) diphenylamine (abbreviation: DPNF), 2- [N- (4-diphenylaminophenyl) -N-phenylamino] spiro-9,9'-bifluorene (abbreviation: DPASF), 4-phenyl-4'- (9-phenyl-9H-carbazol-3-yl) triphenylamine (abbreviation: PCBA1BP), 3- [4- (9-phenanthryl) -phenyl] -9-phenyl-9H-carbazole (abbreviation: PCPPn), N -(4-Biphenyl) -N- (9,9-dimethyl-9H-fluoren-2-yl) -9-phenyl-9H-carbazole 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: PCBBANB), 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), 2- [N- (9-phenylcarbazol-3-yl) -N-phenylamino] spiro-9,9′-bifluorene (abbreviation: PCASF), 2 7-bis [N- (4-diphenylaminophenyl) -N-phenylamino] -spiro-9,9′-bifluorene (abbreviation: DPA2SF), 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 the like can be used. In addition, 3- [4- (1-naphthyl) -phenyl] -9-phenyl-9H-carbazole (abbreviation: PCPN), 4,4 ′, 4 ″ -tris (carbazol-9-yl) triphenylamine ( Abbreviation: TCTA), 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] biphe Nyl (abbreviation: DPAB), N, N′-bis {4- [bis (3-methylphenyl) amino] phenyl} -N, N′-diphenyl- (1,1′-biphenyl) -4,4′- Compounds having an aromatic amine skeleton such as diamine (abbreviation: DNTPD), 1,3,5-tris [N- (4-diphenylaminophenyl) -N-phenylamino] benzene (abbreviation: DPA3B), 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), 3,3′-bis (9-phenyl-9H-carbazole) (abbreviation: PCCP), 3- [N- (4-diphenylaminophenyl) -N-phenylamino] -9-pheny Carbazole (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), 3- [N- (9-phenylcarbazol-3-yl) -N-phenylamino] -9-phenyl Carbazole (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: PCz) CN1), 1,3,5-tris [4- (N-carbazolyl) phenyl] benzene (abbreviation: TCPB), 9- [4- (10-phenyl-9-anthracenyl) phenyl] -9H-carbazole (abbreviation: CzPA) and other compounds having a carbazole skeleton, 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: DBTF)
LP-III), 4- [4- (9-phenyl-9H-fluoren-9-yl) phenyl] -6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and the like, 4,4 ′ , 4 ″-(benzene-1,3,5-triyl) tri (dibenzofuran) (abbreviation: DBF3P-II), 4- {3- [3- (9-phenyl-9H-fluoren-9-yl) phenyl ] A compound having a furan skeleton such as phenyl} dibenzofuran (abbreviation: mmDBFFLBi-II).

Further, 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: Polymer compounds such as Poly-TPD can also be used.

However, the hole transporting material is not limited to the above, and a hole injection layer (111, 111a, 111b) and a hole transporting layer may be used as a hole transporting material by combining one or more known various materials. (112, 112a, 112b). Note that each of the hole transport layers (112, 112a, 112b) may be formed of a plurality of layers. That is, for example, a first hole transport layer and a second hole transport layer may be laminated.

In the light-emitting element illustrated in FIG. 1D, the light-emitting layer 113a is formed over the hole-transport layer 112a of the EL layer 103a by a vacuum evaporation method. In addition, after the EL layer 103a and the charge generation layer 104 are formed, the light emitting layer 113b is formed on the hole transport layer 112b of the EL layer 103b by a vacuum evaporation method.

<Light emitting layer>
The light emitting layers (113, 113a, 113b) are layers containing a light emitting substance. Note that as the light-emitting substance, a substance exhibiting a luminescent color such as blue, purple, blue-violet, green, yellow-green, yellow, orange, or red is appropriately used. In addition, by using different light emitting substances for the plurality of light emitting layers (113a, 113b), a structure that exhibits different light emission colors (for example, white light emission obtained by combining light emission colors having complementary colors) can be obtained. Furthermore, a stacked structure in which one light emitting layer includes different light emitting substances may be used.

In addition to the light emitting substance (guest material), the light emitting layer (113, 113a, 113b) may include one or more organic compounds (host material, assist material). As the one or more kinds of organic compounds, one or both of a hole transporting material and an electron transporting material described in this embodiment can be used.

There is no particular limitation on a light-emitting substance that can be used for the light-emitting layers (113, 113a, and 113b), and a light-emitting substance that changes singlet excitation energy into light emission in the visible light region or triplet excitation energy for light emission in the visible light region. A luminescent material can be used. Examples of the light emitting substance include the following.

Examples of the light-emitting substance that converts singlet excitation energy into light emission include substances that emit fluorescence (fluorescent materials). For example, pyrene derivatives, anthracene derivatives, triphenylene derivatives, fluorene derivatives, carbazole derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, dibenzos Examples include quinoxaline derivatives, quinoxaline derivatives, pyridine derivatives, pyrimidine derivatives, phenanthrene derivatives, and naphthalene derivatives. In particular, a pyrene derivative is preferable because of its high emission quantum yield. Specific examples of the pyrene derivative include N, N′-bis (3-methylphenyl) -N, N′-bis [3- (9-phenyl-9H-fluoren-9-yl) phenyl] pyrene-1,6. -Diamine (abbreviation: 1,6 mM emFLPAPrn), N, N'-diphenyl-N, N'-bis [4- (9-phenyl-9H-fluoren-9-yl) phenyl] pyrene-1,6-diamine (abbreviation) : 1,6FLPAPrn), N, N′-bis (dibenzofuran-2-yl) -N, N′-diphenylpyrene-1,6-diamine (abbreviation: 1,6FrAPrn), N, N′-bis (dibenzothiophene) -2-yl) -N, N′-diphenylpyrene-1,6-diamine (abbreviation: 1,6ThAPrn), N, N ′-(pyrene-1,6-diyl) bis [(N-phenylbenzo [b ] [1,2-d] furan) -6-amine] (abbreviation: 1,6BnfAPrn), N, N ′-(pyrene-1,6-diyl) bis [(N-phenylbenzo [b] naphtho [1 , 2-d] furan) -8-amine] (abbreviation: 1,6BnfAPrn-02), N, N ′-(pyrene-1,6-diyl) bis [(6, N-diphenylbenzo [b] naphtho [ 1,2-d] furan) -8-amine] (abbreviation: 1,6BnfAPrn-03).

In addition, 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′-bis [4- (9H-carbazol-9-yl) phenyl] -N, N′-diphenyl Stilbene-4,4′-diamine (abbreviation: YGA2S), 4- (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), 4- (10-phenyl-9-anthryl) -4 ′-(9-phenyl-9H-carbazol-3-yl) Triphenylamine (abbreviation: PCBAPA), 4- [4- (10-phenyl-9-anthryl) phenyl] -4 ′-(9-phenyl-9H-carbazol-3-yl) triphenylamine (abbreviation: PCBAPBA) Perylene, 2,5,8,11-tetra- (tert-butyl) perylene (abbreviation: TBP), 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) or the like can be used.

Examples of the light-emitting substance that converts triplet excitation energy into light emission include a substance that emits phosphorescence (phosphorescent material) and a thermally activated delayed fluorescence (TADF) material that exhibits thermally activated delayed fluorescence. .

Examples of phosphorescent materials include organometallic complexes, metal complexes (platinum complexes), and rare earth metal complexes. Since these exhibit different emission colors (emission peaks) for each substance, they are appropriately selected and used as necessary.

Examples of phosphorescent materials that exhibit blue or green color and whose emission spectrum peak wavelength is 450 nm or more and 570 nm or less include the following substances.

For example, tris {2- [5- (2-methylphenyl) -4- (2,6-dimethylphenyl) -4H-1,2,4-triazol-3-yl-κN2] phenyl-κC} iridium (III ) (Abbreviation: [Ir (mpppz-dmp) ₃ ]), tris (5-methyl-3,4-diphenyl-4H-1,2,4-triazolato) iridium (III) (abbreviation: [Ir (Mptz) ₃ ], Tris [4- (3-biphenyl) -5-isopropyl-3-phenyl-4H-1,2,4-triazolate] iridium (III) (abbreviation: [Ir (iPrptz-3b) ₃ ]), tris [3- (5-biphenyl) -5-isopropyl-4-phenyl-4H-1,2,4-triazolato] iridium (III) _{(abbreviation: [Ir (iPr5btz) 3]} ), like An organometallic complex having a 4H-triazole skeleton, tris [3-methyl-1- (2-methylphenyl) -5-phenyl-1H-1,2,4-triazolato] iridium (III) (abbreviation: [Ir (Mptz1 -Mp) ₃ ]), tris (1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolate) iridium (III) (abbreviation: [Ir (Prptz1-Me) ₃ ]) An organometallic complex having a 1H-triazole skeleton, fac-tris [1- (2,6-diisopropylphenyl) -2-phenyl-1H-imidazole] iridium (III) (abbreviation: [Ir (iPrpmi) ₃ ]), Tris [3- (2,6-dimethylphenyl) -7-methylimidazo [1,2-f] phenanthridinato] iridium (III) (abbreviated _{: [Ir (dmpimpt-Me)} 3] an organometallic complex having an imidazole skeleton, such as), bis [2- (4 ', 6'-difluorophenyl) pyridinato -N, C ^2'] iridium (III) tetrakis ( 1-pyrazolyl) borate (abbreviation: FIr6), bis [2- (4 ′, 6′-difluorophenyl) pyridinato-N, C ^{2 ′} ] iridium (III) picolinate (abbreviation: FIrpic), bis {2- [3 ', 5'-bis (trifluoromethyl) phenyl] pyridinato-N, C ^2' } iridium (III) picolinate (abbreviation: [Ir (CF ₃ ppy) ₂ (pic)]), bis [2- (4 ′ , 6'-difluorophenyl) pyridinato -N, C ^{2 ']} iridium (III) acetylacetonate (abbreviation: FIracac) having a electron-withdrawing group such as Organometallic complexes of phenylpyridine derivative ligand.

Examples of the phosphorescent material which exhibits green or yellow and has an emission spectrum peak wavelength of 495 nm or more and 590 nm or less include the following substances.

For example, tris (4-methyl-6-phenylpyrimidinato) iridium (III) (abbreviation: [Ir (mppm) ₃ ]), tris (4-t-butyl-6-phenylpyrimidinato) iridium (III) (Abbreviation: [Ir (tBupppm) 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 (tBupppm) ₂ (acac)]), (acetylacetonato) bis [6- (2- Norbornyl) -4-phenylpyrimidinato] iridium (III) (abbreviation: [Ir (nbppm) ₂ (acac)]), (acetylacetona G) Bis [5-methyl-6- (2-methylphenyl) -4-phenylpyrimidinato] iridium (III) (abbreviation: [Ir (mpmppm) ₂ (acac)]), (acetylacetonato) bis { 4,6-dimethyl-2- [6- (2,6-dimethylphenyl) -4-pyrimidinyl-κN3] phenyl-κC} iridium (III) (abbreviation: [Ir (dmppm-dmp) ₂ (acac)]) , (Acetylacetonato) bis (4,6-diphenylpyrimidinato) iridium (III) (abbreviation: [Ir (dppm) ₂ (acac)]), an organometallic complex having a pyrimidine skeleton, (acetylacetonato ) bis (3,5-dimethyl-2-phenylpyrazinato) iridium (III) _{(abbreviation: [Ir (mppr-Me)} 2 (acac)]), ( Sechiruasetonato) bis (5-isopropyl-3-methyl-2-phenylpyrazinato) iridium (III) _{(abbreviation: [Ir (mppr-iPr)} 2 (acac)]) organometallic complex having a pyrazine 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 ')} b Indium (III) _{(abbreviation: [Ir (pq) 3]} ), bis (2-phenylquinolinato--N, C ^{2 ')} iridium (III) acetylacetonate _{(abbreviation: [Ir (pq) 2 (} acac)] ), An bis (2,4-diphenyl-1,3-oxazolate-N, C ^{2 ′} ) iridium (III) acetylacetonate (abbreviation: [Ir (dpo) ₂ (acac )]), Bis {2- [4 ′-(perfluorophenyl) phenyl] pyridinato-N, C ^{2 ′} } iridium (III) acetylacetonate (abbreviation: [Ir (p-PF-ph) ₂ (acac)) ], Bis (2-phenylbenzothiazolate-N, C ^{2 ′} ) iridium (III) acetylacetonate (abbreviation: [Ir (bt) ₂ (acac)]) In addition to metal complexes, rare earth metal complexes such as tris (acetylacetonato) (monophenanthroline) terbium (III) (abbreviation: [Tb (acac) ₃ (Phen)]) can be given.

