WO2020261446A1 - Electroluminescent device and display - Google Patents
Electroluminescent device and display Download PDFInfo
- Publication number
- WO2020261446A1 WO2020261446A1 PCT/JP2019/025465 JP2019025465W WO2020261446A1 WO 2020261446 A1 WO2020261446 A1 WO 2020261446A1 JP 2019025465 W JP2019025465 W JP 2019025465W WO 2020261446 A1 WO2020261446 A1 WO 2020261446A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- light emitting
- electrode
- cathode
- anode
- layer
- Prior art date
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
- G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
- G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B33/00—Electroluminescent light sources
- H05B33/12—Light sources with substantially two-dimensional radiating surfaces
- H05B33/14—Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of the electroluminescent material, or by the simultaneous addition of the electroluminescent material in or onto the light source
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B33/00—Electroluminescent light sources
- H05B33/12—Light sources with substantially two-dimensional radiating surfaces
- H05B33/22—Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of auxiliary dielectric or reflective layers
- H05B33/24—Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of auxiliary dielectric or reflective layers of metallic reflective layers
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B33/00—Electroluminescent light sources
- H05B33/12—Light sources with substantially two-dimensional radiating surfaces
- H05B33/26—Light sources with substantially two-dimensional radiating surfaces characterised by the composition or arrangement of the conductive material used as an electrode
Definitions
- the present disclosure relates to an electroluminescent element and a display device.
- a display device using an electroluminescent element provided with a light emitting layer containing quantum dots (QD) is expected to be applied to a display device such as a portable terminal.
- QD quantum dots
- one aspect of the present disclosure is to provide an electroluminescent element and a display device capable of improving the brightness while suppressing the increase in power consumption in a bright place such as under sunlight. To do.
- the electroluminescent device includes a first electrode, a light emitting layer containing quantum dots, and a second electrode in this order, and the first electrode and the above. At least one of the second electrodes contains selenium.
- the display device includes the above electroluminescent element according to one aspect of the present disclosure.
- an electrode containing selenium having a photoconducting effect as at least one of the first electrode and the second electrode, in a bright place such as under sunlight.
- the value of the current flowing through the electrodes can be increased by the photoconducting effect without increasing the value of the current supplied from the external power source. Therefore, according to one aspect of the present disclosure, there is provided an electroluminescent element and a display device capable of improving the brightness while suppressing the increase in power consumption in a bright place such as under sunlight. Can be done.
- FIG. It is sectional drawing which shows typically an example of the schematic structure of the light emitting element which concerns on Embodiment 1.
- FIG. It is sectional drawing which shows typically an example of the schematic structure of the display device which concerns on Embodiment 1.
- FIG. It is sectional drawing which shows typically an example of the schematic structure of the light emitting element which concerns on Embodiment 2.
- FIG. It is sectional drawing which shows typically an example of the schematic structure of the light emitting element which concerns on Embodiment 3.
- FIG. 1 is a cross-sectional view schematically showing an example of a schematic configuration of a light emitting element 10 according to the present embodiment.
- the layer formed in the process before the layer to be compared is referred to as the "lower layer”
- the layer formed in the process after the layer to be compared is referred to as the "upper layer”.
- the direction from the light emitting layer 4 to the substrate 1 is defined as “downward”
- the direction from the substrate 1 toward the light emitting layer 4 is defined as "upward”.
- the light emitting element 10 is an electroluminescent element in which a light emitting layer 4 is provided between the anode 2 and the cathode 6.
- the anode 2 and the cathode 6 are connected to a power source (not shown) so that a voltage is applied between them.
- the light emitting element 10 includes an anode 2, a hole transport layer 3, a light emitting layer 4, an electron transport layer 5, and a cathode 6 in this order.
- the light emitting element 10 may include a substrate 1 as a support. In FIG.
- the light emitting element 10 includes a substrate 1, an anode 2, a hole transport layer 3, a light emitting layer 4, an electron transport layer 5, and a cathode 6, and is provided on the substrate 1.
- An example is shown in which the anode 2, the hole transport layer 3, the light emitting layer 4, the electron transport layer 5, and the cathode 6 are provided in this order from the substrate 1 side.
- the electroluminescent element when manufacturing an electroluminescent element, it is possible to manufacture the electroluminescent element more stably by laminating from the anode side. Therefore, when the substrate 1 is under the anode 2 as shown in FIG. 1, the yield can be improved. As shown in the second embodiment described later, the stacking order from the anode 2 to the cathode 6 can be reversed.
- the light emitting element 10 can be suitably used as, for example, a light emitting element in a display device.
- FIG. 2 is a cross-sectional view schematically showing an example of a schematic configuration of the display device 100 according to the present embodiment.
- the display device 100 has a configuration in which the light emitting element layer 11 is provided on the substrate 101 as a support.
- the light emitting element layer 11 has, for example, a configuration in which the first electrode, the first carrier transport layer, the light emitting layer, the second carrier transport layer, and the second electrode are laminated in this order from the substrate 101 side on the substrate 101. ing.
- the first electrode, the first carrier transport layer, the second carrier transport layer, and the second electrode are the anode 2, the hole transport layer 3, the electron transport layer 5, and the cathode 6 in this order, and are on the substrate 101.
- the case where the anode 2, the hole transport layer 3, the light emitting layer 4, the electron transport layer 5, and the cathode 6 are provided in this order from the substrate 101 side is shown as an example.
- Each of the anode 2, the hole transport layer 3, the light emitting layer 4, and the electron transport layer 5 is separated into islands for each pixel (light emitting pixel) by the bank BK.
- the cathode 6 is not separated into islands by the bank BK, and is formed in common with each pixel.
- the display device 100 has red pixel RP, green pixel GP, and blue pixel BP as pixels.
- the light emitting element 10 is formed for each pixel corresponding to the pixel.
- the red pixel RP is provided with a red light emitting element 10R having a light emitting layer 4 having a red light emitting peak as the light emitting element 10.
- the green pixel GP is provided with a green light emitting element 10G having a light emitting layer 4 having a green light emitting peak as the light emitting element 10.
- the blue pixel BP is provided with a blue light emitting element 10B having a light emitting layer 4 having a blue light emitting peak as the light emitting element 10.
- having a red emission peak means “having an emission peak wavelength in a wavelength band of 600 nm or more and 780 nm or less”.
- having a green emission peak means “having an emission peak wavelength in a wavelength band of 500 nm or more and 600 nm or less”.
- having a blue emission peak means “having an emission peak wavelength in a wavelength band of 400 nm or more and 500 nm or less”.
- the pixel RP (in other words, the red light emitting element 10 used for the pixel RP) preferably has an emission peak wavelength in a wavelength band of 620 nm or more and 650 nm or less.
- the pixel GP (in other words, the green light emitting element 10 used for the pixel GP) preferably has an emission peak wavelength in a wavelength band of 520 nm or more and 540 nm or less.
- the pixel BP (in other words, the blue light emitting element 10 used for the pixel BP) preferably has an emission peak wavelength in a wavelength band of 440 nm or more and 460 nm or less. This makes it possible to realize a wide color reproduction range in the display device 100 provided with the light emitting element 10.
- the case where the anode 2, the hole transport layer 3, the light emitting layer 4, and the electron transport layer 5 excluding the cathode 6 are formed in an island shape for each pixel will be described as an example. However, it is not limited to this.
- the hole transport layer 3, the electron transport layer 5, and the cathode 6 excluding the anode 2 and the light emitting layer 4 may be formed as a solid common layer. In this case, it is not necessary to provide the bank BK. Further, as will be described later, the stacking order from the anode 2 to the cathode 6 can be reversed.
- the hole transport layer 3 and the electron transport layer 5 may be formed of a material common to the light emitting elements 10R, 10G, and 10B regardless of whether or not they are island-shaped as described above, or emit light.
- the elements 10R, 10G, and 10B may be made of different materials.
- the light emitting element 10 is usually formed on a substrate 1 that supports the light emitting element 10.
- the substrate 1 is a base substrate for forming the light emitting element 10, and functions as a support for supporting the anode 2 to the cathode 6 as described above.
- the light emitting element 10 may be used as a light source of a light emitting device (electronic device) such as a display device 100, for example.
- the substrate 101 of the light emitting device such as the display device 100 is used as the substrate 1.
- the light emitting element 10 may be referred to as a light emitting element 10 including the substrate 1, or may be referred to as a light emitting element 10 without including the substrate 1. Therefore, the light emitting element 10 may include the substrate 1, and the substrate 1 provided by the light emitting element 10 may be the substrate 101 of the display device 100 provided with the light emitting element 10. Therefore, the substrate 1 can be read as the substrate 101, and the substrate 101 can be read as the substrate 1.
- the substrate 1 may be, for example, a glass substrate or a flexible substrate such as a resin substrate. Further, when the light emitting element 10 is a part of a light emitting device such as a display device 100, for example, an array substrate on which a plurality of thin film transistors are formed may be used for the substrate 1 (in other words, the substrate 101). .. In this case, the anode 2 which is the first electrode provided on the substrate 1 may be electrically connected to the thin film transistor of the array substrate.
- the substrate 1 may be made of a translucent material or a light-reflecting material.
- a translucent substrate made of a translucent material is used for the substrate 1.
- the hole transport layer 3 is a layer that transports holes from the anode 2 to the light emitting layer 4.
- the material of the hole transport layer 3 may be any hole transport material capable of stabilizing the transport of holes into the light emitting layer 4, but among them, those having high hole mobility are used. preferable.
- the hole transport layer 3 may have a function of inhibiting the transport of electrons.
- the hole transporting material is preferably an electron blocking material that prevents the penetration of electrons that have moved from the cathode. As a result, the recombination efficiency of holes and electrons in the light emitting layer 4 can be increased.
- the hole transport layer 3 may also have a function as a hole injection layer that promotes the injection of holes from the anode 2 into the light emitting layer 4.
- the hole transporting material examples include arylamine derivatives, anthracene derivatives, carbazole derivatives, thiophene derivatives, fluorene derivatives, distyrylbenzene derivatives, spiro compounds and the like.
- the materials used for the hole transport layer 3 are polyvinylcarbazole (PVK) and poly [(9,9-dioctylfluorenyl-2,7-diyl) -co- (4,4'-(N). -(4-sec-Butylphenyl)) diphenylamine)] (TFB) is more preferably contained.
- PVK and TFB have the effect of improving the light emitting characteristics of the light emitting element 10 in order to improve the light emitting efficiency due to the recombination of electrons and holes in the light emitting layer 4. Only one kind of these hole transporting materials may be used, or two or more kinds may be mixed and used as appropriate.
- the light emitting element 10 may have a layer other than the hole transport layer 3 between the anode 2 and the light emitting layer 4.
- a hole injection layer (not shown) may be formed between the anode 2 and the hole transport layer 3.
- the material used for the hole injection layer may be any hole injectable material capable of stabilizing the injection of holes into the light emitting layer 4.
- the hole-injectable material include conductive polymers such as arylamine derivatives, porphyrin derivatives, phthalocyanine derivatives, carbazole derivatives, polyaniline derivatives, polythiophene derivatives, and polyphenylene vinylene derivatives.
- the hole-injectable material is more preferably poly (3,4-ethylenedioxythiophene) -polystyrene sulfonic acid (PEDOT-PSS).
- PEDOT-PSS has the effect of improving the light emitting characteristics of the light emitting element 10 in order to improve the light emitting efficiency due to the recombination of electrons and holes in the light emitting layer 4. Only one kind of these hole-injectable materials may be used, or two or more kinds may be mixed and used as appropriate.
- the thickness of the hole transport layer 3 and the hole injection layer is not particularly limited as long as the hole transport function and the hole injection function are sufficiently exhibited.
- Examples of the method for forming the hole transport layer 3 and the hole injection layer include a vapor deposition method, a printing method, an inkjet method, a spin coating method, a casting method, a dipping method, a bar coating method, a blade coating method, and a roll coating method. , Gravure coating method, flexographic printing method, spray coating method, photolithography method, self-assembling method (alternate adsorption method, self-assembled monolayer method) and the like, but are not limited thereto. Among them, it is preferable to use a vapor deposition method, a spin coating method, an inkjet method, or a photolithography method.
- the light emitting layer 4 is a quantum dot light emitting layer containing quantum dots (semiconductor nanoparticles) as a light emitting material and having a light emitting peak in the visible light region.
- the light emitting layer 4 emits visible light due to recombination of holes (h + ) transported from the anode 2 and electrons (e ⁇ ) transported from the cathode 6.
- a quantum dot has a valence band level (equal to ionization potential) and a conduction band level (equal to electron affinity), and the holes in the valence band level and the electrons in the conduction band level are recombined. It is a luminescent material that emits light by bonding. Since the light emitted from the light emitting layer 4 has a narrow spectrum due to the quantum confinement effect, it is possible to obtain light emission having a relatively deep chromaticity.
- the light emitting layer 4 in the light emitting element 10R includes a quantum dot QR having a red light emitting peak as a quantum dot.
- the light emitting layer 4 in the light emitting element 10G includes quantum dots QG having a green light emitting peak as quantum dots.
- the light emitting layer 4 in the light emitting element 10B includes quantum dots QB having a blue light emitting peak as quantum dots.
- quantum dots QR / QG / QB are, for example, Cd (cadmium), S (sulfur), Te (tellurium), Se (selenium), Zn (zinc), In (indium), N (nitrogen), P (phosphorus). ), As (arsenic), Sb (antimony), aluminum (Al), Ga (gallium), Pb (lead), Si (silicon), Ge (germanium), Mg (magnesium), at least selected from the group. It may contain at least one semiconductor material composed of one element.
