JP2021093520A - Quantum-dot light-emitting element and display device - Google Patents

Abstract

To provide a quantum-dot light-emitting element that makes a drive voltage low and that exhibits high luminous efficiency.SOLUTION: A quantum-dot light-emitting element 1 comprises a cathode 3, a light-emitting layer 6 and an anode 9. The light-emitting layer 6, which is positioned between the cathode 3 and the anode 9, contains a quantum dot, and a compound having a 1,3,5-triazine skeleton.SELECTED DRAWING: Figure 1

Description

The present invention relates to a quantum dot light emitting device and a display device.

In recent years, as a light emitting element used in a display device, a light emitting element having high color purity is required. For example, in ultra-high definition television (UHDTV), it is recommended to use a wide color gamut color system in which the three primary colors of red, green, and blue are located on the spectral locus. It is defined in 2020 (see, for example, Non-Patent Document 1).

Further, in recent years, an electroluminescent device (quantum dot light emitting device) using quantum dots made of semiconductor nanocrystals as a light emitting material has been proposed (see, for example, Patent Document 1 and Non-Patent Document 2). The emission color of the quantum dots can be controlled by changing the crystal grain size, and the full width at half maximum (FWHM) of the emission spectrum can be reduced by making the particle size distribution uniform. Quantum dots have the potential to be used as a light emitting material with high color purity for display devices, taking advantage of the small FWHM.

As research and development of applying quantum dots to light emitting elements, there is an example in which FWHM is 30 nm or less and the external quantum efficiency is about 15% (see, for example, Non-Patent Document 3). Further, it has been reported that quantum dots using InP or CuInZnS as a main component are used as a light emitting material for a light emitting element (see, for example, Non-Patent Documents 4 and 5).

On the other hand, many electron transporting materials used for light emitting devices have been reported so far, and for example, TmPyPB and TPBi shown below are generally used.

Further, as an electron transporting material suitable for an organic EL device utilizing phosphorescence, an electron transporting material having a high triplet energy and a deep minimum unoccupied molecular orbital (LUMO) level has been reported (for example, Non-Patent Document 6). ).

Japanese Patent No. 4948747

Recognition ITU-R BT. 2020-2 (2015) Shirasaki et al. (Y. Shirasaki et. Al), Nature Photonics, 7, 13 (2013) Y. Y. Yang et al., Nature Photonics, 9,259 (2015) J. Lim et al., Chemistry of Materials, 23,4459 (2011) Z. Liu et al. (Z. Liu et al.), Organic Electronics, 36, 97 (2016). S. Su et al. (S. Su et al.), Advanced Materials, 22, 3311 (2010).

As described above, research and development is underway to apply quantum dots to light-emitting devices, but there is room for improvement in luminous performance in conventional light-emitting devices using quantum dots, and in particular, the drive voltage is low. However, it is required to improve the luminous efficiency.

Therefore, it is an object of the present invention to solve the above-mentioned problems of the prior art and to provide a quantum dot light emitting device having a low driving voltage and high luminous efficiency.
Another object of the present invention is to provide a display device provided with such a quantum dot light emitting element and having excellent light emitting characteristics.

As a result of diligent studies to solve the above problems, the present inventors have shown by the following general formula (1), which has a 1,3,5-triazine skeleton together with quantum dots in the light emitting layer of the quantum dot light emitting element. We have found that a low driving voltage can be realized while ensuring high luminous efficiency by containing the compound, and have completed the present invention.
The gist structure of the present invention for solving the above problems is as follows.

［一般式（１）中のＲ¹は、それぞれ独立に、水素原子、又は炭素数１〜１０のアルキル基、炭素数１〜１０のアルコキシ基、炭素数１〜１０のアルキルチオ基、炭素数１〜１０のアルキルアミノ基、炭素数２〜１０のアシル基、炭素数７〜２０のアラルキル基、炭素数５〜３０の芳香族炭化水素基、及び、炭素数３〜３０の芳香族複素環基からなる群から選択される置換基、或いは、該置換基が複数連結した基であり、該置換基中の水素原子は他の置換基で更に置換されていても、未置換でもよく、隣り合う置換基は一体となって環を形成していてもよい。］で示される化合物と、を含有することを特徴とする。
かかる本発明の量子ドット発光素子は、駆動電圧が低く、高い発光効率を示す。 The quantum dot light emitting device of the present invention includes a cathode, a light emitting layer, and an anode, and the light emitting layer is a quantum dot light emitting device located between the cathode and the anode.
The light emitting layer has quantum dots and the following general formula (1):

^{[R 1} in the general formula (1) is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, and 1 carbon group. An alkylamino group of 10 to 10, an acyl group having 2 to 10 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, an aromatic hydrocarbon group having 5 to 30 carbon atoms, and an aromatic heterocyclic group having 3 to 30 carbon atoms. It is a substituent selected from the group consisting of, or a group in which a plurality of the substituents are linked, and the hydrogen atom in the substituent may be further substituted with another substituent or may be unsubstituted or adjacent to each other. The substituents may be integrated to form a ring. ], And the compound represented by.
The quantum dot light emitting device of the present invention has a low drive voltage and exhibits high luminous efficiency.

［一般式（２）中のＲ²は、それぞれ独立に、炭素数５〜３０の二価の芳香族炭素環、及び、炭素数３〜３０の二価の芳香族複素環からなる群から選択される環構造であり、Ｒ³は、それぞれ独立に、炭素数５〜３０の一価の芳香族炭素環、及び、炭素数３〜３０の一価の芳香族複素環からなる群から選択される環構造であり、前記環構造中の水素原子は他の置換基で更に置換されていても、未置換でもよく、隣り合う環構造は一体となって更に環を形成していてもよく、ｎは、それぞれ独立に０〜３の整数である。］で示される化合物ある。一般式（２）で示される化合物は、量子ドットへの電子注入に適したＬＵＭＯレベル、及び、量子ドットからの正孔ブロックに適したＨＯＭＯレベルを有するため、量子ドット発光素子の駆動電圧を更に低くしつつ、発光効率を向上させることができ、また、一般式（２）で示される化合物は、有機溶媒への溶解性にも優れる。 In a preferred example of the quantum dot light emitting device of the present invention, the compound represented by the general formula (1) is the following general formula (2):

^{[R 2} in the general formula (2) is independently selected from the group consisting of a divalent aromatic carbocycle having 5 to 30 carbon atoms and a divalent aromatic heterocycle having 3 to 30 carbon atoms. R ³ is independently selected from the group consisting of a monovalent aromatic carbocycle having 5 to 30 carbon atoms and a monovalent aromatic heterocycle having 3 to 30 carbon atoms. The hydrogen atom in the ring structure may be further substituted or unsubstituted by another substituent, and the adjacent ring structures may be integrated to form a ring. n is an integer of 0 to 3 independently. ] There are compounds indicated by. Since the compound represented by the general formula (2) has a LUMO level suitable for injecting electrons into the quantum dots and a HOMO level suitable for blocking holes from the quantum dots, the driving voltage of the quantum dot light emitting element is further increased. The emission efficiency can be improved while lowering the value, and the compound represented by the general formula (2) is also excellent in solubility in an organic solvent.