Examples of the phosphorescent material which exhibits yellow or red and has an emission spectrum peak wavelength of 570 nm or more and 750 nm or less include the following substances.

For example, (diisobutyrylmethanato) bis [4,6-bis (3-methylphenyl) pyrimidinato] iridium (III) (abbreviation: [Ir (5 mdppm) ₂ (divm)]), bis [4,6-bis ( 3-methylphenyl) pyrimidinato] (dipivaloylmethanato) iridium (III) (abbreviation: [Ir (5 mdppm) ₂ (dpm)]), (dipivaloylmethanato) bis [4,6-di (naphthalene- Organometallic complexes having a pyrimidine skeleton such as 1-yl) pyrimidinato] iridium (III) (abbreviation: [Ir (d1npm) ₂ (dpm)]), (acetylacetonato) bis (2,3,5-triphenyl) Pirajinato) iridium (III) _{(abbreviation: [Ir (tppr) 2 (} acac)]), bis (2,3,5-triphenylpyrazinato (Dipivaloylmethanato) iridium (III) _{(abbreviation: [Ir (tppr) 2 (} dpm)]), ( acetylacetonato) bis [2,3-bis (4-fluorophenyl) quinoxalinato] iridium (III) (Abbreviation: [Ir (Fdpq) ₂ (acac)]) or an organometallic complex having a pyrazine skeleton, or tris (1-phenylisoquinolinato-N, C ^{2 ′} ) iridium (III) (abbreviation: [Ir (Piq) ₃ ]), bis (1-phenylisoquinolinato-N, C ^{2 ′} ) iridium (III) acetylacetonate (abbreviation: [Ir (piq) ₂ (acac)]) Organometallic complex, 2,3,7,8,12,13,17,18-octaethyl-21H, 23H-porphyrin platinum (II) (abbreviation: [PtOEP ) Platinum complex, tris such as (1,3-diphenyl-1,3-propanedionato) (monophenanthroline) europium (III) _{(abbreviation: [Eu (DBM) 3 (} Phen)]), tris [1- And a rare earth metal complex such as (2-thenoyl) -3,3,3-trifluoroacetonato] (monophenanthroline) europium (III) (abbreviation: [Eu (TTA) ₃ (Phen)]).

As the organic compound (host material, assist material) used for the light emitting layer (113, 113a, 113b), a substance having an energy gap larger than the energy gap of the light emitting substance (guest material) may be selected and used. Good. In addition, what was mentioned as a positive hole transport material mentioned above, and the material mentioned as an electron transport material mentioned later can also be used as such an organic compound (host material, assist material).

When the light-emitting substance is a fluorescent material, it is preferable to use an organic compound having a large singlet excited state energy level and a small triplet excited state energy level as the host material. Note that in addition to the hole-transporting material and the electron-transporting material described in this embodiment, a bipolar material can be used as the host material; however, a substance that satisfies the above conditions is more preferable. For example, anthracene derivatives and tetracene derivatives are also suitable.

Therefore, as a host material combined with a fluorescent light-emitting substance, for example, 9-phenyl-3- [4- (10-phenyl-9-anthryl) phenyl] -9H-carbazole (abbreviation: PCzPA), PCPN, 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: 2 mBnfPPA), 9-phenyl-10- {4- (9-phenyl-9H-fluoren-9-yl) biphenyl-4'-yl} anthracene (Abbreviation: FLPPA), 5,12-diphenyltetracene, 5,12-bis (biphenyl-2-yl) tetracene, etc. .

When the light-emitting substance is a phosphorescent material, an organic compound having a triplet excitation energy larger than the triplet excitation energy (energy difference between the ground state and the triplet excited state) of the light-emitting substance may be selected as the host material. Note that in addition to the hole-transporting material and the electron-transporting material described in this embodiment, a bipolar material can be used as the host material; however, a substance that satisfies the above conditions is more preferable. For example, condensed polycyclic aromatic compounds such as anthracene derivatives, phenanthrene derivatives, pyrene derivatives, chrysene derivatives and dibenzo [g, p] chrysene derivatives are also suitable.

Therefore, as a host material combined with a phosphorescent light-emitting substance, for example, 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, 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 ′ ″-octaphenyldibenzo [g, p] chrysene-2,7,10,15-tetraa (Abbreviation: DBC1), CzPA, 3,6-diphenyl-9- [4- (10-phenyl-9-anthryl) phenyl] -9H-carbazole (abbreviation: DPCzPA), 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 ′-(stilbene-3,3′-diyl) diphenanthrene (abbreviation: DPNS), 9,9 ′-(stilbene-4,4 ′ -Diyl) diphenanthrene (abbreviation: DPNS2), 1,3,5-tri (1-pyrenyl) benzene (abbreviation: TPB3), and the like.

In the case where a plurality of organic compounds are used for the light emitting layer (113, 113a, 113b), it is preferable to use a compound that forms an exciplex mixed with a phosphorescent material. Note that with such a structure, light emission using ExTET (Exciplex-Triple Energy Transfer), which is energy transfer from the exciplex to the light-emitting substance, can be obtained. In this case, various organic compounds can be used in appropriate combination. However, in order to efficiently form an exciplex, a compound that easily receives holes (hole transporting material) and a compound that easily receives electrons (electrons) A combination with a transportable material) is particularly preferred.

TADF material is a material that can up-convert triplet excited state to singlet excited state with a little thermal energy (interverse crossing) and efficiently emits light (fluorescence) from singlet excited state. is there. As a condition for efficiently obtaining thermally activated delayed fluorescence, the energy difference between the triplet excited level and the singlet excited level is 0 eV or more and 0.2 eV or less, preferably 0 eV or more and 0.1 eV or less. Can be mentioned. In addition, delayed fluorescence in the TADF material refers to light emission having a remarkably long lifetime while having a spectrum similar to that of normal fluorescence. The lifetime is 10 ⁻⁶ seconds or longer, preferably 10 ⁻³ seconds or longer.

Examples of the TADF material include fullerene and derivatives thereof, acridine derivatives such as proflavine, and eosin. In addition, metal-containing porphyrins including magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), palladium (Pd), and the like can be given. Examples of the metal-containing porphyrin include a protoporphyrin-tin fluoride complex (SnF ₂ (Proto IX)), a mesoporphyrin-tin fluoride complex (SnF ₂ (Meso IX)), and a hematoporphyrin-tin fluoride complex (SnF _2). (Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF ₂ (Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF ₂ (OEP)), etioporphyrin-tin fluoride complex (SnF ₂ (Etio I)), octaethylporphyrin-platinum chloride complex (PtCl ₂ OEP), and the like.

Other TADF materials include 2- (biphenyl-4-yl) -4,6-bis (12-phenylindolo [2,3-a] carbazol-11-yl) -1,3,5-triazine ( PIC-TRZ), 2- {4- [3- (N-phenyl-9H-carbazol-3-yl) -9H-carbazol-9-yl] phenyl} -4,6-diphenyl-1,3,5- Triazine (PCCzPTzn), 2- [4- (10H-phenoxazin-10-yl) phenyl] -4,6-diphenyl-1,3,5-triazine (PXZ-TRZ), 3- [4- (5- Phenyl-5,10-dihydrophenazin-10-yl) phenyl] -4,5-diphenyl-1,2,4-triazole (PPZ-3TPT), 3- (9,9-dimethyl-9H-acridine-10- ) -9H-xanthen-9-one (ACRXTN), bis [4- (9,9-dimethyl-9,10-dihydroacridine) phenyl] sulfone (DMAC-DPS), 10-phenyl-10H, 10′H A heterocyclic compound having a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring such as spiro [acridine-9,9′-anthracene] -10′-one (ACRSA) can be used. In addition, a substance in which a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring are directly bonded increases both the donor property of the π-electron rich heteroaromatic ring and the acceptor property of the π-electron deficient heteroaromatic ring. This is particularly preferable because the energy difference between the singlet excited state and the triplet excited state becomes small.

In addition, when using TADF material, it can also be used in combination with another organic compound.

The light emitting layer (113, 113a, 113b) can be formed by appropriately using the above materials. The above materials can be used for forming the light emitting layers (113, 113a, 113b) by combining with a low molecular material or a high molecular material.

In the light-emitting element illustrated in FIG. 1D, an electron-transport layer 114a is formed over the light-emitting layer 113a of the EL layer 103a. Further, after the EL layer 103a and the charge generation layer 104 are formed, the electron transport layer 114b is formed over the light emitting layer 113b of the EL layer 103b.

<Electron transport layer>
The electron transport layer (114, 114a, 114b) is a layer that transports electrons injected from the second electrode 102 to the light emitting layer (113, 113a, 113b) by the electron injection layer (115, 115a, 115b). . Note that the electron transport layers (114, 114a, 114b) are layers containing an electron transport material. The electron transporting material used for the electron transporting layer (114, 114a, 114b) is preferably a substance having an electron mobility of 1 × 10 ⁻⁶ cm ² / Vs or higher. Note that other than these substances, any substance that has a property of transporting more electrons than holes can be used.

As an electron transporting material, in addition to a metal complex having a quinoline skeleton, a metal complex having a benzoquinoline skeleton, a metal complex having an oxazole skeleton, a metal complex having a thiazole skeleton, etc., an oxadiazole derivative, a triazole derivative, an imidazole derivative, Π-electron deficiency including oxazole derivatives, thiazole derivatives, phenanthroline derivatives, quinoline derivatives with quinoline ligands, benzoquinoline derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, and other nitrogen-containing heteroaromatic compounds A material having a high electron transporting property such as a type heteroaromatic compound can be used.

Specific examples of the electron transporting material include tris (8-quinolinolato) aluminum (III) (abbreviation: Alq ₃ ), tris (4-methyl-8-quinolinolato) aluminum (abbreviation: Almq ₃ ), bis (10-hydroxy). Benzo [h] quinolinato) beryllium (abbreviation: BeBq ₂ ), bis (2-methyl-8-quinolinolato) (4-phenylphenolato) aluminum (III) (abbreviation: BAlq), bis (8-quinolinolato) zinc (II) ) (Abbreviation: Znq), a metal complex having a quinoline skeleton or a benzoquinoline skeleton, bis [2- (2-benzoxazolyl) phenolato] zinc (II) (abbreviation: ZnPBO), bis [2- (2- Benzothiazolyl) phenolato] zinc (II) (abbreviation: ZnBTZ), bis [2- (2-hydroxyphenyl) Nzochiazorato] zinc (abbreviation: Zn _{(BTZ) 2)} metal complex having oxazole skeleton or thiazole skeleton of the like.

