WO2021079437A1

WO2021079437A1 - Light-emitting element, display device, production method for light-emitting element, and production method for display device

Info

Publication number: WO2021079437A1
Application number: PCT/JP2019/041552
Authority: WO
Inventors: 貴洋土江
Original assignee: シャープ株式会社
Priority date: 2019-10-23
Filing date: 2019-10-23
Publication date: 2021-04-29

Abstract

A light-emitting layer (2) in a light-emitting element (1A) has: an insulating body (3) having formed therein a plurality of through-holes (4) that penetrate the light-emitting layer (2) in the thickness direction; and at least one quantum dot (5) inserted into each of the plurality of through-holes (4).

Description

Light emitting element, display device, manufacturing method of light emitting element, and manufacturing method of display device

The present invention relates to a light emitting element having a light emitting layer including quantum dots, a display device, a method for manufacturing the light emitting element, and a method for manufacturing the display device.

If there is a gap (Void) between the quantum dots that make up the light emitting layer provided in the electro-Luminescence Device, which is a space where the quantum dots do not exist, the drive current concentrates in this gap, so that the electroluminescence device is electroluminescent. In order to solve the problem that the light emitting efficiency and the life of the light emitting element are reduced, an electroluminescent element in which the gap between the quantum dots of the light emitting layer is filled with an insulator is known (Patent Document 1).

Japanese Patent Publication "Japanese Patent Laid-Open No. 2007-95685 (published on April 12, 2007)"

The configuration disclosed in Patent Document 1 is highly effective when the quantum dots are composed of a single layer, but when the quantum dots are stacked in a plurality of layers of two or more layers, the quantum dots are close to each other. The resistance of the is relatively small, the drive current flows only in the specific quantum dots that are close to each other, and only the specific quantum dots emit light. As a result, the present inventors have discovered the problem that the deterioration of the specific quantum dots progresses.

In order to solve the above problems, the light emitting element according to one aspect of the present invention includes a light emitting layer, and the light emitting layer is insulated in which a plurality of through holes penetrating in the thickness direction of the light emitting layer are formed. It has a body and at least one quantum dot inserted into each of the plurality of through holes.

In order to solve the above problems, the display device according to one aspect of the present invention is provided with a plurality of pixels including a light emitting element according to one aspect of the present invention.
It is provided with a partition wall that separates the light emitting elements included in the plurality of pixels for each pixel.

In order to solve the above problems, the method for manufacturing a light emitting element according to one aspect of the present invention is an insulator in which a plurality of through holes penetrating in the thickness direction of the light emitting layer are formed as a step of forming the light emitting layer. It includes an insulator forming step of forming the above, and a quantum dot insertion step of inserting at least one quantum dot into each of the plurality of through holes.

In order to solve the above problems, the method for manufacturing a display device according to one aspect of the present invention is a light emitting element that forms a light emitting element for each of a plurality of pixels by the method for manufacturing a light emitting element according to one aspect of the present invention. It includes a forming step and a partition forming step of forming a partition that separates light emitting elements of a plurality of pixels for each pixel.

According to one aspect of the present invention, it is possible to provide a light emitting element, a display device, a method for manufacturing the light emitting element, and a method for manufacturing the display device, which can suppress deterioration of quantum dots in the light emitting layer.

It is sectional drawing of the light emitting element which concerns on Embodiment 1. FIG. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is a top view which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing of the light emitting element which concerns on Embodiment 2. FIG. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing of the light emitting element which concerns on Embodiment 3. FIG. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is a figure which shows the light emitting element which concerns on Embodiment 4, and is the plan sectional view along the plane AA shown in FIG. It is sectional drawing of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is a top view which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing of the light emitting element which concerns on Embodiment 5. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is a top view which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element. It is sectional drawing which shows the manufacturing method of the said light emitting element.

(Embodiment 1)
FIG. 1 is a cross-sectional view of the light emitting element 1A according to the first embodiment. The light emitting element 1A includes a light emitting layer 2. The light emitting layer 2 has an insulator 3 in which a plurality of through holes 4 penetrating in the thickness direction of the light emitting layer 2 are formed, and at least one quantum dot 5 inserted into each of the plurality of through holes 4. doing. In the example shown in FIG. 1, the same number of quantum dots 5 are inserted into each of the plurality of through holes 4. One of the plurality of quantum dots 5 inserted into each of the plurality of through holes 4 and the other one are laminated in the thickness direction of the light emitting layer 2 so as to be in contact with each other.