- the quantum dots QR / QG / QB may be a two-component core type, a three-component core type, a four-component core type, a core-shell type or a core multi-shell type. Further, the quantum dots QR, QG, and QB may contain nanoparticles doped with at least one of the above elements, and may have a structure with an inclined composition. However, it is preferable that the quantum dots QR, QG, and QB include Se. Specifically, it is preferable that the core material of the quantum dots QR / QG / QB is a material containing Se.
- Examples of the material containing Se include CdSe (cadmium selenide), ZnSe (zinc selenide), and a material containing these as a main component.
- CdSe cadmium selenide
- ZnSe zinc selenide
- a material containing these as a main component As a result, most of the core materials of quantum dots QR, QG, and QB are composed of binary compounds (two kinds of elements), and one of the two kinds of elements will be described later. Since Se is contained in the electrode, the material required for manufacturing the light emitting element 10 is reduced as compared with the case where quantum dots made of two types of materials other than Se are used, so that cost reduction is possible. The fact that the electrodes contain selenium will be described later.
- the particle size of the core of the quantum dots QR / QG / QB is, for example, 1 to 30 nm, and the outermost particle size of the quantum dots QR / QG / QB including the shell is, for example, 1 to 50 nm.
- the number of overlapping layers of the quantum dot QR, the quantum dot QG, or the quantum dot QB in each of the light emitting elements 10R, 10G, and 10B is, for example, 1 to 20 layers.
- the layer thickness of the light emitting layer 4 is not particularly limited as long as it can provide a field for recombination of electrons and holes and exhibit a function of emitting light, and can be, for example, about 1 nm to 200 nm. ..
- the layer thickness of the light emitting layer 4 in each of the light emitting elements 10R, 10G, and 10B is preferably about several times the outermost particle size of the quantum dots in each light emitting layer 4.
- the method for forming the light emitting layer 4 is not particularly limited as long as it is a method capable of forming a fine pattern required for the light emitting element 10.
- thin-film deposition method, printing method, inkjet method, spin coating method, casting method, dipping method, bar coating method, blade coating method, roll coating method, gravure coating method, flexographic printing method, spray coating method, photolithography method, or self examples thereof include an organizing method (alternate adsorption method, self-assembling monolayer method).
- Examples of the vapor deposition method include a vacuum vapor deposition method, a sputtering method, an ion plating method, and the like.
- Specific examples of the vacuum vapor deposition method include a resistance heating vapor deposition method, a flash vapor deposition method, an arc vapor deposition method, a laser vapor deposition method, a high frequency heat vapor deposition method, an electron beam vapor deposition method, and the like.
- the solvent of the coating liquid is not particularly limited as long as each constituent material of the light emitting layer 4 can be dissolved or dispersed.
- the solvent include toluene, xylene, cyclohexanone, cyclohexanol, tetralin, mesitylene, methylene chloride, tetrahydrofuran, dichloroethane, chloroform and the like.
- the electron transport layer 5 is a layer that transports electrons from the cathode 6 to the light emitting layer 4.
- the material of the electron transport layer 5 may be any electron transportable material capable of transporting electrons injected from the cathode 6 into the light emitting layer 4, and among them, a material having high electron mobility is preferable. ..
- the electron transport layer 5 may have a function of inhibiting the transport of holes.
- the electron transporting material is preferably a hole blocking material that prevents the penetration of holes that have moved from the anode. As a result, the recombination efficiency of holes and electrons in the light emitting layer 4 can be increased.
- the electron transport layer 5 may not be provided.
- the electron transport layer 5 may also have a function as an electron injection layer that promotes the injection of electrons from the cathode 6 into the light emitting layer 4.
- Examples of the electron-transporting material include oxadiazoles, triazoles, phenanthrolines, silol derivatives, cyclopentadiene derivatives, aluminum complexes, metal oxides and the like.
- examples of the oxadiazole derivative include (2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole) (PBD).
- phenanthrolines include vasocuproin (BCP) and vasofenanthroline (BPhen).
- Examples of the aluminum complex include a tris (8-quinolinol) aluminum complex (Alq3), a bis (2-methyl-8-quinolilato) (p-phenylphenolate) aluminum complex (BAlq), and the like.
- Examples of the metal oxide include zinc oxide such as ZnO (zinc oxide), TiO 2 (titanium oxide), Ta 2 O 3 (tantal oxide), SrTIO 3 (strontium oxide titanium), Mg Zn O or Mg x Zn 1-x O. And so on. Only one kind of these hole-injectable materials may be used, or two or more kinds may be mixed and used as appropriate.
- Mg x Zn 1-x O indicates a structure in which a part of ZnO Zn is replaced with Mg, and x indicates a ratio of ZnO Zn replaced with Mg.
- the electron-transporting material is preferably Mg x Zn 1-x O, and the range of x is more preferably in the range of 0 to 0.7. Since the ionization potential and electron affinity of Mg x Zn 1-x O can be adjusted by adjusting the range of x, it is possible to easily prepare the electron transport layer 5 suitable for the emission wavelength of the light emitting layer 4. .. It should be noted that ZnO has a property that the higher the ratio of Zn replaced with Mg, the smaller the ionization potential and electron affinity.
- the light emitting element 10 may have a layer other than the electron transport layer 5 between the cathode 6 and the light emitting layer 4.
- an electron injection layer (not shown) may be formed between the cathode 6 and the electron transport layer 5.
- the material used for the electron injection layer may be any electron injectable material capable of stabilizing the injection of electrons into the light emitting layer 4.
- the electron injecting material e.g., Li (lithium), Cs alkali metal (cesium) or the like; alkali metal oxides such as Li 2 O (lithium oxide); Sr (strontium), alkali such as Ca (calcium) Earth metal; Oxide of alkaline earth metal such as MgO (magnesium oxide), SrO (strontium oxide); Fluoride of alkali metal such as LiF (lithium fluoride), CsF (cesium fluoride); MgF 2 (huh) Fluoride of alkaline earth metals such as magnesium oxide), SrF 2 (strontium fluoride), CaF 2 (calcium fluoride), BaF 2 (barium fluoride); organic complexes of alkali metals; others such as Al (aluminum) Metals; oxides of metals such as Al 2 O 3 (aluminum oxide
- the thickness of the electron transport layer 5 and the electron injection layer is not particularly limited as long as the electron transport function and the electron injection function are sufficiently exhibited.
- Examples of the method for forming the electron transport layer 5 and the electron injection layer include a vapor deposition method, a printing method, an inkjet method, a spin coating method, a casting method, a dipping method, a bar coating method, a blade coating method, a roll coating method, and a gravure coating method.
- the method, flexographic printing method, spray coating method, photolithography method, self-assembling method (alternate adsorption method, self-assembling monomolecular film method) and the like can be mentioned, but the method is not limited thereto. Among them, it is preferable to use a vapor deposition method, a spin coating method, an inkjet method, or a photolithography method.
- the anode 2 and the cathode 6 contain a conductive material and are electrically connected to the hole transport layer 3 and the electron transport layer 5, respectively.
- the anode 2 has a function of injecting holes into the hole transport layer 3.
- the cathode 6 has a function of injecting electrons into the electron transport layer 5.
- the anode 2 and the cathode 6 have low resistance.
- any of a metal material, an organic compound, and an inorganic compound may be used, but it is preferable that at least one of the anode 2 and the cathode 6 contains a metal material. Electrodes made of metal material have high conductivity.
- a conductive material having a large work function for the anode 2 so that holes can be easily injected.
- conductive materials include Au (gold), Ta (tantal), W (tungsten), Pt (platinum), Ni (nickel), Pd (palladium), Cr (chromium), and Cu (copper).
- Mo mobdenum
- oxides of these metals AlLi (aluminum-lithium alloy), AlCa (aluminum-calcium alloy), AlMg (aluminum-magnesium alloy), etc.
- Mg alloys such as MgAg (magnesium / silver alloy), Ni alloys, Cr alloys, alkali metal alloys, alkaline earth metal alloys, etc.
- ITO indium tin oxide
- IZO indium zinc oxide
- ZnO zinc oxide
- conductive polymers such as metal-doped polythiophene, polyaniline, polyacetylene, polyalkylthiophene derivatives, polysilane derivatives; ⁇ -Si (amorphous silicon), ⁇ -SiC ( Amorphous silicon carbide); etc. These conductive materials may be used alone or in combination of two or more as appropriate.
- ITO Indium Tin Oxide
- a conductive material having a small work function for the cathode 6 so that electrons can be easily injected.
- magnesium alloys such as MgAg; Al alloys such as AlLi, AlCa and AlMg; alloys of alkali metals such as Li, Cs and Ba (barium); alloys of alkaline earth metals such as Sr and Ca; and the like. Be done.
- Al or Al alloy is highly versatile as an electrode and is relatively inexpensive. Therefore, by using Al or an Al alloy as the conductive material used for the cathode 6, the manufacturing cost can be suppressed.
- the electrode on the light extraction surface side needs to be transparent.
- the electrode on the side opposite to the light extraction surface may or may not be transparent.
- the light emitting element 10 may have a bottom emission structure in which the lower anode 2 is a translucent electrode and the upper cathode 6 is a light reflecting electrode.
- the anode 2 on the light extraction surface side is formed of a light-transmitting material
- the cathode 6 is formed of a light-reflecting material.
- the light emitting element 10 may have a top emission structure in which the anode 2 which is the lower layer is a light reflecting electrode and the cathode 6 which is the upper layer is a translucent electrode.
- the cathode 6 on the light extraction surface side is formed of a light-transmitting material
- the anode 2 is formed of a light-reflecting material.
- Se is contained in at least one of the electrodes of the anode 2 and the cathode 6.
- Se has a photoconducting effect.
- the photoconducting effect indicates an effect of improving the conductivity by irradiating white light.
- the proportion of Se contained in the electrode containing Se is preferably 0.1 atomic% or more and 90 atomic% or less in terms of molars. More preferably, it is 1 atomic% or more and 50 atomic% or less. Se has the benefit of the photoconducting effect even if it is present in the electrode as much as possible. However, if the proportion of Se in the electrode is less than 0.1 atomic%, it becomes difficult to confirm the effect. On the contrary, if the ratio of Se in the electrode exceeds 90 atomic%, the performance as the original electrode material may not be maintained. When the proportion of Se in the electrode is 1 atomic% or more and 50 atomic% or less in terms of molars, it is possible to more effectively achieve both the original performance of the electrode material and the photoconducting effect of Se. it can.
- Se is contained in the entire electrode including Se.
- Se is preferably contained in at least one of the electrodes of the anode 2 and the cathode 6.
- a current due to the photoconducting effect of Se flows through the entire electrode including Se, so that power consumption can be suppressed more effectively.
- Whether or not Se is contained in the electrode and the ratio of Se in the electrode are measured by, for example, an energy dispersive X-ray (EDX) analyzer (TEM-EDX) attached to a transmission electron microscope (TEM). can do.
- EDX energy dispersive X-ray
- TEM-EDX transmission electron microscope
- the fact that Se is contained in the entire electrode containing Se is confirmed, for example, by detecting the Se peak at any point of the electrode by EDX measurement.
- FIG. 1 a case where the light emitting element 10 is a bottom emission type light emitting element having a bottom emission structure and the cathode 6 contains Se is shown as an example.
- Se is uniformly diffused (distributed) over the entire cathode 6. Therefore, in the example shown in FIG. 1, a current due to the photoconducting effect of Se flows through the entire cathode 6, so that power consumption can be suppressed more effectively.
- Se is contained in the cathode 6 as described above.
- a transparent electrode such as ITO is adopted on the anode side, and the anode side is often the light extraction surface.
- the electrode on the light extraction surface side must have translucency. Therefore, the range of selection of the material used for the cathode is generally wider than that of the anode. Therefore, when Se is contained in the cathode 6, as compared with the case where an electrode containing Se is used for the anode 2, the electrode containing Se has the characteristics of increasing the current value due to the photoconducting effect, as well as durability and the like. It is possible to select the characteristics as a comprehensive electrode, and it is possible to improve the characteristics of the light emitting element 10.
- the cathode 6 contains a metal material as the conductive material.
- Se is a chalcogen element and a non-metallic element. Therefore, it is preferable that the cathode 6 further contains a metal element in addition to Se.
- the metal material is preferably, for example, Al or an Al alloy. Therefore, the metal element preferably contains Al.
- the cathode 6 may have, for example, a structure in which Se is diffused in the Al electrode.
- the film forming method of the electrode containing Se is not particularly limited as long as the electrode material containing Se can be formed.
- a film forming method for the anode 2 and the cathode 6 a general electrode forming method can be used.
- the film forming method of the anode 2 and the cathode 6 include a physical vapor deposition method (PVD method) such as a vacuum vapor deposition method, a sputtering method, an electron beam (EB) vapor deposition method, and an ion plating method, or a chemical vapor deposition method.
- PVD method physical vapor deposition method
- EB electron beam
- ion plating method a chemical vapor deposition method
- CVD method chemical vapor deposition method
- the patterning method of the anode 2 and the cathode 6 is not particularly limited as long as it can be formed in a desired pattern with high accuracy.
- Specific examples of the patterning method of the anode 2 and the cathode 6 include a photolithography method, an ink jot method, and the like.
- the display device 100 includes three types of light emitting elements 10 that emit red, green, and blue light, respectively, has been described as an example.
- the display device 100 is not limited to this, and may include four or more types of light emitting elements that emit light of different colors.
- FIG. 3 is a cross-sectional view schematically showing an example of a schematic configuration of the light emitting element 10 according to the present embodiment.
- the stacking order from the anode 2 to the cathode 6 can be reversed.
- the case where the substrate 1 is under the anode 2 is illustrated as an example.
- the substrate 1 may be below the cathode 6 (above the cathode 6 in FIG. 1).
- the first electrode, the first carrier transport layer, the second carrier transport layer, and the second electrode are, in that order, a cathode 6, an electron transport layer 5, a hole transport layer 3, and an anode 2, and are substrates as supports. 1 is provided, and the case where the electrode 6, the electron transport layer 5, the light emitting layer 4, the hole transport layer 3, and the anode 2 are provided on the substrate 1 in this order from the substrate 1 side is shown as an example. There is.
