JP6142498B2 - Light emitting element, light emitting device, authentication device, and electronic device - Google Patents

Description

  The present invention relates to a light emitting element, a light emitting device, an authentication device, and an electronic device.

  An organic electroluminescence element (so-called organic EL element) is a light emitting element having a structure in which at least one light emitting organic layer is interposed between an anode and a cathode. In such a light emitting device, by applying an electric field between the cathode and the anode, electrons are injected into the light emitting layer from the cathode side and holes are injected from the anode side, and electrons and holes are injected into the light emitting layer. Recombination generates excitons, and when the excitons return to the ground state, the energy is emitted as light.

As such a light emitting element, one emitting light in a long wavelength region exceeding 700 nm is known (for example, see Patent Documents 1 and 2).
For example, in the light-emitting element described in Patent Documents 1 and 2, light emission is achieved by using a material in which an amine as an electron donor and a nitrile group as an electron acceptor are used as functional groups in the molecule as a dopant in the light-emitting layer. The wavelength is increased.

Japanese Patent Laid-Open No. 2000-091073 JP 2001-110570 A

However, conventionally, it has not been possible to realize a highly efficient and long-life device that emits light in the near infrared region.
In addition, a highly efficient and long-life light emitting element that emits light in the near infrared region is desired to be realized as a light source for biometric authentication that authenticates an individual using biometric information such as veins and fingerprints.
An object of the present invention is to provide a high-efficiency and long-life light-emitting element that emits light in the near infrared region, a light-emitting device including the light-emitting element, an authentication device, and an electronic apparatus.

［前記式（２）中、Ａは、それぞれ独立に、水素原子、アルキル基、置換基を有していてもよいアリール基、アリールアミノ基またはトリアリールアミンを示す。］ Such an object is achieved by the present invention described below.
The light emitting device of the present invention comprises an anode,
A cathode,
A light emitting layer that is provided between the anode and the cathode, and emits light when energized between the anode and the cathode;
An electron transport layer provided between and in contact with the light emitting layer between the cathode and the light emitting layer, and having an electron transporting property;
The light-emitting layer includes a thiadiazole-based compound that is a compound represented by the following formula ( 2 ) as a light-emitting material,
The electron transport layer includes an azaindolizine compound having an azaindolizine skeleton and an anthracene skeleton in the molecule as an electron transporting material.

[In said Formula (2), A shows a hydrogen atom, an alkyl group, the aryl group which may have a substituent, an arylamino group, or a triarylamine each independently. ]

According to the light emitting device configured as described above, since the thiadiazole compound having the basic skeleton represented by the formula (1) in the molecule is used as the light emitting material, in a wavelength region of 700 nm or more (near infrared region). Luminescence can be obtained.
In addition, since an azaindolizine-based compound having an azaindolizine skeleton and an anthracene skeleton in the molecule is used as the electron transporting material adjacent to the light-emitting layer, electrons are efficiently transferred from the electron-transporting layer to the light-emitting layer. Can be transported to. Therefore, the light emission efficiency of the light emitting element can be improved.

［前記式（３）、（４）、（５）中、Ｒは、それぞれ独立に、水素原子、アルキル基、置換基を有していてもよいアリール基を示す。また、隣り合う２つのＲの炭素同士が連結して環状をなしていてもよい。］
これにより、発光素子の高効率化および長寿命化をさらに図ることができる。 In the light emitting device of the present invention, the compound represented by the formula (2) is preferably a compound represented by any one of the following formulas (3), (4), and (5).

[In said formula (3), (4), (5), R shows the aryl group which may have a hydrogen atom, an alkyl group, and a substituent each independently. Two adjacent R carbons may be linked to form a ring. ]
Thereby, it is possible to further increase the efficiency and the life of the light emitting element.

In the light-emitting device of the present invention, the azaindolizine compound preferably has one or two azaindolizine skeletons and anthracene skeletons in one molecule.
Thereby, the electron transport property and the electron injection property of the electron transport layer can be made excellent.

In the light-emitting element of the present invention, it is preferable that the light-emitting layer includes a host material that holds the light-emitting material.
Accordingly, the host material can recombine holes and electrons to generate excitons, and the energy of the excitons can be transferred to the light emitting material to excite the light emitting material. Therefore, the light emission efficiency of the light emitting element can be increased.

In the light emitting device of the present invention, the host material is preferably an acene-based material.
Thereby, the luminous efficiency of the light emitting element can be increased.
In the light emitting device of the present invention, the acene material is preferably an anthracene material.
Accordingly, since an anthracene-based material is used as the host material, energy can be efficiently transferred from the host material to the light-emitting material. Therefore, the light emission efficiency of the light emitting element can be improved.
In addition, since the anthracene-based material is excellent in stability (resistance) against electrons and holes, it is possible to extend the life of the light-emitting layer and thus the light-emitting element.

In the light emitting device of the present invention, the acene material is preferably a tetracene material.
Thereby, since a tetracene-based material is used as the host material, energy can be efficiently transferred from the host material to the light emitting material. Therefore, the light emission efficiency of the light emitting element can be improved.
In addition, since the tetracene-based material is excellent in stability (resistance) against electrons and holes, the lifetime of the light-emitting layer can be extended, and thus the lifetime of the light-emitting element can be increased.

In the light emitting device of the present invention, the acene-based material is preferably composed of carbon atoms and hydrogen atoms.
Thereby, it is possible to prevent unintended interaction between the host material and the light emitting material. Therefore, the light emission efficiency of the light emitting element can be increased. In addition, the resistance of the host material to potential and holes can be increased. Therefore, the lifetime of the light emitting element can be extended.
In the light emitting device of the present invention, the host material is preferably a quinolinolato metal complex.
Thereby, the luminous efficiency of the light emitting element can be increased.

The light-emitting device of the present invention includes the light-emitting element of the present invention.
Such a light emitting device can emit light in the near infrared region. Further, since the light-emitting element with high efficiency and long life is provided, the reliability is excellent.
The authentication apparatus of the present invention includes the light emitting element of the present invention.
Such an authentication apparatus can perform biometric authentication using near infrared light. Further, since the light-emitting element with high efficiency and long life is provided, the reliability is excellent.
The electronic device of the present invention includes the light emitting element of the present invention.
Since such an electronic device includes a light-emitting element with high efficiency and a long lifetime, it has excellent reliability.

It is sectional drawing which shows typically the light emitting element which concerns on embodiment of this invention. It is a longitudinal cross-sectional view which shows embodiment of the display apparatus to which the light-emitting device of this invention is applied. It is a figure which shows embodiment of the authentication apparatus of this invention. 1 is a perspective view showing a configuration of a mobile (or notebook) personal computer to which an electronic apparatus of the present invention is applied.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a light-emitting element, a light-emitting device, an authentication device, and an electronic device of the invention will be described with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view schematically showing a light emitting device according to an embodiment of the present invention. In the following description, for convenience of explanation, the upper side in FIG. 1 will be described as “upper” and the lower side as “lower”.
A light-emitting element (electroluminescence element) 1 shown in FIG. 1 includes an anode 3, a hole injection layer 4, a hole transport layer 5, a light-emitting layer 6, an electron transport layer 7, an electron injection layer 8, and a cathode 9 stacked in this order. It has been made. That is, in the light emitting element 1, the hole injection layer 4, the hole transport layer 5, the light emitting layer 6, the electron transport layer 7, and the electron injection layer 8 are arranged between the anode 3 and the cathode 9 from the anode 3 side to the cathode 9 side. And the laminated body 14 laminated | stacked in this order is inserted.
The entire light emitting element 1 is provided on the substrate 2 and is sealed with a sealing member 10.

In such a light emitting element 1, when a driving voltage is applied to the anode 3 and the cathode 9, electrons are supplied (injected) from the cathode 9 side to the light emitting layer 6, and from the anode 3 side. Holes are supplied (injected). In the light emitting layer 6, holes and electrons are recombined, and excitons (excitons) are generated by the energy released upon the recombination, and energy (fluorescence or phosphorescence) is generated when the excitons return to the ground state. Is emitted (emitted). Thereby, the light emitting element 1 emits light.
In particular, the light-emitting element 1 emits light in the near infrared region by using a thiadiazole-based compound (compound for light-emitting element) as a light-emitting material of the light-emitting layer 6 as described later. In the present specification, the “near infrared region” refers to a wavelength region of 700 nm to 1500 nm.

The substrate 2 supports the anode 3. Since the light-emitting element 1 of the present embodiment is configured to extract light from the substrate 2 side (bottom emission type), the substrate 2 and the anode 3 are substantially transparent (colorless transparent, colored transparent, or translucent), respectively. Has been.
Examples of the constituent material of the substrate 2 include resin materials such as polyethylene terephthalate, polyethylene naphthalate, polypropylene, cycloolefin polymer, polyamide, polyethersulfone, polymethyl methacrylate, polycarbonate, and polyarylate, quartz glass, and soda glass. Such glass materials can be used, and one or more of these can be used in combination.