Insulator 3 contains aluminum oxide. Thereby, the insulator 3 can be easily realized. The plurality of quantum dots 5 are filled in the through hole 4 so as not to protrude from the through hole 4 of the insulator 3. The insulator 3 in which the plurality of through holes 4 are formed constitutes a tubular oxide.

As described above, the light emitting layer 2 is not formed of the laminated film of the quantum dots 5, but is formed by filling the plurality of through holes 4 formed in the insulator 3 with the quantum dots 5.

Since the quantum dots 5 are inserted into the through holes 4 formed in the insulator 3 of the light emitting layer 2, it is possible to prevent the quantum dots 5 from being randomly arranged. As a result, it is possible to prevent variations in the length of the current path 36 for each of the current paths 36 composed of the quantum dots 5 in the light emitting layer 2. Therefore, it is possible to suppress the variation in the ease of current flow to the quantum dots 5 in the light emitting layer 2. Therefore, the luminous efficiency is lowered because the current does not flow through the quantum dots 5 forming the long current path, and the current flows too much through the quantum dots 5 forming the short current path, and the quantum dots 5 are liable to deteriorate. You can prevent that.

Since the same number of quantum dots 5 are arranged in each through hole 4, it is possible to remarkably suppress the occurrence of variation in the length of each of the current paths 36 composed of the quantum dots 5 in the light emitting layer 2. Can be done.

The light emitting element 1A is in contact with the lower end of the insulator 3, and has a first carrier transport layer 6 which is one of an electron transport layer (Electron Transportation Layer, ETL) and a hole transport layer (Hole Transportation Layer, HTL). It is in contact with the upper end of the insulator 3 and includes a second carrier transport layer 7 which is the other of the electron transport layer and the hole transport layer. In the example shown in FIG. 1, the first carrier transport layer 6 is a hole transport layer, and the second carrier transport layer 7 is an electron transport layer.

The light emitting element 1A includes a glass substrate 14. The anode 12 is formed on the glass substrate 14. The first carrier transport layer 6 is arranged on the anode 12. A cathode 13 is formed on the second carrier transport layer 7. A power supply 15 is provided between the anode 12 and the cathode 13.

The cathode 13 can be made of, for example, Al. The anode 12 can be made of, for example, ITO (Indium Tin Oxide). The electron transport layer of the second carrier transport layer 7 can be composed of, for example, ZnO. The hole transport layer of the first carrier transport layer 6 can be formed, for example, by laminating PVK and PEDOT: PSS.

In the light emitting layer 2, the quantum dots 5 are filled in the plurality of through holes 4 of the insulator 3 mainly in the solution, and the quantum dots 5 do not protrude from the plurality of through holes 4 of the insulator 3.

2 to 15 are diagrams showing a method of manufacturing the light emitting element 1A. As a method for producing an insulator 3 which is a porous metal oxide having a through hole 4, there is a method using anodized alumina as a template.

Anodized alumina can form porous alumina by anisotropic etching and oxidation of metallic aluminum when electrolyzing in an aqueous solution using metallic aluminum as an anode. The pore diameter, pore shape, etc. formed in the porous alumina can be controlled by the electrolysis conditions.

A self-supporting film of anodized alumina can be obtained by removing and peeling off the metallic aluminum among the obtained anodized alumina on the metallic aluminum. Many methods have been proposed for these pore diameters, pore shapes, patterns, and peeling methods. For example, when the conditions of Non-Patent Document 1 are used, a self-supporting film of anodized alumina can be obtained by the following method.

First, the metal-aluminum thin film 16 shown in FIG. 2 is ultrasonically washed with acetone, and the surface of the metal-aluminum thin film 16 is electrolytically polished by etching with a 3 mol / L NaOH solution to remove the surface oxide film and smooth it. To become.

Then, as shown in FIG. 3, the smoothed metallic aluminum thin film 16 is immersed in a 0.5 M oxalic acid aqueous solution at 15 ° C., anodized for the first time under the conditions of 20-80 V and 1 h, and an oxide film is formed. 17 is formed.

Next, as shown in FIG. 4, the oxide film 17 formed by the first anodization was immersed in a phosphoric acid (6 wt%) and chromic acid (1.8 wt%) solution at 60 ° C. for 30 minutes. Removed from the metallic aluminum thin film 16. As a result, a regular texture structure (unevenness structure) can be obtained on the metal-aluminum thin film 16.