- a transparent electrode such as ITO is generally used as the translucent electrode on the anode side of the display device.
- the anode side serves as the light extraction surface.
- the stacking order from the anode 2 to the cathode 6 in the display device 100 is FIG. It is the opposite of the example shown in.
- the cathode 6, the electron transport layer 5, the light emitting layer 4, and the hole transport layer 3 excluding the anode 2 may be formed in an island shape for each pixel. Further, the electron transport layer 5, the hole transport layer 3, and the anode 2 excluding the cathode 6 and the light emitting layer 4 may be formed as a solid common layer. In this case, it is not necessary to provide the bank BK. Further, the hole transport layer 3 and the electron transport layer 5 may be formed of a material common to the light emitting elements 10R, 10G, and 10B regardless of whether or not they are island-shaped as described above, or emit light. The elements 10R, 10G, and 10B may be made of different materials.
- FIG. 3 as an example, a case where the light emitting element 10 is a top emission type light emitting element having a top emission structure and the cathode 6 contains Se is shown as an example.
- Se is uniformly diffused (distributed) over the entire cathode 6. Therefore, in the example shown in FIG. 3, a current due to the photoconducting effect of Se flows through the entire cathode 6, so that power consumption can be suppressed more effectively.
- a transparent electrode such as ITO is adopted on the anode side, and the anode side is often the light extraction surface. Also in the example shown in FIG. 3, the anode 2 side is the light extraction surface. Therefore, even in the example shown in FIG. 3, since Se is contained in the cathode 6, the current value increases due to the photoconducting effect as the electrode containing Se as compared with the case where the electrode containing Se is used for the anode 2. In addition to the characteristics, it is possible to select the characteristics as a comprehensive electrode such as durability, and it is possible to improve the characteristics of the light emitting element 10.
- FIG. 4 is a cross-sectional view schematically showing an example of a schematic configuration of the light emitting element 10 according to the present embodiment.
- the cathode 6 contains Se is illustrated as an example, but as described in the first embodiment, Se is contained in at least one electrode of the anode 2 and the cathode 6. It suffices if it is. Therefore, Se may be contained only in either the anode 2 or the cathode 6, or may be contained in both the anode 2 and the cathode 6.
- FIG. 4 as an example, a case where the light emitting element 10 is a bottom top emission type light emitting element and the anode 2 and the cathode 6 each contain Se is shown as an example.
- Se is uniformly diffused (distributed) over the entire anode 2 and cathode 6. Therefore, in the example shown in FIG. 4, since the current due to the photoconducting effect of Se flows through the anode 2 and the cathode 6, the power consumption can be suppressed more effectively.
- Se is contained in the electrode on the light extraction surface side and the electrode on the side opposite to the light extraction surface side, respectively, so that the effects described in the first and second embodiments can be obtained. Play at the same time.
- the anode 2 side is the light extraction surface and the range of selection of the material of the cathode 6 is widened, the current value increases due to the photoconductive effect as the electrode containing Se in the cathode 6.
- Se may be contained only in the anode 2, and the light emitting element 10 may be a top emission type.
Abstract
A light emitting device (10) comprises an anode (2), a light emitting layer (4) that contains quantum dots, and a cathode (6) in the stated order, and at least one electrode among the anode and the cathode contains selenium.
Description
本開示は、電界発光素子及び表示装置に関する。
The present disclosure relates to an electroluminescent element and a display device.
例えば特許文献１に示すように、量子ドット（ＱＤ）を含む発光層を備えた電界発光素子を用いた表示装置は、携帯型端末等の表示装置への応用が期待されている。
For example, as shown in Patent Document 1, a display device using an electroluminescent element provided with a light emitting layer containing quantum dots (QD) is expected to be applied to a display device such as a portable terminal.
本願発明者らは、量子ドットを含む発光層を備えた電界発光素子の携帯型端末等の表示装置への応用について検討を重ねた結果、このような表示装置を太陽光の下等の明るい場所で利用する場合、屋内等の暗い場所で利用する場合と比べて、表示装置の輝度を上げる必要があり、消費電力が上がってしまうという新たな課題を見出した。
As a result of repeated studies on the application of an electroluminescent element provided with a light emitting layer containing quantum dots to a display device such as a portable terminal, the inventors of the present application have applied such a display device to a bright place such as under sunlight. We have found a new problem that the brightness of the display device needs to be increased and the power consumption increases as compared with the case of using it in a dark place such as indoors.
この理由としては、以下の通りである。このような表示装置を太陽光の下等の明るい場所で利用する場合、屋内等の暗い場所で利用する場合と比べて、外光の影響で画面が見づらくなる。そのため、このような場合、表示装置の輝度を上げる必要があるが、そのためには、外部電源から供給する電流値を上げる必要がある。そのため、このような表示装置を太陽光の下等の明るい場所で利用する場合、屋内等の暗い場所で利用する場合と比べて、消費電力が上がってしまう。
The reason for this is as follows. When such a display device is used in a bright place such as under sunlight, the screen becomes difficult to see due to the influence of outside light as compared with the case where it is used in a dark place such as indoors. Therefore, in such a case, it is necessary to increase the brightness of the display device, but for that purpose, it is necessary to increase the current value supplied from the external power source. Therefore, when such a display device is used in a bright place such as under sunlight, the power consumption is higher than when it is used in a dark place such as indoors.
そこで、本開示の一態様は、太陽光の下等の明るい場所で、消費電力を上げることを抑制した上で輝度を向上させることができる、電界発光素子及び表示装置を提供することを目的とする。
Therefore, one aspect of the present disclosure is to provide an electroluminescent element and a display device capable of improving the brightness while suppressing the increase in power consumption in a bright place such as under sunlight. To do.
上記の課題を解決するために、本開示の一態様に係る電界発光素子は、第１電極と、量子ドットを含む発光層と、第２電極と、をこの順に備え、前記第１電極及び前記第２電極のうち少なくとも一方の電極がセレンを含む。
In order to solve the above problems, the electroluminescent device according to one aspect of the present disclosure includes a first electrode, a light emitting layer containing quantum dots, and a second electrode in this order, and the first electrode and the above. At least one of the second electrodes contains selenium.
上記の課題を解決するために、本開示の一態様に係る表示装置は、本開示の一態様に係る上記電界発光素子を備えている。
In order to solve the above problems, the display device according to one aspect of the present disclosure includes the above electroluminescent element according to one aspect of the present disclosure.
本開示の一態様によれば、前記第１電極及び前記第２電極のうち少なくとも一方の電極に、光導電効果を有するセレンを含む電極を用いることで、太陽光の下等の明るい場所で、外部電源から供給する電流値を上げることなく、光導電効果により、上記電極を流れる電流の値を増加させることができる。このため、本開示の一態様によれば、太陽光の下等の明るい場所で、消費電力を上げることを抑制した上で輝度を向上させることができる、電界発光素子及び表示装置を提供することができる。
According to one aspect of the present disclosure, by using an electrode containing selenium having a photoconducting effect as at least one of the first electrode and the second electrode, in a bright place such as under sunlight. The value of the current flowing through the electrodes can be increased by the photoconducting effect without increasing the value of the current supplied from the external power source. Therefore, according to one aspect of the present disclosure, there is provided an electroluminescent element and a display device capable of improving the brightness while suppressing the increase in power consumption in a bright place such as under sunlight. Can be done.
〔実施形態１〕
＜発光素子の概略構成＞
図１は、本実施形態に係る発光素子１０の概略構成の一例を模式的に示す断面図である。以下では、比較対象の層よりも先のプロセスで形成されている層を「下層」とし、比較対象の層よりも後のプロセスで形成されている層を「上層」とする。また、発光層４から基板１に向かう方向を「下方向」とし、基板１から発光層４に向かう方向を「上方向」とする。 [Embodiment 1]
<Outline configuration of light emitting element>
FIG. 1 is a cross-sectional view schematically showing an example of a schematic configuration of alight emitting element 10 according to the present embodiment. In the following, the layer formed in the process before the layer to be compared is referred to as the "lower layer", and the layer formed in the process after the layer to be compared is referred to as the "upper layer". Further, the direction from the light emitting layer 4 to the substrate 1 is defined as "downward", and the direction from the substrate 1 toward the light emitting layer 4 is defined as "upward".
＜発光素子の概略構成＞
図１は、本実施形態に係る発光素子１０の概略構成の一例を模式的に示す断面図である。以下では、比較対象の層よりも先のプロセスで形成されている層を「下層」とし、比較対象の層よりも後のプロセスで形成されている層を「上層」とする。また、発光層４から基板１に向かう方向を「下方向」とし、基板１から発光層４に向かう方向を「上方向」とする。 [Embodiment 1]
<Outline configuration of light emitting element>
FIG. 1 is a cross-sectional view schematically showing an example of a schematic configuration of a
図１に示すように、発光素子１０は、陽極２と陰極６との間に発光層４が設けられた電界発光素子である。陽極２および陰極６は、図示しない電源と接続されることで、それらの間に電圧が印加されるようになっている。一例として、発光素子１０は、陽極２と、正孔輸送層３と、発光層４と、電子輸送層５と、陰極６と、をこの順に備える。なお、発光素子１０は、支持体として基板１を備えていてもよい。図１では、一例として、発光素子１０が、基板１と、陽極２と、正孔輸送層３と、発光層４と、電子輸送層５と、陰極６と、を備え、基板１上に、陽極２と、正孔輸送層３と、発光層４と、電子輸送層５と、陰極６と、が基板１側からこの順に設けられている場合を例に挙げて示している。
As shown in FIG. 1, the light emitting element 10 is an electroluminescent element in which a light emitting layer 4 is provided between the anode 2 and the cathode 6. The anode 2 and the cathode 6 are connected to a power source (not shown) so that a voltage is applied between them. As an example, the light emitting element 10 includes an anode 2, a hole transport layer 3, a light emitting layer 4, an electron transport layer 5, and a cathode 6 in this order. The light emitting element 10 may include a substrate 1 as a support. In FIG. 1, as an example, the light emitting element 10 includes a substrate 1, an anode 2, a hole transport layer 3, a light emitting layer 4, an electron transport layer 5, and a cathode 6, and is provided on the substrate 1. An example is shown in which the anode 2, the hole transport layer 3, the light emitting layer 4, the electron transport layer 5, and the cathode 6 are provided in this order from the substrate 1 side.
一般的に、電界発光素子を作製する際には、陽極側から積層する方が安定して電界発光素子を作製できる。したがって、図１のように基板１が陽極２の下にある場合、歩留まりを向上させることができる。なお、後述する実施形態２に示すように、陽極２から陰極６までの積層順は、逆にすることもできる。発光素子１０は、例えば、表示装置における発光素子として好適に用いることができる。
Generally, when manufacturing an electroluminescent element, it is possible to manufacture the electroluminescent element more stably by laminating from the anode side. Therefore, when the substrate 1 is under the anode 2 as shown in FIG. 1, the yield can be improved. As shown in the second embodiment described later, the stacking order from the anode 2 to the cathode 6 can be reversed. The light emitting element 10 can be suitably used as, for example, a light emitting element in a display device.
＜表示装置の概略構成＞
図２は、本実施形態に係る表示装置１００の概略構成の一例を模式的に示す断面図である。 <Outline configuration of display device>
FIG. 2 is a cross-sectional view schematically showing an example of a schematic configuration of thedisplay device 100 according to the present embodiment.
図２は、本実施形態に係る表示装置１００の概略構成の一例を模式的に示す断面図である。 <Outline configuration of display device>
FIG. 2 is a cross-sectional view schematically showing an example of a schematic configuration of the
本実施形態に係る表示装置１００は、支持体としての基板１０１上に、発光素子層１１が設けられた構成を有している。発光素子層１１は、例えば、基板１０１上に、第１電極、第１キャリア輸送層、発光層、第２キャリア輸送層、第２電極が、基板１０１側からこの順に積層された構成を有している。図２では、第１電極、第１キャリア輸送層、第２キャリア輸送層、第２電極が、順に、陽極２、正孔輸送層３、電子輸送層５、陰極６であり、基板１０１上に、陽極２、正孔輸送層３、発光層４、電子輸送層５、陰極６、が、基板１０１側からこの順に設けられている場合を例に挙げて示している。
The display device 100 according to the present embodiment has a configuration in which the light emitting element layer 11 is provided on the substrate 101 as a support. The light emitting element layer 11 has, for example, a configuration in which the first electrode, the first carrier transport layer, the light emitting layer, the second carrier transport layer, and the second electrode are laminated in this order from the substrate 101 side on the substrate 101. ing. In FIG. 2, the first electrode, the first carrier transport layer, the second carrier transport layer, and the second electrode are the anode 2, the hole transport layer 3, the electron transport layer 5, and the cathode 6 in this order, and are on the substrate 101. The case where the anode 2, the hole transport layer 3, the light emitting layer 4, the electron transport layer 5, and the cathode 6 are provided in this order from the substrate 101 side is shown as an example.
陽極２、正孔輸送層３、発光層４、電子輸送層５のそれぞれは、バンクＢＫによって画素（発光画素）毎に島状に分離されている。陰極６は、バンクＢＫによって島状に分離されず、各画素に共通して形成されている。表示装置１００は、画素として、赤色の画素ＲＰ、緑色の画素ＧＰ、青色の画素ＢＰを有している。発光素子１０は、画素に対応して、画素毎に形成されている。
Each of the anode 2, the hole transport layer 3, the light emitting layer 4, and the electron transport layer 5 is separated into islands for each pixel (light emitting pixel) by the bank BK. The cathode 6 is not separated into islands by the bank BK, and is formed in common with each pixel. The display device 100 has red pixel RP, green pixel GP, and blue pixel BP as pixels. The light emitting element 10 is formed for each pixel corresponding to the pixel.