Although the average thickness of such a board | substrate 2 is not specifically limited, It is preferable that it is about 0.1-30 mm, and it is more preferable that it is about 0.1-10 mm.
The light emitting element 1 may be configured to extract light from the side opposite to the substrate 2 (top emission type). In this case, the substrate 2 can be either a transparent substrate or an opaque substrate.

Examples of the opaque substrate include a substrate made of a ceramic material such as alumina, an oxide film (insulating film) formed on the surface of a metal substrate such as stainless steel, and a substrate made of a resin material. It is done.
In such a light-emitting element 1, the distance between the anode 3 and the cathode 9 (that is, the average thickness of the laminate 14) is preferably 100 to 500 nm, and more preferably 100 to 300 nm. 100 to 250 nm is more preferable. Thereby, the drive voltage of the light emitting element 1 can be set within a practical range easily and reliably.

Hereinafter, each part which comprises the light emitting element 1 is demonstrated sequentially.
(anode)
The anode 3 is an electrode that injects holes into the hole transport layer 5 through a hole injection layer 4 described later. As a constituent material of the anode 3, it is preferable to use a material having a large work function and excellent conductivity.

Examples of the constituent material of the anode 3 include oxides such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), In ₃ O ₃ , SnO ₂ , Sb-containing SnO ₂ , and Al-containing ZnO, Au, Pt, and Ag. Cu, alloys containing these, and the like can be used, and one or more of these can be used in combination.
In particular, the anode 3 is preferably made of ITO. ITO is a material having transparency, a large work function, and excellent conductivity. Thereby, holes can be efficiently injected from the anode 3 into the hole injection layer 4.

Further, the surface of the anode 3 on the hole injection layer 4 side (the upper surface in FIG. 1) is preferably subjected to plasma treatment. Thereby, the chemical and mechanical stability of the joint surface between the anode 3 and the hole injection layer 4 can be enhanced. As a result, the hole injection property from the anode 3 to the hole injection layer 4 can be improved. Such plasma treatment will be described in detail in the description of the method for manufacturing the light emitting element 1 described later.
The average thickness of the anode 3 is not particularly limited, but is preferably about 10 to 200 nm, and more preferably about 50 to 150 nm.

(cathode)
On the other hand, the cathode 9 is an electrode that injects electrons into the electron transport layer 7 through an electron injection layer 8 described later. As a constituent material of the cathode 9, it is preferable to use a material having a small work function.
Examples of the constituent material of the cathode 9 include Li, Mg, Ca, Sr, La, Ce, Er, Eu, Sc, Y, Yb, Ag, Cu, Al, Cs, Rb, and alloys containing these. These can be used alone or in combination of two or more thereof (for example, as a laminate of a plurality of layers, a mixed layer of a plurality of types, or the like).
In particular, when an alloy is used as the constituent material of the cathode 9, it is preferable to use an alloy containing a stable metal element such as Ag, Al, or Cu, specifically, an alloy such as MgAg, AlLi, or CuLi. By using such an alloy as the constituent material of the cathode 9, the electron injection efficiency and stability of the cathode 9 can be improved.

Further, as the constituent material of the cathode 9, it is preferable to use any one of Al, Ag, and Mg / Ag, and more preferable to use Mg / Ag because of excellent reflectivity with respect to light in the near infrared region. .
Mg / Ag constituting the cathode 9 preferably has a ratio of Mg and Ag (Mg: Ag) of 1: 100 to 100: 1 from the viewpoint of enhancing reflectivity for light in the near infrared region.
The average thickness of the cathode 9 is not particularly limited, but is preferably about 2 to 10,000 nm, and more preferably about 50 to 200 nm.

In addition, since the light emitting element 1 of this embodiment is a bottom emission type, the light transmittance of the cathode 9 is not particularly required. In the case of the top emission type, since it is necessary to transmit light from the cathode 9 side, the average thickness of the cathode 9 is preferably about 1 to 50 nm.
Further, a reflective layer having reflectivity for near-infrared light may be provided on the upper side of the cathode 9 (on the side opposite to the light emitting layer 6). Such a reflective layer is preferably made of, for example, any one of Al, Ag, and Mg. Further, such a reflective layer is preferably in contact with the cathode 9.

(Hole injection layer)
The hole injection layer 4 has a function of improving the hole injection efficiency from the anode 3 (that is, has a hole injection property).
Thus, by providing the hole injection layer 4 between the anode 3 and the hole transport layer 5 described later, the hole property from the anode 3 is improved, and as a result, the light emission efficiency of the light emitting element 1 is increased. Can do.

The hole injection layer 4 includes a material having a hole injection property (that is, a hole injection material).
The hole injecting material contained in the hole injecting layer 4 is not particularly limited. For example, copper phthalocyanine, 4,4 ′, 4 ″ -tris (N, N-phenyl-3-methylphenylamino) ) Triphenylamine (m-MTDATA), N, N′-bis- (4-diphenylamino-phenyl) -N, N′-diphenyl-biphenyl-4-4′-diamine, and the like.

Among them, as the hole injecting material contained in the hole injecting layer 4, it is preferable to use an amine-based material from the viewpoint of excellent hole injecting property and hole transporting property, and a diaminobenzene derivative, a benzidine derivative (benzidine) It is more preferable to use a triamine-based compound or a tetraamine-based compound having both a “diaminobenzene” unit and a “benzidine” unit in the molecule.
The average thickness of the hole injection layer 4 is not particularly limited, but is preferably about 5 to 90 nm, and more preferably about 10 to 70 nm.
The hole injection layer 4 may be omitted depending on the constituent materials of the anode 3 and the hole transport layer 5.

(Hole transport layer)
The hole transport layer 5 has a function of transporting holes injected from the anode 3 through the hole injection layer 4 to the light emitting layer 6 (that is, has a hole transport property).
The hole transport layer 5 includes a material having a hole transport property (that is, a hole transport material).

  As the hole transporting material contained in the hole transporting layer 5, various p-type polymer materials and various p-type low molecular materials can be used alone or in combination. For example, N, N′— Di (1-naphthyl) -N, N′-diphenyl-1,1′-diphenyl-4,4′-diamine (NPD), N, N′-diphenyl-N, N′-bis (3-methylphenyl) And tetraarylbenzidine derivatives such as -1,1′-diphenyl-4,4′-diamine (TPD), tetraaryldiaminofluorene compounds or derivatives thereof (amine compounds), etc., and one or two of these A combination of more than one species can be used.

Among them, the hole transport material contained in the hole transport layer 5 is preferably an amine-based material from the viewpoint of excellent hole injection property and hole transport property, and a benzidine derivative (a material having a benzidine skeleton). Is more preferable.
The average thickness of the hole transport layer 5 is not particularly limited, but is preferably about 5 to 90 nm, and more preferably about 10 to 70 nm.

(Light emitting layer)
The light emitting layer 6 emits light when energized between the anode 3 and the cathode 9 described above.
Such a light emitting layer 6 includes a light emitting material.
In particular, the light-emitting layer 6 includes a thiadiazole compound (hereinafter, also simply referred to as “thiadiazole compound”) that is a compound having a basic skeleton represented by the following formula (1) in the molecule as a light-emitting material. ing.

The light emitting layer 6 containing such a thiadiazole-based compound can obtain light emission in a wavelength region (near infrared region) of 700 nm or more.
Further, as the light emitting material (thiadiazole compound) used for the light emitting layer 6, it is preferable to use a compound represented by the following formula (2) from the viewpoint of improving the efficiency and extending the life. To (5) are more preferred, and specifically, compounds represented by the following formulas D-1 to D-3 are preferably used.

［前記式（２）中、Ａは、それぞれ独立に、水素原子、アルキル基、置換基を有していてもよいアリール基、アリールアミノ基またはトリアリールアミンを示す。］

[In said Formula (2), A shows a hydrogen atom, an alkyl group, the aryl group which may have a substituent, an arylamino group, or a triarylamine each independently. ]

［前記式（３）、（４）、（５）中、Ｒは、それぞれ独立に、水素原子、アルキル基、置換基を有していてもよいアリール基を示す。また、隣り合う２つのＲの炭素同士が連結して環状をなしていてもよい。］

[In said formula (3), (4), (5), R shows the aryl group which may have a hydrogen atom, an alkyl group, and a substituent each independently. Two adjacent R carbons may be linked to form a ring. ]

In addition, the light emitting layer 6 may contain light emitting materials (various fluorescent materials, various phosphorescent materials) other than the above-described light emitting materials.
As a constituent material of the light emitting layer 6, in addition to the light emitting material (thiadiazole compound) as described above, a host material to which this light emitting material is added (supported) as a guest material (dopant) is used. This host material recombines holes and electrons to generate excitons and to transfer the exciton energy to the luminescent material (Felster movement or Dexter movement) to excite the luminescent material. Have. Therefore, the thiadiazole compound having the basic skeleton represented by the formula (1) in the molecule can be excited efficiently. As a result, the light emission efficiency of the light emitting element 1 can be increased. Such a host material can be used by, for example, doping a host material with a light-emitting material that is a guest material as a dopant.