After that, as shown in FIG. 5, the second anodizing for 4 hours is performed under the same solution conditions as the first anodizing to form anodized alumina 18 having a desired thickness.

Then, as shown in FIG. 6, in order to exfoliate the anodized alumina 18 from the metallic aluminum thin film 16, the anodizing conditions were set in a 1: 1 mixed solution of perchloric acid (72 wt%) and 98% diacetyl. By applying a voltage higher by 5 V for 3 s, a plurality of through holes 4 can be generated, and the anodized alumina 18 can be peeled off from the metal aluminum thin film 16.

By the above process, a self-supporting film of anodized alumina 18 having through holes 4 can be obtained. As shown in FIG. 8, the anodized alumina template 19 thus obtained has a plurality of thin through holes 4 having a regular arrangement of honeycomb structures, and forms an optimum hole size and depth. To do.

The hole size and depth of the through hole 4 can be controlled by the solute, temperature, voltage, and time during anodizing, and various methods other than the anodizing method mentioned above have been proposed as the peeling method after anodizing. Has been done. Currently, the anodized alumina template 19 is commercially available as a film (membrane) having a fine through hole 4 having a size of 10 nm.

The size of the peripheral region of the through hole 4 is about the same as the hole size of the through hole 4 of 10 nm in order to suppress a decrease in the packing density (volume density) of the quantum dots 5 when considering the entire light emitting element 1A. Or less than that.

Here, the hole size of the through hole 4 is 1 times or more and less than 2 times the diameter of the quantum dot 5 in order to avoid filling a plurality of quantum dots 5 in the horizontal direction when filling the through hole 4 (of the quantum dot 5). When the diameter is 5-10 nm, the hole size of the through hole 4 is preferably 5-20 nm). As a result, it is possible to prevent a plurality of quantum dots 5 from lining up in the same through hole 4 in a direction perpendicular to the through direction of the through hole 4, so that it is more preferable that the quantum dots 5 are randomly arranged. It can be suppressed.

Further, the depth of the through hole 4 is also 10 times the diameter of the quantum dot 5 because the current flowing in the horizontal direction (the current including the alumina partition wall in the current path) is suppressed and the current is preferentially passed through the quantum dot 5. It is desirable that it is as follows. Normally, the film thickness of the light emitting layer 2 containing the quantum dots 5 is 50 nm or less, and considering that the diameter of the quantum dots 5 is about 5 nm to 10 nm, the film thickness is 10 times or less. As a result, it is possible to prevent a large number of quantum dots 5 from being inserted into the through holes 4, so that it is possible to more preferably suppress the random arrangement of the quantum dots 5.

Next, as shown in FIG. 9, the obtained anodized alumina template 19 was placed on the first carrier transport layer 6 of the HTL produced by the spin coating method on the anode 12 composed of ITO, and added. Press and transfer.

After that, as shown in FIG. 10, the glass substrate 14 to which the anodized alumina template 19 is transferred is immersed in the quantum dot dispersion solution 21 in which the quantum dots 5 are dispersed for a predetermined time. Then, as shown in FIG. 11, the glass substrate 14 to which the anodized alumina template 19 immersed in the quantum dot dispersion solution 21 in which the quantum dots 5 are dispersed is transferred is washed. Then, as shown in FIG. 12, the glass substrate 14 to which the anodized alumina template 19 is transferred is dried. Next, this immersion, washing, and drying are repeated to fill the through holes 4 of the anodized alumina template 19 with the quantum dots 5. When the quantum dot dispersion solution 21 flows into the thin through hole 4 in the dry state due to the capillary phenomenon, the quantum dot 5 is filled inside the through hole 4.

Since the quantum dots 5 once filled do not easily separate from the through holes 4 due to the intermolecular force in the through holes 4, most of the inside of the through holes 4 are filled with the quantum dots 5 by repeating the above cleaning, drying, and filling. Can be filled. As another filling method of the quantum dot 5, there is a known filling method by electrophoresis.

By the above steps, as shown in FIG. 13, a light emitting layer 2 in which the quantum dots 5 are filled in the through holes 4 of the anodized alumina template 19 can be obtained. The quantum dots 5 once filled in the through holes 4 of the anodized alumina template 19 are not easily removed by washing due to the surface tension of the anodized alumina template 19, and the anodized alumina template is repeatedly filled, washed, and dried. The quantum dots 5 are filled up to the height of the through holes 4 of 19, and a light emitting layer 2 having a uniform number of quantum dots 5 in the vertical direction among the plurality of through holes 4 can be obtained.