赤色の画素ＲＰには、発光素子１０として、赤色発光ピークを有する発光層４を備えた、赤色発光の発光素子１０Ｒが設けられている。緑色の画素ＧＰには、発光素子１０として、緑色発光ピークを有する発光層４を備えた、緑色発光の発光素子１０Ｇが設けられている。青色の画素ＢＰには、発光素子１０として、青色発光ピークを有する発光層４を備えた、青色発光の発光素子１０Ｂが設けられている。
The red pixel RP is provided with a red light emitting element 10R having a light emitting layer 4 having a red light emitting peak as the light emitting element 10. The green pixel GP is provided with a green light emitting element 10G having a light emitting layer 4 having a green light emitting peak as the light emitting element 10. The blue pixel BP is provided with a blue light emitting element 10B having a light emitting layer 4 having a blue light emitting peak as the light emitting element 10.
なお、本実施形態において、「赤色発光ピークを有する」とは、「６００ｎｍ以上、７８０ｎｍ以下の波長帯域に発光ピーク波長を有する」ことを意味する。また、「緑色発光ピークを有する」とは、「５００ｎｍ以上、６００ｎｍ以下の波長帯域に発光ピーク波長を有する」ことを意味する。「青色発光ピークを有する」とは、「４００ｎｍ以上、５００ｎｍ以下の波長帯域に発光ピーク波長を有する」ことを意味する。なお、画素ＲＰ（言い換えれば、画素ＲＰに用いられる赤色発光の発光素子１０）は、６２０ｎｍ以上、６５０ｎｍ以下の波長帯域に発光ピーク波長を有することが好ましい。また、画素ＧＰ（言い換えれば、画素ＧＰに用いられる緑色発光の発光素子１０）は、５２０ｎｍ以上、５４０ｎｍ以下の波長帯域に発光ピーク波長を有することが好ましい。画素ＢＰ（言い換えれば、画素ＢＰに用いられる青色発光の発光素子１０）は、４４０ｎｍ以上、４６０ｎｍ以下の波長帯域に発光ピーク波長を有することが好ましい。これにより、発光素子１０を備えた表示装置１００において、広い色再現域を実現することが可能となる。
In the present embodiment, "having a red emission peak" means "having an emission peak wavelength in a wavelength band of 600 nm or more and 780 nm or less". Further, "having a green emission peak" means "having an emission peak wavelength in a wavelength band of 500 nm or more and 600 nm or less". "Having a blue emission peak" means "having an emission peak wavelength in a wavelength band of 400 nm or more and 500 nm or less". The pixel RP (in other words, the red light emitting element 10 used for the pixel RP) preferably has an emission peak wavelength in a wavelength band of 620 nm or more and 650 nm or less. Further, the pixel GP (in other words, the green light emitting element 10 used for the pixel GP) preferably has an emission peak wavelength in a wavelength band of 520 nm or more and 540 nm or less. The pixel BP (in other words, the blue light emitting element 10 used for the pixel BP) preferably has an emission peak wavelength in a wavelength band of 440 nm or more and 460 nm or less. This makes it possible to realize a wide color reproduction range in the display device 100 provided with the light emitting element 10.
なお、図２では、陰極６を除いた、陽極２と、正孔輸送層３と、発光層４と、電子輸送層５とを、画素毎に島状に形成した場合を一例に挙げて説明したが、これに限定されることはない。例えば、陽極２と発光層４とを除いた、正孔輸送層３と、電子輸送層５と、陰極６とは、ベタ状の共通層として形成してもよい。なお、この場合には、バンクＢＫを設けなくてもよい。また、後述するように、陽極２から陰極６までの積層順は、逆にすることもできる。また、正孔輸送層３及び電子輸送層５は、上述したように島状であるか否かに拘らず、発光素子１０Ｒ・１０Ｇ・１０Ｂに共通の材料で形成されていてもよいし、発光素子１０Ｒ・１０Ｇ・１０Ｂ毎に、異なる材料で形成されていてもよい。
In FIG. 2, the case where the anode 2, the hole transport layer 3, the light emitting layer 4, and the electron transport layer 5 excluding the cathode 6 are formed in an island shape for each pixel will be described as an example. However, it is not limited to this. For example, the hole transport layer 3, the electron transport layer 5, and the cathode 6 excluding the anode 2 and the light emitting layer 4 may be formed as a solid common layer. In this case, it is not necessary to provide the bank BK. Further, as will be described later, the stacking order from the anode 2 to the cathode 6 can be reversed. Further, the hole transport layer 3 and the electron transport layer 5 may be formed of a material common to the light emitting elements 10R, 10G, and 10B regardless of whether or not they are island-shaped as described above, or emit light. The elements 10R, 10G, and 10B may be made of different materials.
以下に、発光素子１０及び表示装置１００における上記各層について、より詳細に説明する。
The above-mentioned layers in the light emitting element 10 and the display device 100 will be described in more detail below.
＜基板１・１０１＞
図１に示すように、通常、発光素子１０は、該発光素子１０を支持する基板１上に形成される。基板１は、発光素子１０を形成するためのベース基板であり、上述したように陽極２～陰極６を支持する支持体として機能する。発光素子１０は、例えば、表示装置１００等の発光装置（電子機器）の光源として用いられてよい。発光素子１０が、これら表示装置１００等の発光装置の一部である場合、基板１には、これら表示装置１００等の発光装置の基板１０１が用いられる。このため、発光素子１０は、基板１を含めて発光素子１０と称される場合もあれば、基板１を含めずに発光素子１０と称される場合もある。したがって、発光素子１０は、基板１を備えていてもよく、発光素子１０が備えている基板１は、当該発光素子１０を備えた表示装置１００の基板１０１であってもよい。したがって、基板１は、基板１０１と読み替えることができるし、基板１０１は、基板１と読み替えることができる。 <Board 1.101>
As shown in FIG. 1, thelight emitting element 10 is usually formed on a substrate 1 that supports the light emitting element 10. The substrate 1 is a base substrate for forming the light emitting element 10, and functions as a support for supporting the anode 2 to the cathode 6 as described above. The light emitting element 10 may be used as a light source of a light emitting device (electronic device) such as a display device 100, for example. When the light emitting element 10 is a part of a light emitting device such as the display device 100, the substrate 101 of the light emitting device such as the display device 100 is used as the substrate 1. Therefore, the light emitting element 10 may be referred to as a light emitting element 10 including the substrate 1, or may be referred to as a light emitting element 10 without including the substrate 1. Therefore, the light emitting element 10 may include the substrate 1, and the substrate 1 provided by the light emitting element 10 may be the substrate 101 of the display device 100 provided with the light emitting element 10. Therefore, the substrate 1 can be read as the substrate 101, and the substrate 101 can be read as the substrate 1.
図１に示すように、通常、発光素子１０は、該発光素子１０を支持する基板１上に形成される。基板１は、発光素子１０を形成するためのベース基板であり、上述したように陽極２～陰極６を支持する支持体として機能する。発光素子１０は、例えば、表示装置１００等の発光装置（電子機器）の光源として用いられてよい。発光素子１０が、これら表示装置１００等の発光装置の一部である場合、基板１には、これら表示装置１００等の発光装置の基板１０１が用いられる。このため、発光素子１０は、基板１を含めて発光素子１０と称される場合もあれば、基板１を含めずに発光素子１０と称される場合もある。したがって、発光素子１０は、基板１を備えていてもよく、発光素子１０が備えている基板１は、当該発光素子１０を備えた表示装置１００の基板１０１であってもよい。したがって、基板１は、基板１０１と読み替えることができるし、基板１０１は、基板１と読み替えることができる。 <Board 1.101>
As shown in FIG. 1, the
基板１は、例えば、ガラス基板、あるいは、樹脂基板等のフレキシブル基板であってもよい。また、発光素子１０が例えば表示装置１００等の発光装置の一部である場合、基板１（言い換えれば、基板１０１）には、例えば、複数の薄膜トランジスタが形成されたアレイ基板が用いられてもよい。この場合、基板１上に設けられた第１電極である陽極２は、アレイ基板の薄膜トランジスタと電気的に接続されていてもよい。
The substrate 1 may be, for example, a glass substrate or a flexible substrate such as a resin substrate. Further, when the light emitting element 10 is a part of a light emitting device such as a display device 100, for example, an array substrate on which a plurality of thin film transistors are formed may be used for the substrate 1 (in other words, the substrate 101). .. In this case, the anode 2 which is the first electrode provided on the substrate 1 may be electrically connected to the thin film transistor of the array substrate.
また、基板１は、透光性材料によって構成されてもよいし、光反射性材料によって構成されてもよい。但し、発光素子１０が、ボトムエミッション構造もしくは両面発光構造を有する場合、基板１には、透光性材料からなる透光性基板が用いられる。
Further, the substrate 1 may be made of a translucent material or a light-reflecting material. However, when the light emitting element 10 has a bottom emission structure or a double-sided light emitting structure, a translucent substrate made of a translucent material is used for the substrate 1.
＜正孔輸送層３＞
正孔輸送層３は、陽極２から発光層４に正孔を輸送する層である。正孔輸送層３の材料としては、発光層４内への正孔の輸送を安定化させることができる正孔輸送性材料であればよいが、そのなかでも、正孔移動度が高いものが好ましい。 <Hole transport layer 3>
Thehole transport layer 3 is a layer that transports holes from the anode 2 to the light emitting layer 4. The material of the hole transport layer 3 may be any hole transport material capable of stabilizing the transport of holes into the light emitting layer 4, but among them, those having high hole mobility are used. preferable.
正孔輸送層３は、陽極２から発光層４に正孔を輸送する層である。正孔輸送層３の材料としては、発光層４内への正孔の輸送を安定化させることができる正孔輸送性材料であればよいが、そのなかでも、正孔移動度が高いものが好ましい。 <
The
また、正孔輸送層３は、電子の輸送を阻害する機能を有していてもよい。この場合、正孔輸送性材料は、陰極から移動してきた電子の突き抜けを防止する電子ブロック性材料であることが好ましい。これにより、発光層４内での正孔及び電子の再結合効率を高めることができる。また、正孔輸送層３は、陽極２から発光層４への正孔の注入を促進する正孔注入層としての機能を併有していてもよい。
Further, the hole transport layer 3 may have a function of inhibiting the transport of electrons. In this case, the hole transporting material is preferably an electron blocking material that prevents the penetration of electrons that have moved from the cathode. As a result, the recombination efficiency of holes and electrons in the light emitting layer 4 can be increased. Further, the hole transport layer 3 may also have a function as a hole injection layer that promotes the injection of holes from the anode 2 into the light emitting layer 4.
上記正孔輸送性材料としては、例えば、アリールアミン誘導体、アントラセン誘導体、カルバゾール誘導体、チオフェン誘導体、フルオレン誘導体、ジスチリルベンゼン誘導体、スピロ化合物等を挙げることができる。そのなかでも、正孔輸送層３に用いられる材料は、ポリビニルカルバゾール（ＰＶＫ）及びポリ［（９，９－ジオクチルフルオレニル－２，７－ジイル）－ｃｏ－（４，４’－（Ｎ－（４－ｓｅｃ－ブチルフェニル））ジフェニルアミン）］（ＴＦＢ）のうち、少なくとも一方を含んでいることがより好ましい。ＰＶＫ及びＴＦＢは、発光層４で電子と正孔とが再結合することによる発光の効率を向上するため、発光素子１０の発光特性を改善するという効果を奏する。これら正孔輸送性材料は、一種類のみを用いてもよく、適宜、二種類以上を混合して用いてもよい。
Examples of the hole transporting material include arylamine derivatives, anthracene derivatives, carbazole derivatives, thiophene derivatives, fluorene derivatives, distyrylbenzene derivatives, spiro compounds and the like. Among them, the materials used for the hole transport layer 3 are polyvinylcarbazole (PVK) and poly [(9,9-dioctylfluorenyl-2,7-diyl) -co- (4,4'-(N). -(4-sec-Butylphenyl)) diphenylamine)] (TFB) is more preferably contained. PVK and TFB have the effect of improving the light emitting characteristics of the light emitting element 10 in order to improve the light emitting efficiency due to the recombination of electrons and holes in the light emitting layer 4. Only one kind of these hole transporting materials may be used, or two or more kinds may be mixed and used as appropriate.
なお、発光素子１０は、陽極２と発光層４との間に、正孔輸送層３以外の層を有していてもよい。例えば、陽極２と正孔輸送層３との間には、図示しない正孔注入層が形成されていてもよい。
The light emitting element 10 may have a layer other than the hole transport layer 3 between the anode 2 and the light emitting layer 4. For example, a hole injection layer (not shown) may be formed between the anode 2 and the hole transport layer 3.
正孔注入層に用いられる材料としては、発光層４内への正孔の注入を安定化させることができる正孔注入性材料であればよい。正孔注入性材料としては、例えば、アリールアミン誘導体、ポルフィリン誘導体、フタロシアニン誘導体、カルバゾール誘導体、さらにはポリアニリン誘導体、ポリチオフェン誘導体、ポリフェニレンビニレン誘導体等の導電性高分子等が挙げられる。なお、上記正孔注入性材料は、ポリ（３，４－エチレンジオキシチオフェン）－ポリスチレンスルホン酸（ＰＥＤＯＴ－ＰＳＳ）であることがより好ましい。ＰＥＤＯＴ－ＰＳＳは、発光層４で電子と正孔とが再結合することによる発光の効率を向上するため、発光素子１０の発光特性を改善するという効果を奏する。これら正孔注入性材料は、一種類のみを用いてもよく、適宜、二種類以上を混合して用いてもよい。
The material used for the hole injection layer may be any hole injectable material capable of stabilizing the injection of holes into the light emitting layer 4. Examples of the hole-injectable material include conductive polymers such as arylamine derivatives, porphyrin derivatives, phthalocyanine derivatives, carbazole derivatives, polyaniline derivatives, polythiophene derivatives, and polyphenylene vinylene derivatives. The hole-injectable material is more preferably poly (3,4-ethylenedioxythiophene) -polystyrene sulfonic acid (PEDOT-PSS). PEDOT-PSS has the effect of improving the light emitting characteristics of the light emitting element 10 in order to improve the light emitting efficiency due to the recombination of electrons and holes in the light emitting layer 4. Only one kind of these hole-injectable materials may be used, or two or more kinds may be mixed and used as appropriate.