Such a host material is not particularly limited as long as it exhibits the functions described above for the light emitting material to be used. For example, acene-based materials such as a distyrylarylene derivative, a naphthacene derivative, and an anthracene derivative, Quinolinolato such as perylene derivatives, distyrylbenzene derivatives, distyrylamine derivatives, bis (2-methyl-8-quinolinolato) (p-phenylphenolato) aluminum (BAlq), tris (8-quinolinolato) aluminum complexes (Alq ₃ ), etc. Metal complexes, triarylamine derivatives such as triphenylamine tetramer, oxadiazole derivatives, rubrene and its derivatives, silole derivatives, dicarbazole derivatives, oligothiophene derivatives, benzopyran derivatives, triazole derivatives, benzoxazo Derivatives, benzothiazole derivatives, quinoline derivatives, 4,4′-bis (2,2′-diphenylvinyl) biphenyl (DPVBi), 3-phenyl-4- (1′-naphthyl) -5-phenylcarbazole, 4, Examples thereof include carbazole derivatives such as 4′-N, N′-dicarbazole biphenyl (CBP), and one of these can be used alone or two or more can be used in combination.
Among these, as the host material, an acene-based material or a quinolinolato-based metal complex is preferably used, and an acene-based material is more preferably used.

The acene-based material is rarely used for unintentional mutual materials with the light emitting material as described above. In addition, when an acene-based material (particularly an anthracene-based material or a tetracene-based material) is used as the host material, energy transfer from the host material to the light-emitting material can be efficiently performed. This is because (a) it is possible to generate a singlet excited state of the luminescent material by energy transfer from the triplet excited state of the acene-based material, and (b) a π electron cloud of the acene-based material and an electron cloud of the luminescent material. And (c) the overlap between the fluorescence spectrum of the acene-based material and the absorption spectrum of the light-emitting material is increased.
Therefore, when an acene-based material is used as the host material, the light emission efficiency of the light-emitting element 1 can be increased.

Acene-based materials are excellent in resistance to electrons and holes. Acene-based materials are also excellent in thermal stability. Therefore, the life of the light emitting element 1 can be extended. In addition, since the acene-based material is excellent in thermal stability, the host material can be prevented from being decomposed by heat at the time of film formation when the light emitting layer is formed using the vapor phase film formation method. Therefore, a light emitting layer having excellent film quality can be formed. As a result, the light emission efficiency of the light emitting element 1 can be increased and the life can be extended.
Furthermore, since the acene-based material itself does not easily emit light, the host material can be prevented from adversely affecting the emission spectrum of the light-emitting element 1.

  Such an acene-based material is not particularly limited as long as it has an acene skeleton and exhibits the effects described above. For example, naphthalene derivatives, anthracene derivatives, naphthacene derivatives (tetracene derivatives), pentacene Derivatives can be used, and one or more of these can be used in combination, but anthracene-based materials (anthracene derivatives) or tetracene-based materials (tetracene derivatives) are preferably used, and tetracene-based materials are used. Is more preferable.

  The tetracene-based material is not particularly limited as long as it has at least one tetracene skeleton in one molecule and can function as a host material as described above. A compound represented by the following formula IRH-1 is preferably used, a compound represented by the following formula IRH-2 is more preferably used, and a compound represented by the following IRH-3 is more preferably used.

［前記式ＩＲＨ−１中、ｎは、１〜１２の自然数を示し、Ｒは置換機または官能基を表し、それぞれ独立に、水素原子、アルキル基、置換基を有していてもよいアリール基、アリールアミノ基を示す。また、前記式ＩＲＨ−２、ＩＲＨ−３中、Ｒ_１〜Ｒ_４は、それぞれ独立に、水素原子、アルキル基、置換基を有していてもよいアリール基、アリールアミノ基を示す。また、Ｒ_１〜Ｒ_４は、互いに同じであっても異なっていてもよい。］

[In the formula IRH-1, n represents a natural number of 1 to 12, R represents a substituent or a functional group, and each independently represents a hydrogen atom, an alkyl group, or an aryl group optionally having a substituent. Represents an arylamino group. Moreover, R < ₁ > -R < ₄ > shows the aryl group and arylamino group which may have a hydrogen atom, an alkyl group, and a substituent each independently in said Formula IRH-2 and IRH-3. R _{1 to} R ₄ may be the same as or different from each other. ]

The tetracene-based material used as the host material is preferably composed of carbon atoms and hydrogen atoms. Thereby, it is possible to prevent unintended interaction between the host material and the light emitting material. Therefore, the light emission efficiency of the light emitting element 1 can be increased. In addition, the resistance of the host material to potential and holes can be increased. Therefore, the lifetime of the light emitting element 1 can be extended.
Specifically, as the tetracene-based material, for example, it is preferable to use compounds represented by the following formulas H1-1 to H1-27.

  The anthracene-based material is not particularly limited as long as it has at least one anthracene skeleton in one molecule and can exhibit the function as the host material as described above. It is preferable to use a compound having a skeleton represented by the following formula IRH-4, and it is more preferable to use a compound represented by the following formula IRH-5 to IRH-8.

［前記式ＩＲＨ−４中、ｎは、１〜１０の自然数を示し、Ｒは置換基または官能基を表し、それぞれ独立に、水素原子、アルキル基、置換基を有していてもよいアリール基、アリールアミノ基を示す。また、前記式ＩＲＨ−５〜ＩＲＨ−８中、Ｒ_１、Ｒ_２は、それぞれ独立に、水素原子、アルキル基、置換基を有していてもよいアリール基、アリールアミノ基を示す。また、Ｒ_１、Ｒ_２は、互いに同じであっても異なっていてもよい。］

[In the formula IRH-4, n represents a natural number of 1 to 10, R represents a substituent or a functional group, and each independently represents a hydrogen atom, an alkyl group, or an aryl group optionally having a substituent. Represents an arylamino group. Moreover, R < ₁ >, R < ₂ > shows the aryl group and arylamino group which may have a hydrogen atom, an alkyl group, and a substituent each independently in said Formula IRH-5-IRH-8. R ₁ and R ₂ may be the same as or different from each other. ]

The anthracene-based material used as the host material is preferably composed of carbon atoms and hydrogen atoms. Thereby, it is possible to prevent unintended interaction between the host material and the light emitting material. Therefore, the light emission efficiency of the light emitting element 1 can be increased. In addition, the resistance of the host material to potential and holes can be increased. Therefore, the lifetime of the light emitting element 1 can be extended.
Specifically, as an anthracene-based material, for example, it is preferable to use compounds represented by the following formulas H2-1 to H2-56.

The content (doping amount) of the light emitting material in the light emitting layer 6 including such a light emitting material and the host material is preferably 0.01 to 10 wt%, and more preferably 0.1 to 5 wt%. . Luminous efficiency can be optimized by setting the content of the light emitting material within such a range.
Moreover, although the average thickness of the light emitting layer 6 is not specifically limited, It is preferable that it is about 1-60 nm, and it is more preferable that it is about 3-50 nm.

(Electron transport layer)
The electron transport layer 7 has a function of transporting electrons injected from the cathode 9 through the electron injection layer 8 to the light emitting layer 6.
In particular, the electron transport layer 7 includes an azaindolizine compound having an azaindolizine skeleton and an anthracene skeleton in the molecule (hereinafter also simply referred to as “azaindolizine compound”) as an electron transporting material. Yes.
Thus, by using a compound having an azaindolizine skeleton and an anthracene skeleton in the molecule as the electron transporting material of the electron transport layer 7 adjacent to the light emitting layer 6, electrons are transferred from the electron transport layer 7 to the light emitting layer 6. Can be transported efficiently. Therefore, the light emission efficiency of the light emitting element 1 can be improved.

In addition, since the electron transport from the electron transport layer 7 to the light emitting layer 6 can be efficiently performed, the driving voltage of the light emitting element 1 can be lowered, and accordingly, the life of the light emitting element 1 is extended. be able to.
Furthermore, since a compound having an azaindolizine skeleton and an anthracene skeleton in a molecule is excellent in stability (resistance) against electrons and holes, the life of the light-emitting element 1 can also be extended in this respect.

The electron transporting material (azaindolizine compound) used for the electron transporting layer 7 preferably has one or two azaindolizine skeletons and anthracene skeletons contained in one molecule. Thereby, the electron transport property and the electron injection property of the electron transport layer 7 can be made excellent.
Specifically, examples of the azaindolizine compound used for the electron transport layer 7 include compounds represented by the following formulas ELT-A1 to ELT-A24, and formulas ELT-B1 to ELT-B12. It is preferable to use such a compound and the compounds represented by the following ELT-C1 to ELT-C20.