The number of quantum dots 5 filled in the vertical direction can be controlled by controlling the height of the anodized alumina template 19.

In the light emitting layer 2 filled with the quantum dots 5, the quantum dots 5 are filled in the through holes 4 of the anodized alumina template 19, and the quantum dots 5 do not protrude from the through holes 4 of the anodized alumina template 19. As shown in 13, there may be some through holes 4 in which the quantum dots 5 are not completely filled among the plurality of through holes 4.

The depth of the through hole 4 is 10 times or less the cross-sectional dimension of the through hole 4. Therefore, the number of quantum dots 5 filled in one through hole 4 is 10 or less. The example shown in FIG. 13 shows an example in which the dimension of the quantum dot 5 is 10 nm and the depth of the through hole 4 is 50 nm.

As shown in FIG. 14, the second carrier transport layer 7 to be the ETL layer is formed by applying ZnO nanoparticles 22 by a spin coating method. The diameter of the ZnO nanoparticles 22 may be the same as the size of the through hole 4 of the anodized alumina template 19 so that it can be reliably contacted with the quantum dots 5, but it is more desirable that the diameter of the ZnO nanoparticles 22 is slightly larger than the size of the through hole 4. .. In the example shown in FIG. 14, the ZnO nanoparticles 22 are larger than the quantum dots 5 and have a size of about 10 to 20 nm.

Since the particle size of the ZnO nanoparticles 22 is larger than the size of the through holes 4, the ZnO nanoparticles 22 are not filled inside the through holes 4, so that the quantum dots 5 are sufficiently filled as shown in FIGS. 13 and 14. In the through hole 4 where the gap 23 is not formed, the quantum dots 5 do not come into contact with the ZnO nanoparticles 22 in the ETL layer, and the through holes 4 not filled with the quantum dots have relatively high resistance and current flows. However, the quantum dots 5 in the through hole 4 do not contribute to light emission. As a result, the number of the quantum dots 5 in the vertical direction in each through hole 4 filled until the quantum dots 5 come into contact with the ZnO nanoparticles 22 becomes constant, so that the electrical resistance in the vertical direction becomes constant and the light emission becomes uniform. To do.

Since the ZnO nanoparticles 22 constituting the second carrier transport layer 7 do not enter the through holes 4, the configuration of the second light emitting row can be easily realized.

Next, as shown in FIG. 15, a cathode 13 made of Al is formed on the second carrier transport layer 7 to be the ETL layer by a vacuum vapor deposition method using a metal mask, and a QLED (quantum dot light emitting diode, Quantum dot) is formed. Light Emitting Diode) light emitting element 1A can be obtained.

In this way, the light emitting element 1A is packed tightly in the thickness direction of the light emitting layer 2 between the first carrier transport layer 6 and the second carrier transport layer 7, and n quantum dots 5 are inserted into the through holes 4. The p quantum dots 5 are inserted into the through holes without being packed in the thickness direction of the light emitting layer 2 between the first light emitting row and the first carrier transport layer 6 to the second carrier transport layer 7. Includes a second light emitting column. n is greater than p. The configuration shown in FIG. 15 shows an example of n = 5 and p = 4.

When the current path 37 composed of the quantum dots 5 of the second light emitting row is shorter than the current path 38 composed of the quantum dots 5 of the first light emitting row, the second light emitting row and the ZnO nanoparticles 22 Since the quantum dots 5 and the second carrier transport layer 7 are insulated by the gap 23 between them, the quantum dots 5 in the second light emitting row do not emit light. Therefore, it is possible to prevent the quantum dots 5 in the second light emitting column from rapidly deteriorating, and thus the light emission quality due to the light emission of the deteriorated quantum dots 5.

One of the plurality of ZnO nanoparticles 22 in the second carrier transport layer 7 is in contact with one quantum dot 5, and is in contact with the other plurality of ZnO nanoparticles 22 among the plurality of ZnO nanoparticles 22.

In the QLED light emitting element 1A thus obtained, the number of quantum dots 5 existing in the current path 36 of the light emitting layer 2 becomes uniform when a voltage is applied, the light emitting characteristics can be made uniform, and local quantum dots become possible. The deterioration of 5 can be suppressed.