In addition to metal complexes, 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-oxadiazole) Oxadiazole derivatives such as 2-yl) phenyl] -9H-carbazole (abbreviation: CO11), 3- (4′-tert-butylphenyl) -4-phenyl-5- (4 ″ -biphenyl) -1 , 2,4-triazole (abbreviation: TAZ), 3- (4-tert-butylphenyl) -4- (4-ethylphenyl) -5- (4-biphenylyl) -1,2,4-triazole (abbreviation: p-EtTAZ) An azole derivative, 2,2 ′, 2 ″-(1,3,5-benzenetriyl) tris (1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2- [3- (dibenzothiophene-4) -Il) phenyl] -1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II) and other imidazole derivatives (including benzimidazole derivatives) and 4,4′-bis (5-methylbenzoxazol-2-yl) ) Oxazole derivatives such as stilbene (abbreviation: BzOs), bathophenanthroline (abbreviation: Bphen), bathocuproin (abbreviation: BCP), 2,9-bis (naphthalen-2-yl) -4,7-diphenyl-1,10- Phenanthroline derivatives such as phenanthroline (abbreviation: NBphen), 2- [3- (dibenzothiol N-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] dibe Quinoxaline derivatives such as Nzo [f, h] quinoxaline (abbreviation: 6mDBTPDBq-II), or dibenzoquinoxaline derivatives, 3,5-bis [3- (9H-carbazol-9-yl) phenyl] pyridine (abbreviation: 35DCzPPy) Pyridine derivatives such as 1,3,5-tri [3- (3-pyridyl) phenyl] benzene (abbreviation: TmPyPB), 4,6-bis [3- (phenanthrene-9-yl) phenyl] pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis [3- (4-dibenzothienyl) phenyl] pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis [3- (9H-carbazol-9-yl) phenyl ] Pyrimidine derivatives such as pyrimidine (abbreviation: 4,6mCzP2Pm), 2- {4- [3- (N-phenyl-) H- carbazol-3-yl) -9H- carbazol-9-yl] phenyl} -4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn) can be used triazine derivatives and the like.

In addition, poly (2,5-pyridinediyl) (abbreviation: PPy), poly [(9,9-dihexylfluorene-2,7-diyl) -co- (pyridine-3,5-diyl)] (abbreviation: PF -Py), poly [(9,9-dioctylfluorene-2,7-diyl) -co- (2,2′-bipyridine-6,6′-diyl)] (abbreviation: PF-BPy) Molecular compounds can also be used.

Further, the electron-transport layer (114, 114a, 114b) is not limited to a single layer, and may have a structure in which two or more layers made of the above substances are stacked.

Next, in the light-emitting element illustrated in FIG. 1D, an electron injection layer 115a is formed over the electron transport layer 114a of the EL layer 103a by a vacuum evaporation method. Thereafter, the EL layer 103a and the charge generation layer 104 are formed, and the electron transport layer 114b of the EL layer 103b is formed, and then the electron injection layer 115b is formed thereon by a vacuum deposition method.

<Electron injection layer>
The electron injection layers (115, 115a, 115b) are layers containing a substance having a high electron injection property. The electron injection layer (115, 115a, 115b) includes an alkali metal such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF ₂ ), lithium oxide (LiO _x ), or the like. Earth metals or their compounds can be used. Alternatively, a rare earth metal compound such as erbium fluoride (ErF ₃ ) can be used. Further, electride may be used for the electron injection layer (115, 115a, 115b). Examples of the electride include a substance obtained by adding a high concentration of electrons to a mixed oxide of calcium and aluminum. In addition, the substance which comprises the electron carrying layer (114, 114a, 114b) mentioned above can also be used.

Alternatively, a composite material obtained by mixing an organic compound and an electron donor (donor) may be used for the electron injection layer (115, 115a, 115b). Such a composite material is excellent in electron injecting property and electron transporting property because electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material excellent in transporting the generated electrons. Specifically, for example, an electron transport material (metal complex) used for the electron transport layer (114, 114a, 114b) described above, for example. Or a heteroaromatic compound). The electron donor may be any substance that exhibits an electron donating property to the organic compound. Specifically, alkali metals, alkaline earth metals, and rare earth metals are preferable, and lithium, cesium, magnesium, calcium, erbium, ytterbium, and the like can be given. Alkali metal oxides and alkaline earth metal oxides are preferable, and lithium oxide, calcium oxide, barium oxide, and the like can be given. A Lewis base such as magnesium oxide can also be used. Alternatively, an organic compound such as tetrathiafulvalene (abbreviation: TTF) can be used.

Note that in the light-emitting element illustrated in FIG. 1D, in the case where light obtained from the light-emitting layer 113b is amplified, the optical distance between the second electrode 102 and the light-emitting layer 113b is equal to the light emitted from the light-emitting layer 113b. It is preferable to form so as to be less than λ / 4 with respect to the wavelength. In this case, adjustment can be performed by changing the film thickness of the electron transport layer 114b or the electron injection layer 115b.

<Charge generation layer>
In the light-emitting element illustrated in FIG. 1D, the charge generation layer 104 has electrons in the EL layer 103a when voltage is applied between the first electrode (anode) 101 and the second electrode (cathode) 102. And has a function of injecting holes into the EL layer 103b. Note that the charge generation layer 104 may have a structure in which an electron acceptor is added to a hole transporting material or a structure in which an electron donor (donor) is added to an electron transporting material. Good. Moreover, both these structures may be laminated | stacked. Note that by forming the charge generation layer 104 using the above-described material, an increase in driving voltage in the case where an EL layer is stacked can be suppressed.

In the case where the charge generation layer 104 has a structure in which an electron acceptor is added to a hole-transporting material, the materials described in this embodiment can be used as the hole-transporting material. Examples of the electron acceptor include 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F ₄ -TCNQ), chloranil, and the like. In addition, oxides of metals belonging to Groups 4 to 8 in the periodic table can be given. Specific examples include vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide.

In the case where the charge generation layer 104 has a structure in which an electron donor is added to an electron transporting material, the materials described in this embodiment can be used as the electron transporting material. As the electron donor, an alkali metal, an alkaline earth metal, a rare earth metal, a metal belonging to Groups 2 and 13 of the periodic table, or an oxide or carbonate thereof can be used. Specifically, lithium (Li), cesium (Cs), magnesium (Mg), calcium (Ca), ytterbium (Yb), indium (In), lithium oxide, cesium carbonate, or the like is preferably used. An organic compound such as tetrathianaphthacene may be used as an electron donor.

<Board>
The light-emitting element described in this embodiment can be formed over various substrates. In addition, the kind of board | substrate is not limited to a specific thing. As an example of the substrate, a semiconductor substrate (for example, a single crystal substrate or a silicon substrate), an SOI substrate, a glass substrate, a quartz substrate, a plastic substrate, a metal substrate, a stainless steel substrate, a substrate having stainless steel foil, a tungsten substrate, Examples include a substrate having a tungsten foil, a flexible substrate, a laminated film, a paper containing a fibrous material, or a base film.

Note that examples of the glass substrate include barium borosilicate glass, aluminoborosilicate glass, and soda lime glass. Moreover, as an example of a flexible substrate, a laminated film, a base film, etc., plastics such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyethersulfone (PES), acrylic resin, etc. Synthetic resin, polypropylene, polyester, polyvinyl fluoride, polyvinyl chloride, polyamide, polyimide, aramid resin, epoxy resin, inorganic vapor deposition film, papers, and the like can be given.

Note that for manufacturing the light-emitting element described in this embodiment, a vacuum process such as an evaporation method or a solution process such as a spin coating method or an inkjet method can be used. When vapor deposition is used, physical vapor deposition (PVD) such as sputtering, ion plating, ion beam vapor deposition, molecular beam vapor deposition, or vacuum vapor deposition, or chemical vapor deposition (CVD) is used. be able to. In particular, functional layers (hole injection layer (111a, 111b), hole transport layer (112a, 112b), light-emitting layer (113a, 113b), electron transport layer (114a, 114b), electron included in the EL layer of the light-emitting element For the injection layer (115a, 115b)) and the charge generation layer 104, a vapor deposition method (vacuum vapor deposition method, etc.), a coating method (dip coating method, die coating method, bar coating method, spin coating method, spray coating method, etc.), It can be formed by a method such as a printing method (inkjet method, screen (stencil printing) method, offset (lithographic printing) method, flexographic (letter printing) method, gravure method, microcontact method, nanoimprint method, etc.).

Note that each functional layer (a hole injection layer (111a, 111b), a hole transport layer (112a, 112b), a light emitting layer (113a, 103b)) included in the EL layer (103a, 103b) of the light emitting element shown in this embodiment mode. 113b), the electron transport layer (114a, 114b), the electron injection layer (115a, 115b)) and the charge generation layer 104 are not limited to the materials described above, and the function of each layer can be achieved even with other materials. Any combination that can be used can be used. For example, a high molecular compound (oligomer, dendrimer, polymer, etc.), a medium molecular compound (compound in the middle region between low and high molecules: molecular weight 400 to 4000), an inorganic compound (quantum dot material, etc.), etc. are used. it can. As the quantum dot material, a colloidal quantum dot material, an alloy type quantum dot material, a core / shell type quantum dot material, a core type quantum dot material, or the like can be used.

The structure described in this embodiment can be combined as appropriate with any of the structures described in the other embodiments.

(Embodiment 3)
In this embodiment, a light-emitting device which is one embodiment of the present invention will be described. 2A is an active matrix light-emitting device in which a transistor (FET) 202 over a first substrate 201 and light-emitting elements (203R, 203G, 203B, and 203W) are electrically connected to each other. The plurality of light emitting elements (203R, 203G, 203B, 203W) have a common EL layer 204, and the optical distance between the electrodes of each light emitting element depends on the emission color of each light emitting element. It has a tuned microcavity structure. In addition, the light-emitting device is a top-emission light-emitting device in which light emission obtained from the EL layer 204 is emitted through color filters (206R, 206G, and 206B) formed over the second substrate 205.

In the light-emitting device illustrated in FIG. 2A, the first electrode 207 is formed so as to function as a reflective electrode. Further, the second electrode 208 is formed so as to function as a semi-transmissive / semi-reflective electrode. Note that an electrode material for forming the first electrode 207 and the second electrode 208 may be used as appropriate with reference to the description of the other embodiments.

In FIG. 2A, for example, when the light emitting element 203R is a red light emitting element, the light emitting element 203G is a green light emitting element, the light emitting element 203B is a blue light emitting element, and the light emitting element 203W is a white light emitting element, FIG. ), The light emitting element 203R is adjusted so that the optical distance 200R is between the first electrode 207 and the second electrode 208, and the light emitting element 203G includes the first electrode 207 and the second electrode. The light emitting element 203B is adjusted so that the optical distance 200B is between the first electrode 207 and the second electrode 208. Note that as illustrated in FIG. 2B, optical adjustment can be performed by stacking the conductive layer 210R over the first electrode 207 in the light-emitting element 203R and stacking the conductive layer 210G in the light-emitting element 203G.