Such an azaindolizine compound is excellent in electron transport property and electron injection property. Therefore, the light emission efficiency of the light emitting element 1 can be improved.
The reason why such an azaindolizine compound has excellent electron transport properties and electron injection properties is considered to be as follows.
In the azaindolizine-based compound having an azaindolizine skeleton and an anthracene skeleton in the molecule as described above, the entire molecule is connected by a π-conjugated system, and therefore the electron cloud spreads over the entire molecule.

  The azaindolizine skeleton portion of the azaindolizine compound has a function of accepting electrons and a function of sending the received electrons to the anthracene skeleton portion. On the other hand, the portion of the anthracene skeleton of the azaindolizine compound has a function of accepting electrons from the portion of the azaindolizine skeleton and a layer adjacent to the anode 3 side of the electron transport layer 7, that is, a light emitting layer. 6 is provided.

  More specifically, the azaindolizine skeleton portion of such an azaindolizine compound has two nitrogen atoms, one of which (on the side closer to the anthracene skeleton portion) has an sp2 hybrid orbital. On the other hand, the nitrogen atom on the other side (the side far from the anthracene skeleton portion) has an sp3 hybrid orbital. Nitrogen atom having sp2 hybrid orbital constitutes part of the conjugated system of azaindolizine compound molecule, and has higher electronegativity than carbon atom, and has higher strength to attract electrons. Function as. On the other hand, a nitrogen atom having an sp3 hybrid orbital is not a normal conjugated system, but has an unshared electron pair, so that the electron functions as a part that sends electrons toward the conjugated system of the molecule of the azaindolizine compound. .

  On the other hand, since the anthracene skeleton portion of the azaindolizine compound is electrically neutral, electrons can be easily accepted from the azaindolizine skeleton portion. In addition, since the anthracene skeleton portion of the azaindolizine compound has a large orbital overlap with the constituent material of the light emitting layer 6, particularly the host material (acene material), electrons are easily received by the host material of the light emitting layer 6. Can pass.

In addition, since the azaindolizine-based compound is excellent in the electron transporting property and the electron injecting property as described above, the driving voltage of the light emitting element 1 can be lowered as a result.
The azaindolizine skeleton portion is stable even when a nitrogen atom having an sp2 hybrid orbital is reduced, and is stable even if a nitrogen atom having an sp3 hybrid orbital is oxidized. Therefore, such an azaindolizine compound has high stability against electrons and holes. As a result, the lifetime of the light emitting element 1 can be extended.
Although the average thickness of the electron carrying layer 7 is not specifically limited, It is preferable that it is about 1.0-200 nm, and it is more preferable that it is about 10-100 nm.

The electron transport layer 7 may contain materials other than the azaindolizine compounds described above. Examples of such a material (electron transporting material) include phenanthroline derivatives such as 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), tris (8-quinolinolato) aluminum (Alq ₃ ), and the like. Quinoline derivatives such as organometallic complexes having 8-quinolinol or a derivative thereof as a ligand, oxadiazole derivatives, perylene derivatives, pyridine derivatives, pyrimidine derivatives, quinoxaline derivatives, diphenylquinone derivatives, nitro-substituted fluorene derivatives, etc. These can be used alone or in combination of two or more. In this case, the content of the azaindolizine compound in the electron transport layer 7 is preferably 50 wt% or more, more preferably 70 wt% or more, and further preferably 90 wt% or more.
Further, when the electron transport layer 7 is used in combination with an azaindolizine compound and a material other than the azaindolizine compound, the electron transport layer 7 may be composed of a mixed material obtained by mixing these materials, or a different material. It may be configured by stacking a plurality of configured layers.

When the electron transport layer 7 is configured by laminating a plurality of layers, the electron transport layer 7 includes a first electron transport configured to include the azaindolizine-based compound described above as a first electron transport material. And a second electron transporting material different from the first electron transporting material is provided between the first electron transporting layer and the light emitting layer 6 in contact with both layers. And a second electron transport layer. Thereby, the lifetime of the light emitting element 1 can be extended.
In this case, as the second electron transport material, for example, Alq ₃ (quinolinolato metal complex), tetracene material, anthracene material, or the like can be used. One of these materials can be used alone or in combination of two or more (mixed or laminated).

In the case where the second electron transport layer is formed by laminating a plurality of layers (two layers), the second electron transport layer is formed of a tetracene-based material or an anthracene-based material in contact with the light-emitting layer. The layer in contact with the first electron transport layer is preferably composed of a quinolinolato metal complex.
In addition, when the second electron transport layer is composed of a single material or a mixed material, the average thickness of the second electron transport layer is not particularly limited, but is preferably about 5 nm to 20 nm, for example. . Thereby, since the second electron transport layer forms a mixed layer with the light emitting layer 6 or a part of the first electron transport layer, the electron transport property from the electron transport layer 7 to the light emitting layer 6 is improved. Thus, the life of the light emitting element 1 can be extended.

(Electron injection layer)
The electron injection layer 8 has a function of improving the electron injection efficiency from the cathode 9.
Examples of the constituent material (electron injectable material) of the electron injection layer 8 include various inorganic insulating materials and various inorganic semiconductor materials.
Examples of such inorganic insulating materials include alkali metal chalcogenides (oxides, sulfides, selenides, tellurides), alkaline earth metal chalcogenides, alkali metal halides, and alkaline earth metal halides. Of these, one or two or more of these can be used in combination. By forming the electron injection layer 8 using these as main materials, the electron injection property can be further improved. In particular, alkali metal compounds (alkali metal chalcogenides, alkali metal halides, and the like) have a very low work function, and the light-emitting element 1 can be obtained with high luminance by forming the electron injection layer 8 using the work function. Become.

Examples of the alkali metal chalcogenide include Li ₂ O, LiO, Na ₂ S, Na ₂ Se, and NaO.
Examples of the alkaline earth metal chalcogenide include CaO, BaO, SrO, BeO, BaS, MgO, and CaSe.
Examples of the alkali metal halide include CsF, LiF, NaF, KF, LiCl, KCl, and NaCl.
Examples of the alkaline earth metal halide include CaF ₂ , BaF ₂ , SrF ₂ , MgF ₂ , and BeF ₂ .

In addition, as the inorganic semiconductor material, for example, an oxide including at least one element of Li, Na, Ba, Ca, Sr, Yb, Al, Ga, In, Cd, Mg, Si, Ta, Sb, and Zn , Nitrides, oxynitrides, and the like, and one or more of these can be used in combination.
In particular, when any one of Al, Ag, and Mg / Ag is used as the constituent material of the cathode 9, it is preferable to use an oxide or halide of Li.

The average thickness of the electron injection layer 8 is not particularly limited, but is preferably about 0.1 to 1000 nm, more preferably about 0.2 to 100 nm, and about 0.2 to 50 nm. Further preferred.
The electron injection layer 8 may be omitted depending on the constituent materials and thicknesses of the cathode 9 and the electron transport layer 7.

(Sealing member)
The sealing member 10 is provided so as to cover the anode 3, the laminate 14, and the cathode 9, and has a function of hermetically sealing them and blocking oxygen and moisture. By providing the sealing member 10, effects such as improvement of the reliability of the light emitting element 1 and prevention of deterioration / deterioration (improvement of durability) can be obtained.
Examples of the constituent material of the sealing member 10 include Al, Au, Cr, Nb, Ta, Ti, alloys containing these, silicon oxide, various resin materials, and the like. In addition, when using the material which has electroconductivity as a constituent material of the sealing member 10, in order to prevent a short circuit, between the sealing member 10 and the anode 3, the laminated body 14, and the cathode 9 is required. Accordingly, an insulating film is preferably provided.
Further, the sealing member 10 may be formed in a flat plate shape so as to face the substrate 2 and be sealed with a sealing material such as a thermosetting resin.

  According to the light-emitting element 1 configured as described above, a thiadiazole-based compound is used as the light-emitting material of the light-emitting layer 6, and an azaindolizine-based compound is used as the electron-transporting material of the electron transport layer 7. Light emission in the outer region can be achieved, and high efficiency and long life can be achieved.

The above light emitting element 1 can be manufactured as follows, for example.
[1] First, the substrate 2 is prepared, and the anode 3 is formed on the substrate 2.
The anode 3 is, for example, a chemical vapor deposition method (CVD) such as plasma CVD or thermal CVD, a dry plating method such as vacuum deposition, a wet plating method such as electrolytic plating, a thermal spraying method, a sol-gel method, a MOD method, or a metal foil. It can be formed by using, for example, bonding.

[2] Next, the hole injection layer 4 is formed on the anode 3.
The hole injection layer 4 is preferably formed by, for example, a vapor phase process using a CVD method, a dry plating method such as vacuum deposition or sputtering, or the like.
For example, the hole injection layer 4 may be dried (desolvent or solvent-free) after supplying a material for forming a hole injection layer obtained by dissolving a hole injection material in a solvent or dispersing in a dispersion medium onto the anode 3. It can also be formed by dedispersing medium).