(Embodiment 2)
FIG. 16 is a cross-sectional view of the light emitting element 1B according to the second embodiment. 17 to 19 are views showing a method of manufacturing the light emitting element 1B. The same components as those described above are designated by the same reference numerals, and the detailed description thereof will not be repeated.

As shown in FIGS. 17 and 18, the plurality of quantum dots 5B of the light emitting element 1B are filled in the through holes 4 so that a part of them protrudes from the through holes 4 of the light emitting layer 2 toward the second carrier transport layer 7. Will be done. The quantum dot 5B can be made of the same material as the quantum dot 5 described in the first embodiment.

The manufacturing process described with reference to FIGS. 2 to 9 of the first embodiment is common to the second embodiment. Therefore, the detailed description will not be repeated. After performing the manufacturing process described with reference to FIGS. 2 to 9 of the first embodiment, as shown in FIG. 17, quantum dots are obtained with respect to the anodized alumina template 19 transferred onto the first carrier transport layer 6 of the HTL. The solution 24 is dropped by a coating method such as spin coating, or filled by an inkjet method or a screen printing method using a squeegee.

In the inkjet method, since minute droplets can be produced by a piezo method or electrostatic method nozzle head, it can be applied to a local region (10 μm or more) such as a pixel pattern. Further, in the screen printing method using a squeegee, since the quantum dot solution 24 to be applied through the mask on which the pattern is formed in advance is brought into contact with the anodized alumina template 19 and filled, it is possible to deal with a large area pattern.

Since these methods can select the coating area, they are more desirable as methods capable of forming a pixel pattern of three RGB colors.

On the other hand, when a large amount of quantum dots 5B is applied to the anodized alumina template 19 and a pixel pattern is formed, it becomes difficult to take a cleaning step. Therefore, when the quantum dots 5B protrude from the anodized alumina template 19. There is.

In this case, the height at which the quantum dots 5B protrude from the anodized alumina template 19 is set to be equal to or less than the diameter of the quantum dots 5B by appropriately controlling the QD concentration and the coating amount of the quantum dot solution 24 to be coated. As a result, the number of quantum dots 5B in the current path 39 can be made uniform, and the resistance and light emission can be made uniform, as in the first embodiment.

As described above in the first embodiment, the quantum dots 5B may slightly protrude from the through holes 4 of the anodized alumina template 19 because the quantum dots 5B homogenize the current path 39, or FIG. 17 As shown in FIGS. 18 and 19, about one layer of the quantum dots 5B may protrude from the through hole 4 of the anodized alumina template 19.

In the second embodiment, the region where the ZnO nanoparticles 22 of the second carrier transport layer 7 to be the ETL layer and the quantum dots 5B can be reliably contacted is increased as compared with the first embodiment, and the through holes 4 that do not emit light are formed. Less.

Further, referring to FIG. 19, in the current path 39 from the second carrier transport layer 7 which is the ETL layer to the first carrier transport layer 6 which is the HTL layer, the current path 39 is the second carrier transport layer 7 to the first. The number of quantum dots 5B passing through to the carrier transport layer 6 is the same in each through hole 4. The cross-sectional size of the through hole 4 is 5 nm or more and 20 nm or less, which corresponds to less than 1-2 quantum dots 5B. The depth of the through hole 4 is 50 nm or less, which corresponds to less than 10 quantum dots 5B.

Then, similarly to the first embodiment, when the second carrier transport layer 7 which is the ETL layer made of ZnO nanoparticles 22 and the cathode 13 made of Al are formed as shown in FIG. 18, the light emitting element 1B of the QLED is obtained. Be done.

In the QLED light emitting element 1B thus obtained, the number of quantum dots 5B existing in the current path 39 of the light emitting layer 2 becomes uniform when a voltage is applied, the light emitting characteristics can be made uniform, and local quantum dots become possible. Deterioration of 5B can be suppressed. Further, the number of through holes 4 in which the quantum dots 5B emit light is larger than that in the first embodiment. Therefore, the light emitting element 1B can obtain light emission with higher efficiency than that of the first embodiment.

(Embodiment 3)
FIG. 20 is a cross-sectional view of the light emitting element 1C according to the third embodiment. FIG. 21 is a diagram showing a method of manufacturing the light emitting element 1C. The same components as those described above are designated by the same reference numerals, and the detailed description thereof will not be repeated.