で示される化合物である。構造式（１−１）又は構造式（１−２）で示される化合物は、電子移動度が高く、量子ドットへの電子注入に適したＬＵＭＯレベル、及び、量子ドットからの正孔ブロックに適したＨＯＭＯレベルを有するため、量子ドット発光素子の駆動電圧を更に低くしつつ、発光効率を更に向上させることができる。 In another preferred example of the quantum dot light emitting device of the present invention, the compound represented by the general formula (1) is the following structural formula (1-1) or structural formula (1-2):

It is a compound indicated by. The compound represented by the structural formula (1-1) or the structural formula (1-2) has high electron mobility and is suitable for LUMO levels suitable for electron injection into quantum dots and hole blocking from quantum dots. Since it has a HOMO level, it is possible to further improve the light emission efficiency while further lowering the drive voltage of the quantum dot light emitting element.

In another preferred example of the quantum dot light emitting device of the present invention, the quantum dot is a core which is a fine particle of a semiconductor crystal, a shell which covers the surface of the core, and a ligand formed on the surface of the shell. With
The core comprises CdSe, CdS, InP, ZnSe, ZnTe, or ZnSeTe. In this case, the luminous efficiency can be improved while further lowering the driving voltage of the quantum dot light emitting element.

Further, the display device of the present invention is characterized by including the above-mentioned quantum dot light emitting element. The display device of the present invention is excellent in light emitting characteristics.

According to the present invention, it is possible to provide a quantum dot light emitting device having a low driving voltage and high luminous efficiency.
Further, according to the present invention, it is possible to provide a display device having such a quantum dot light emitting element and having excellent light emitting characteristics.

It is sectional drawing for demonstrating an example of the quantum dot light emitting element of this embodiment. It is a schematic diagram which showed an example of the structure of a quantum dot. It is a graph which showed the relationship between the applied voltage and the luminance in the quantum dot light emitting element of Example 1, Example 2, and Comparative Example 1. It is a graph which showed the relationship between the current density and the power efficiency in the quantum dot light emitting device of Example 1, Example 2, and Comparative Example 1.

Hereinafter, the quantum dot light emitting device and the display device of the present invention will be described in detail by way of examples based on the embodiments thereof.

<< Quantum dot light emitting device >>
The quantum dot light emitting element of the present invention includes a cathode, a light emitting layer, and an anode, and the light emitting layer is a quantum dot light emitting element located between the cathode and the anode, and the light emitting layer is , Quantum dots and the compound represented by the above general formula (1). In the light emitting layer, the quantum dots and the compound represented by the general formula (1) may or may not be uniformly distributed, and the layer composed of the quantum dots and the general formula It may be separated into a layer composed of the compound represented by (1). Here, when the layer composed of quantum dots and the layer composed of the compound represented by the general formula (1) are separated, the layer composed of the quantum dots and the layer composed of the compound represented by the general formula (1) are formed. Corresponds to the light emitting layer.

In order to solve the above problems and realize a light emitting device having high luminous efficiency and low driving voltage, the present inventors have focused on quantum dot light emitting devices and repeated diligent studies. As a result, the present inventors, as a light emitting device, include a quantum dot between the cathode and the anode and a compound represented by the above general formula (1) having a 1,3,5-triazine skeleton. I found that I should have
The compound represented by the general formula (1) contributes to deepening the lowest unoccupied molecular orbital (LUMO) level of the 1,3,5-triazine skeleton. Therefore, the compound represented by the general formula (1) can improve the electron injection property from the cathode to the quantum dots. Therefore, in a light emitting device having a light emitting layer containing quantum dots and a compound represented by the above general formula (1) having a 1,3,5-triazine skeleton, the driving voltage is low.
In addition, the compound represented by the general formula (1) has a high hole blocking property because it has a deep maximum occupied molecular orbital (HOMO) level. Therefore, the compound represented by the general formula (1) can prevent holes from flowing from the quantum dots to the cathode side, and can improve the luminous efficiency.
Therefore, the quantum dot light emitting device of the present invention has a low drive voltage and exhibits high luminous efficiency.

Next, one aspect of the quantum dot light emitting device of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic view showing an example of the structure of the quantum dot light emitting device of the present embodiment. The quantum dot light emitting device 1 shown in FIG. 1 has a cathode 3, an electron injection layer 4, an electron transport layer 5, a light emitting layer 6, a hole transport layer 7, a hole injection layer 8 and an anode 9 on the substrate 2. It has a structure in which they are laminated in order. The quantum dot light emitting device 1 shown in FIG. 1 has a configuration in which electrons are injected from the cathode 3 side arranged at the lower part and holes are injected from the anode 9 arranged at the upper part. The light emitting element is not limited to this, and may have a structure that is upside down.

<Board>
In the case of a bottom emission type element that extracts light from the substrate 2 side, the substrate 2 is preferably made of a transparent material. Examples of such transparent materials include glass and plastic films. Here, examples of the material of the plastic film include polyimide, polyethylene terephthalate, polyethylene naphthalate, polypropylene, cycloolefin polymer, polyamide, polyether sulfone, polymethylmethacrylate, polycarbonate, polyarylate and the like.
On the other hand, in the case of a top emission type element that extracts light from the upper electrode side, the material of the substrate 2 does not necessarily have to be a transparent material. When an opaque substrate is used as the substrate 2, the opaque substrate may be, for example, a colored plastic film substrate, a substrate made of a ceramic material such as alumina, or an oxide film (insulating film) on the surface of a metal plate such as stainless steel. Examples thereof include a substrate on which the above is formed.
Further, when a flexible substrate such as a plastic film is used as the substrate 2 and a quantum dot light emitting element is formed on the flexible substrate, the flexible quantum dot light emitting element capable of easily deforming the image display unit is used. can do.
The average thickness of the substrate 2 is not particularly limited, but is preferably 0.01 to 30 mm, more preferably 0.01 to 10 mm.