As a method for supplying the hole injection layer forming material, for example, various coating methods such as a spin coating method, a roll coating method, and an ink jet printing method can be used. By using such a coating method, the hole injection layer 4 can be formed relatively easily.
Examples of the solvent or dispersion medium used for the preparation of the hole injection layer forming material include various inorganic solvents, various organic solvents, or mixed solvents containing these.
The drying can be performed, for example, by standing in an atmospheric pressure or a reduced pressure atmosphere, heat treatment, or blowing an inert gas.

Prior to this step, the upper surface of the anode 3 may be subjected to oxygen plasma treatment. Thereby, it is possible to impart lyophilicity to the upper surface of the anode 3, remove (clean) organic substances adhering to the upper surface of the anode 3, adjust the work function near the upper surface of the anode 3, and the like. .
Here, the oxygen plasma treatment conditions include, for example, a plasma power of about 100 to 800 W, an oxygen gas flow rate of about 50 to 100 mL / min, a conveyance speed of the member to be treated (anode 3) of about 0.5 to 10 mm / sec, and a substrate. The temperature of 2 is preferably about 70 to 90 ° C.

[3] Next, the hole transport layer 5 is formed on the hole injection layer 4.
The hole transport layer 5 is preferably formed by a vapor phase process using, for example, a CVD method, a dry plating method such as vacuum evaporation or sputtering.
In addition, a hole transport layer forming material obtained by dissolving a hole transport material in a solvent or dispersing in a dispersion medium is supplied onto the hole injection layer 4 and then dried (desolvent or dedispersion medium). Can also be formed.

[4] Next, the light emitting layer 6 is formed on the hole transport layer 5.
The light emitting layer 6 can be formed, for example, by a vapor phase process using a dry plating method such as vacuum deposition.
[5] Next, the electron transport layer 7 is formed on the light emitting layer 6.
The electron transport layer 7 is preferably formed, for example, by a vapor phase process using a dry plating method such as vacuum deposition.
For example, the electron transport layer 7 is dried (desolvent or dedispersed) after supplying an electron transport layer forming material obtained by dissolving an electron transport material in a solvent or dispersing in a dispersion medium onto the light emitting layer 6. It can also be formed by the medium.

[6] Next, the electron injection layer 8 is formed on the electron transport layer 7.
In the case where an inorganic material is used as the constituent material of the electron injection layer 8, the electron injection layer 8 is formed by, for example, a vapor phase process using a CVD method, a dry plating method such as vacuum deposition or sputtering, or the application and baking of inorganic fine particle ink. Etc. can be used.
[7] Next, the cathode 9 is formed on the electron injection layer 8.
The cathode 9 can be formed by using, for example, a vacuum deposition method, a sputtering method, bonding of metal foil, application and firing of metal fine particle ink, or the like.
The light emitting element 1 is obtained through the steps as described above.
Finally, the sealing member 10 is covered so as to cover the obtained light emitting element 1 and bonded to the substrate 2.

(Light emitting device)
Next, an embodiment of the light emitting device of the present invention will be described.
FIG. 2 is a longitudinal sectional view showing an embodiment of a display device to which the light emitting device of the present invention is applied.
A display device 100 shown in FIG. 2 includes a substrate 21, a plurality of light emitting elements 1A, and a plurality of driving transistors 24 for driving the respective light emitting elements 1A. Here, the display device 100 is a display panel having a top emission structure.

A plurality of driving transistors 24 are provided on the substrate 21, and a planarizing layer 22 made of an insulating material is formed so as to cover these driving transistors 24.
Each driving transistor 24 includes a semiconductor layer 241 made of silicon, a gate insulating layer 242 formed on the semiconductor layer 241, a gate electrode 243 formed on the gate insulating layer 242, a source electrode 244, and a drain electrode. H.245.

On the planarization layer, the light emitting element 1A is provided corresponding to each driving transistor 24.
In the light emitting element 1 </ b> A, a reflective film 32, a corrosion preventing film 33, an anode 3, a stacked body (organic EL light emitting unit) 14, a cathode 13, and a cathode cover 34 are stacked in this order on a planarizing layer 22. In the present embodiment, the anode 3 of each light emitting element 1 </ b> A constitutes a pixel electrode and is electrically connected to the drain electrode 245 of each driving transistor 24 by a conductive portion (wiring) 27. Moreover, the cathode 13 of each light emitting element 1A is a common electrode.

2A emits light in the near infrared region.
A partition wall 31 is provided between the adjacent light emitting elements 1A. Further, an epoxy layer 35 made of an epoxy resin is formed on these light emitting elements 1A so as to cover them.
A sealing substrate 20 is provided on the epoxy layer 35 so as to cover them.

The display device 100 as described above can be used as a near infrared display for military use, for example.
According to such a display device 100, light emission in the near infrared region is possible. In addition, since the light-emitting element 1A having high efficiency and long life is provided, the reliability is excellent.

(Authentication device)
Next, an embodiment of the authentication device of the present invention will be described.
FIG. 3 is a diagram showing an embodiment of the authentication device of the present invention.
An authentication apparatus 1000 shown in FIG. 3 is a biometric authentication apparatus that authenticates an individual using biometric information of the biometric F (fingertip in this embodiment).
The authentication apparatus 1000 includes a light source 100B, a cover glass 1001, a microlens array 1002, a light receiving element group 1003, a light emitting element driving unit 1006, a light receiving element driving unit 1004, and a control unit 1005.

The light source 100 </ b> B includes a plurality of the light emitting elements 1 described above, and irradiates near-infrared light toward the living body F that is an imaging target. For example, the plurality of light emitting elements 1 of the light source 100 </ b> B are arranged along the outer periphery of the cover glass 1001.
The cover glass 1001 is a part where the living body F is in contact with or close to.
The microlens array 1002 is provided on the side opposite to the side of the cover glass 1001 where the living body F is in contact with or close to. The microlens array 1002 includes a plurality of microlenses arranged in a matrix.

The light receiving element group 1003 is provided on the side opposite to the cover glass 1001 with respect to the microlens array 1002. The light receiving element group 1003 includes a plurality of light receiving elements provided in a matrix corresponding to the plurality of microlenses of the microlens array 1002. As each light receiving element of the light receiving element group 1003, for example, a CCD (Charge Coupled Device), a CMOS, or the like can be used.
The light emitting element driving unit 1006 is a driving circuit that drives the light source 100B.
The light receiving element driving unit 1004 is a drive circuit that drives the light receiving element group 1003.

The control unit 1005 is, for example, an MPU, and has a function of controlling driving of the light emitting element driving unit 1006 and the light receiving element driving unit 1004.
In addition, the control unit 1005 has a function of performing authentication of the living body F by comparing the light reception result of the light receiving element group 1003 with biometric authentication information stored in advance.
For example, the control unit 1005 generates an image pattern (for example, a vein pattern) related to the living body F based on the light reception result of the light receiving element group 1003. Then, the control unit 1005 compares the image pattern with an image pattern stored in advance as biometric authentication information, and performs authentication (for example, vein authentication) of the biometric F based on the comparison result.
According to such an authentication apparatus 1000, biometric authentication can be performed using near infrared light. Further, since the light-emitting element 1 having high efficiency and long life is provided, the reliability is excellent.
Such an authentication apparatus 1000 can be incorporated into various electronic devices.

(Electronics)
FIG. 4 is a perspective view showing a configuration of a mobile (or notebook) personal computer to which the electronic apparatus of the present invention is applied.
In this figure, a personal computer 1100 includes a main body 1104 provided with a keyboard 1102 and a display unit 1106 provided with a display. The display unit 1106 is rotatable with respect to the main body 1104 via a hinge structure. It is supported by.
In the personal computer 1100, the main body 1104 is provided with the authentication device 1000 described above.
According to such a personal computer 1100, since the light-emitting element 1 with high efficiency and long life is provided, the reliability is excellent.

  In addition to the personal computer (mobile personal computer) shown in FIG. 4, the electronic apparatus of the present invention may be, for example, a mobile phone, a digital still camera, a television, a video camera, a viewfinder type, or a monitor direct view type video tape. Recorder, laptop personal computer, car navigation system, pager, electronic organizer (including communication function), electronic dictionary, calculator, electronic game device, word processor, workstation, video phone, security TV monitor, electronic binoculars, POS Terminals, devices equipped with a touch panel (for example, cash dispensers of financial institutions, automatic ticket vending machines), medical devices (for example, electronic thermometers, blood pressure monitors, blood glucose meters, pulse measuring devices, pulse measuring devices, electrocardiographic display devices, ultrasonic diagnostics) Device, endoscope display device), fish finder Various measuring instruments, gauges (e.g., gages for vehicles, aircraft, and ships), a flight simulator, various monitors, and a projection display such as a projector.

As described above, the light-emitting element, the light-emitting device, the authentication device, and the electronic device of the present invention have been described based on the illustrated embodiments, but the present invention is not limited to these.
For example, the light emitting element and the light emitting device of the present invention may be used as a light source for illumination.
In addition, for example, in addition to the light emitting layer containing the thiadiazole compound according to the present invention, a light emitting layer that emits light in the visible light region may be provided between the anode and the cathode.