The light emitting device 1C according to the third embodiment is different from the light emitting device 1A according to the first embodiment in that the particle size of the ZnO nanoparticles 22C of the second carrier transport layer 7C is smaller than the cross-sectional size of the through hole 4. ..

When the particle size of the ZnO nanoparticles 22C is smaller than the cross-sectional size of the through hole 4, the ZnO nanoparticles 22C are filled inside the through hole 4. Therefore, as shown in FIG. 21, the ZnO nanoparticles 22C come into contact with the quantum dots 5 in all the through holes 4. Therefore, since the quantum dots 5 in all the through holes 4 emit light, a more efficient light emitting element 1C can be obtained.

Further, even when the quantum dot 5B protrudes from the through hole 4 as in the second embodiment, the region where the ZnO nanoparticles 22C come into contact with the quantum dot 5B increases. Therefore, the electrical resistance between the ZnO nanoparticles 22C and the quantum dots 5B is reduced, and more efficient light emission can be obtained.

As described above, the light emitting layer 2 is packed tightly in the thickness direction of the light emitting layer 2 between the first carrier transport layer 6 and the ZnO nanoparticles 22C of the second carrier transport layer 7C, and n through holes 4 are filled. The first light emitting row in which the quantum dots 5 are inserted and the first carrier transport layer 6 to the second carrier transport layer 7C are packed tightly in the thickness direction of the light emitting layer 2, and p through holes 4 are filled. It includes a second emission sequence in which the quantum dots 5 are inserted, and n may be larger than p. The example shown in FIG. 21 shows an example of n = 5 and p = 4. The quantum dots 5 are tightly packed in the thickness direction of the light emitting layer 2 between the first carrier transport layer 6 and the ZnO nanoparticles 22C of the second carrier transport layer 7C filled inside the through hole 4.

As a result, when the current path composed of the quantum dots 5 in the second light emitting column is shorter than the current path composed of the quantum dots 5 in the first light emitting column, the quantum dots 5 in the second light emitting column emit light. To do. Therefore, the luminous efficiency can be increased.

In the method for manufacturing the light emitting device 1C of the third embodiment, the steps other than the step of forming the ETL layer of the second carrier transport layer 7 are the same as the steps described in the first and second embodiments. Do not repeat.

The ETL layer of the second carrier transport layer 7C is formed by applying ZnO nanoparticles 22C to the anodized alumina template 19 by a spin coating method. In some quantum dots 5, the deterioration factor of the emission brightness may not be the quantum dots 5 but the HTL (ETL) layer itself (Non-Patent Document 2). This has been reported in the band diagram for quantum dots with deep conduction band levels (high electron affinity) such as red quantum dots, and only one or two of the three RGB colors do not consider the deterioration of the quantum dots. It may be acceptable. At this time, more quantum dots 5 contribute to light emission when all the through holes 4 are made to emit light as in the third embodiment without forming the through holes 4 which do not emit light as in the first and second embodiments. The overall luminous efficiency of the light emitting element 1C is also high.

(Embodiment 4)
FIG. 22 is a view showing the light emitting element 1D according to the fourth embodiment, and is a plan sectional view taken along the plane AA shown in FIG. 23. FIG. 23 is a cross-sectional view of the light emitting element 1D according to the fourth embodiment. The same components as those described above are designated by the same reference numerals, and the detailed description thereof will not be repeated.

The light emitting element 1D includes

light emitting layers

2R, 2G, and 2B corresponding to the pixel patterns of the three colors of RGB, respectively. Each of the

light emitting layers

2R, 2G, and 2B has an insulator 3 in which a plurality of through holes 4 penetrating in the thickness direction of the

light emitting layers

2R, 2G, and 2B are formed, and quantum dots inserted in each of the plurality of through holes 4. It has 5R, 5G, and 5B. The insulator 3 in which the plurality of through holes 4 are formed constitutes a tubular oxide.

Each of the three color pixel patterns of the light emitting element 1D is in contact with the lower end of the insulator 3, and the first carrier transport layer 6 which is one of the electron transport layer and the hole transport layer and the upper end of the insulator 3 It is in contact with and includes a second carrier transport layer 7, which is the other of the electron transport layer and the hole transport layer. In the example shown in FIG. 23, the first carrier transport layer 6 is a hole transport layer, and the second carrier transport layer 7 is an electron transport layer.