<Cathode>
In the case of a bottom emission type element that extracts light from the substrate 2 side, the cathode 3 is preferably made of a transparent and highly conductive material. As the cathode 3, for example, a conductive transparent oxide such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO) can be used.
On the other hand, in the case of a top emission type element that extracts light from the upper electrode side, the material of the cathode 3 does not necessarily have to be a transparent material, so that a metal electrode may be used as the cathode 3. Examples of the metal used for the metal electrode include Ca, Mg, Al, Sn, In, Cu, Ag, Au, Pt and the like.
The average thickness of the cathode 3 is not particularly limited, but is preferably 10 to 500 nm, more preferably 50 to 200 nm.

<Electron injection layer>
The electron injection layer 4 is used for the purpose of facilitating electron injection from the cathode 3. As the material of the electron injection layer 4, an inorganic material, or an organic material made of an electron-injectable low-molecular-weight material or a polymer material can be used. More specifically, zinc oxide (ZnO), titanium oxide (TiO ₂ ), silicon oxide (SiO ₂ ), tin oxide (SnO ₂ ), tungsten oxide (WO ₃ ), and tantalum oxide can be used as materials for the electron injection layer 4. Metal oxides such as (Ta ₂ O ₃ ), zirconium oxide (ZrO ₂ ), hafnium oxide (HfO ₂ ), and aluminum oxide (Al ₂ O ₃ ) are preferable, and among these, zinc oxide is preferable from the viewpoint of electron injection. , Titanium oxide is more preferable, and zinc oxide is particularly preferable.

It is preferable to use nanoparticles for forming the electron injection layer 4. The particle size of the nanoparticles is preferably 1 nm to 100 nm, more preferably 1 nm to 10 nm, and even more preferably 1 nm to 5 nm. Preferably, a thin film formed by forming metal oxide nanoparticles such as zinc oxide nanoparticles by a spin coating method can be used as the electron injection layer 4.
The average thickness of the electron injection layer 4 is not particularly limited, but is preferably 5 to 200 nm, more preferably 10 to 100 nm.

<Electron transport layer>
The electron transport layer 5 is used to transport the electrons injected from the cathode 3 to the light emitting layer 6. When the electron transport layer 5 having an appropriate LUMO level is provided between the cathode 3 or the electron injection layer 4 and the light emitting layer 6, the electron injection barrier from the cathode 3 or the electron injection layer 4 to the electron transport layer 5 is relaxed. Then, the electron injection barrier from the electron transport layer 5 to the light emitting layer 6 is relaxed. Also, if the material used for the electron transport layer 5 has an appropriate highest occupied molecular orbital (HOMO) level, holes that flow out to the counter electrode without recombination in the light emitting layer 6 are blocked. As a result, holes are confined in the light emitting layer 6, and the recombination efficiency in the light emitting layer 6 is enhanced.
The electron transport layer 5 may be omitted if the electron injection barrier does not matter and the electron transport capacity of the light emitting layer 6 is sufficiently high.

Examples of the material of the electron transport layer 5 include pyridine derivatives such as Tris-1,3,5- (3'-(pyridine-3 "-yl) phenyl) benzene (TmPyPB), (2- (3-) Kinolin derivatives such as (9-carbazolyl) phenyl) quinoline (mCQ)), pyrimidine derivatives such as 2-phenyl-4,6-bis (3,5-dipyridylphenyl) pyrimidine (BPyPPM), pyrazine derivatives, vasophenantroline Phenantroline derivatives such as (BPhen), such as 2,4-bis (4-biphenyl) -6- (4'-(2-pyridinyl) -4-biphenyl)-[1,3,5] triazine (MPT) Triazine derivatives, triazole derivatives such as 3-phenyl-4- (1'-naphthyl) -5-phenyl-1,2,4-triazole (TAZ), oxazole derivatives, 2- (4-biphenylyl) -5- Oxaziazole derivatives such as (4-tert-butylphenyl-1,3,4-oxadiazole) (PBD), 2,2', 2 "-(1,3,5-ventryyl) -tris (1) Imidazole derivatives such as −phenyl-1-H-benzimidazole) (TPBi), aromatic ring tetracarboxylic acid anhydrides such as naphthalene and perylene, bis [2- (2'-hydroxyphenyl) pyridine] berylium (Bepp ₂ ). , Tris (8-hydroxyquinolinato) Aluminum (Alq ₃ ) and other various metal complexes, 2,5-bis (6'-(2', 2 "-bipyridyl))-1,1-dimethyl-3 , 4-Diphenylcyclol (PyPySPyPy) and other syrol derivatives, organic silane derivatives, boron-containing compounds and the like can be mentioned, and one or more of these can be used. Among these, the electron transport layer 5 As the material, it is preferable to use a pyridine derivative such as TmPyPB or a compound represented by the general formula (1).
The average thickness of the electron transport layer 5 is not particularly limited, but is preferably 5 to 200 nm, more preferably 10 to 100 nm.

<Light emitting layer>
The light emitting layer 6 contains quantum dots and a compound represented by the general formula (1). The light emitting layer 6 may contain other compounds, if necessary, or may be formed only of the quantum dots and the compound represented by the general formula (1).

"Quantum dot"
In the light emitting layer 6, the holes injected from the anode 9 and the electrons injected from the cathode 3 are recombined to obtain light emission from the quantum dots. The emission color of the light emitting layer 6 can be changed depending on the crystal grain size and type (material) of the quantum dots contained in the light emitting layer 6. Here, the crystal grain size of the quantum dots can be selected according to the desired emission color, and is preferably 1 to 10 nm, for example. The quantum dots are preferably composed of a central portion called a core made of semiconductor fine particles and an organic substance called a ligand that covers the surface of the core (or the surface of a shell described later).

Examples of semiconductors constituting the core portion of the quantum dots include II-VI group compounds, II-V group compounds, III-VI group compounds, III-V group compounds, and IV-VI group compounds. I-III-VI group compounds, II-IV-VI group compounds, and II-IV-V group compounds, such as ZnS, ZnSe, ZnTe, ZnSeTe, CdS, CdSe, CdTe, InN, InP, InAs, Examples thereof include InSb and CuInS. Among these, the core of the quantum dot is CdSe from the viewpoints of ease of synthesis, ease of controlling the particle size and / or particle size distribution for obtaining light emission of a desired wavelength, and quantum yield of light emission. , CdS, InP, ZnSe, ZnSeTe are preferable. In the semiconductor constituting the core portion, the ratio of each element may or may not be stoichiometric.