正孔輸送層３及び正孔注入層の厚みとしては、正孔輸送機能及び正孔注入機能がそれぞれ十分に発揮される厚みであれば、特に限定されるものではない。
The thickness of the hole transport layer 3 and the hole injection layer is not particularly limited as long as the hole transport function and the hole injection function are sufficiently exhibited.
また、正孔輸送層３及び正孔注入層の形成方法としては、例えば、蒸着法、印刷法、インクジェット法、スピンコート法、キャスティング法、ディッピング法、バーコート法、ブレードコート法、ロールコート法、グラビアコート法、フレキソ印刷法、スプレーコート法、フォトリソグラフィー法、もしくは自己組織化法（交互吸着法、自己組織化単分子膜法）等を挙げることができるが、これに限定されない。そのなかでも、蒸着法、スピンコート法、インクジェット法、もしくは、フォトリソグラフィー法を用いることが好ましい。
Examples of the method for forming the hole transport layer 3 and the hole injection layer include a vapor deposition method, a printing method, an inkjet method, a spin coating method, a casting method, a dipping method, a bar coating method, a blade coating method, and a roll coating method. , Gravure coating method, flexographic printing method, spray coating method, photolithography method, self-assembling method (alternate adsorption method, self-assembled monolayer method) and the like, but are not limited thereto. Among them, it is preferable to use a vapor deposition method, a spin coating method, an inkjet method, or a photolithography method.
＜発光層４＞
発光層４は、発光材料として量子ドット（半導体ナノ粒子）を含み、可視光域に発光ピークを有する量子ドット発光層である。発光層４は、陽極２から輸送された正孔（ｈ＋）と、陰極６から輸送された電子（ｅ－）と、の再結合が発生することにより、可視光を発する。 <Light emitting layer 4>
Thelight emitting layer 4 is a quantum dot light emitting layer containing quantum dots (semiconductor nanoparticles) as a light emitting material and having a light emitting peak in the visible light region. The light emitting layer 4 emits visible light due to recombination of holes (h + ) transported from the anode 2 and electrons (e − ) transported from the cathode 6.
発光層４は、発光材料として量子ドット（半導体ナノ粒子）を含み、可視光域に発光ピークを有する量子ドット発光層である。発光層４は、陽極２から輸送された正孔（ｈ＋）と、陰極６から輸送された電子（ｅ－）と、の再結合が発生することにより、可視光を発する。 <
The
量子ドットは、価電子帯準位（イオン化ポテンシャルに等しい）と、伝導帯準位（電子親和力に等しい）とを有し、価電子帯準位の正孔と伝導帯準位の電子との再結合によって発光する発光材料である。発光層４からの発光は、量子閉じ込め効果により狭いスペクトルを有するため、比較的深い色度の発光を得ることが可能である。
A quantum dot has a valence band level (equal to ionization potential) and a conduction band level (equal to electron affinity), and the holes in the valence band level and the electrons in the conduction band level are recombined. It is a luminescent material that emits light by bonding. Since the light emitted from the light emitting layer 4 has a narrow spectrum due to the quantum confinement effect, it is possible to obtain light emission having a relatively deep chromaticity.
発光素子１０Ｒにおける発光層４は、量子ドットとして、赤色発光ピークを有する量子ドットＱＲを備えている。発光素子１０Ｇにおける発光層４は、量子ドットとして、緑色発光ピークを有する量子ドットＱＧを備えている。発光素子１０Ｂにおける発光層４は、量子ドットとして、青色発光ピークを有する量子ドットＱＢを備えている。
The light emitting layer 4 in the light emitting element 10R includes a quantum dot QR having a red light emitting peak as a quantum dot. The light emitting layer 4 in the light emitting element 10G includes quantum dots QG having a green light emitting peak as quantum dots. The light emitting layer 4 in the light emitting element 10B includes quantum dots QB having a blue light emitting peak as quantum dots.
これら量子ドットＱＲ・ＱＧ・ＱＢは、例えば、Ｃｄ（カドミウム）、Ｓ（硫黄）、Ｔｅ（テルル）、Ｓｅ（セレン）、Ｚｎ（亜鉛）、Ｉｎ（インジウム）、Ｎ（窒素）、Ｐ（リン）、Ａｓ（ヒ素）、Ｓｂ（アンチモン）、アルミニウム（Ａｌ）、Ｇａ（ガリウム）、Ｐｂ（鉛）、Ｓｉ（ケイ素）、Ｇｅ（ゲルマニウム）、Ｍｇ（マグネシウム）、からなる群より選択される少なくとも一種の元素で構成されている少なくとも一種の半導体材料を含んでもよい。また、量子ドットＱＲ・ＱＧ・ＱＢは、二成分コア型、三成分コア型、四成分コア型、コアシェル型またはコアマルチシェル型であってもよい。また、量子ドットＱＲ・ＱＧ・ＱＢは、上記元素の少なくとも一種がドープされたナノ粒子を含んでいてもよく、組成傾斜した構造を備えていてもよい。但し、量子ドットＱＲ・ＱＧ・ＱＢは、Ｓｅを含むことが好ましい。具体的には、量子ドットＱＲ・ＱＧ・ＱＢのコア材料がＳｅを含む材料であることが好ましい。Ｓｅを含む材料としては、例えばＣｄＳｅ（セレン化カドミウム）、ＺｎＳｅ（セレン化亜鉛）、または、これらを主成分とする材料が挙げられる。これにより、量子ドットＱＲ・ＱＧ・ＱＢのコア材料は、その多くが二元型化合物（二種類の元素）で構成されるが、その二種類の元素のうちの一種類が、後述するように電極に含まれるＳｅであるため、Ｓｅ以外の二種類の材料からなる量子ドットを用いる場合に比べて発光素子１０の作製に必要な材料が減るため、コスト削減が可能となる。なお、電極にセレンが含まれることについては、後述する。
These quantum dots QR / QG / QB are, for example, Cd (cadmium), S (sulfur), Te (tellurium), Se (selenium), Zn (zinc), In (indium), N (nitrogen), P (phosphorus). ), As (arsenic), Sb (antimony), aluminum (Al), Ga (gallium), Pb (lead), Si (silicon), Ge (germanium), Mg (magnesium), at least selected from the group. It may contain at least one semiconductor material composed of one element. Further, the quantum dots QR / QG / QB may be a two-component core type, a three-component core type, a four-component core type, a core-shell type or a core multi-shell type. Further, the quantum dots QR, QG, and QB may contain nanoparticles doped with at least one of the above elements, and may have a structure with an inclined composition. However, it is preferable that the quantum dots QR, QG, and QB include Se. Specifically, it is preferable that the core material of the quantum dots QR / QG / QB is a material containing Se. Examples of the material containing Se include CdSe (cadmium selenide), ZnSe (zinc selenide), and a material containing these as a main component. As a result, most of the core materials of quantum dots QR, QG, and QB are composed of binary compounds (two kinds of elements), and one of the two kinds of elements will be described later. Since Se is contained in the electrode, the material required for manufacturing the light emitting element 10 is reduced as compared with the case where quantum dots made of two types of materials other than Se are used, so that cost reduction is possible. The fact that the electrodes contain selenium will be described later.
量子ドットＱＲ・ＱＧ・ＱＢのコアの粒径は、例えば１～３０ｎｍであり、シェルを含めた量子ドットＱＲ・ＱＧ・ＱＢの最外粒径は、例えば、１～５０ｎｍである。各発光素子１０Ｒ・１０Ｇ・１０Ｂにおける、量子ドットＱＲ、量子ドットＱＧ、または量子ドットＱＢの重なり層数は、例えば、１～２０層である。発光層４の層厚は、電子と正孔との再結合の場を提供して発光する機能を発現することができる厚みであれば特に限定されず、例えば１ｎｍ～２００ｎｍ程度とすることができる。なお、各発光素子１０Ｒ・１０Ｇ・１０Ｂにおける発光層４の層厚は、各発光層４における量子ドットの最外粒径の数倍程度であることが好ましい。
The particle size of the core of the quantum dots QR / QG / QB is, for example, 1 to 30 nm, and the outermost particle size of the quantum dots QR / QG / QB including the shell is, for example, 1 to 50 nm. The number of overlapping layers of the quantum dot QR, the quantum dot QG, or the quantum dot QB in each of the light emitting elements 10R, 10G, and 10B is, for example, 1 to 20 layers. The layer thickness of the light emitting layer 4 is not particularly limited as long as it can provide a field for recombination of electrons and holes and exhibit a function of emitting light, and can be, for example, about 1 nm to 200 nm. .. The layer thickness of the light emitting layer 4 in each of the light emitting elements 10R, 10G, and 10B is preferably about several times the outermost particle size of the quantum dots in each light emitting layer 4.
発光層４を形成する方法としては、発光素子１０に要求される微細なパターンの形成が可能な方法であれば特に限定されるものではない。例えば蒸着法、印刷法、インクジェット法、スピンコート法、キャスティング法、ディッピング法、バーコート法、ブレードコート法、ロールコート法、グラビアコート法、フレキソ印刷法、スプレーコート法、フォトリソグラフィー法、もしくは自己組織化法（交互吸着法、自己組織化単分子膜法）等を挙げることができる。そのなかでも、蒸着法、スピンコート法、インクジェット法、もしくは、フォトリソグラフィー法を用いることが好ましい。
The method for forming the light emitting layer 4 is not particularly limited as long as it is a method capable of forming a fine pattern required for the light emitting element 10. For example, thin-film deposition method, printing method, inkjet method, spin coating method, casting method, dipping method, bar coating method, blade coating method, roll coating method, gravure coating method, flexographic printing method, spray coating method, photolithography method, or self. Examples thereof include an organizing method (alternate adsorption method, self-assembling monolayer method). Among them, it is preferable to use a vapor deposition method, a spin coating method, an inkjet method, or a photolithography method.
蒸着法としては、例えば、真空蒸着法、スパッタリング法、イオンプレーティング法等が挙げられる。真空蒸着法の具体例としては、抵抗加熱蒸着法、フラッシュ蒸着法、アーク蒸着法、レーザー蒸着法、高周波加熱蒸着法、電子ビーム蒸着法等が挙げられる。
Examples of the vapor deposition method include a vacuum vapor deposition method, a sputtering method, an ion plating method, and the like. Specific examples of the vacuum vapor deposition method include a resistance heating vapor deposition method, a flash vapor deposition method, an arc vapor deposition method, a laser vapor deposition method, a high frequency heat vapor deposition method, an electron beam vapor deposition method, and the like.
スピンコート法あるいはインクジェット法等の塗工液の塗布により発光層４を形成する場合、塗工液の溶媒としては、発光層４の各構成材料を溶解または分散させることができれば特に限定されない。上記溶媒としては、例えば、トルエン、キシレン、シクロヘキサノン、シクロヘキサノール、テトラリン、メシチレン、塩化メチレン、テトラヒドロフラン、ジクロロエタン、クロロホルム等を挙げることができる。
When the light emitting layer 4 is formed by applying a coating liquid such as a spin coating method or an inkjet method, the solvent of the coating liquid is not particularly limited as long as each constituent material of the light emitting layer 4 can be dissolved or dispersed. Examples of the solvent include toluene, xylene, cyclohexanone, cyclohexanol, tetralin, mesitylene, methylene chloride, tetrahydrofuran, dichloroethane, chloroform and the like.
＜電子輸送層５＞
電子輸送層５は、陰極６から発光層４に電子を輸送する層である。電子輸送層５の材料としては、陰極６から注入された電子を発光層４内へ輸送することが可能な電子輸送性材料であればよいが、そのなかでも、電子移動度が高いものが好ましい。 <Electron transport layer 5>
Theelectron transport layer 5 is a layer that transports electrons from the cathode 6 to the light emitting layer 4. The material of the electron transport layer 5 may be any electron transportable material capable of transporting electrons injected from the cathode 6 into the light emitting layer 4, and among them, a material having high electron mobility is preferable. ..
電子輸送層５は、陰極６から発光層４に電子を輸送する層である。電子輸送層５の材料としては、陰極６から注入された電子を発光層４内へ輸送することが可能な電子輸送性材料であればよいが、そのなかでも、電子移動度が高いものが好ましい。 <
The
また、電子輸送層５は、正孔の輸送を阻害する機能を有していてもよい。この場合、電子輸送性材料は、陽極から移動してきた正孔の突き抜けを防止する正孔ブロック性材料であることが好ましい。これにより、発光層４内での正孔及び電子の再結合効率を高めることができる。なお、電子輸送層５は、設けられていなくてもよい。また、電子輸送層５は、陰極６から発光層４への電子の注入を促進する電子注入層としての機能を併有していてもよい。
Further, the electron transport layer 5 may have a function of inhibiting the transport of holes. In this case, the electron transporting material is preferably a hole blocking material that prevents the penetration of holes that have moved from the anode. As a result, the recombination efficiency of holes and electrons in the light emitting layer 4 can be increased. The electron transport layer 5 may not be provided. Further, the electron transport layer 5 may also have a function as an electron injection layer that promotes the injection of electrons from the cathode 6 into the light emitting layer 4.