  In the above-described embodiment, the case where the thiadiazole compound according to the present invention is used as a light emitting material has been described as an example. However, the present invention is not limited thereto, and the thiadiazole compound according to the present invention is used for applications other than the light emitting material. be able to. For example, the thiadiazole-based compound according to the present invention can also be used as a material that traps carriers and converts them into heat (infrared rays) in a layer provided between an anode and a cathode. As a result, electrons (carriers) that have not been consumed in the light emitting layer are injected into the hole transport layer side, which causes the constituent materials of the hole transport layer and the hole injection layer to be altered and deteriorated. It can be suppressed or prevented accurately. As a result, the lifetime of the light emitting element can be extended.

Next, specific examples of the present invention will be described.
1. Production of thiadiazole compound (Synthesis Example A1) Synthesis of compound represented by Formula D-1

Synthesis (A1-1)
A 5-liter flask was charged with 1500 ml of fuming nitric acid and cooled. Thereto, 1500 ml of sulfuric acid was added in portions while maintaining the temperature at 10 to 50 ° C. Furthermore, 150 g of compound (a), which is a raw material dibromobenzothiadiazole, was added in small portions over 1 hour. At that time, the solution temperature was adjusted to 5 ° C. or lower. After adding the whole amount, the reaction was allowed to proceed at room temperature (25 ° C.) for 20 hours. After the reaction, the reaction solution was poured into 3 kg of ice and stirred overnight. Thereafter, the mixture was filtered and washed with methanol and heptane.
The residue remaining after filtration was dissolved in 200 ml of toluene by heating, and then gradually cooled to room temperature, followed by filtration. The residue was washed with a small amount of toluene and then dried under reduced pressure.
As a result, 60 g of a compound (b) (4,7-dibromo-5,6-dinitro-benzo [1,2,5] thiadiazole) having a HPLC purity of 95% was obtained.

Synthesis (A1-2)
Under Ar, a 5 liter flask was charged with 30 g of the obtained dibromo compound (b) and 23 g of phenylboronic acid (commercial product), 2500 ml of toluene, 2 M aqueous cesium carbonate solution (152 g / (distilled water) 234 ml), The reaction was allowed to proceed overnight at 90 ° C. After the reaction, filtration, liquid separation, and concentration were performed, and 52 g of the resulting crude product was separated with a silica gel column (SiO ₂ 5 kg) to obtain a reddish purple solid.
As a result, 6 g of compound (c) (5,6-dinitro-4,7-diphenyl-benzo [1,2,5] thiadiazole) having an HPLC purity of 96% was obtained.

Synthesis (A1-3)
Under Ar, 6 g of the obtained dinitro compound (c), 7 g of reduced iron, and 600 ml of acetic acid were placed in a 1 liter flask, reacted at 80 ° C. for 4 hours, and cooled to room temperature. After the reaction, the reaction solution was poured into 1.5 liters of ion exchange water, and 1.5 liters of ethyl acetate was further added thereto. After the addition, since a solid was precipitated, 1 liter of tetrahydrofuran and 300 g of sodium chloride were added and separated. The aqueous layer was re-extracted with 1 liter of tetrahydrofuran. The concentrated and dried product was washed again with a small amount of water and methanol to obtain an orange solid.
As a result, 7 g of compound (d) (4,7-diphenyl-benzo [1,5,5] thiadiazolo-5,6-diamine) having an HPLC purity of 80% was obtained.

Synthesis (A1-4)
Under Ar, in a 1 liter flask, 1.5 g of the obtained diamine compound (d), o-benzoquinone aqueous solution (1 mol / L) 12 cm ³ (Voigt Global Distribution Inc.), 300 ml of acetic acid as a solvent, The reaction was performed at 80 ° C. for 2 hours. After the reaction, the reaction solution was cooled to room temperature, poured into 1 liter of ion-exchanged water, and the crystals were filtered, washed with water, and 2 g of a black-green solid was obtained. The black-green solid was purified with a silica gel column (SiO ₂ 1 kg).
As a result, 0.9 g of a compound (e) (compound represented by the formula D-1) having a HPLC purity of 99% was obtained. Mass analysis of this compound (e) showed M +: 390.
Furthermore, the obtained compound (e) was purified by sublimation at a set temperature of 340 ° C. The HPLC purity of the compound (e) after the sublimation purification was 99%.

  (Synthesis Example A2) Synthesis of compound represented by Formula D-2

Synthesis was performed in the same manner as in Synthesis Example A1 except that in Example Synthesis A1 described above, a boronic acid form of triphenylamine was used instead of phenylboronic acid used in Synthesis (A1-2). Thereby, the compound (h) represented by the formula D-2 was obtained.
Here, in synthesizing the boronic acid form of triphenylamine, 246 g of 4-bromotriphenylamine (commercial product) and 1500 ml of dehydrated tetrahydrofuran were placed in a 5-liter flask under Ar, and 1.6 M n at −60 ° C. -570 ml of a BuLi / hexane solution was added dropwise over 3 hours. After 30 minutes, 429 g of triisopropyl borate was added dropwise over 1 hour. After dropping, the reaction was allowed to proceed overnight at the expected temperature. After the reaction, 2 liters of water was added dropwise, and then extracted with 2 liters of toluene and separated. The organic layer was concentrated, recrystallized, filtered and dried to obtain 160 g of a boronic acid compound as a white target product.
The HPLC purity of the obtained boronic acid compound was 99%.

And the synthesis | combination similar to the synthesis | combination (A1-2) of the synthesis example A1 mentioned above was performed using the obtained boronic acid body, and the compound (f) was obtained.
Using the obtained compound (f), the same synthesis as the synthesis (A1-3) of Synthesis Example A1 described above was performed to obtain a compound (g).
Using the obtained compound (g), the synthesis similar to the synthesis (A1-4) of Synthesis Example A1 described above was performed to obtain the compound (h) represented by the formula D-2.

As a result, 3 g of a compound (h) (compound represented by the formula D-2) having an HPLC appearance of 99% and having a dark blue solid appearance was obtained. Mass analysis of this compound (h) showed M +: 724.
Furthermore, the obtained compound (h) was purified by sublimation at a preset temperature of 360 ° C. The HPLC purity of the compound (h) after the sublimation purification was 99%.

  (Synthesis Example A3) Synthesis of compound represented by Formula D-3

Synthesis was performed in the same manner as in Synthesis Example A1, except that diphenylamine was used instead of phenylboronic acid used in Synthesis (A1-2) in Synthesis Example A1. Thereby, the compound (k) represented by the formula D-3 was obtained.
Here, in the synthesis using diphenylamine, 11 g of tetrakistriphenyl Pd (0) was dissolved in 100 ml of toluene and heated to 100 ° C. in a 300 ml flask under Ar. Thereto, 8 g of tri-t-butylphosphine was added and reacted for 30 minutes to obtain a catalyst (Pd catalyst).

On the other hand, 30 g of dibromo compound (b) and 33 g of diphenylamine (commercial product) were dissolved in 2500 ml of toluene and heated to 100 ° C. in a 5-liter flask under Ar. The previously prepared Pd catalyst and 20 g of t-BuOK were added thereto and heated to reflux for 3 hours.
After the reaction, the reaction mixture was cooled to room temperature, 100 ml of water was added, and the mixture was stirred for about 1 hour. The obtained solid was separated with a silica gel column (SiO ₂ 5 kg) to obtain a purple solid.
As a result, 10 g of compound (i) (5,6-dinitro-N, N, N ′, N′-tetraphenyl-benzo [1,2,5] thiadiazole) having an HPLC purity of 96% was obtained.

And using the obtained compound (i), the synthesis | combination similar to the synthesis | combination (A1-3) of the synthesis example A1 mentioned above was performed, and the compound (j) was obtained.
Using the obtained compound (j), the synthesis similar to the synthesis (A1-4) of Synthesis Example A1 described above was performed to obtain the compound (k) represented by the formula D-3.
As a result, 3 g of a compound (k) (compound represented by the formula D-3) having an HPLC appearance of 99% and having a dark blue solid appearance was obtained. Mass analysis of this compound (k) showed M +: 572.
Furthermore, the obtained compound (k) was purified by sublimation at a preset temperature of 340 ° C. The HPLC purity of the compound (k) after the sublimation purification was 99%.

2. Production of host material (tetracene-based material) (Synthesis Example B1) Synthesis of compound represented by formula H1-5

Synthesis (B1-1)
Under Ar, a 300 ml flask was charged with 6 g of 4′-bromo- [1,1 ′; 3 ′, 1 ″] terphenyl and 50 ml of dry diethyl ether. At room temperature, 14.5 ml of 1.6M n-BuLi / hexane solution was added dropwise and reacted for 30 minutes.
Separately, 2 g of 5,12-naphthacenequinone and 100 ml of dry toluene were placed in a 500 ml flask under Ar. The terphenyl lithium adjusted previously was dripped there and it was made to react for 3 hours. After the reaction, 20 ml of distilled water was added, stirred for 30 minutes, put into methanol, and the solid was separated by filtration. The obtained solid was purified on silica gel (SiO ₂ 500 g).
This gives 5 g of a white solid (5,12-bis- [1,1 ′; 3 ′, 1 ″] terphenyl-4′-yl-5,12-dihydronaphthacene-5,12-diol). It was.