The quantum dots may have one or more semiconductor layers called shells so as to surround the core. Here, as the semiconductor constituting the shell portion, a semiconductor having the same composition as the semiconductor constituting the core portion can be used. The shell of the quantum dots is preferably selected according to the semiconductor used for the core to be coated, and the shell preferably uses a semiconductor having a band gap larger than that of the core. In this case, the excitation energy of the core is efficiently confined in the core by the shell. Specifically, for example, when the core is composed of CdSe, CdS, and InP, it is preferable to use ZnS and ZnSe having a larger band gap for the shell. In the semiconductor constituting the shell portion, the ratio of each element may or may not be stoichiometric.

In the quantum dots, it is preferable to cap the surface of the semiconductor fine particles with an organic ligand called a ligand in order to stabilize the semiconductor surface and suppress the aggregation of the semiconductor fine particles. When the ligand portion for capping contains a lipophilic long-chain alkyl group or the like, the solubility in an organic solvent is improved, and a quantum dot solution in which quantum dots are dissolved in an organic solvent can be prepared. Examples of the ligand (organic ligand) include an amine having a hydrocarbon group bonded, a carboxylic acid having a hydrocarbon group bonded, a phosphine having a hydrocarbon group bonded, an oxidized phosphine having a hydrocarbon group bonded, and a hydrocarbon group bond. Examples thereof include thiol and the like. The hydrocarbon group is preferably a lipophilic chain hydrocarbon group. Examples of the amine to which the lipophilic chain hydrocarbon group is bonded include hexadecylamine and oleylamine. Examples of the carboxylic acid to which a lipophilic chain hydrocarbon group is bonded include oleic acid and the like. Examples of the phosphine to which a lipophilic chain hydrocarbon group is bonded include trioctylphosphine and the like. Examples of the oxidized phosphine to which a lipophilic chain hydrocarbon group is bonded include tri-n-octylphosphine oxide. Examples of the thiol to which a lipophilic chain hydrocarbon group is bonded include dodecane thiol and the like.

FIG. 2 shows an example of a quantum dot structure that can be suitably used for the quantum dot light emitting device of the present invention. The quantum dot 10 shown in FIG. 2 includes a core 11, a shell 12 surrounding the core 11, and a ligand 13 covering the surface of the shell 12. The quantum dots 10 have high chemical stability and are less likely to agglomerate. Further, the quantum dots 10 have an advantage that they can be easily prepared as a solution and can be easily formed into a film by a spin coating method or the like.

"Compound represented by the general formula (1)"
In this embodiment, a light emitting layer 6 containing the quantum dots and a compound represented by the following general formula (1) having a 1,3,5-triazine skeleton is used.

^{R 1} in the general formula (1) is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, and 1 to 10 carbon atoms. From an alkylamino group of 10, an acyl group having 2 to 10 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, an aromatic hydrocarbon group having 5 to 30 carbon atoms, and an aromatic heterocyclic group having 3 to 30 carbon atoms. A substituent selected from the above group, or a group in which a plurality of the substituents are linked, and the hydrogen atom in the substituent may be further substituted with another substituent or may be not substituted, and adjacent substituents may be used. The groups may be integrated to form a ring.

^{Regarding R 1} in the general formula (1), examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group and a nonyl group. Examples of the alkoxy group having 1 to 10 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a tert-butoxy group, a pentyloxy group, a hexyloxy group and a heptyloxy group. Examples of the alkylthio group having 1 to 10 carbon atoms include a methylthio group, an ethylthio group, a propylthio group, a butylthio group, a pentylthio group, a hexylthio group, a heptylthio group, an octylthio group, a nonylthio group and the like. Examples of the alkylamino group having 1 to 10 carbon atoms include a methylamino group, an ethylamino group, a propylamino group, a butylamino group, a pentylamino group, a hexylamino group, a heptylamino group, an octylamino group and a nonylamino group. Examples of the acyl group having 2 to 10 carbon atoms include an acetyl group, a propionyl group and a butyryl group, and examples of the aralkyl group having 7 to 20 carbon atoms include a benzyl group, a phenethyl group, a phenylpropyl group and a naphthylmethyl group. Examples of the aromatic hydrocarbon group having 5 to 30 carbon atoms include a phenyl group, a 2,6-xysilyl group, a mesityl group, a duryl group, a biphenyl group, a terphenyl group, a naphthyl group, an anthryl group, and a pyrenyl group. Examples thereof include a toluyl group, anisyl group, fluorophenyl group, diphenylaminophenyl group, dimethylaminophenyl group, diethylaminophenyl group, pyridylphenyl group, phenanthrenyl group and the like, and examples of the aromatic heterocyclic group having 3 to 30 carbon atoms are pyridyl. Examples thereof include a group, a pyrazinyl group, a pyrimidinyl group, a pyridadinyl group, a triazine group and the like. ^{Further, R 1} in the general formula (1) may be a group in which a plurality of the above-mentioned substituents are linked, and the plurality of linked substituents may be the same or different.

Among the compounds represented by the general formula (1), the compound represented by the following general formula (2) is preferable. The compound represented by the general formula (2) has a LUMO level suitable for electron injection into quantum dots and a HOMO level suitable for hole blocking from quantum dots, and therefore has a compound represented by the general formula (2). By using the above, it is possible to further improve the luminous efficiency while further lowering the driving voltage of the quantum dot light emitting element.

^{R 2} in the general formula (2) is independently selected from the group consisting of a divalent aromatic carbocycle having 5 to 30 carbon atoms and a divalent aromatic heterocycle having 3 to 30 carbon atoms. R ³ is independently selected from the group consisting of a monovalent aromatic carbocycle having 5 to 30 carbon atoms and a monovalent aromatic heterocycle having 3 to 30 carbon atoms. It has a ring structure, and the hydrogen atom in the ring structure may be further substituted with another substituent or may not be substituted, and the adjacent ring structures may be integrated to form a ring. Are independently integers from 0 to 3.
Here, the aromatic carbocycle is a ring structure in which a ring is formed by carbon atoms and exhibits aromaticity, and the aromatic heterocycle is a ring in which a ring is formed by carbon atoms and heteroatoms and exhibits aromaticity. Hydrogen atoms and various substituents are bonded to carbon atoms (and heteroatoms) that form a ring and have a structure. Examples of the heteroatom of the aromatic heterocycle include a nitrogen atom, a sulfur atom, an oxygen atom and the like. Further, the monovalent and divalent aromatic carbocycles may be a monocyclic ring or a condensed ring, and the monovalent and divalent aromatic heterocycles may be a monocyclic ring or a condensed ring.