On the second substrate 205, color filters (206R, 206G, 206B) are formed. The color filter is a filter that passes a specific wavelength range of visible light and blocks the specific wavelength range. Therefore, as shown in FIG. 2A, red light emission can be obtained from the light emitting element 203R by providing the color filter 206R that allows only the red wavelength region to pass through the position overlapping the light emitting element 203R. In addition, by providing the color filter 206G that allows only the green wavelength region to pass at a position overlapping the light emitting element 203G, green light emission can be obtained from the light emitting element 203G. Further, by providing the color filter 206B that allows only the blue wavelength region to pass at a position overlapping the light emitting element 203B, blue light emission can be obtained from the light emitting element 203B. However, the light emitting element 203W can obtain white light emission without providing a color filter. Note that a black layer (black matrix) 209 may be provided at an end of one type of color filter. Further, the color filters (206R, 206G, 206B) and the black layer 209 may be covered with an overcoat layer using a transparent material.

In FIG. 2A, a light emitting device having a structure for extracting light emission to the second substrate 205 side (top emission type) is shown, but the first substrate on which the FET 202 is formed as shown in FIG. A light emitting device having a structure for extracting light to the 201 side (bottom emission type) may be used. Note that in the case of a bottom emission type light-emitting device, the first electrode 207 is formed to function as a semi-transmissive / semi-reflective electrode, and the second electrode 208 is formed to function as a reflective electrode. The first substrate 201 is at least a light-transmitting substrate. Further, the color filters (206R ′, 206G ′, and 206B ′) may be provided on the first substrate 201 side with respect to the light emitting elements (203R, 203G, and 203B) as shown in FIG.

2A illustrates the case where the light-emitting element is a red light-emitting element, a green light-emitting element, a blue light-emitting element, or a white light-emitting element, the light-emitting element which is one embodiment of the present invention is limited to the structure. In other words, a structure having a yellow light emitting element or an orange light emitting element may be used. In addition, as a material used for 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, etc.) for manufacturing these light emitting elements, other embodiments are used. May be used as appropriate with reference to the description. In this case, it is necessary to select a color filter as appropriate in accordance with the emission color of the light emitting element.

With the above structure, a light-emitting device including a light-emitting element that exhibits a plurality of emission colors can be obtained.

Note that the structure described in this embodiment can be combined as appropriate with any of the structures described in the other embodiments.

(Embodiment 4)
In this embodiment, a light-emitting device which is one embodiment of the present invention will be described.

By applying the element structure of the light-emitting element which is one embodiment of the present invention, an active matrix light-emitting device or a passive matrix light-emitting device can be manufactured. Note that an active matrix light-emitting device has a structure in which a light-emitting element and a transistor (FET) are combined. Therefore, both a passive matrix light-emitting device and an active matrix light-emitting device are included in one embodiment of the present invention. Note that the light-emitting element described in any of the other embodiments can be applied to the light-emitting device described in this embodiment.

In this embodiment, an active matrix light-emitting device is described with reference to FIGS.

3A is a top view showing the light-emitting device 21, and FIG. 3B is a cross-sectional view taken along the chain line A-A 'in FIG. 3A. The active matrix light-emitting device includes a pixel portion 302, a driver circuit portion (source line driver circuit) 303, and driver circuit portions (gate line driver circuits) (304a and 304b) provided over the first substrate 301. . The pixel portion 302 and the driver circuit portions (303, 304a, and 304b) are sealed between the first substrate 301 and the second substrate 306 by a sealant 305.

A lead wiring 307 is provided over the first substrate 301. The lead wiring 307 is electrically connected to the FPC 308 which is an external input terminal. Note that the FPC 308 transmits signals (eg, a video signal, a clock signal, a start signal, a reset signal, and the like) and a potential from the outside to the driving circuit units (303, 304a, and 304b). Further, a printed wiring board (PWB) may be attached to the FPC 308. Note that the state in which the FPC or PWB is attached is included in the light emitting device.

Next, a cross-sectional structure is shown in FIG.

The pixel portion 302 is formed by a plurality of pixels including a FET (switching FET) 311, a FET (current control FET) 312, and a first electrode 313 electrically connected to the FET 312. Note that the number of FETs included in each pixel is not particularly limited, and can be appropriately provided as necessary.

The FETs 309, 310, 311, and 312 are not particularly limited, and for example, a staggered type transistor or an inverted staggered type transistor can be applied. Further, a transistor structure such as a top gate type or a bottom gate type may be used.

Note that there is no particular limitation on the crystallinity of the semiconductor that can be used for these FETs 309, 310, 311, and 312; an amorphous semiconductor, a semiconductor having crystallinity (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, Alternatively, a semiconductor having a crystal region in part) may be used. Note that it is preferable to use a crystalline semiconductor because deterioration of transistor characteristics can be suppressed.

As these semiconductors, for example, Group 14 elements, compound semiconductors, oxide semiconductors, organic semiconductors, and the like can be used. Typically, a semiconductor containing silicon, a semiconductor containing gallium arsenide, an oxide semiconductor containing indium, or the like can be used.

The drive circuit unit 303 includes an FET 309 and an FET 310. Note that the FET 309 and the FET 310 may be formed of a circuit including a unipolar transistor (N-type or P-type only) or a CMOS circuit including an N-type transistor and a P-type transistor. May be. In addition, a configuration in which a drive circuit is provided outside may be employed.

An end portion of the first electrode 313 is covered with an insulator 314. Note that 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 oxide, silicon oxynitride, or silicon nitride. . It is preferable that an upper end portion or a lower end portion of the insulator 314 have a curved surface having a curvature. Thereby, the coverage of the film formed on the upper layer of the insulator 314 can be improved.

An EL layer 315 and a second electrode 316 are stacked over the first electrode 313. The EL layer 315 includes 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.

Note that the structures and materials described in the other embodiments can be applied to the structure of the light-emitting element 317 described in this embodiment. Although not shown here, the second electrode 316 is electrically connected to the FPC 308 which is an external input terminal.

3B illustrates only one light-emitting element 317, it is assumed that a plurality of light-emitting elements are arranged in a matrix in the pixel portion 302. In the pixel portion 302, light emitting elements capable of emitting three types (R, G, and B) of light emission can be selectively formed, so that a light emitting device capable of full color display can be formed. In addition to the light emitting element that can obtain three types of light emission (R, G, B), for example, light emission that can emit light such as white (W), yellow (Y), magenta (M), and cyan (C). An element may be formed. For example, by adding the above-described light emitting elements capable of obtaining several types of light emission (R, G, B) to the light emitting elements capable of obtaining three types of light emission (R, G, B), effects such as improvement in color purity and reduction in power consumption can be obtained. Can do. Alternatively, a light emitting device capable of full color display may be obtained by combining with a color filter. Note that as types of color filters, red (R), green (G), blue (B), cyan (C), magenta (M), yellow (Y), and the like can be used.

The FETs (309, 310, 311 and 312) and the light emitting element 317 over the first substrate 301 are bonded to each other by attaching the second substrate 306 and the first substrate 301 with the sealant 305. 301, the second substrate 306, and a structure provided in a space 318 surrounded by the sealant 305. Note that the space 318 may be filled with an inert gas (such as nitrogen or argon) or an organic substance (including the sealant 305).

As the sealant 305, an epoxy resin or glass frit can be used. Note that it is preferable to use a material that does not transmit moisture and oxygen as much as possible for the sealant 305. In addition, as the second substrate 306, a substrate that can be used for the first substrate 301 can be used as well. Therefore, various substrates described in other embodiments can be used as appropriate. In addition to a glass substrate or a quartz substrate, a plastic substrate made of FRP (Fiber-Reinforced Plastics), PVF (polyvinyl fluoride), polyester, acrylic resin, or the like can be used as the substrate. In the case where glass frit is used as the sealing material, the first substrate 301 and the second substrate 306 are preferably glass substrates from the viewpoint of adhesiveness.

As described above, an active matrix light-emitting device can be obtained.

In the case where an active matrix light-emitting device is formed over a flexible substrate, the FET and the light-emitting element may be directly formed over the flexible substrate, but the FET and the light-emitting element are formed over another substrate having a release layer. After forming, the FET and the light-emitting element may be peeled off by a peeling layer by applying heat, force, laser irradiation, and transferred to a flexible substrate. Note that as the peeling layer, for example, a laminated inorganic film of a tungsten film and a silicon oxide film, an organic resin film such as polyimide, or the like can be used. In addition to substrates that can form transistors, flexible substrates include paper substrates, cellophane substrates, aramid film substrates, polyimide film substrates, fabric substrates (natural fibers (silk, cotton, hemp), synthetic fibers ( Nylon, polyurethane, polyester) or recycled fibers (including acetate, cupra, rayon, recycled polyester), leather substrates, rubber substrates, and the like. By using these substrates, it is excellent in durability and heat resistance, and can be reduced in weight and thickness.

Note that the structure described in this embodiment can be combined with any of the structures described in other embodiments as appropriate.

(Embodiment 5)
In this embodiment, examples of various electronic devices and automobiles completed by applying the light-emitting element which is one embodiment of the present invention and the light-emitting device including the light-emitting element which is one embodiment of the present invention will be described. Note that the light-emitting device can be mainly applied to a display portion in the electronic device described in this embodiment.

An electronic device illustrated in FIGS. 4A to 4E includes a housing 7000, a display portion 7001, a speaker 7003, an LED lamp 7004, operation keys 7005 (including a power switch or an operation switch), a connection terminal 7006, Sensor 7007 (force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity , Including a function of measuring inclination, vibration, odor, or infrared light), a microphone 7008, and the like.

FIG. 4A illustrates a mobile computer, which can include a switch 7009, an infrared port 7010, and the like in addition to the above objects.

FIG. 4B illustrates a portable image reproducing device (eg, a DVD reproducing device) provided with a recording medium, which includes a second display portion 7002, a recording medium reading portion 7011, and the like in addition to those described above. it can.

FIG. 4C illustrates a digital camera with a television receiving function, which can include an antenna 7014, a shutter button 7015, an image receiving portion 7016, and the like in addition to the above objects.

FIG. 4D illustrates a portable information terminal. The portable information terminal has a function of displaying information on three or more surfaces of the display portion 7001. Here, an example is shown in which information 7052, information 7053, and information 7054 are displayed on different planes. For example, the user can check the information 7053 displayed at a position where the portable information terminal can be observed from above the portable information terminal in a state where the portable information terminal is stored in the chest pocket of the clothes. The user can confirm the display without taking out the portable information terminal from the pocket, and can determine whether to receive a call, for example.

FIG. 4E illustrates a portable information terminal (including a smartphone), which can include a display portion 7001, operation keys 7005, and the like in a housing 7000. Note that the portable information terminal may include a speaker 9003, a connection terminal 7006, a sensor 9007, and the like. Moreover, the portable information terminal can display characters and image information on the plurality of surfaces. Here, an example in which three icons 7050 are displayed is shown. In addition, information 7051 indicated by a broken-line rectangle can be displayed on another surface of the display portion 7001. Examples of the information 7051 include notifications of incoming calls such as e-mail, SNS, and telephone, titles of e-mail and SNS, sender name, date / time, time, remaining battery level, antenna reception strength, and the like. Alternatively, an icon 7050 or the like may be displayed at a position where the information 7051 is displayed.