上記電子輸送性材料としては、例えば、オキサジアゾール類、トリアゾール類、フェナントロリン類、シロール誘導体、シクロペンタジエン誘導体、アルミニウム錯体、金属酸化物等を挙げることができる。具体的には、オキサジアゾール誘導体としては、（２－（４－ビフェニリル）－５－（４－ｔｅｒｔ－ブチルフェニル）－１，３，４－オキサジアゾール）（ＰＢＤ）等が挙げられる。フェナントロリン類としては、バソキュプロイン（ＢＣＰ）、バソフェナントロリン（ＢＰｈｅｎ）等が挙げられる。アルミニウム錯体としては、トリス（８－キノリノール）アルミニウム錯体（Ａｌｑ３）、ビス（２－メチル－８－キノリラト）（ｐ－フェニルフェノラート）アルミニウム錯体（ＢＡｌｑ）等が挙げられる。金属酸化物としては、ＺｎＯ（酸化亜鉛）、ＴｉＯ２（酸化チタン）、Ｔａ２Ｏ３（酸化タンタル）、ＳｒＴｉＯ３（酸化ストロンチウムチタン）、ＭｇＺｎＯあるいはＭｇｘＺｎ１－ｘＯ等の酸化マグネシウム亜鉛等が挙げられる。これら正孔注入性材料は、一種類のみを用いてもよく、適宜、二種類以上を混合して用いてもよい。
Examples of the electron-transporting material include oxadiazoles, triazoles, phenanthrolines, silol derivatives, cyclopentadiene derivatives, aluminum complexes, metal oxides and the like. Specifically, examples of the oxadiazole derivative include (2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole) (PBD). Examples of phenanthrolines include vasocuproin (BCP) and vasofenanthroline (BPhen). Examples of the aluminum complex include a tris (8-quinolinol) aluminum complex (Alq3), a bis (2-methyl-8-quinolilato) (p-phenylphenolate) aluminum complex (BAlq), and the like. Examples of the metal oxide include zinc oxide such as ZnO (zinc oxide), TiO 2 (titanium oxide), Ta 2 O 3 (tantal oxide), SrTIO 3 (strontium oxide titanium), Mg Zn O or Mg x Zn 1-x O. And so on. Only one kind of these hole-injectable materials may be used, or two or more kinds may be mixed and used as appropriate.
なお、ここで、ＭｇｘＺｎ１－ｘＯは、ＺｎＯの一部のＺｎがＭｇに置き換わった構造を示し、ｘは、ＺｎＯのＺｎがＭｇに置き換わった割合を示す。上記電子輸送性材料としては、ＭｇｘＺｎ１－ｘＯであることが好ましく、ｘの範囲は、０～０．７の範囲内がより好ましい。ＭｇｘＺｎ１－ｘＯは、ｘの範囲を調整することでイオン化ポテンシャル及び電子親和力を調整できるため、発光層４の発光波長に適した電子輸送層５を容易に準備することが可能となる。なお、ＺｎＯは、ＺｎがＭｇに置き換わる割合が高いほど、イオン化ポテンシャル及び電子親和力が小さくなる性質を有する。
Here, Mg x Zn 1-x O indicates a structure in which a part of ZnO Zn is replaced with Mg, and x indicates a ratio of ZnO Zn replaced with Mg. The electron-transporting material is preferably Mg x Zn 1-x O, and the range of x is more preferably in the range of 0 to 0.7. Since the ionization potential and electron affinity of Mg x Zn 1-x O can be adjusted by adjusting the range of x, it is possible to easily prepare the electron transport layer 5 suitable for the emission wavelength of the light emitting layer 4. .. It should be noted that ZnO has a property that the higher the ratio of Zn replaced with Mg, the smaller the ionization potential and electron affinity.
なお、発光素子１０は、陰極６と発光層４との間に、電子輸送層５以外の層を有していてもよい。例えば、陰極６と電子輸送層５との間には、図示しない電子注入層が形成されていてもよい。
Note that the light emitting element 10 may have a layer other than the electron transport layer 5 between the cathode 6 and the light emitting layer 4. For example, an electron injection layer (not shown) may be formed between the cathode 6 and the electron transport layer 5.
電子注入層に用いられる材料としては、発光層４内への電子の注入を安定化させることができる電子注入性材料であればよい。電子注入性材料としては、例えば、Ｌｉ（リチウム）、Ｃｓ（セシウム）等のアルカリ金属；Ｌｉ２Ｏ（酸化リチウム）等のアルカリ金属の酸化物；Ｓｒ（ストロンチウム）、Ｃａ（カルシウム）等のアルカリ土類金属；ＭｇＯ（酸化マグネシウム）、ＳｒＯ（酸化ストロンチウム）等のアルカリ土類金属の酸化物；ＬｉＦ（フッ化リチウム）、ＣｓＦ（フッ化セシウム）等のアルカリ金属のフッ化物；ＭｇＦ２（フッ化マグネシウム）、ＳｒＦ２（フッ化ストロンチウム）、ＣａＦ２（フッ化カルシウム）、ＢａＦ２（フッ化バリウム）等のアルカリ土類金属のフッ化物；アルカリ金属の有機錯体；Ａｌ（アルミニウム）等のその他の金属；Ａｌ２Ｏ３（酸化アルミニウム）等の金属の酸化物；ポリメチルメタクリレートポリスチレンスルホン酸ナトリウム；等が挙げられる。これら電子注入性材料は、一種類のみを用いてもよく、適宜、二種類以上を混合して用いてもよい。
The material used for the electron injection layer may be any electron injectable material capable of stabilizing the injection of electrons into the light emitting layer 4. As the electron injecting material, e.g., Li (lithium), Cs alkali metal (cesium) or the like; alkali metal oxides such as Li 2 O (lithium oxide); Sr (strontium), alkali such as Ca (calcium) Earth metal; Oxide of alkaline earth metal such as MgO (magnesium oxide), SrO (strontium oxide); Fluoride of alkali metal such as LiF (lithium fluoride), CsF (cesium fluoride); MgF 2 (huh) Fluoride of alkaline earth metals such as magnesium oxide), SrF 2 (strontium fluoride), CaF 2 (calcium fluoride), BaF 2 (barium fluoride); organic complexes of alkali metals; others such as Al (aluminum) Metals; oxides of metals such as Al 2 O 3 (aluminum oxide); sodium polymethylmethacrylate polystyrene sulfonate; and the like. Only one kind of these electron-injectable materials may be used, or two or more kinds may be mixed and used as appropriate.
電子輸送層５及び電子注入層の厚みとしては、電子輸送機能及び電子注入機能がそれぞれ十分に発揮される厚みであれば、特に限定されるものではない。
The thickness of the electron transport layer 5 and the electron injection layer is not particularly limited as long as the electron transport function and the electron injection function are sufficiently exhibited.
また、電子輸送層５及び電子注入層の形成方法としては、例えば蒸着法、印刷法、インクジェット法、スピンコート法、キャスティング法、ディッピング法、バーコート法、ブレードコート法、ロールコート法、グラビアコート法、フレキソ印刷法、スプレーコート法、フォトリソグラフィー法、もしくは自己組織化法（交互吸着法、自己組織化単分子膜法）等を挙げることができるが、これに限定されない。そのなかでも、蒸着法、スピンコート法、インクジェット法、もしくは、フォトリソグラフィー法を用いることが好ましい。
Examples of the method for forming the electron transport layer 5 and the electron injection layer include a vapor deposition method, a printing method, an inkjet method, a spin coating method, a casting method, a dipping method, a bar coating method, a blade coating method, a roll coating method, and a gravure coating method. The method, flexographic printing method, spray coating method, photolithography method, self-assembling method (alternate adsorption method, self-assembling monomolecular film method) and the like can be mentioned, but the method is not limited thereto. Among them, it is preferable to use a vapor deposition method, a spin coating method, an inkjet method, or a photolithography method.
＜陽極２及び陰極６＞
陽極２及び陰極６は、導電性材料を含み、それぞれ、正孔輸送層３及び電子輸送層５と電気的に接続されている。陽極２は、正孔輸送層３に正孔を注入する機能を有する。陰極６は、電子輸送層５に電子を注入する機能を有する。 <Anode 2 and Cathode 6>
Theanode 2 and the cathode 6 contain a conductive material and are electrically connected to the hole transport layer 3 and the electron transport layer 5, respectively. The anode 2 has a function of injecting holes into the hole transport layer 3. The cathode 6 has a function of injecting electrons into the electron transport layer 5.
陽極２及び陰極６は、導電性材料を含み、それぞれ、正孔輸送層３及び電子輸送層５と電気的に接続されている。陽極２は、正孔輸送層３に正孔を注入する機能を有する。陰極６は、電子輸送層５に電子を注入する機能を有する。 <
The
陽極２及び陰極６は、抵抗が小さいことが好ましい。陽極２及び陰極６の材料としては、金属材料、有機化合物、無機化合物、の何れを用いてもよいが、陽極２及び陰極６のうち、少なくとも一方の材料は、金属材料を含むことが好ましい。金属材料からなる電極は、高い導電性を有する。
It is preferable that the anode 2 and the cathode 6 have low resistance. As the material of the anode 2 and the cathode 6, any of a metal material, an organic compound, and an inorganic compound may be used, but it is preferable that at least one of the anode 2 and the cathode 6 contains a metal material. Electrodes made of metal material have high conductivity.
陽極２には、正孔を注入し易いように、仕事関数の大きい導電性材料を用いることが好ましい。そのような導電性材料としては、例えば、Ａｕ（金）、Ｔａ（タンタル）、Ｗ（タングステン）、Ｐｔ（白金）、Ｎｉ（ニッケル）、Ｐｄ（パラジウム）、Ｃｒ（クロム）、Ｃｕ（銅）、Ｍｏ（モリブデン）、アルカリ金属、アルカリ土類金属、等の金属；これら金属の酸化物；ＡｌＬｉ（アルミニウム・リチウム合金）、ＡｌＣａ（アルミニウム・カルシウム合金）、ＡｌＭｇ（アルミニウム・マグネシウム合金）等のＡｌ合金、ＭｇＡｇ（マグネシウム・銀合金）等のＭｇ合金、Ｎｉ合金、Ｃｒ合金、アルカリ金属の合金、アルカリ土類金属の合金、等の合金；酸化インジウム錫（ＩＴＯ）、酸化インジウム亜鉛（ＩＺＯ）、酸化亜鉛（ＺｎＯ）、酸化インジウム等の無機酸化物；金属ドープされたポリチオフェン、ポリアニリン、ポリアセチレン、ポリアルキルチオフェン誘導体、ポリシラン誘導体等の導電性高分子；α－Ｓｉ（アモルファスシリコン）、α－ＳｉＣ（アモルファス炭化ケイ素）；等が挙げられる。これらの導電性材料は、単独で用いてもよく、適宜、二種類以上を組み合わせて用いてもよい。これらの導電性材料のうち二種類以上を用いる場合には、各導電性材料からなる層を積層してもよい。これらの導電性材料のなかでも、ＩＴＯを用いることがより好ましい。ＩＴＯは、透明電極として多くの表示装置に採用されている実績があり、製造装置の転用が可能なため、製造コストを抑えることが可能となる。
It is preferable to use a conductive material having a large work function for the anode 2 so that holes can be easily injected. Examples of such conductive materials include Au (gold), Ta (tantal), W (tungsten), Pt (platinum), Ni (nickel), Pd (palladium), Cr (chromium), and Cu (copper). , Mo (molybdenum), alkali metals, alkaline earth metals, etc .; oxides of these metals; AlLi (aluminum-lithium alloy), AlCa (aluminum-calcium alloy), AlMg (aluminum-magnesium alloy), etc. Alloys, Mg alloys such as MgAg (magnesium / silver alloy), Ni alloys, Cr alloys, alkali metal alloys, alkaline earth metal alloys, etc.; indium tin oxide (ITO), indium zinc oxide (IZO), Inorganic oxides such as zinc oxide (ZnO) and indium oxide; conductive polymers such as metal-doped polythiophene, polyaniline, polyacetylene, polyalkylthiophene derivatives, polysilane derivatives; α-Si (amorphous silicon), α-SiC ( Amorphous silicon carbide); etc. These conductive materials may be used alone or in combination of two or more as appropriate. When two or more of these conductive materials are used, layers made of each conductive material may be laminated. Among these conductive materials, it is more preferable to use ITO. ITO has a track record of being used in many display devices as a transparent electrode, and since the manufacturing device can be diverted, it is possible to reduce the manufacturing cost.
陰極６には、電子を注入し易いように、仕事関数の小さい導電性材料を用いることが好ましい。例えば、ＭｇＡｇ等のマグネシウム合金；ＡｌＬｉ、ＡｌＣａ、ＡｌＭｇ等のＡｌ合金；Ｌｉ、Ｃｓ、Ｂａ（バリウム）等のアルカリ金属類の合金；Ｓｒ、Ｃａ等のアルカリ土類金属類の合金；等が挙げられる。これら導電性材料のなかでも、ＡｌまたはＡｌ合金を用いることがより好ましい。ＡｌまたはＡｌ合金は、電極として汎用性が高く、比較的安価である。このため、陰極６に用いられる導電性材料として、ＡｌまたはＡｌ合金を用いることで、製造コストを抑えることが可能となる。
It is preferable to use a conductive material having a small work function for the cathode 6 so that electrons can be easily injected. For example, magnesium alloys such as MgAg; Al alloys such as AlLi, AlCa and AlMg; alloys of alkali metals such as Li, Cs and Ba (barium); alloys of alkaline earth metals such as Sr and Ca; and the like. Be done. Among these conductive materials, it is more preferable to use Al or Al alloy. Al or Al alloy is highly versatile as an electrode and is relatively inexpensive. Therefore, by using Al or an Al alloy as the conductive material used for the cathode 6, the manufacturing cost can be suppressed.