^{Regarding R 2} in the general formula (2), examples of the divalent aromatic carbocycle (aromatic carbocyclic ring group) having 5 to 30 carbon atoms include a phenylene group, a naphthylene group, an anthrylene group, a phenanthrylene group and the like. Examples of the divalent aromatic heterocycle (aromatic heterocyclic group) having 3 to 30 carbon atoms include a pyridinediyl group, a pyrazinediyl group, a pyrimidinediyl group, a pyridazinzyl group and a triazinediyl group. As R ² , among the divalent aromatic carbocycles (aromatic carbocyclic groups) having 5 to 30 carbon atoms, a phenylene group is particularly preferable, and a divalent aromatic heterocycle having 3 to 30 carbon atoms is particularly preferable. Among (aromatic heterocyclic groups), a pyridinediyl group is particularly preferable.

^{Regarding R 3} in the general formula (2), the monovalent aromatic carbocycle (aromatic carbocyclic ring group) having 5 to 30 carbon atoms includes a phenyl group, a naphthyl group, an anthryl group, a pyrenyl group, a phenanthrenyl group and the like. Examples of the monovalent aromatic heterocycle (aromatic heterocyclic group) having 3 to 30 carbon atoms include a pyridyl group, a pyrazinyl group, a pyrimidinyl group, a pyridadinyl group, and a triazine group. Among these, ^{as R 3} , a monovalent aromatic heterocycle having 3 to 30 carbon atoms (aromatic heterocyclic group) is preferable, and a pyridyl group is particularly preferable.

N in the general formula (2) is an integer of 0 to 3 independently, that is, the compound represented by the general formula (2) is each of the three carbon atoms in the 1,3,5-triazine skeleton. Has a structure in which 1 to 4 aromatic carbocycles and / or aromatic heterocycles are bonded. Since the compound represented by the general formula (2) has n of 3 or less, it has excellent solubility in an organic solvent and is easy to handle. N in the general formula (2) is preferably 1 or 2. When n is 1 or more, the LUMO level becomes deeper, and the electron injection property from the cathode to the quantum dots is further improved. Further, when n is 2 or less, the solubility in an organic solvent is further improved.

^{Regarding R 1} in the general formula (1) and R ^{2 and R 3} in the general formula (2), the substituent and the hydrogen atom in the ring structure are further substituted with other substituents. However, it may be unsubstituted, and adjacent substituents may be integrated to form a ring. Examples of the substituent and the substituent of the hydrogen atom in the ring structure (that is, the “other substituent”) include a halogen atom of a fluorine atom, a chlorine atom, a bromine atom and an iodine atom; a methyl chloride group and a methyl bromide. Group, haloalkyl group such as methyl iodide group, fluoromethyl group, difluoromethyl group, trifluoromethyl group; methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl A linear or branched alkyl group having 1 to 20 carbon atoms such as a group; a cyclic alkyl group having 5 to 7 carbon atoms such as a cyclopentyl group, a cyclohexyl group and a cycloheptyl group; a methoxy group, an ethoxy group, a propoxy group and an iso Linear or branched alkoxy group having 1 to 20 carbon atoms such as propoxy group, butoxy group, isobutoxy group, tert-butoxy group, pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group; hydroxy group; A mono or dialkylamino group having an alkyl group having 1 to 40 carbon atoms such as a thiol group; a nitro group; a cyano group; an amino group; an azo group; a methylamino group, an ethylamino group, a dimethylamino group, a diethylamino group; Amino groups such as carbazolyl group; acyl groups such as acetyl group, propionyl group and butyryl group; alkenyl group having 2 to 20 carbon atoms such as vinyl group, 1-propenyl group, allyl group, butenyl group and styryl group; ethynyl group , 1-Propinyl group, propargyl group, phenylacetylyl group and other alkynyl groups having 2 to 20 carbon atoms; vinyloxy group, allyloxy group and other alkenyloxy groups; ethynyloxy group, phenylacetyloxy group and other alkynyloxy groups; phenoxy group , Aryloxy groups such as naphthoxy group, biphenyloxy group, pyrenyloxy group; perfluoro groups such as trifluoromethyl group, trifluoromethoxy group, pentafluoroethoxy group, perfluorophenyl group and longer chain perfluoro groups; diphenyl Boryl groups such as boryl group, dimesitylboryl group, bis (perfluorophenyl) boryl group, 4,4,5,5-tetramethyl-1,3,2-dioxaborolanyl group; acetyl group, benzoyl group and the like. Carbonyl group; carbonyloxy group such as acetoxy group and benzoyloxy group; alkoxycarbonyl group such as methoxycarbonyl group, ethoxycarbonyl group and phenoxycarbonyl group; sulfinyl group such as methylsulfinyl group and phenylsulfinyl group; methylsulfonyl group , A sulfonyl group such as a phenylsulfonyl group; an alkylsulfonyloxy group; an arylsulfonyloxy group; a phosphino group; a phosphinyl group such as a diethylphosphinyl group and a diphenylphosphinyl group; a trimethylsilyl group, a triisopropylsilyl group, a dimethyl-tert- Cyril groups such as butylsilyl group, trimethoxysilyl group, triphenylsilyl group; silyloxy group; stenyl group; phenyl group optionally substituted with halogen atom, alkyl group, alkoxy group, etc., 2,6-xylyl group, mesityl Aryl such as group, duryl group, biphenyl group, terphenyl group, naphthyl group, anthryl group, pyrenyl group, toluyl group, anisyl group, fluorophenyl group, diphenylaminophenyl group, dimethylaminophenyl group, diethylaminophenyl group, phenanthrenyl group and the like. Group (optionally substituted aromatic hydrocarbon ring group); optionally substituted with a halogen atom, an alkyl group, an alkoxy group, etc., a thienyl group, a fryl group, a silacyclopentadienyl group, an oxazolyl group, an oxadiazolyl. Group, thiazolyl group, thiadiazolyl group, acridinyl group, quinolyl group, quinoxaloyl group, phenanthloryl group, benzothienyl group, benzothiazolyl group, indolyl group, carbazolyl group, pyridyl group, pyrrolyl group, benzoxazolyl group, pyrimidyl group, imidazolyl group Heterocyclic groups such as (optionally substituted aromatic heterocyclic groups); carboxyl groups; carboxylic acid esters; epoxy groups; isocyano groups; cyanate groups; isocyanate groups; thiocyanate groups; isothiocyanate groups; carbamoyl groups; N, Examples thereof include N, N-dialkylcarbamoyl groups such as N-dimethylcarbamoyl group and N, N-diethylcarbamoyl group; formyl group; nitroso group; formyloxy group; and the like.