Synthesis (B1-2)
5 g of the diol obtained in the synthesis (B1-1) and 300 ml of acetic acid were weighed and put into a 1000 ml flask. A solution prepared by dissolving 5 g of tin (II) chloride (anhydrous) in 5 g of hydrochloric acid (35%) was added and stirred for 30 minutes. Then, it moved to the separating funnel, added toluene, liquid-separated and washed with distilled water, and dried. The obtained solid was purified with silica gel (SiO ₂ 500 g) to obtain 4.5 g of a yellow solid (compound represented by the formula H1-5).

  (Synthesis Example B2) Synthesis of a compound represented by Formula H1-13

Synthesis (B2-1)
A 500 ml flask was charged with 100 ml of dichloromethane, 5.2 g of naphthoquinone, and 10 g of 1,3-diphenylisobenzofuran, and stirred for 1 hour. After stirring, 33 ml of commercially available boron tribromide (dichloromethane solution 1 mol / L) was added over 10 minutes to obtain 7.1 g of yellow needle crystals (6,11-diphenyl-5,12-naphthacenequinone). Obtained.

Synthesis (B2-2)
Under Ar, a 200 ml flask was charged with 6 g of 4-bromo-biphenyl and 80 ml of dry diethyl ether. At room temperature, 16 ml of 1.6M n-BuLi / hexane solution was added dropwise and reacted for 30 minutes.
Separately, 4.2 g of the quinone obtained by synthesis (B2-1) and 100 ml of dry toluene were charged into a 500 ml flask under Ar. The biphenyllithium prepared previously was dripped there and it was made to react for 3 hours. After the reaction, 20 ml of distilled water was added, stirred for 30 minutes, poured into methanol, and the solid was separated by filtration. The obtained solid was purified on silica gel (SiO ₂ 500 g).
This gave 5.5 g of a white solid (5,12-bisbiphenyl-4-yl-6,11-diphenyl-5,12-dihydro-naphthacene-5,12-diol).

Synthesis (B2-3)
5 g of the diol obtained in the synthesis (B2-2) and 200 ml of tetrahydrofuran were weighed and put into a 500 ml flask. Thereto was added 10 g of hydroiodic acid (55% aqueous solution), and the mixture was stirred for 2 hours while being shielded from light. Then, it moved to the separating funnel, added toluene, liquid-separated and washed with distilled water, and dried. The obtained solid was purified with silica gel (SiO ₂ 500 g) to obtain 3 g of a red solid (compound represented by the formula H1-13).

3. Production of Electron Transport Material (Azaindolizine Compound) (Synthesis Example D1) Synthesis of Compound Represented by Formula ETL-A3

Synthesis (D1-1)
Commercially available 2-naphthaleneboronic acid (2.1 g) and 9,10-dibromoanthracene (5 g) were dissolved in 50 ml of dimethoxyethane and heated to 80 ° C. Thereto, 50 ml of distilled water and 10 g of sodium carbonate were added. Further, 0.4 g of tetrakistriphenylphosphine palladium (0) was added thereto.
After 3 hours, toluene was extracted with a separatory funnel and purified with silica gel (SiO ₂ 500 g).
As a result, 3 g of pale yellowish white crystals (9-bromo-10-naphthalen-2-yl-anthracene) were obtained.

Synthesis (D1-2)
Under Ar, in a 1-liter flask, 3 g of 9-bromo-10-naphthalen-2-yl-anthracene obtained in Synthesis (D1-1) and 500 ml of dehydrated tetrahydrofuran were placed, and 1.6M n-BuLi was added at -60 ° C. / 6 ml of hexane solution was added dropwise over 10 minutes. After 30 minutes, 1.5 g of triisopropyl borate was added. After dropping, the reaction was allowed to proceed for 3 hours at the expected temperature. After the reaction, 50 mL of distilled water was added dropwise, and then extracted and separated with 1 liter of toluene. The organic layer was concentrated, recrystallized, filtered and dried to obtain 2 g of a white target product (boronic acid form).

Synthesis (D1-3)
Under Ar, 3.4 g of 2-aminopyridine was weighed into a 300 ml flask, and 40 ml of ethanol and 40 ml of acetone were added and dissolved therein. 4-bromophenacyl bromide 10g was added there, and it was made to heat and reflux. After 3 hours, heating was discontinued and cooled to room temperature. After removing the solvent under reduced pressure, it was dissolved by heating in 1 liter of methanol, and after removing insoluble impurities by filtration, the concentrated and precipitated product was collected.
As a result, 8 g of a target white solid (2- (4-bromophenyl) -imidazo [1,2-a] pyridine) was obtained.

Synthesis (D1-4)
Under Ar, in a 500 ml flask, 2 g of the boronic acid compound obtained by synthesis (D1-2) and 1.7 g of the imidazopyridine derivative obtained by synthesis (D1-3) were dissolved in 200 ml of dimethoxyethane. Heated to ° C. Thereto, 250 ml of distilled water and 10 g of sodium carbonate were added. Further, 0.5 g of tetrakistriphenylphosphine palladium (0) was added thereto.
After 3 hours, toluene was extracted with a separatory funnel and purified with silica gel (SiO ₂ 500 g).
As a result, 2 g of a white solid (compound represented by the formula ETL-A3) was obtained.

5). Production of light emitting device (Example 1)
<1> First, a transparent glass substrate having an average thickness of 0.5 mm was prepared. Next, an ITO electrode (anode) having an average thickness of 100 nm was formed on the substrate by sputtering.
And after immersing a board | substrate in order of acetone and 2-propanol and ultrasonically cleaning, oxygen plasma treatment and argon plasma treatment were performed. Each of these plasma treatments was performed at a plasma power of 100 W, a gas flow rate of 20 sccm, and a treatment time of 5 seconds with the substrate heated to 70 to 90 ° C.

  <2> Next, tetrakis-p-biphenylyl-benzidine (a compound represented by the following formula HTL-1) is vapor-deposited on the ITO electrode as an amine-based hole transporting material by a vacuum vapor deposition method, and the average thickness is measured. A 60 nm hole transport layer was formed.

<3> Next, the constituent material of the light emitting layer was vapor-deposited on the hole transport layer by a vacuum vapor deposition method to form a light emitting layer having an average thickness of 25 nm. As a constituent material of the light emitting layer, a compound represented by the formula D-2 was used as a light emitting material (guest material), and Alq ₃ was used as a host material. Further, the content (dope concentration) of the light emitting material (dopant) in the light emitting layer was 4.0 wt%.
<4> Next, on the light emitting layer, the compound represented by the formula ETL-A3 was formed into a film by a vacuum deposition method to form an electron transport layer having an average thickness of 90 nm.

<5> Next, on the electron transport layer, lithium fluoride (LiF) was formed by a vacuum deposition method to form an electron injection layer having an average thickness of 1 nm.
<6> Next, Al was formed into a film by the vacuum evaporation method on the electron injection layer. Thereby, a cathode having an average thickness of 100 nm made of Al was formed.
<7> Next, a glass protective cover (sealing member) was placed over the formed layers, and fixed and sealed with an epoxy resin.
The light emitting device was manufactured through the above steps.

(Example 2)
A light emitting device was produced in the same manner as in Example 1 except that the compound represented by the formula H1-5 (tetracene material) was used as the host material of the light emitting layer.
(Example 3)
A light emitting device was manufactured in the same manner as in Example 1 except that the compound represented by the formula H1-13 (tetracene material) was used as the host material of the light emitting layer.

Example 4
The above-described implementation was performed except that the compound represented by the formula H1-5 (tetracene-based material) was used as the host material of the light emitting layer, the average thickness of the light emitting layer was 45 nm, and the average thickness of the electron transport layer was 70 nm. A light emitting device was produced in the same manner as in Example 1.
That is, a light emitting device was manufactured in the same manner as in Example 2 except that the average thickness of the light emitting layer was 45 nm and the average thickness of the electron transport layer was 70 nm.

(Example 5)
The implementation described above, except that the compound represented by the formula H1-5 (tetracene-based material) is used as the host material of the light emitting layer, the average thickness of the light emitting layer is 15 nm, and the average thickness of the electron transport layer is 100 nm. A light emitting device was produced in the same manner as in Example 1.
That is, a light emitting device was manufactured in the same manner as in Example 2 except that the average thickness of the light emitting layer was 15 nm and the average thickness of the electron transport layer was 100 nm.

(Example 6)
The compound represented by the formula H1-5 (tetracene-based material) is used as the host material of the light-emitting layer, the electron transport layer is formed of Alq ₃ , and the compound represented by the formula ETL-A3 is vacuum-deposited in this order. A light emitting device was manufactured in the same manner as in Example 1 except that the layers were formed by lamination.