FIG. 4F illustrates a large television device (also referred to as a television or a television receiver) which can include a housing 7000, a display portion 7001, and the like. Here, a configuration in which the casing 7000 is supported by a stand 7018 is shown. The television device can be operated by a separate remote controller 7111 or the like. Note that the display portion 7001 may be provided with a touch sensor, and may be operated by touching the display portion 7001 with a finger or the like. The remote controller 7111 may include a display unit that displays information output from the remote controller 7111. Channels and volume can be operated with an operation key or a touch panel included in the remote controller 7111, and an image displayed on the display portion 7001 can be operated.

The electronic devices illustrated in FIGS. 4A to 4F can have a variety of functions. For example, a function for displaying various information (still images, moving images, text images, etc.) on the display unit, a touch panel function, a function for displaying a calendar, date or time, etc., a function for controlling processing by various software (programs) , Wireless communication function, function to connect to various computer networks using wireless communication function, function to transmit or receive various data using wireless communication function, read program or data recorded in recording medium A function of displaying on the display portion can be provided. Further, in an electronic device having a plurality of display units, one display unit mainly displays image information and another one display unit mainly displays character information, or the plurality of display units consider parallax. It is possible to have a function of displaying a three-dimensional image, etc. by displaying the obtained image. Furthermore, in an electronic device having an image receiving unit, a function for capturing a still image, a function for capturing a moving image, a function for correcting a captured image automatically or manually, and a captured image on a recording medium (externally or incorporated in a camera) A function of saving, a function of displaying a photographed image on a display portion, and the like can be provided. Note that the functions of the electronic devices illustrated in FIGS. 4A to 4F are not limited to these, and the electronic devices can have various functions.

FIG. 4G illustrates a wristwatch-type portable information terminal, which can be used as a smart watch, for example. This wristwatch-type portable information terminal includes a housing 7000, a display portion 7001, operation buttons 7022 and 7023, a connection terminal 7024, a band 7025, a microphone 7026, a sensor 7029, a speaker 7030, and the like. The display portion 7001 has a curved display surface and can perform display along the curved display surface. In addition, this portable information terminal can make a hands-free call by mutual communication with a headset capable of wireless communication, for example. Note that the connection terminal 7024 can perform data transmission with another information terminal or can be charged. The charging operation can also be performed by wireless power feeding.

A display portion 7001 mounted on a housing 7000 that also serves as a bezel portion has a non-rectangular display region. The display portion 7001 can display an icon 7027 representing time, other icons 7028, and the like. The display unit 7001 may be a touch panel (input / output device) equipped with a touch sensor (input device).

Note that the smart watch illustrated in FIG. 4G can have a variety of functions. For example, a function for displaying various information (still images, moving images, text images, etc.) on the display unit, a touch panel function, a function for displaying a calendar, date or time, etc., a function for controlling processing by various software (programs) , Wireless communication function, function to connect to various computer networks using wireless communication function, function to transmit or receive various data using wireless communication function, read program or data recorded in recording medium A function of displaying on the display portion can be provided.

In addition, a speaker, a sensor (force, displacement, position, velocity, acceleration, angular velocity, number of rotations, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current are included in the housing 7000. , Voltage, power, radiation, flow rate, humidity, gradient, vibration, odor or infrared measurement function), microphone, and the like.

Note that the light-emitting device which is one embodiment of the present invention and the display device including the light-emitting element which is one embodiment of the present invention can be used for each display portion of the electronic device described in this embodiment, and the electronic device has a long lifetime. Can be realized.

In addition, as an electronic device to which the light-emitting device is applied, a foldable portable information terminal as illustrated in FIGS. FIG. 5A illustrates the portable information terminal 9310 in a developed state. FIG. 5B illustrates the portable information terminal 9310 in a state of changing from one of the expanded state and the folded state to the other. Further, FIG. 5C illustrates the portable information terminal 9310 in a folded state. The portable information terminal 9310 is excellent in portability in the folded state and excellent in display listability due to a seamless wide display area in the expanded state.

The display portion 9311 is supported by three housings 9315 connected by a hinge 9313. Note that the display unit 9311 may be a touch panel (input / output device) equipped with a touch sensor (input device). In addition, the display portion 9311 can be reversibly deformed from the expanded state to the folded state by bending the two housings 9315 via the hinge 9313. Note that the light-emitting device of one embodiment of the present invention can be used for the display portion 9311. In addition, a long-life electronic device can be realized. A display region 9312 in the display portion 9311 is a display region located on a side surface of the portable information terminal 9310 in a folded state. In the display area 9312, information icons, frequently used applications, program shortcuts, and the like can be displayed, so that information can be confirmed and applications can be activated smoothly.

FIGS. 6A and 6B illustrate an automobile to which the light-emitting device is applied. That is, the light emitting device can be provided integrally with the automobile. Specifically, the present invention can be applied to a light 5101 (including a rear part of a vehicle body), a wheel 5102 of a tire, a part of or the whole of a door 5103 shown in FIG. Further, the present invention can be applied to a display portion 5104, a handle 5105, a shift lever 5106, a seat seat 5107, an inner rear view mirror 5108, and the like inside the automobile shown in FIG. In addition, you may apply to some glass windows.

As described above, an electronic device or a vehicle using the light-emitting device or the display device which is one embodiment of the present invention can be obtained. In that case, a long-life electronic device can be realized. Note that applicable electronic devices and automobiles are not limited to those described in this embodiment, and can be applied in any field.

Note that the structure described in this embodiment can be combined as appropriate with any of the structures described in the other embodiments.

(Embodiment 6)
In this embodiment, a structure of a light-emitting device which is one embodiment of the present invention or a lighting device manufactured using a light-emitting element which is a part thereof will be described with reference to FIGS.

7A and 7B illustrate examples of cross-sectional views of the lighting device. Note that FIG. 7A illustrates a bottom emission type illumination device that extracts light to the substrate side, and FIG. 7B illustrates a top emission type illumination device that extracts light to the sealing substrate side.

A lighting device 4000 illustrated in FIG. 7A includes a light-emitting element 4002 over a substrate 4001. In addition, a substrate 4003 having unevenness is provided outside the substrate 4001. The light-emitting element 4002 includes a first electrode 4004, an EL layer 4005, and a second electrode 4006.

The first electrode 4004 is electrically connected to the electrode 4007, and the second electrode 4006 is electrically connected to the electrode 4008. Further, an auxiliary wiring 4009 that is electrically connected to the first electrode 4004 may be provided. Note that an insulating layer 4010 is formed over the auxiliary wiring 4009.

In addition, the substrate 4001 and the sealing substrate 4011 are bonded with a sealant 4012. In addition, a desiccant 4013 is preferably provided between the sealing substrate 4011 and the light-emitting element 4002. Note that since the substrate 4003 has unevenness as illustrated in FIG. 7A, the light extraction efficiency of the light-emitting element 4002 can be improved.

A lighting device 4200 in FIG. 7B includes a light-emitting element 4202 over a substrate 4201. The light-emitting element 4202 includes a first electrode 4204, an EL layer 4205, and a second electrode 4206.

The first electrode 4204 is electrically connected to the electrode 4207, and the second electrode 4206 is electrically connected to the electrode 4208. Further, an auxiliary wiring 4209 that is electrically connected to the second electrode 4206 may be provided. Further, an insulating layer 4210 may be provided below the auxiliary wiring 4209.

The substrate 4201 and the uneven sealing substrate 4211 are bonded with a sealant 4212. Further, a barrier film 4213 and a planarization film 4214 may be provided between the sealing substrate 4211 and the light-emitting element 4202. Note that the sealing substrate 4211 has unevenness as illustrated in FIG. 7B; thus, extraction efficiency of light generated in the light-emitting element 4202 can be improved.

Moreover, as an application example of these lighting devices, a ceiling light for indoor lighting can be cited. Ceiling lights include a direct ceiling type and a ceiling embedded type. Note that such an illumination device is configured by combining a light emitting device with a housing or a cover.

In addition, it can be applied to a foot lamp that can illuminate the floor surface and enhance the safety of the foot. For example, the foot lamp is effective for use in a bedroom, a staircase, a passage, or the like. In that case, the size and shape can be appropriately changed according to the size and structure of the room. In addition, a stationary illumination device configured by combining a light emitting device and a support base can be provided.

Moreover, it is also possible to apply as a sheet-like illumination device (sheet-like illumination). Since the sheet-like illumination is used by being attached to the wall surface, it can be used for a wide range of applications without taking up space. It is easy to increase the area. In addition, it can also be used for the wall surface and housing | casing which have a curved surface.

In addition to the above, a light-emitting device which is one embodiment of the present invention or a light-emitting element which is a part of the light-emitting device which is an embodiment of the present invention is applied to part of furniture provided in the room, whereby a lighting device having a function as furniture is provided. Can do.

As described above, various lighting devices to which the light-emitting device is applied can be obtained. Note that these lighting devices are included in one embodiment of the present invention.

The structure described in this embodiment can be combined as appropriate with any of the structures described in the other embodiments.

<< Synthesis Example 1 >>
In this example, an organometallic complex which is one embodiment of the present invention represented by the structural formula (100) of Embodiment 1, [4- (4-cyano-2,6-dimethylphenyl) -2- (2 A method for synthesizing —pyridyl-κN) phenyl-κC] bis [2- (2-pyridyl-κN) phenyl-κC] iridium (III) (abbreviation: [Ir (ppy) ₂ (dmCN5bpy)]) will be described. The structure of [Ir (ppy) ₂ (dmCN5bpy)] is shown below.

<Synthesis of [Ir (ppy) ₂ (dmCN5bpy)]>
Di-μ-chlorotetrakis [2- (2-pyridyl-κN) phenyl-κC] diiridium (III) (abbreviation: [Ir (ppy) ₂ Cl) ₂ ]) 3.4 g (3.2 mmol) and dichloromethane 300 mL was placed in a three-necked flask, and 50 mL of a methanol solution of 2.5 g (9.7 mmol) of silver trifluoromethanesulfonate (TfOAg) was added dropwise to the mixture, followed by stirring at room temperature for 18 hours. After a predetermined time, the resulting mixture was suction filtered through celite, and the filtrate was concentrated to obtain an oily substance.

3.0 g of this oil, 2.4 g (8.4 mmol) of 2,6-dimethyl-3 ′-(2-pyridyl) -1,1′-biphenyl-4-carbonitrile (abbreviation: HdmCN5bpy), 2-ethoxy Ethanol (100 mL) and dimethylformamide (DMF) (100 mL) were placed in a three-necked flask and heated and stirred at 135 ° C. for 16 hours. The obtained reaction product was concentrated, and the residue was purified by silica gel column chromatography. As a developing solvent, first, a mixed solvent of dichloromethane: hexane = 1: 1 was used, and the polarity was increased by gradually increasing dichloromethane. The obtained fraction was concentrated and recrystallized with a mixed solvent of dichloromethane and methanol to obtain the desired product (yellow solid 1.4 g, yield 28%). A synthesis scheme of the above synthesis method is shown in the following formula (a).

The results of analysis of the yellow solid obtained by the above synthesis method by nuclear magnetic resonance spectroscopy ( ¹ H-NMR) are shown below. A ¹ H-NMR chart is shown in FIG. From this result, it was found that in this example, an organometallic complex, [Ir (ppy) ₂ (dmCN5bpy)], which is one embodiment of the present invention represented by the above structural formula (100), was obtained.