Among the compounds represented by the general formula (1), the compounds represented by the following structural formula (1-1) or structural formula (1-2) are particularly preferable. The compounds represented by the following structural formulas (1-1) or (1-2) have high electron mobilities, and have LUMO levels suitable for electron injection into quantum dots, and hole blocks from quantum dots. Since it has a suitable HOMO level, by using the compound represented by the structural formula (1-1) or the structural formula (1-2), the driving voltage of the quantum dot light emitting element is further lowered, and the light emitting efficiency is further improved. Can be made to.

As described above, in the light emitting layer 6, the quantum dots and the compound represented by the general formula (1) may or may not be uniformly distributed, and the layer composed of the quantum dots. And a layer made of the compound represented by the general formula (1) may be separated.
Further, when the light emitting layer 6 is formed, it may be a mixed layer in which quantum dots and a compound represented by the general formula (1) are collectively formed, or it may be laminated separately to form a two-layer structure. ..

The mass ratio (quantum dots / compound represented by the general formula (1)) of the quantum dots and the compound represented by the general formula (1) in the light emitting layer 6 is not particularly limited, but is 1 /. The range of 10 to 10/1 is preferable, and the range of 1/5 to 5/1 is more preferable. When the mass ratio of the quantum dot to the compound represented by the general formula (1) is within the above range, the effect of reducing the driving voltage of the quantum dot light emitting device and the effect of improving the luminous efficiency are further improved.

The average thickness of the light emitting layer 6 is not particularly limited, but is preferably 5 to 200 nm, more preferably 10 to 100 nm.

<Hole transport layer>
The hole transport layer 7 is used to transport the holes injected from the anode 9 to the light emitting layer 6. As the material constituting the hole transport layer 7, a hole transporting inorganic material or an organic material can be used. The material constituting the hole transport layer 7 is preferably a hole transporting organic material, for example, 2,2'-bis (N-carbazoyl) -9,9'-spirobifluorene (CFL), 4 , 4', 4 "-tris (carbazole-9-yl) triphenylamine (TCTA), 4,4'-bis (carbazole-9-yl) biphenyl (CBP), 4,4', 4" -trimethyltri Phenylamine, N, N, N', N'-tetraphenyl-1,1'-biphenyl-4,4'-diamine, N, N'-diphenyl-N, N'-bis (3-methylphenyl)- 1,1'-biphenyl-4,4'-diamine (TPD1), N, N'-diphenyl-N, N'-bis (4-methoxyphenyl) -1,1'-biphenyl-4,4'-diamine (TPD2), N, N, N', N'-tetrakis (4-methoxyphenyl) -1,1'-biphenyl-4,4'-diamine (TPD3), N, N'-di (1-naphthyl) -N, N'-diphenyl-1,1'-biphenyl-4,4'-diamine (α-NPD), 4,4', 4 "-tris (N-3-methylphenyl-N-phenylamino) tri Examples thereof include phenylamine (m-MTDATA), and one or more of these can be used. Among these, 2,2'-bis (N-carbazoyl)-from the viewpoint of hole transportability. 9,9'-spirobifluorene (CFL), 4,4', 4 "-tris (carbazole-9-yl) triphenylamine (TCTA) are preferred.
The average thickness of the hole transport layer 7 is not particularly limited, but is preferably 10 to 500 nm, more preferably 20 to 100 nm.

<Hole injection layer>
The hole injection layer 8 is formed to facilitate hole injection from the anode 9. Both an organic material and an inorganic material can be used for the hole injection layer 8. Typical materials used for the hole injection layer 8 include metal oxidation of molybdenum trioxide (MoO ₃ ), vanadium oxide (V ₂ O ₅ ), ruthenium oxide (RuO ₂ ), renium oxide, tungsten oxide, manganese oxide and the like. Things can be mentioned. The organic materials used for the hole injection layer 8 include 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane (F4-TCNQ) and hexafluorotetracyanonaphthoquinodimethane. (F6-TNAP), 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HAT-CN) and the like can be mentioned. One or more of these can be used for the hole injection layer 8. Among these, molybdenum trioxide is preferable as the material used for the hole injection layer 8 from the viewpoint of hole injection property.
The average thickness of the hole injection layer 8 is not particularly limited, but is preferably 1 to 500 nm, more preferably 3 to 50 nm.

<Anode>
As the material of the anode 9, a metal having a relatively large work function is preferable. By using a metal having a large work function, the hole injection barrier from the anode to the organic layer can be lowered, and holes can be easily injected. Examples of the metal used for the anode 9 include, but are not limited to, Al, Au, Pt, Ni, W, Cr, Mo, Fe, Co, Cu and the like. Further, if a transparent material is used for the anode 9, it can be a top emission type element that extracts light from the upper electrode.
The average thickness of the anode 9 is not particularly limited, but is preferably 10 to 500 nm, more preferably 30 to 150 nm.

The electron injection layer 4, the electron transport layer 5, the light emitting layer 6, the hole transport layer 7, and the hole injection layer 8 may be one layer each, or each layer has a structure in which each layer has a plurality of roles. You may. Further, for example, it is possible to use both the hole injection layer and the hole transport layer in one layer. Further, even if the structure has another layer between the anode 9, the hole injection layer 8, the hole transport layer 7, the light emitting layer 6, the electron transport layer 5, the electron injection layer 4, and the cathode 3. Good.

<Formation method of each layer>
The method for forming the cathode 3, the electron injection layer 4, the electron transport layer 5, the light emitting layer 6, the hole transport layer 7, the hole injection layer 8, and the anode 9 is not particularly limited, and the vacuum vapor deposition method and the electron Methods such as a beam method, a sputtering method, a spin coating method, an inkjet method, and a printing method can be used. Further, using these methods, the thicknesses of the cathode 3, the electron injection layer 4, the electron transport layer 5, the light emitting layer 6, the hole transport layer 7, the hole injection layer 8, and the anode 9 can be adjusted according to the purpose. It can be adjusted as appropriate. Further, these methods are preferably selected according to the characteristics of the material of each layer, and the production method may be different for each layer.
As described above, the quantum dot light emitting device 1 shown in FIG. 1 is completed.