That is, a light emitting device was manufactured in the same manner as in Example 2 except that the electron transport layer was formed by stacking Alq ₃ and the compound represented by the formula ETL-A3 in this order by vacuum deposition.
Here, in the electron transport layer, the average thickness of the layer composed of Alq ₃ was 20 nm, and the average thickness of the layer composed of the compound represented by the formula ETL-A3 was 70 nm.

(Example 7)
The compound represented by the formula H1-5 (tetracene material) is used as the host material of the light emitting layer, and the electron transport layer is represented by the compound represented by the formula H1-5, Alq ₃ , or the formula ETL-A3. A light emitting device was manufactured in the same manner as in Example 1 except that the above compounds were laminated in this order by the vacuum deposition method.

That is, Example 2 described above except that the electron transport layer was formed by laminating the compound represented by the formula H1-5, Alq ₃ , and the compound represented by the formula ETL-A3 in this order by the vacuum deposition method. A light emitting device was manufactured in the same manner as described above.
Here, the electron transport layer has an average thickness of a layer composed of the compound represented by the formula H1-5 of 20 nm, an average thickness of a layer composed of Alq ₃ of 20 nm, and is represented by the formula ETL-A3. The average thickness of the layer composed of the compound to be obtained was 50 nm.

(Example 8)
Example 1 described above, except that the compound represented by the formula D-1 was used as the light emitting material of the light emitting layer, and the compound (tetracene-based material) represented by the formula H1-5 was used as the host material of the light emitting layer. A light emitting device was manufactured in the same manner.
That is, a light emitting device was manufactured in the same manner as in Example 2 except that the compound represented by the formula D-1 was used as the light emitting material of the light emitting layer.

Example 9
Example 1 described above except that the compound represented by Formula D-3 was used as the light emitting material of the light emitting layer, and the compound (tetracene-based material) represented by Formula H1-5 was used as the host material of the light emitting layer. A light emitting device was manufactured in the same manner.
That is, a light emitting device was manufactured in the same manner as in Example 2 except that the compound represented by the formula D-3 was used as the light emitting material of the light emitting layer.

(Reference Example 1)
A light emitting device was produced in the same manner as in Example 1 except that 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) was used as the electron transporting material for the electron transport layer.
(Reference Example 2)
The compound represented by the formula H1-5 (tetracene material) is used as the host material of the light emitting layer, and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline ( A light emitting device was manufactured in the same manner as in Example 1 except that BCP) was used.

(Reference Example 3)
The compound represented by the formula H1-13 (tetracene-based material) is used as the host material of the light emitting layer, and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline ( A light emitting device was manufactured in the same manner as in Example 1 except that BCP) was used.

(Reference Example 4)
The compound represented by the formula H1-5 (tetracene material) is used as the host material of the light emitting layer, and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline ( BCP) was used, and a light emitting device was manufactured in the same manner as in Example 1 except that the average thickness of the light emitting layer was 45 nm and the average thickness of the electron transport layer was 70 nm.

(Reference Example 5)
The compound represented by the formula H1-5 (tetracene material) is used as the host material of the light emitting layer, and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline ( BCP) was used, and a light emitting device was manufactured in the same manner as in Example 1 except that the average thickness of the light emitting layer was 15 nm and the average thickness of the electron transport layer was 100 nm.

(Reference Example 6)
Except that the compound represented by the formula H1-5 (tetracene-based material) is used as the host material of the light emitting layer, and the electron transport layer is formed by laminating Alq ₃ and BCP in this order by the vacuum evaporation method. A light emitting device was manufactured in the same manner as in Example 1 described above.
Here, in the electron transport layer, the average thickness of the layer composed of Alq ₃ was 20 nm, and the average thickness of the layer composed of BCP was 70 nm.

(Reference Example 7)
The compound represented by the formula H1-5 (tetracene-based material) is used as the host material of the light emitting layer, and the compound represented by the formula H1-5, Alq ₃ and BCP are vacuum-deposited in this order on the electron transport layer. A light emitting device was manufactured in the same manner as in Example 1 except that the layers were formed by the method.
Here, the electron transport layer has an average thickness of a layer composed of the compound represented by the formula H1-5 of 20 nm, an average thickness of a layer composed of Alq ₃ of 20 nm, and a layer composed of BCP. The average thickness was 50 nm.

(Reference Example 8)
As a light-emitting material for the light-emitting layer, the compound represented by the formula D-1 is used. As a host material for the light-emitting layer, the compound represented by the formula H1-5 (tetracene-based material) is used. A light emitting device was manufactured in the same manner as in Example 1 except that BCP was used.

(Reference Example 9)
As a light-emitting material for the light-emitting layer, the compound represented by the formula D-3 is used, and as a host material for the light-emitting layer, the compound represented by the formula H1-5 (tetracene-based material) is used. A light emitting device was manufactured in the same manner as in Example 1 except that BCP was used.

6). Evaluation For each example and each reference example, a constant current of 100 mA / cm ² was passed through the light-emitting element using a constant current power source (KEITLEY2400 manufactured by Toyo Corporation), and the emission peak wavelength at that time was measured with a small fiber optical spectrometer. (Ocean Optics S2000) was used for measurement. The light emission power was measured using an optical power measuring device (Optical Power Meter 8230, manufactured by ADC Corporation).
The voltage value (drive voltage) at that time was also measured.
Furthermore, the time (LT80) during which the luminance was 80% of the initial luminance was measured.
These measurement results are shown in Table 1.

As is clear from Table 1, the light-emitting elements of the respective examples emit light in the near infrared region and obtain a relatively high light emission power. Moreover, the light emitting element of each Example can suppress a drive voltage. For these reasons, the light emitting elements of the respective examples have excellent luminous efficiency.
Moreover, the light emitting element of each Example has a long lifetime compared with the light emitting element of each reference example.

  DESCRIPTION OF SYMBOLS 1, 1A ... Light emitting element 2 ... Substrate 3 ... Anode 4 ... Hole injection layer 5 ... Hole transport layer 6 ... Light emitting layer 7 ... Electron transport layer 8 ... Electron injection layer 9 ... Cathode DESCRIPTION OF SYMBOLS 10 ... Sealing member 13 ... Cathode 14 ... Laminated body 100 ... Display apparatus 100B ... Light source 1000 ... Authentication apparatus 1001 ... Cover glass 1002 ... Micro lens array 1003 ... Light receiving element group 1004 ... Light reception Element driving unit 1005... Control unit 1006 .. Light emitting element driving unit 20... Sealing substrate 21... Substrate 22 .. Flattening layer 24 .. Driving transistor 241 ... Semiconductor layer 242 ... Gate insulating layer 243. … Gate electrode 244 …… Source electrode 245 …… Drain electrode 27 …… Wiring 31 …… Partition wall 32 …… Reflection film 33 …… Corrosion prevention film 34 …… Cathode electrode Over 35 ...... epoxy layer 1100 ...... personal computer 1102 ...... keyboard 1104 ...... body portion 1106 ...... Display unit F ...... vivo

Claims (12)

The anode,
A cathode,
A light emitting layer that is provided between the anode and the cathode, and emits light when energized between the anode and the cathode;
An electron transport layer provided between and in contact with the light emitting layer between the cathode and the light emitting layer, and having an electron transporting property;
The light-emitting layer includes a thiadiazole-based compound that is a compound represented by the following formula ( 2 ) as a light-emitting material,
The light-emitting element, wherein the electron transporting layer includes an azaindolizine compound having an azaindolizine skeleton and an anthracene skeleton in the molecule as an electron transporting material.

[In said Formula (2), A shows a hydrogen atom, an alkyl group, the aryl group which may have a substituent, an arylamino group, or a triarylamine each independently. ] The light emitting device according to claim 1 , wherein the compound represented by the formula (2) is a compound represented by any one of the following formulas (3), (4), and (5).

[In said formula (3), (4), (5), R shows the aryl group which may have a hydrogen atom, an alkyl group, and a substituent each independently. Two adjacent R carbons may be linked to form a ring. ] The azaindolizine-based compound light-emitting element according to claim 1 or 2 Number of azaindolizine skeleton and anthracene skeleton are contained in one molecule is 1 or 2, respectively. The EML emitting device according to any one of claims 1 is configured to include a host material for holding 3 the light emitting material. The light emitting device according to claim 4 , wherein the host material is an acene-based material. The light emitting device according to claim 5 , wherein the acene-based material is an anthracene-based material. The light-emitting element according to claim 5 , wherein the acene-based material is a tetracene-based material. The acene-based material, light-emitting device according to any one of claims 5 to 7 is constituted by carbon and hydrogen atoms.   The light-emitting element according to claim 4, wherein the host material is a quinolinolato metal complex. Emitting device characterized by including a light emitting device according to any one of claims 1 to 9. Authentication device characterized by including a light emitting device according to any one of claims 1 to 9. An electronic apparatus comprising: a light-emitting device according to any one of claims 1 to 9.

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