なお、陽極２及び陰極６のうち、光の取出し面側となる電極は透明である必要がある。一方、光の取出し面と反対側の電極は、透明であってもなくてもよい。一例として、発光素子１０は、下層である陽極２が透光性電極であり、上層である陰極６が光反射電極である、ボトムエミッション構造を有していてもよい。この場合、光の取出し面側となる陽極２を透光性材料で形成し、陰極６を光反射性材料で形成する。また、発光素子１０は、下層である陽極２が光反射電極であり、上層である陰極６が透光性電極である、トップエミッション構造を有していてもよい。この場合、光の取出し面側となる陰極６を透光性材料で形成し、陽極２を光反射性材料で形成する。
Of the anode 2 and the cathode 6, the electrode on the light extraction surface side needs to be transparent. On the other hand, the electrode on the side opposite to the light extraction surface may or may not be transparent. As an example, the light emitting element 10 may have a bottom emission structure in which the lower anode 2 is a translucent electrode and the upper cathode 6 is a light reflecting electrode. In this case, the anode 2 on the light extraction surface side is formed of a light-transmitting material, and the cathode 6 is formed of a light-reflecting material. Further, the light emitting element 10 may have a top emission structure in which the anode 2 which is the lower layer is a light reflecting electrode and the cathode 6 which is the upper layer is a translucent electrode. In this case, the cathode 6 on the light extraction surface side is formed of a light-transmitting material, and the anode 2 is formed of a light-reflecting material.
陽極２及び陰極６のうち少なくとも一方の電極には、Ｓｅが含まれている。Ｓｅは、光導電効果を有する。このように、電極に、光導電効果を有するＳｅを含む材料を採用することにより、太陽光の下等の明るい場所で、外部電源から供給する電流値を上げることなく、光導電効果により、発光素子１０の電極を流れる電流の値が増加する。このため、消費電力を上げることを抑制した上で、輝度を向上することが可能になる。なお、ここで、光導電効果とは、白色光の照射により導電率が向上する効果を示す。
Se is contained in at least one of the electrodes of the anode 2 and the cathode 6. Se has a photoconducting effect. In this way, by adopting a material containing Se having a photoconducting effect for the electrodes, light is emitted by the photoconducting effect in a bright place such as sunlight without increasing the current value supplied from an external power source. The value of the current flowing through the electrodes of the element 10 increases. Therefore, it is possible to improve the brightness while suppressing the increase in power consumption. Here, the photoconducting effect indicates an effect of improving the conductivity by irradiating white light.
Ｓｅを含む電極中に含まれるＳｅの割合（言い換えれば、Ｓｅを含む電極を構成する材料におけるＳｅの割合）は、モル換算で、０．１原子％以上、９０原子％以下であることが好ましく、１原子％以上、５０原子％以下であることがより好ましい。Ｓｅは電極中に少しでも存在するだけで光導電効果の恩恵がある。しかしながら、電極中のＳｅの割合が０．１原子％未満では、その効果を確認することが困難になる。逆に、電極中のＳｅの割合が９０原子％を超えると、本来の電極材料としての性能を維持できなくなるおそれがある。電極中のＳｅの割合が、モル換算で、１原子％以上、５０原子％以下であれば、電極材料の本来の性能と、Ｓｅによる光導電効果との両立を、より効果的に行うことができる。
The proportion of Se contained in the electrode containing Se (in other words, the proportion of Se in the material constituting the electrode containing Se) is preferably 0.1 atomic% or more and 90 atomic% or less in terms of molars. More preferably, it is 1 atomic% or more and 50 atomic% or less. Se has the benefit of the photoconducting effect even if it is present in the electrode as much as possible. However, if the proportion of Se in the electrode is less than 0.1 atomic%, it becomes difficult to confirm the effect. On the contrary, if the ratio of Se in the electrode exceeds 90 atomic%, the performance as the original electrode material may not be maintained. When the proportion of Se in the electrode is 1 atomic% or more and 50 atomic% or less in terms of molars, it is possible to more effectively achieve both the original performance of the electrode material and the photoconducting effect of Se. it can.
また、Ｓｅは、Ｓｅを含む電極全体に含まれていることが好ましい。言い換えれば、Ｓｅは、陽極２及び陰極６のうち少なくとも一方の電極全体に含まれていることが好ましい。これにより、Ｓｅを含む電極全体に、Ｓｅの光導電効果による電流が流れるため、より効果的に消費電力抑制が可能となる。
Further, it is preferable that Se is contained in the entire electrode including Se. In other words, Se is preferably contained in at least one of the electrodes of the anode 2 and the cathode 6. As a result, a current due to the photoconducting effect of Se flows through the entire electrode including Se, so that power consumption can be suppressed more effectively.
電極中にＳｅが含まれるか否か、並びに、電極中のＳｅの割合は、例えば、透過型電子顕微鏡（ＴＥＭ）に付属したエネルギー分散型Ｘ線（ＥＤＸ）分析装置（ＴＥＭ－ＥＤＸ）によって測定することができる。Ｓｅが、Ｓｅを含む電極全体に含まれていることは、例えば、電極の何れの点でＥＤＸ測定してもＳｅピークが検出されることで確認される。
Whether or not Se is contained in the electrode and the ratio of Se in the electrode are measured by, for example, an energy dispersive X-ray (EDX) analyzer (TEM-EDX) attached to a transmission electron microscope (TEM). can do. The fact that Se is contained in the entire electrode containing Se is confirmed, for example, by detecting the Se peak at any point of the electrode by EDX measurement.
図１では、一例として、発光素子１０が、ボトムエミッション構造を有するボトムエミッション型の発光素子であり、陰極６がＳｅを含んでいる場合を例に挙げて図示している。図１に示すように、Ｓｅは、陰極６全体に均一に拡散（分布）している。このため、図１に示す例では、陰極６全体に、Ｓｅの光導電効果による電流が流れるため、より効果的に消費電力抑制が可能となる。
In FIG. 1, as an example, a case where the light emitting element 10 is a bottom emission type light emitting element having a bottom emission structure and the cathode 6 contains Se is shown as an example. As shown in FIG. 1, Se is uniformly diffused (distributed) over the entire cathode 6. Therefore, in the example shown in FIG. 1, a current due to the photoconducting effect of Se flows through the entire cathode 6, so that power consumption can be suppressed more effectively.
また、図１に示すように、Ｓｅが、光の取出し面側と反対側の電極に含まれている場合、発光層４で発光した可視光を取り出す際に、Ｓｅにより、その光の一部が吸収されて取出し効率が落ちることが無いため、発光層４から発光した可視光の取出し効率を悪化させない、という利点がある。
Further, as shown in FIG. 1, when Se is included in the electrodes on the side opposite to the light extraction surface side, when the visible light emitted by the light emitting layer 4 is taken out, a part of the light is produced by Se. Is not absorbed and the extraction efficiency is not lowered, so that there is an advantage that the extraction efficiency of visible light emitted from the light emitting layer 4 is not deteriorated.
また、Ｓｅは、上述したように陰極６に含まれていることが好ましい。一般的に、表示装置では、陽極側に、ＩＴＯ等の透明電極が採用され、陽極側が光の取出し面となることが多い。光の取出し面側となる電極は透光性を有している必要がある。このため、陽極に比べて陰極に用いられる材料の選択の幅が一般的に広い。したがって、陰極６にＳｅが含まれている場合、陽極２にＳｅを含む電極を用いる場合と比較して、Ｓｅを含む電極として、光導電効果による電流値増加の特性以外に、耐久性等の総合的な電極としての特性を選択することが可能となり、発光素子１０の特性を向上させることができる。
Further, it is preferable that Se is contained in the cathode 6 as described above. Generally, in a display device, a transparent electrode such as ITO is adopted on the anode side, and the anode side is often the light extraction surface. The electrode on the light extraction surface side must have translucency. Therefore, the range of selection of the material used for the cathode is generally wider than that of the anode. Therefore, when Se is contained in the cathode 6, as compared with the case where an electrode containing Se is used for the anode 2, the electrode containing Se has the characteristics of increasing the current value due to the photoconducting effect, as well as durability and the like. It is possible to select the characteristics as a comprehensive electrode, and it is possible to improve the characteristics of the light emitting element 10.
なお、前述したように、陽極２及び陰極６のうち、少なくとも一方の材料は、導電性材料として金属材料を含むことが好ましい。Ｓｅは、カルコゲン元素であり、非金属元素である。したがって、陰極６は、Ｓｅに加え、さらに金属元素を含んでいることが好ましい。また、前述したように、上記金属材料は、例えば、ＡｌまたはＡｌ合金であることが好ましい。したがって、上記金属元素は、Ａｌを含むことが好ましい。陰極６は、例えば、Ａｌ電極にＳｅが拡散している構造を有していてもよい。
As described above, it is preferable that at least one of the anode 2 and the cathode 6 contains a metal material as the conductive material. Se is a chalcogen element and a non-metallic element. Therefore, it is preferable that the cathode 6 further contains a metal element in addition to Se. Further, as described above, the metal material is preferably, for example, Al or an Al alloy. Therefore, the metal element preferably contains Al. The cathode 6 may have, for example, a structure in which Se is diffused in the Al electrode.
Ｓｅを含む電極の成膜方法は、Ｓｅを含む電極材料を形成可能であれば、特に限定されるものではない。陽極２及び陰極６の成膜方法としては、一般的な電極の形成方法を用いることができる。陽極２及び陰極６の成膜方法としては、例えば、真空蒸着法、スパッタリング法、電子線（ＥＢ）蒸着法、イオンプレーティング法等の物理気相蒸着法（ＰＶＤ法）、あるいは、化学気相蒸着法（ＣＶＤ法）等を挙げることができる。
The film forming method of the electrode containing Se is not particularly limited as long as the electrode material containing Se can be formed. As a film forming method for the anode 2 and the cathode 6, a general electrode forming method can be used. Examples of the film forming method of the anode 2 and the cathode 6 include a physical vapor deposition method (PVD method) such as a vacuum vapor deposition method, a sputtering method, an electron beam (EB) vapor deposition method, and an ion plating method, or a chemical vapor deposition method. A vapor deposition method (CVD method) and the like can be mentioned.
また、陽極２及び陰極６のパターニング方法としては、所望のパターンに精度よく形成することができる方法であれば、特に限定されるものではない。陽極２及び陰極６のパターニング方法としては、具体的には、フォトリソグラフィー法、インクジョット法、等を挙げることができる。
Further, the patterning method of the anode 2 and the cathode 6 is not particularly limited as long as it can be formed in a desired pattern with high accuracy. Specific examples of the patterning method of the anode 2 and the cathode 6 include a photolithography method, an ink jot method, and the like.
＜変形例＞
なお、本実施形態では、表示装置１００が、赤色、緑色、及び青色の光をそれぞれ発光する３種類の発光素子１０を備えている場合を例に挙げて説明した。しかしながら、表示装置１００は、これに限定されることはなく、それぞれ異なる色の光を発光する４種類以上の発光素子を備えていてもよい。 <Modification example>
In the present embodiment, the case where thedisplay device 100 includes three types of light emitting elements 10 that emit red, green, and blue light, respectively, has been described as an example. However, the display device 100 is not limited to this, and may include four or more types of light emitting elements that emit light of different colors.
なお、本実施形態では、表示装置１００が、赤色、緑色、及び青色の光をそれぞれ発光する３種類の発光素子１０を備えている場合を例に挙げて説明した。しかしながら、表示装置１００は、これに限定されることはなく、それぞれ異なる色の光を発光する４種類以上の発光素子を備えていてもよい。 <Modification example>
In the present embodiment, the case where the
〔実施形態２〕
本実施形態では、実施形態１との相異点について説明する。なお、説明の便宜上、実施形態１で説明した構成要素と同じ機能を有する構成要素については、同じ符号を付記し、その詳細な説明を省略する。 [Embodiment 2]
In this embodiment, the differences from the first embodiment will be described. For convenience of explanation, components having the same functions as the components described in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.
本実施形態では、実施形態１との相異点について説明する。なお、説明の便宜上、実施形態１で説明した構成要素と同じ機能を有する構成要素については、同じ符号を付記し、その詳細な説明を省略する。 [Embodiment 2]
In this embodiment, the differences from the first embodiment will be described. For convenience of explanation, components having the same functions as the components described in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.
図３は、本実施形態に係る発光素子１０の概略構成の一例を模式的に示す断面図である。実施形態１で説明したように、陽極２から陰極６までの積層順は、逆にすることもできる。図１では、基板１が、陽極２の下にある場合を例に挙げて図示した。しかしながら、図３に示すように、基板１は、陰極６の下（図１で言えば陰極６の上）にあってもよい。
FIG. 3 is a cross-sectional view schematically showing an example of a schematic configuration of the light emitting element 10 according to the present embodiment. As described in the first embodiment, the stacking order from the anode 2 to the cathode 6 can be reversed. In FIG. 1, the case where the substrate 1 is under the anode 2 is illustrated as an example. However, as shown in FIG. 3, the substrate 1 may be below the cathode 6 (above the cathode 6 in FIG. 1).
図３では、第１電極、第１キャリア輸送層、第２キャリア輸送層、第２電極が、順に、陰極６、電子輸送層５、正孔輸送層３、陽極２であり、支持体として基板１を備え、基板１上に、陰極６、電子輸送層５、発光層４、正孔輸送層３、陽極２、が、基板１側からこの順に設けられている場合を例に挙げて示している。
In FIG. 3, the first electrode, the first carrier transport layer, the second carrier transport layer, and the second electrode are, in that order, a cathode 6, an electron transport layer 5, a hole transport layer 3, and an anode 2, and are substrates as supports. 1 is provided, and the case where the electrode 6, the electron transport layer 5, the light emitting layer 4, the hole transport layer 3, and the anode 2 are provided on the substrate 1 in this order from the substrate 1 side is shown as an example. There is.