<< Display device >>
The display device of the present invention is characterized by including the above-mentioned quantum dot light emitting device. Since the display device of the present invention includes the quantum dot light emitting element having a small driving voltage and high luminous efficiency as described above, it is excellent in light emitting characteristics. In addition to the quantum dot light emitting element described above, the display device of the present invention can include other components generally used in the display device.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

(Example 1)
<Synthesis of quantum dots>
J. Quantum dots CdSe / ZnS (core / shell type) exhibiting green light emission according to the method disclosed in J. Kwak et al., Nano Letters, 12, 2362-2366 (2012). Quantum dots) were synthesized. The specific synthesis method is shown below.
0.257 g of cadmium oxide, 7.34 g of zinc acetate, 30.13 g of oleic acid and 150 ml of octadecene were added to the flask. After heating at 150 ° C. for 30 minutes under reduced pressure, it leaked with argon, and the temperature was raised to 280 ° C. under argon flow (solution 1). A solution prepared by dissolving 0.079 g of selenium and 1.122 g of sulfur in 20 ml of trioctylphosphine was prepared and added to solution 1. After mixing at 280 ° C. for 10 minutes, the mixture was cooled to room temperature (solution 2). Ethanol was added to this solution 2, and the precipitate was recovered by centrifugation. The recovered product was dispersed in chloroform to adjust the concentration to 20 mg / ml.

<Synthesis of zinc oxide nanoparticles>
J. Zinc oxide nanoparticles were synthesized according to the method disclosed in J. Kwak et al., Nano Letters, 12, 2362-2366 (2012). The specific method is shown below.
6.7 mmol of zinc acetate was dissolved in 55 ml of methanol to give a 0.12 mol / l solution. 8.6 mmol of potassium hydroxide was dissolved in 25 ml of methanol to give a 0.34 mol / l solution. The zinc acetate-methanol solution was heated to 60 ° C. under a nitrogen atmosphere, the potassium hydroxide-methanol solution was added dropwise with stirring, and the reaction was carried out for 2 hours. The solution became cloudy. Zinc acetate recovered by centrifugation from the obtained cloudy liquid was washed with methanol and finally redispersed in butanol to obtain a 20 mg / ml zinc oxide nanoparticle butanol dispersion.

で示される化合物と、を質量比１：１で、クロロホルムに溶解させたクロロホルム溶液を調製し、スピンコート法によって成膜した（発光層、厚さ：３５ｎｍ）。窒素雰囲気下、１００℃にて３０分間加熱した。
次に、基板を真空蒸着成膜装置に入れ、真空蒸着法によって、下記式（７−１）：

で示される構造式を有する材料からなる正孔輸送層を成膜した（厚さ：４０ｎｍ）。
続いて、真空蒸着により、三酸化モリブデンからなる正孔注入層（厚さ：１０ｎｍ）、アルミニウムからなる電極（陽極、厚さ：６０ｎｍ）を成膜した。
なお、図１には示していないが、量子ドット発光素子は、窒素ガスで満たされたグローブボックス中で、封止用ガラスの周縁部に紫外線硬化樹脂を塗布した後、量子ドット発光素子を形成した前記基板の周縁部に貼り合せて、封止を行った。 <Manufacturing of quantum dot light emitting device>
A quantum dot light emitting device having a structure similar to that shown in FIG. 1 was manufactured as follows, except that the electron transport layer 5 was omitted.
First, a transparent electrode made of ITO (cathode, thickness: 100 nm) was formed on a glass substrate, and this was patterned in a line shape.
Next, a layer of zinc oxide nanoparticles synthesized in the previous section was formed as an electron injection layer. The zinc oxide nanoparticles were formed into a film by a spin coating method and heated at 130 ° C. for 30 minutes (electron injection layer, thickness: 30 nm).
Next, the quantum dots CdSe / ZnS synthesized in the previous section and the following structural formula (1-1):

A chloroform solution prepared by dissolving the compound represented by (1) in chloroform at a mass ratio of 1: 1 was formed by a spin coating method (light emitting layer, thickness: 35 nm). It was heated at 100 ° C. for 30 minutes in a nitrogen atmosphere.
Next, the substrate is placed in a vacuum thin-film deposition apparatus, and the following formula (7-1):

A hole transport layer made of a material having the structural formula shown by (thickness: 40 nm) was formed.
Subsequently, a hole injection layer made of molybdenum trioxide (thickness: 10 nm) and an electrode made of aluminum (anode, thickness: 60 nm) were formed by vacuum vapor deposition.
Although not shown in FIG. 1, the quantum dot light emitting element forms a quantum dot light emitting element after applying an ultraviolet curable resin to the peripheral portion of the sealing glass in a glove box filled with nitrogen gas. It was attached to the peripheral edge of the substrate and sealed.

で示される化合物と、を質量比１：１で、クロロホルムに溶解させたクロロホルム溶液をスピンコート法によって成膜したものを用いた。 (Example 2)
Quantum dots CdSe / ZnS and zinc oxide nanoparticles were synthesized in the same manner as in Example 1 above. Using these materials, a quantum dot light emitting device was produced in the same manner as in Example 1. At this time, as the light emitting layer, the quantum dots CdSe / ZnS synthesized in the previous section and the following structural formula (1-2):

A chloroform solution in which the compound represented by (1) was dissolved in chloroform at a mass ratio of 1: 1 was formed into a film by a spin coating method.

で示される化合物と、を質量比１：１で、クロロホルムに溶解させたクロロホルム溶液をスピンコート法によって成膜したものを用いた。 (Comparative Example 1)
Quantum dots CdSe / ZnS and zinc oxide nanoparticles were synthesized in the same manner as in Example 1 above. Using these materials, a quantum dot light emitting device was produced in the same manner as in Example 1. At this time, as the light emitting layer, the quantum dots CdSe / ZnS synthesized in the previous section and the following structural formula (6-1):

A chloroform solution in which the compound represented by (1) was dissolved in chloroform at a mass ratio of 1: 1 was formed into a film by a spin coating method.

で示される化合物と、を質量比１：１で、クロロホルムに溶解させたクロロホルム溶液をスピンコート法によって成膜したものを用いた。 (Comparative Example 2)
Quantum dots CdSe / ZnS and zinc oxide nanoparticles were synthesized in the same manner as in Example 1 above. Using these materials, a quantum dot light emitting device was produced in the same manner as in Example 1. At this time, as the light emitting layer, the quantum dots CdSe / ZnS synthesized in the previous section and the following structural formula (6-2):

A chloroform solution in which the compound represented by (1) was dissolved in chloroform at a mass ratio of 1: 1 was formed into a film by a spin coating method.