¹ H-NMR. δ (CDCl ₃ ): 2.00 (s, 3H), 2.16 (s, 3H), 6.53 (dd, 1H), 6.84-6.93 (m, 10H), 7.31 ( d, 1H), 7.34 (s, 1H), 7.39 (s, 1H), 7.53-7.69 (m, 8H), 7.79 (d, 1H), 7.88 (d , 1H), 7.92 (d, 1H).

Next, an ultraviolet-visible absorption spectrum (hereinafter, simply referred to as “absorption spectrum”) and an emission spectrum of [Ir (ppy) ₂ (dmCN5bpy)] in a dichloromethane solution (0.010 mmol / L) were measured.

The absorption spectrum was measured at room temperature using an ultraviolet-visible spectrophotometer (V550 type manufactured by JASCO Corporation). In addition, an absolute PL quantum yield measuring device (C11347-01 manufactured by Hamamatsu Photonics Co., Ltd.) was used to measure the emission spectrum, and a dichloromethane deoxygenated solution (0.010 mmol / L) in a glove box under a nitrogen atmosphere. Was sealed in a quartz cell and measured at room temperature.

The measurement results of the obtained absorption spectrum and emission spectrum are shown in FIG. The horizontal axis represents wavelength, and the vertical axis represents absorption intensity and emission intensity. In addition, the absorption spectrum shown in FIG. 9 shows the result of subtracting the absorption spectrum measured by putting only dichloromethane in the quartz cell from the absorption spectrum measured by putting the dichloromethane solution in the quartz cell.

From the result of FIG. 9, green light emission having an emission peak at 516 nm was observed in a dichloromethane solution of [Ir (ppy) ₂ (dmCN5bpy)].

<< Synthesis Example 2 >>
In this example, an organometallic complex represented by the structural formula (101) of Embodiment 1 which is one embodiment of the present invention, tris [4- (4-cyano-2,6-dimethylphenyl) -2- ( A method for synthesizing 2-pyridyl-κN) phenyl-κC] iridium (III) (abbreviation: [Ir (dmCN5bpy) ₃ ]) will be described. The structure of [Ir (dmCN5bpy) ₃ ] is shown below.

<Synthesis of [Ir (dmCN5bpy) ₃ ]>
HdmCN 5 bpy 1.3 g (4.4 mmol) and tris (acetylacetonato) iridium (III) 0.72 g (1.5 mmol) were placed in a reaction vessel equipped with a three-way cock and stirred at 250 ° C. for 34 hours under an argon atmosphere. Reacted. After a predetermined time, the obtained mixture was dissolved in dichloromethane and purified by silica gel column chromatography.

As a developing solvent, dichloromethane was first used, and then a mixed solvent of dichloromethane: ethyl acetate = 1: 1 was used. The obtained fraction was concentrated and recrystallized from a mixed solvent of dichloromethane and hexane to obtain the desired product (orange solid 0.12 g, yield 8%). A synthesis scheme of the above synthesis method is shown in the following formula (b).

The analysis result by nuclear magnetic resonance spectroscopy ( ¹ H-NMR) of the orange solid obtained by the above synthesis method is shown below. Further, the ¹ H-NMR chart is shown in FIG. From this result, it was found that in this example, an organometallic complex, [Ir (dmCN5bpy) ₃ ], which is one embodiment of the present invention represented by the above structural formula (101), was obtained.

¹ H-NMR. δ (CDCl ₃ ): 2.02 (s, 9H), 2.14 (s, 9H), 6.59 (dd, 3H), 6.92 (d, 3H), 6.98 (t, 3H) 7.35 (s, 3H), 7.37-7.38 (m, 6H), 7.65-7.68 (m, 6H), 7.88 (d, 3H).

Next, an absorption spectrum and an emission spectrum of [Ir (dmCN5bpy) ₃ ] in a dichloromethane solution (0.014 mmol / L) were measured. The measurement was performed in the same manner as in Example 1.

Measurement results of the obtained absorption spectrum and emission spectrum are shown in FIG. The horizontal axis represents wavelength, and the vertical axis represents absorption intensity and emission intensity. In addition, the absorption spectrum shown in FIG. 11 shows the result of subtracting the absorption spectrum measured by putting only dichloromethane in the quartz cell from the absorption spectrum measured by putting the dichloromethane solution in the quartz cell.

From the results of FIG. 11, green light emission having an emission peak near 513 nm was observed in a dichloromethane solution of [Ir (dmCN5bpy) ₃ ].

<< Synthesis Example 3 >>
In this example, an organometallic complex which is one embodiment of the present invention represented by the structural formula (102) of Embodiment Mode 1, [9- (4-cyano-2,6-dimethylphenyl) -3- (2 -Pyridyl-κN) -9H-carbazol-2-yl-κC] bis [2- (2-pyridyl-κN) phenyl-κC] iridium (III) (abbreviation: [Ir (ppy) ₂ (CNpczpy)]) A synthesis method will be described. The structure of [Ir (ppy) ₂ (CNpczpy)] is shown below.

<Step 1: Synthesis of 9- (4-cyano-2,6-dimethylphenyl) -9H-carbazole>
2,2′-dibromobiphenyl 22 g (68 mmol), 4-amino-3,5-dimethylbenzonitrile 9.9 g (68 mmol), 2-dicyclohexylphosphino-2 ′, 6′-dimethoxybiphenyl (S-Phos) 2 0.1 g (5.1 mmol), sodium tert-butoxide 19 g (192 mmol), and toluene 500 mL were placed in a three-necked flask, and the atmosphere in the flask was replaced with nitrogen. While stirring this mixture at 60 ° C., 1.2 g (1.3 mmol) of tris (dibenzylideneacetone) dipalladium (0) was added, and the mixture was stirred at 80 ° C. for 15 hours.

The obtained mixture was subjected to suction filtration, and the filtrate was separated into an aqueous layer and an organic layer. The aqueous layer was extracted with toluene, the extracted solution and the organic layer were combined, washed with saturated brine, and dried over anhydrous magnesium sulfate. The filtrate obtained by gravity filtration of this mixture was concentrated to obtain a solid. This solid was dissolved in toluene and purified by silica gel column chromatography. As a developing solvent, a mixed solvent of toluene: hexane = 7: 3 was used. The obtained fraction was concentrated to obtain the target product (white solid 11 g, yield 54%). The synthesis scheme of Step 1 is shown in the following formula (c-1).

<Step 2: Synthesis of 3-bromo-9- (4-cyano-2,6-dimethylphenyl) -9H-carbazole>
Next, 10-g (34 mmol) of 9- (4-cyano-2,6-dimethylphenyl) -9H-carbazole obtained in Step 1 above and 320 mL of ethyl acetate were added to a three-necked flask, and N-bromosuccinimide ( NBS) 6.0 g (34 mmol) was added and stirred at 50 ° C. for 26 hours.

Water was added to the resulting mixture, and the organic layer was separated, washed with a saturated aqueous sodium hydrogen carbonate solution and saturated brine, and dried over anhydrous magnesium sulfate. The mixture was gravity filtered, and the filtrate was concentrated to obtain a solid. The obtained solid was dissolved in a mixed solvent of ethyl acetate and hexane to remove insoluble solids. The solid obtained by concentrating the filtrate was washed with hexane to obtain the desired product (9.8 g of brown solid, yield 78%). The synthesis scheme of Step 2 is shown in the following formula (c-2).

<Step 3: of 9- (4-cyano-2,6-dimethylphenyl) -3- (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) -9H-carbazole Synthesis>
Next, 9.8 g (26 mmol) of 3-bromo-9- (4-cyano-2,6-dimethylphenyl) -9H-carbazole obtained in Step 2 above, 9.9 g (39 mmol) of bis (pinacolato) diboron Then, 12 g (118 mmol) of potassium acetate and 170 mL of dimethyl sulfoxide (DMSO) were placed in a three-necked flask, and the atmosphere in the flask was replaced with nitrogen.

The mixture was heated to 60 ° C., [1,1′-bis (diphenylphosphino) ferrocene] palladium (II) dichloride dichloromethane adduct 0.53 g (0.65 mmol) was added, and the mixture was stirred at 85 ° C. for 15 hours. .

After a predetermined time, water was added to the mixture, and the mixture was separated into an aqueous layer and an organic layer, and the aqueous layer was extracted with toluene. The extracted solution and the organic layer were combined, washed with saturated brine, dried over anhydrous magnesium sulfate. The mixture was naturally filtered, and the obtained filtrate was concentrated to obtain a solid. This solid was purified by silica gel column chromatography. As a developing solvent, a mixed solvent of dichloromethane: hexane = 4: 1 was used. The obtained fraction was concentrated to obtain an oily substance. This oily substance was washed with hexane to obtain the desired product (7.6 g of white solid, yield 69%). The synthesis scheme of Step 3 is shown in the following formula (c-3).

<Step 4: Synthesis of 9- (4-cyano-2,6-dimethylphenyl) -3- (2-pyridyl) -9H-carbazole (abbreviation: HCNpczy)>
Next, 9- (4-cyano-2,6-dimethylphenyl) -3- (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl obtained in Step 3 above was used. ) -9H-carbazole 7.5 g (18 mmol), 2-bromopyridine 4.3 g (27 mmol), 2M aqueous potassium carbonate solution 18 mL, toluene 90 mL, and ethanol 9 mL were placed in a three-necked flask, and the atmosphere in the flask was replaced with nitrogen.

To this mixture, 0.93 g (0.80 mmol) of tetrakis (triphenylphosphine) palladium (0) was added and refluxed for 21 hours. After a predetermined period of time, 0.46 g (0.40 mmol) of tetrakis (triphenylphosphine) palladium (0) was added to this mixture and refluxed for 8 hours. After a predetermined time, 9 mL of 2M potassium carbonate aqueous solution and 2.1 g (13 mmol) of bromopyridine were further added to the mixture, and the mixture was refluxed for 8 hours. After a predetermined time elapsed, the organic layer and the aqueous layer of the obtained reaction mixture were separated, and the aqueous layer was extracted with toluene. The obtained extracted solution and the organic layer were combined and washed with saturated brine, and anhydrous magnesium sulfate was added to the organic layer for drying. The mixture was naturally filtered, and the filtrate was concentrated to obtain a solid.

This solid was purified by silica gel column chromatography. As a developing solvent, a mixed solvent of toluene: ethyl acetate = 95: 5 was used. The obtained fraction was concentrated to obtain the desired product (2.5 g of white solid, yield 38%). The synthesis scheme of Step 4 is shown by the following formula (c-4).

<Step 5: Synthesis of [Ir (ppy) ₂ (CNpczpy)]>
Next, di-μ-chlorotetrakis [2- (2-pyridyl-κN) phenyl-κC] diiridium (III) (abbreviation: [Ir (ppy) ₂ Cl) ₂ ]) 2.2 g (2.1 mmol) Then, 200 mL of dichloromethane was placed in a three-necked flask, and 20 mL of a methanol solution of 1.4 g (4.1 mmol) of silver trifluoromethanesulfonate (TfOAg) was added dropwise to the mixture, followed by stirring at room temperature for 18 hours. After a predetermined time elapsed, the obtained mixture was suction filtered through celite, and the filtrate was concentrated to obtain an oily substance. 2.7 g of this oil, 130 mL of ethanol, and 2.5 g (6.8 mmol) of the ligand HCNpczy obtained in Step 4 above were placed in a three-necked flask, and the mixture was heated and stirred at 80 ° C. for 20 hours. The obtained reaction product was subjected to suction filtration, and the obtained solid was washed with ethanol. This solid was purified by silica gel column chromatography. Dichloromethane was used as a developing solvent. The obtained fraction was concentrated and recrystallized with a mixed solvent of dichloromethane and hexane to obtain the desired product (yellow solid 0.85 g, yield 24%). The synthesis scheme of Step 5 is shown in the following formula (c-5).