図３に示す発光素子１０のように基板が陰極の下にある発光素子を表示装置に用いる場合、一般的に、表示装置の陽極側に、透光性電極として、ＩＴＯ等の透明電極が採用され、陽極側が光の取出し面となることが多い。このように発光素子１０がトップエミッション構造を有する場合、基板１が透明である必要がなくなり、基板１の選択の自由度が広がるため、製造コストを抑えることができる。
When a light emitting element whose substrate is below the cathode is used for the display device as in the light emitting element 10 shown in FIG. 3, a transparent electrode such as ITO is generally used as the translucent electrode on the anode side of the display device. In many cases, the anode side serves as the light extraction surface. When the light emitting element 10 has a top emission structure as described above, the substrate 1 does not need to be transparent, and the degree of freedom in selecting the substrate 1 is widened, so that the manufacturing cost can be suppressed.
なお、図３に示すように基板１が陰極６の下にある発光素子１０を、図２に示す表示装置１００に用いる場合、表示装置１００における陽極２から陰極６までの積層順が、図２に示す例とは逆になる。
When the light emitting element 10 in which the substrate 1 is under the cathode 6 as shown in FIG. 3 is used for the display device 100 shown in FIG. 2, the stacking order from the anode 2 to the cathode 6 in the display device 100 is FIG. It is the opposite of the example shown in.
この場合、表示装置１００では、陽極２を除いた、陰極６と、電子輸送層５と、発光層４と、正孔輸送層３とが、画素毎に島状に形成されていてもよい。また、陰極６と発光層４とを除いた、電子輸送層５と、正孔輸送層３と、陽極２とは、ベタ状の共通層として形成してもよい。なお、この場合には、バンクＢＫを設けなくてもよい。また、正孔輸送層３及び電子輸送層５は、上述したように島状であるか否かに拘らず、発光素子１０Ｒ・１０Ｇ・１０Ｂに共通の材料で形成されていてもよいし、発光素子１０Ｒ・１０Ｇ・１０Ｂ毎に、異なる材料で形成されていてもよい。
In this case, in the display device 100, the cathode 6, the electron transport layer 5, the light emitting layer 4, and the hole transport layer 3 excluding the anode 2 may be formed in an island shape for each pixel. Further, the electron transport layer 5, the hole transport layer 3, and the anode 2 excluding the cathode 6 and the light emitting layer 4 may be formed as a solid common layer. In this case, it is not necessary to provide the bank BK. Further, the hole transport layer 3 and the electron transport layer 5 may be formed of a material common to the light emitting elements 10R, 10G, and 10B regardless of whether or not they are island-shaped as described above, or emit light. The elements 10R, 10G, and 10B may be made of different materials.
図３では、一例として、発光素子１０が、トップエミッション構造を有するトップエミッション型の発光素子であり、陰極６がＳｅを含んでいる場合を例に挙げて図示している。図３に示す例でも、Ｓｅは、陰極６全体に均一に拡散（分布）している。このため、図３に示す例では、陰極６全体に、Ｓｅの光導電効果による電流が流れるため、より効果的に消費電力抑制が可能となる。
In FIG. 3, as an example, a case where the light emitting element 10 is a top emission type light emitting element having a top emission structure and the cathode 6 contains Se is shown as an example. In the example shown in FIG. 3, Se is uniformly diffused (distributed) over the entire cathode 6. Therefore, in the example shown in FIG. 3, a current due to the photoconducting effect of Se flows through the entire cathode 6, so that power consumption can be suppressed more effectively.
また、図３に示すように、Ｓｅが、光の取出し面側となる電極に含まれている場合、太陽光等の外光の光量がほぼロスなく照射されるため、外光のエネルギーの多くを光導電効果に利用できる。このため、消費電力の抑制の効果が高くなる。
Further, as shown in FIG. 3, when Se is included in the electrode on the light extraction surface side, the amount of external light such as sunlight is irradiated with almost no loss, so that a large amount of external light energy is generated. Can be used for the photoconducting effect. Therefore, the effect of suppressing power consumption is enhanced.
また、実施形態１で説明したように、一般的に、表示装置では、陽極側に、ＩＴＯ等の透明電極が採用され、陽極側が光の取出し面となることが多い。図３に示す例でも、陽極２側が光の取出し面となっている。したがって、図３に示す例でも、Ｓｅが陰極６に含まれていることで、陽極２にＳｅを含む電極を用いる場合と比較して、Ｓｅを含む電極として、光導電効果による電流値増加の特性以外に、耐久性等の総合的な電極としての特性を選択することが可能となり、発光素子１０の特性を向上させることができる。
Further, as described in the first embodiment, in general, in a display device, a transparent electrode such as ITO is adopted on the anode side, and the anode side is often the light extraction surface. Also in the example shown in FIG. 3, the anode 2 side is the light extraction surface. Therefore, even in the example shown in FIG. 3, since Se is contained in the cathode 6, the current value increases due to the photoconducting effect as the electrode containing Se as compared with the case where the electrode containing Se is used for the anode 2. In addition to the characteristics, it is possible to select the characteristics as a comprehensive electrode such as durability, and it is possible to improve the characteristics of the light emitting element 10.
〔実施形態３〕
本実施形態では、実施形態１、２との相異点について説明する。なお、説明の便宜上、実施形態１、２で説明した構成要素と同じ機能を有する構成要素については、同じ符号を付記し、その詳細な説明を省略する。 [Embodiment 3]
In this embodiment, the differences from the first and second embodiments will be described. For convenience of explanation, the same reference numerals will be added to the components having the same functions as the components described in the first and second embodiments, and detailed description thereof will be omitted.
本実施形態では、実施形態１、２との相異点について説明する。なお、説明の便宜上、実施形態１、２で説明した構成要素と同じ機能を有する構成要素については、同じ符号を付記し、その詳細な説明を省略する。 [Embodiment 3]
In this embodiment, the differences from the first and second embodiments will be described. For convenience of explanation, the same reference numerals will be added to the components having the same functions as the components described in the first and second embodiments, and detailed description thereof will be omitted.
図４は、本実施形態に係る発光素子１０の概略構成の一例を模式的に示す断面図である。図１及び図３では、陰極６がＳｅを含んでいる場合を例に挙げて図示したが、実施形態１で説明したように、Ｓｅは、陽極２及び陰極６のうち少なくとも一方の電極に含まれていればよい。したがって、Ｓｅは、陽極２または陰極６の何れか一方にのみ含まれていてもよいし、陽極２及び陰極６の両方に含まれていてもよい。
FIG. 4 is a cross-sectional view schematically showing an example of a schematic configuration of the light emitting element 10 according to the present embodiment. In FIGS. 1 and 3, the case where the cathode 6 contains Se is illustrated as an example, but as described in the first embodiment, Se is contained in at least one electrode of the anode 2 and the cathode 6. It suffices if it is. Therefore, Se may be contained only in either the anode 2 or the cathode 6, or may be contained in both the anode 2 and the cathode 6.
図４では、一例として、発光素子１０が、ボトムトップエミッション型の発光素子であり、陽極２及び陰極６がそれぞれＳｅを含んでいる場合を例に挙げて図示している。図４に示す例では、Ｓｅは、陽極２及び陰極６全体に均一に拡散（分布）している。このため、図４に示す例では、陽極２及び陰極６全体に、Ｓｅの光導電効果による電流が流れるため、より効果的に消費電力抑制が可能となる。
In FIG. 4, as an example, a case where the light emitting element 10 is a bottom top emission type light emitting element and the anode 2 and the cathode 6 each contain Se is shown as an example. In the example shown in FIG. 4, Se is uniformly diffused (distributed) over the entire anode 2 and cathode 6. Therefore, in the example shown in FIG. 4, since the current due to the photoconducting effect of Se flows through the anode 2 and the cathode 6, the power consumption can be suppressed more effectively.
図４に示す例では、Ｓｅが、光の取出し面側となる電極及び光の取出し面側と反対側の電極にそれぞれ含まれていることで、実施形態１及び実施形態２で説明した効果を併せて奏する。また、図４に示す例でも、陽極２側が光の取出し面であり、陰極６の材料の選択の幅が広がることから、陰極６において、Ｓｅを含む電極として、光導電効果による電流値増加の特性以外に、耐久性等の総合的な電極としての特性を選択することが可能となり、発光素子１０の特性を向上させることができる。
In the example shown in FIG. 4, Se is contained in the electrode on the light extraction surface side and the electrode on the side opposite to the light extraction surface side, respectively, so that the effects described in the first and second embodiments can be obtained. Play at the same time. Further, also in the example shown in FIG. 4, since the anode 2 side is the light extraction surface and the range of selection of the material of the cathode 6 is widened, the current value increases due to the photoconductive effect as the electrode containing Se in the cathode 6. In addition to the characteristics, it is possible to select the characteristics as a comprehensive electrode such as durability, and it is possible to improve the characteristics of the light emitting element 10.
但し、上述したように、Ｓｅは、陽極２にのみ含まれていてもよく、発光素子１０は、トップエミッション型であってもよい。
However, as described above, Se may be contained only in the anode 2, and the light emitting element 10 may be a top emission type.
本開示は上述した各実施形態に限定されるものではなく、請求項に示した範囲で種々の変更が可能であり、異なる実施形態にそれぞれ開示された技術的手段を適宜組み合わせて得られる実施形態についても本開示の技術的範囲に含まれる。さらに、各実施形態にそれぞれ開示された技術的手段を組み合わせることにより、新しい技術的特徴を形成することができる。
The present disclosure is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.
１、１０１ 基板
２ 陽極
４ 発光層
６ 陰極
１０、１０Ｒ、１０Ｇ、１０Ｂ 発光素子
１００ 表示装置 1,101Substrate 2 Anode 4 Light emitting layer 6 Cathode 10, 10R, 10G, 10B Light emitting element 100 Display device
２ 陽極
４ 発光層
６ 陰極
１０、１０Ｒ、１０Ｇ、１０Ｂ 発光素子
１００ 表示装置 1,101
Claims (11)
- 第１電極と、量子ドットを含む発光層と、第２電極と、をこの順に備え、
前記第１電極及び前記第２電極のうち少なくとも一方の電極がセレンを含むことを特徴とする電界発光素子。 A first electrode, a light emitting layer containing quantum dots, and a second electrode are provided in this order.
An electroluminescent device characterized in that at least one of the first electrode and the second electrode contains selenium. - 前記セレンを含む電極が、さらに金属元素を含むことを特徴とする請求項１に記載の電界発光素子。 The electroluminescent device according to claim 1, wherein the electrode containing selenium further contains a metal element.
- 前記金属元素がアルミニウムを含むことを特徴とする請求項２に記載の電界発光素子。 The electroluminescent device according to claim 2, wherein the metal element contains aluminum.
- 前記セレンを含む電極の全体にセレンが含まれていることを特徴とする請求項１～３の何れか１項に記載の電界発光素子。 The electroluminescent device according to any one of claims 1 to 3, wherein the entire electrode containing the selenium contains selenium.
- 基板をさらに備え、
前記第１電極と、前記発光層と、前記第２電極とは、前記基板上に、前記基板側からこの順に積層されており、
前記第１電極が透光性電極であり、前記第２電極が光反射電極である、ボトムエミッション構造を有し、
前記第２電極がセレンを含むことを特徴とする請求項１～４の何れか１項に記載の電界発光素子。 With more boards
The first electrode, the light emitting layer, and the second electrode are laminated on the substrate in this order from the substrate side.
It has a bottom emission structure in which the first electrode is a translucent electrode and the second electrode is a light reflecting electrode.
The electroluminescent device according to any one of claims 1 to 4, wherein the second electrode contains selenium. - 基板をさらに備え、
前記第１電極と、前記発光層と、前記第２電極とは、前記基板上に、前記基板側からこの順に積層されており、
前記第１電極が光反射電極であり、前記第２電極が透光性電極である、トップエミッション構造を有し、
前記第１電極がセレンを含むことを特徴とする請求項１～４の何れか１項に記載の電界発光素子。 With more boards
The first electrode, the light emitting layer, and the second electrode are laminated on the substrate in this order from the substrate side.
It has a top emission structure in which the first electrode is a light reflecting electrode and the second electrode is a translucent electrode.
The electroluminescent device according to any one of claims 1 to 4, wherein the first electrode contains selenium. - 前記セレンを含む電極が陰極であることを特徴とする請求項１～６の何れか１項に記載の電界発光素子。 The electroluminescent device according to any one of claims 1 to 6, wherein the electrode containing selenium is a cathode.
- 前記セレンを含む電極中のセレンの割合が、０．１原子％以上、９０原子％以下であることを特徴とする請求項１～７の何れか１項に記載の電界発光素子。 The electroluminescent device according to any one of claims 1 to 7, wherein the ratio of selenium in the electrode containing the selenium is 0.1 atomic% or more and 90 atomic% or less.
- 前記セレンを含む電極中のセレンの割合が、１原子％以上、５０原子％以下であることを特徴とする請求項１～８の何れか１項に記載の電界発光素子。 The electroluminescent device according to any one of claims 1 to 8, wherein the ratio of selenium in the electrode containing the selenium is 1 atomic% or more and 50 atomic% or less.
- 前記発光層中の量子ドットがセレンを含むことを特徴とする請求項１～９の何れか１項に記載の電界発光素子。 The electroluminescent device according to any one of claims 1 to 9, wherein the quantum dots in the light emitting layer contain selenium.
- 請求項１～１０の何れか１項に記載の電界発光素子を備えていることを特徴とする表示装置。 A display device including the electroluminescent element according to any one of claims 1 to 10.
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| PCT/JP2019/025465 WO2020261446A1 (en) | 2019-06-26 | 2019-06-26 | Electroluminescent device and display |
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| PCT/JP2019/025465 WO2020261446A1 (en) | 2019-06-26 | 2019-06-26 | Electroluminescent device and display |
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