<Experiment 1>
A thin film having a thickness of 50 nm made of the compound represented by the above structural formula (1-1) was formed on a substrate made of a glass material by a vacuum deposition method.

<Experiment 2>
A thin film having a thickness of 50 nm made of the compound represented by the above structural formula (1-2) was formed on a substrate made of a glass material by a vacuum deposition method.

<Experiment 3>
A thin film having a thickness of 50 nm made of the compound represented by the above structural formula (6-1) was formed on a substrate made of a glass material by a vacuum deposition method.

<Experiment 4>
A thin film having a thickness of 50 nm made of the compound represented by the above structural formula (6-2) was formed on a substrate made of a glass material by a vacuum deposition method.

<Evaluation of energy level>
(Measurement of HOMO level)
The HOMO level of the thin film prepared in Experiment 1-4 was measured using an atmospheric photoelectron spectrometer "AC-3" manufactured by RIKEN Keiki Co., Ltd. The results are shown in Table 1.

(Measurement of LUMO level)
The ultraviolet-visible absorption spectrum of the thin film prepared in Experiment 1-4 was measured using an ultraviolet-visible near-infrared spectrophotometer "UV-3100" manufactured by Shimadzu Corporation, and the energy gap calculated from the rise of the absorption spectrum was calculated. LUMO levels were measured by subtracting from the HOMO levels measured by the method. The results are shown in Table 1.

As shown in Table 1, the LUMO levels of the compounds represented by the structural formulas (1-1) and (1-2) are deeper than the LUMO levels of the compounds represented by the structural formula (6-1). Further, the HOMO level of the compound represented by the structural formula (1-1) and the structural formula (1-2) is deeper than the HOMO level of the compound represented by the structural formula (6-2).

<Evaluation of element characteristics>
(Measurement of voltage-luminance characteristics)
The voltage is applied using a "2400 type source meter" manufactured by Caseley Co., Ltd. so that the ITO electrode side of the quantum dot light emitting element of Example 1, Example 2, and Comparative Example 1 is negative and the aluminum electrode side is positive. The voltage was applied, and the brightness was measured using "LS-100" manufactured by Konica Minolta, and the relationship between the applied voltage and the brightness was investigated. The result is shown in FIG.

As shown in FIG. 3, in the quantum dot light emitting devices of Examples 1 and 2, higher brightness is obtained when the applied voltage is the same as compared with the quantum dot light emitting device of Comparative Example 1. The drive voltage was low. This is because the compound represented by the structural formula (1-1) used in Example 1 and the compound represented by the structural formula (1-2) used in Example 2 are the structural formula (6) used in Comparative Example 1. It is presumed that this is because the LUMO level is deeper than that of the compound shown in -1), and the electron injection from the cathode into the quantum dots in the light emitting layer is promoted.

(Measurement of current density-power efficiency characteristics)
For the quantum dot light emitting devices of Example 1, Example 2, and Comparative Example 1, the relationship between the current density and the power efficiency was investigated using a "2400 type source meter" manufactured by Keithley. The result is shown in FIG.

As shown in FIG. 4, the quantum dot light emitting devices of Examples 1 and 2 have higher power efficiency when the current densities are the same as those of the quantum dot light emitting devices of Comparative Example 1. .. This is because the compound represented by the structural formula (1-1) used in Example 1 and the compound represented by the structural formula (1-2) used in Example 2 are the structural formula (6) used in Comparative Example 1. It is presumed that this is because the LUMO level is deeper than that of the compound shown in -1).

(Measurement of external quantum efficiency)
The maximum external quantum efficiency was measured for each of the quantum dot light emitting devices of Example 1, Example 2, and Comparative Example 2. The results are shown in Table 2.

As shown in Table 2, the external quantum efficiencies of the quantum dot light emitting devices of Examples 1 and 2 showed higher values than the external quantum efficiencies of the quantum dot light emitting devices of Comparative Example 2. This is because the compound represented by the structural formula (1-1) used in Example 1 and the compound represented by the structural formula (1-2) used in Example 2 are the structural formula (6) used in Comparative Example 2. It is presumed that this is because the HUMO level is deeper than that of the compound shown in -2).

From the above results, it can be seen that the quantum dot light emitting device using the light emitting layer containing the quantum dots and the compound represented by the general formula (1) exhibits a low driving voltage and a high luminous efficiency.

1: Quantum dot light emitting element 2: Substrate 3: Cathode 4: Electron injection layer 5: Electron transport layer 6: Light emitting layer 7: Hole transport layer 8: Hole injection layer 9: Anode 10: Quantum dot 11: Core 12: Shell 13: ligand

Claims (5)

A quantum dot light emitting device including a cathode, a light emitting layer, and an anode, wherein the light emitting layer is located between the cathode and the anode.
The light emitting layer has quantum dots and the following general formula (1):

^{[R 1} in the general formula (1) is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, and 1 carbon group. An alkylamino group of 10 to 10, an acyl group having 2 to 10 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, an aromatic hydrocarbon group having 5 to 30 carbon atoms, and an aromatic heterocyclic group having 3 to 30 carbon atoms. It is a substituent selected from the group consisting of, or a group in which a plurality of the substituents are linked, and the hydrogen atom in the substituent may be further substituted with another substituent or may be unsubstituted or adjacent to each other. The substituents may be integrated to form a ring. ], And a quantum dot light emitting device. The compound represented by the general formula (1) is the following general formula (2):

^{[R 2} in the general formula (2) is independently selected from the group consisting of a divalent aromatic carbocycle having 5 to 30 carbon atoms and a divalent aromatic heterocycle having 3 to 30 carbon atoms. R ³ is independently selected from the group consisting of a monovalent aromatic carbocycle having 5 to 30 carbon atoms and a monovalent aromatic heterocycle having 3 to 30 carbon atoms. The hydrogen atom in the ring structure may be further substituted or unsubstituted by another substituent, and the adjacent ring structures may be integrated to form a ring. n is an integer of 0 to 3 independently. ], The quantum dot light emitting device according to claim 1. The compound represented by the general formula (1) is the following structural formula (1-1) or structural formula (1-2):

The quantum dot light emitting device according to claim 1 or 2, which is a compound represented by. The quantum dots include a core that is a fine particle of a semiconductor crystal, a shell that covers the surface of the core, and a ligand formed on the surface of the shell.
The quantum dot light emitting device according to any one of claims 1 to 3, wherein the core includes CdSe, CdS, InP, ZnSe, ZnTe, or ZnSeTe. A display device comprising the quantum dot light emitting device according to any one of claims 1 to 4.

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