The analysis result by nuclear magnetic resonance spectroscopy ( ¹ H-NMR) of the yellow solid obtained in Step 5 is shown below. A ¹ H-NMR chart is shown in FIG. From this result, it was found that in this example, an organometallic complex, [Ir (ppy) ₂ (CNpczy)], which is one embodiment of the present invention represented by the above structural formula (102), was obtained.

¹ H-NMR. δ (CD ₂ Cl ₂ ): 1.56 (s, 3H), 1.88 (s, 3H), 5.92 (s, 1H), 6.58 (d, 2H), 6.70 (d, 2H), 6.72-6.75 (m, 2H), 6.84-6.94 (m, 4H), 7.18 (t, 1H), 7.26 (t, 1H), 7.38. (S, 1H), 7.43 (s, 1H), 7.52 (d, 1H), 7.56-7.60 (m, 2H), 7.64-7.69 (m, 5H), 7.83 (d, 1H), 7.92 (d, 1H), 8.08 (d, 2H), 8.44 (d, 1H).

Next, an absorption spectrum and an emission spectrum of [Ir (ppy) ₂ (CNpczpy)] in a dichloromethane solution (0.012 mmol / L) were measured. The measurement was performed in the same manner as in Example 1.

The measurement results of the obtained absorption spectrum and emission spectrum are shown in FIG. The horizontal axis represents wavelength, and the vertical axis represents absorption intensity and emission intensity. In addition, the absorption spectrum shown in FIG. 13 shows the result of subtracting the absorption spectrum measured by putting only dichloromethane in the quartz cell from the absorption spectrum measured by putting the dichloromethane solution in the quartz cell.

From the results shown in FIG. 13, in the dichloromethane solution of [Ir (ppy) ₂ (CNpczpy)], green light emission having an emission peak at 520 nm was observed.

<< Synthesis Example 4 >>
In this example, an organometallic complex represented by the structural formula (103) of Embodiment 1 which is one embodiment of the present invention, tris [9- (4-cyano-2,6-dimethylphenyl) -3- ( A method for synthesizing 2-pyridyl-κN) -9H-carbazol-2-yl-κC] iridium (III) (abbreviation: [Ir (CNpczpy) ₃ ]) will be described. The structure of [Ir (CNpczpy) ₃ ] is shown below.

<Step 1: Di-μ-chlorotetrakis [9- (4-cyano-2,6-dimethylphenyl) -3- (2-pyridyl-κN) -9H-carbazol-2-yl-κC] diiridium (abbreviation) : Synthesis of [Ir (CNpczpy) ₂ Cl) ₂ ])>
Place the ligand obtained in Step 4 of Example 3, HCN pczpy 1.0 g (2.7 mmol), iridium chloride hydrate 0.36 g (1.2 mmol), 2-ethoxyethanol 15 mL, and water 5 mL in an eggplant flask. The inside of the flask was replaced with argon.

The flask was irradiated with microwaves under conditions of 100 W and 100 ° C. for 1 hour to be reacted. After elapse of a predetermined time, the reaction product was subjected to suction filtration, and the solid was washed with water and ethanol to obtain the target product (yellow solid 0.82 g, yield 70%). The synthesis scheme of Step 1 is shown in the following formula (d-1).

<Step 2: Synthesis of [Ir (CNpczpy) ₃ ]>
Next, [Ir (CNpczpy) ₂ Cl) ₂ ] 0.80 g (0.40 mmol) obtained in Step 1 above, potassium carbonate 0.56 g (4.0 mmol), HCN pczpy 0.80 g (2.0 mmol), 8.0 g of phenol was put into a three-necked flask, the inside of the flask was purged with nitrogen, and heated and stirred at 190 ° C. for 11 hours.

50 mL of methanol was added to the obtained reaction product, and suction filtration was performed to obtain a solid. This solid was washed with water and methanol and then purified by silica gel column chromatography. Dichloromethane was used as a developing solvent. The obtained fraction was concentrated to obtain a solid. This solid was recrystallized from toluene to obtain the desired product (86 mg of yellow solid, yield 7%). The synthesis scheme of Step 2 is shown by the following formula (d-2).

The analysis result by nuclear magnetic resonance spectroscopy ( ¹ H-NMR) of the yellow solid obtained in Step 2 is shown below. Further, the ¹ H-NMR chart is shown in FIG. From this result, it was found that the organometallic complex [Ir (CNpczy) ₃ ], which is one embodiment of the present invention represented by the above structural formula (103), was obtained in this example.

¹ H-NMR. δ (CD ₂ Cl ₂ ): 1.46 (s, 9H), 1.52 (s, 9H), 5.90 (s, 3H), 6.60 (d, 3H), 6.88 (t, 3H), 7.03 (d, 6H), 7.24-7.29 (m, 6H), 7.65 (t, 3H), 7.70 (d, 3H), 8.04 (d, 3H) ), 8.11 (d, 3H), 8.40 (s, 3H).

Next, an absorption spectrum and an emission spectrum of [Ir (CNpczpy) ₃ ] in a dichloromethane solution (0.012 mmol / L) were measured. The measurement was performed in the same manner as in Example 1.

Measurement results of the obtained absorption spectrum and emission spectrum are shown in FIG. The horizontal axis represents wavelength, and the vertical axis represents absorption intensity and emission intensity. In addition, the absorption spectrum shown in FIG. 15 shows the result of subtracting the absorption spectrum measured by putting only dichloromethane in the quartz cell from the absorption spectrum measured by putting the dichloromethane solution in the quartz cell.

From the results of FIG. 15, green emission having an emission peak at 510 nm was observed in a dichloromethane solution of [Ir (CNpczpy) ₃ ].

In this example, as a light-emitting element which is one embodiment of the present invention, [4- (4-cyano-2,6-dimethylphenyl) -2- (2-pyridyl-κN) phenyl- described in Example 1 was used. Light-emitting element using κC] bis [2- (2-pyridyl-κN) phenyl-κC] iridium (III) (abbreviation: [Ir (ppy) ₂ (dmCN5bpy)]) (structural formula (100)) for the light-emitting layer 1. [9- (4-Cyano-2,6-dimethylphenyl) -3- (2-pyridyl-κN) -9H-carbazol-2-yl-κC] bis [2- (1) described in Example 3 2-Pyridyl-κN) phenyl-κC] iridium (III) (abbreviation: [Ir (ppy) ₂ (CNpczpy)]) (Structural Formula (102)) for the light-emitting layer, and for comparison As a light emitting element, [4- (4- Anofeniru) -2- (2-pyridyl -KappaN) phenyl-KC] bis [2- (2-pyridyl -KappaN) phenyl-KC] iridium (III) _{(abbreviation: [Ir (ppy) 2 (} CN5bpy)]) ( An element structure, a manufacturing method, and characteristics of the comparative light-emitting element 3 using the structural formula (200) for the light-emitting layer will be described. Note that FIG. 16 shows an element structure of a light-emitting element used in this example, and Table 1 shows a specific structure. In addition, chemical formulas of materials used in this example are shown below.

≪Production of light emitting element≫
As shown in FIG. 16, the light-emitting element described in this example includes a hole injection layer 911, a hole transport layer 912, a light-emitting layer 913, an electron transport layer 914, and a first electrode 901 formed over a substrate 900. The electron injection layer 915 is sequentially stacked, and the second electrode 903 is stacked on the electron injection layer 915.

First, the first electrode 901 was formed over the substrate 900. The electrode area was 4 mm ² (2 mm × 2 mm). As the substrate 900, a glass substrate was used. The first electrode 901 was formed by depositing indium tin oxide containing silicon oxide (ITSO) with a thickness of 70 nm by a sputtering method.

Here, as a pretreatment, the surface of the substrate was washed with water and baked at 200 ° C. for 1 hour, followed by UV ozone treatment for 370 seconds. Thereafter, the substrate is introduced into a vacuum vapor deposition apparatus whose internal pressure is reduced to about 10 ⁻⁴ Pa, vacuum baking is performed at 170 ° C. for 30 minutes in a heating chamber in the vacuum vapor deposition apparatus, and then the substrate is released for about 30 minutes. Chilled.

Next, a hole injection layer 911 was formed over the first electrode 901. The hole-injection layer 911 is obtained by reducing the pressure in the vacuum evaporation apparatus to 10 ⁻⁴ Pa, and then 1,3,5-tri (dibenzothiophen-4-yl) benzene (abbreviation: DBT3P-II) and molybdenum oxide. DBT3P-II: molybdenum oxide = 4: 2 (mass ratio) was formed by co-evaporation so that the film thickness was 70 nm.

Next, a hole transport layer 912 was formed over the hole injection layer 911. The hole-transport layer 912 was formed by vapor deposition using 3,3′-bis (9-phenyl-9H-carbazole) (abbreviation: PCCP) so as to have a film thickness of 20 nm.

Next, a light-emitting layer 913 was formed over the hole transport layer 912.

In the case of the light-emitting element 1, the light-emitting layer 913 uses 4,6-bis [3- (dibenzothiophen-4-yl) phenyl] pyrimidine (abbreviation: 4,6mDBTP2Pm-II) as a host material and PCCP as an assist material. , [Ir (ppy) ₂ (dmCN5bpy)] is used as the guest material (phosphorescent material), and 4,6mDBTP2Pm-II: PCCP: [Ir (ppy) ₂ (dmCN5bpy) ] = 0.5: 0.5: 0.10 (weight ratio) and co-evaporated to form a film with a thickness of 20 nm, and then 4,6mDBTP2Pm-II: PCCP: [Ir (ppy) ₂ ( dmCN5bpy)] = 0.8: 0.2: 0.10 (weight ratio) to form a film with a thickness of 20 nm by co-evaporation.

The light-emitting layer 913 in the case of the light-emitting element 2 uses 4,6mDBTP2Pm-II as a host material, PCCP as an assist material, and an organometallic complex which is one embodiment of the present invention as a guest material (phosphorescent material) [Ir ( ppy) ₂ (CNpczpy)] and co-evaporated so that 4,6mDBTP2Pm-II: PCCP: [Ir (ppy) ₂ (CNpczpy)] = 0.5: 0.5: 0.10 (weight ratio). Then, after forming the film with a film thickness of 20 nm, 4,6mDBTP2Pm-II: PCCP: [Ir (ppy) ₂ (CNpczpy)] = 0.8: 0.2: 0.10 (weight ratio) Co-evaporated to a thickness of 20 nm.

The light-emitting layer 913 in the case of the comparative light-emitting element 3 uses 4,6mDBTP2Pm-II as a host material, PCCP as an assist material, and [Ir (ppy) ₂ (CN5bpy)] as a guest material (phosphorescent material). After co-evaporating to form 4,6mDBTP2Pm-II: PCCP: [Ir (ppy) ₂ (CN5bpy)] = 0.5: 0.5: 0.10 (weight ratio), a film thickness of 20 nm is formed. Furthermore, co-evaporation was performed so as to be 4,6mDBTP2Pm-II: PCCP: [Ir (ppy) ₂ (CN5bpy)] = 0.8: 0.2: 0.10 (weight ratio), and a film thickness of 20 nm was formed. did.

Next, an electron transport layer 914 was formed over the light emitting layer 913. The electron-transport layer 914 was formed by sequentially vapor-depositing so that the film thickness of 4,6mDBTP2Pm-II was 15 nm and the film thickness of bathophenanthroline (abbreviation: Bphen) was 10 nm.

Next, an electron injection layer 915 was formed over the electron transport layer 914. The electron injection layer 915 was formed by vapor deposition using lithium fluoride (LiF) so as to have a film thickness of 1 nm.

Next, a second electrode 903 was formed over the electron injection layer 915. The second electrode 903 was formed by vapor deposition of aluminum so that the film thickness becomes 200 nm. Note that in this embodiment, the second electrode 903 functions as a cathode.

Through the above process, a light-emitting element in which an EL layer was sandwiched between a pair of electrodes was formed over the substrate 900. Note 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 in the above steps are functional layers that constitute the EL layer in one embodiment of the present invention. In addition, in the vapor deposition process in the manufacturing method described above, a vapor deposition method using a resistance heating method was used.

In addition, the light-emitting element manufactured as described above is sealed by another substrate (not shown). When sealing using another substrate (not shown), another substrate (not shown) coated with a sealing agent that is solidified by ultraviolet light is placed on the substrate 900 in a glove box in a nitrogen atmosphere. The substrates were bonded to each other so that the sealant adhered to the periphery of the light emitting element formed on the substrate 900. At the time of sealing, 365 nm ultraviolet light was irradiated at 6 J / cm ² to solidify the sealing agent, and the sealing agent was stabilized by heat treatment at 80 ° C. for 1 hour.

≪Operating characteristics of light emitting element≫
The operating characteristics of each manufactured light emitting element were measured. The measurement was performed at room temperature (atmosphere kept at 25 ° C.). The results are shown in FIGS.

Table 2 below shows main initial characteristic values of the light emitting elements in the vicinity of 1000 cd / m ² .

From the above results, it can be seen that each of the light emitting elements exhibits the same excellent element characteristics.

FIG. 21 shows emission spectra obtained when a current was passed through the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3 at a current density of ^2.5 mA / cm ² . In FIG. 21, the light-emitting element 1 has an emission spectrum having a peak near 518 nm due to light emission of the organometallic complex [Ir (ppy) ₂ (dmCN5bpy)] included in the light-emitting layer 913. In addition, the light-emitting element 2 has an emission spectrum having a peak near 518 nm due to light emission of the organometallic complex [Ir (ppy) ₂ (CNpczpy)] included in the light-emitting layer 913. In addition, the comparative light-emitting element 3 has an emission spectrum having a peak in the vicinity of 518 nm derived from light emission of the organometallic complex [Ir (ppy) ₂ (CN5bpy)] included in the light-emitting layer 913.

Next, a reliability test was performed on the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3. The result of the reliability test is shown in FIG. In FIG. 22, the vertical axis represents normalized luminance (%) when the initial luminance is 100%, and the horizontal axis represents element driving time (h). In the reliability test, the current density was set to 50 mA / cm ² and the light emitting element was driven.

From the result of the reliability test, it was found that the light-emitting element 1 and the light-emitting element 2 showed superior reliability as compared with the comparative light-emitting element 3. This is because the organometallic complexes which are one embodiment of the present invention, [Ir (ppy) ₂ (dmCN5bpy)] and [Ir (ppy) ₂ (CNpczpy)], and [Ir (ppy) ₂ used in the comparative light-emitting element 3 are used. This is probably due to the difference in molecular structure from (CN5bpy)]. That is, the organometallic complex which is one embodiment of the present invention, [Ir (ppy) ₂ (dmCN5bpy)] and [Ir (ppy) ₂ (CNpczpy)] are in an ortho position of a phenyl group having a CN group as a substituent. As a dialkyl group, it has a dimethyl group. Since such a structure can suppress decomposition of the complex due to hole injection as shown in the calculation result of Example 6, the reliability of the light-emitting element can be increased.

(Calculation example)
In this example, molecular orbital calculations are performed on organometallic complexes represented by the structural formulas (C1) and (C2) shown below, and the difference in physical properties on the molecular structure based on the results is specifically shown.

Note that the Gaussian 09 program was used for the molecular orbital calculation. The structure was optimized using 6-311G as the basis function and B3PW91 \ 6-311G as the singlet ground state (S ₀ ) of each molecule.

FIG. 23 shows the electron density distribution of HOMO in each structure obtained by calculation. In the structural formula (C1) shown in FIG. 23 (A) and the structural formula (C2) shown in FIG. 23 (B), HOMO is distributed mainly with respect to phenyl groups and iridium ions that are orthometalated with iridium. The result that it is. However, only in the structural formula (C1), a slight HOMO distribution was observed in the phenyl group having a CN (cyano) group as a substituent.

The portion where HOMO is distributed is usually a hole injection site, but the organometallic complex of the structural formula (C2) has a dimethyl group as a dialkyl group at the ortho position of a phenyl group having a CN group as a substituent. Because of this structure, the phenyl group having the CN group as a substituent and the phenyl group orthometalated with iridium are not flat, thereby suppressing the spread of HOMO to the phenyl group having the CN group as a substituent. As a result, the hole is difficult to enter in this portion.

Note that a phenyl group having a strong electron-attracting group such as a CN group as a substituent is represented by the structural formula (C2), which is a structure in which holes are difficult to enter, because the radical cation is considered unstable. In the organometallic complex, decomposition of the complex due to hole injection is suppressed. Therefore, the reliability of the light-emitting element can be improved by using an organometallic complex having a dialkyl group at the ortho position of the phenyl group having a CN group as a substituent as in Structural Formula (C2) as the light-emitting element. .

101 First electrode 102 Second electrode 103 EL layer 103a, 103b EL layer 104 Charge generation layer 111, 111a, 111b Hole injection layer 112, 112a, 112b Hole transport layer 113, 113a, 113b Light emitting layer 114, 114a , 114b Electron transport layers 115, 115a, 115b Electron injection layers 200R, 200G, 200B Optical distance 201 First substrate 202 Transistor (FET)
203R, 203G, 203B, 203W Light emitting element 204 EL layer 205 Second substrate 206R, 206G, 206B Color filter 206R ′, 206G ′, 206B ′ Color filter 207 First electrode 208 Second electrode 209 Black layer (black matrix )
210R, 210G Conductive layer 301 First substrate 302 Pixel portion 303 Drive circuit portion (source line drive circuit)
304a, 304b Drive circuit section (gate line drive circuit)
305 Sealing material 306 Second substrate 307 Route wiring 308 FPC
309 FET
310 FET
311 FET
312 FET
313 First electrode 314 Insulator 315 EL layer 316 Second electrode 317 Light emitting element 318 Space 900 Substrate 901 First electrode 902 EL layer 903 Second electrode 911 Hole injection layer 912 Hole transport layer 913 Light emitting layer 914 Electron transport layer 915 Electron injection layer 4000 Lighting device 4001 Substrate 4002 Light emitting element 4003 Substrate 4004 First electrode 4005 EL layer 4006 Second electrode 4007 Electrode 4008 Electrode 4009 Auxiliary wiring 4010 Insulating layer 4011 Sealing substrate 4012 Sealing material 4013 Desiccant 4015 Diffuser 4200 Lighting device 4201 Substrate 4202 Light emitting element 4204 First electrode 4205 EL layer 4206 Second electrode 4207 Electrode 4208 Electrode 4209 Auxiliary wiring 4210 Insulating layer 4211 Sealing substrate 4212 Sealing material 4213 Barrier film 4214 Flat Chemical film 4215 Diffusion plate 5101 Light 5102 Wheel 5103 Door 5104 Display unit 5105 Handle 5106 Shift lever 5107 Seat seat 5108 Inner rear view mirror 7000 Case 7001 Display unit 7002 Second display unit 7003 Speaker 7004 LED lamp 7005 Operation key 7006 Connection terminal 7007 Sensor 7008 Microphone 7009 Switch 7010 Infrared port 7011 Recording medium reading unit 7012 Support unit 7013 Earphone 7014 Antenna 7015 Shutter button 7016 Image receiving unit 7018 Stand 7020 Camera 7021 External connection unit 7022, 7023 Operation button 7024 Connection terminal 7025 Band,
7026 Microphone 7027 Time icon 7028 Other icons 7029 Sensor 7030 Speakers 7052, 7053, 7054 Information 9310 Mobile information terminal 9311 Display unit 9312 Display area 9313 Hinge 9315 Case

Claims (11)

An organometallic complex represented by the general formula (G1).

(In the formula, A represents any one of a substituted or unsubstituted aromatic hydrocarbon ring and aromatic heterocyclic ring having 6 to 13 carbon atoms in total forming the ring, and any one of R ^{10 to} R ¹² . Represents a CN group, and R ⁹ and R ¹³ each represent an alkyl group having 1 to 6 carbon atoms, and other R ^{1 to} R ⁸ , R ^{10 to} R ¹² and R ¹⁴ to R ¹⁷ each independently represents hydrogen, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 12 carbon atoms in total forming a ring, or 3 to 3 carbon atoms forming a ring. Represents any of 12 substituted or unsubstituted heteroaryl groups, and n = 0, 1, or 2.) In claim 1,
The A is composed of any one of a benzene ring, a biphenyl skeleton, a naphthalene ring, a fluorene ring, a carbazole ring, a dibenzothiophene ring, and a dibenzofuran ring, and the ring or skeleton may have a substituent. An organometallic complex represented by the general formula (G2).

(In the formula, any one of R ^{10 to} R ¹² represents a CN group. R ⁹ and R ¹³ each represent an alkyl group having 1 to 6 carbon atoms. In addition, other R ^{1 to} R ⁸ , R ^{10 to} R ¹² and R ^{14 to} R ²⁰ are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or a substituted or unsubstituted aryl having 6 to 12 carbon atoms in total forming a ring. Or a substituted or unsubstituted heteroaryl group having a total carbon number of 3 to 12 to form a group or a ring, and n = 0, 1, or 2.) An organometallic complex represented by the general formula (G3).

(In the formula, any one of R ^{10 to} R ¹² represents a CN group. R ⁹ and R ¹³ each represent an alkyl group having 1 to 6 carbon atoms. In addition, other R ^{1 to} R ⁸ , R ^{10 to} R ¹² , R ^{14 to} R ¹⁸ and R ^{20 to} R ²⁴ are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 12 carbon atoms, Or a substituted or unsubstituted heteroaryl group having 3 to 12 carbon atoms, and n = 0, 1, or 2.) An organometallic complex represented by any one of Structural Formula (100), Structural Formula (101), Structural Formula (102), and Structural Formula (103).
  The light emitting element using the organometallic complex as described in any one of Claims 1 thru | or 5. An EL layer between the pair of electrodes;
The EL layer is a light-emitting element having the organometallic complex according to any one of claims 1 to 5. An EL layer between the pair of electrodes;
The EL layer has a light emitting layer,
The said light emitting layer is a light emitting element which has an organometallic complex as described in any one of Claims 1 thru | or 5. A light emitting device according to any one of claims 6 to 8,
Either one of the transistor or the substrate,
A light emitting device. A light emitting device according to claim 9;
With any one of microphone, camera, operation button, external connection, or speaker,
Electronic equipment having A light emitting device according to claim 9;
With any one of the case, cover, or support base,
A lighting device.