The light emitting element 1D includes a glass substrate 14. An anode 12 is formed on the glass substrate 14 in an island shape so as to correspond to each of the three color pixel patterns. Each of the first carrier transport layers 6 is arranged on the anode 12. A cathode 13 common to each of the three color pixel patterns is formed on the second carrier transport layer 7.

In the light emitting element 1D, an edge cover 25 (bulkhead) that separates pixel patterns of three colors penetrates the anode 12, the first carrier transport layer 6, the insulator 3, and the second carrier transport layer 7, and the glass substrate 14 Is formed so as to reach the cathode 13. No tubular oxide is present in the region of the edge cover 25 that separates the three color pixel patterns, and the tubular oxide is formed only on the RGB three color pixel patterns.

The edge cover 25 enables separation for each pixel. In addition, local light emission at the outer periphery and the end of the pixel can be suppressed.

Each layer of the QLED element is intended to separate the pixel patterns of the three colors and to suppress end face light emission at the edge of the junction between the anode 12 and the first carrier transport layer 6. It is desirable to use an insulating material with higher electrical resistance than this. Therefore, assuming a pattern in which the wiring of the anode 12 below the QLED element is embedded in the edge cover 25, the width of the region of the edge cover 25 is 100 nm or more, and the height of the edge cover 25 is 200 nm or more. In FIG. 23, the wiring of the anode 12 in the edge cover 25 is omitted.

In FIGS. 22 and 23, the scale of the three-color pixel pattern and the scale of the edge cover 25 between the pixel patterns are different in order to emphasize the thin through hole 4. As described above, the width of the region of the edge cover 25 is 100 nm or more, the height of the edge cover 25 is 200 nm or more, and the horizontal size per pixel is also 10 μm or more. Therefore, the number of through holes 4 in one pixel and the edge cover region is significantly larger than that shown in FIGS. 22 and 23.

24 to 38 are cross-sectional views showing a method of manufacturing the light emitting element 1D according to the fourth embodiment. The same components as those described above are designated by the same reference numerals, and the detailed description thereof will not be repeated.

In order to form a pixel pattern of 3 pixels of RGB, a semiconductor process for producing a pattern with a photosensitive resist is generally used. In the semiconductor process, a photosensitive resist is exposed to ultraviolet rays, partially altered, and only the altered or non-altered portion is dissolved in a developing solution to produce a pixel pattern. In this embodiment, a method of separately forming a pattern of an anodized alumina template and joining it on HTL will be described.

By this method, it is possible to manufacture a QLED element having an RGB3 color pixel pattern by avoiding end face light emission due to the good insulation of the edge cover material.

First, as shown in FIG. 24, a resist is applied onto the glass substrate 14 to perform pattern exposure, and the pattern of the anode 12 by ITO is formed into a semiconductor on the glass substrate 14 by lift-off to form an ITO film and remove the resist. Formed by process.

Then, by applying a resist and exposing the pattern to develop, as shown in FIG. 25, a resist pattern 26 having a size smaller than that of the anode 12 is formed.

Next, as shown in FIG. 26, the first carrier transport layer 6 composed of the HTL layer is coated to form a film on the entire surface of the anode 12 and the resist pattern 26.

After that, as shown in FIG. 27, the excess first carrier transport layer 6 is removed by lifting off the resist pattern 26.

Then, as shown in FIGS. 28 and 29, the support substrate 27 is attached to the anodized alumina template 19 produced as described above in the first embodiment. The support substrate 27 may be in close contact with the anodized alumina template 19, and is preferably made of a glass substrate or a resin material.

Next, in order to pattern the anodized alumina template 19 on the support substrate 27, as shown in FIG. 30, a sacrificial layer 28 for subsequent etching of the anodized alumina template 19 is formed by resist coating and development. ..

After that, as shown in FIG. 31, the anodized alumina template 19 is etched by an etching solution for dissolving alumina such as KOH or the anodizing described above in the first embodiment. At this time, the sacrificial layer 28 of the resist is also etched, but by forming the sacrificial layer 28 of the resist having a thickness sufficient for the thickness of the anodized alumina template 19, the anodized alumina template 19 on the lower side of the resist is formed. Is protected. Then, the resist is removed with acetone or the like to obtain an anodized alumina template 19 in which a pattern is formed.

Then, the prepared anodized alumina template 19 and the glass substrate 14 formed up to the first carrier transport layer 6 of the HTL layer are aligned, and as shown in FIG. 32, the anodized alumina template 19 and the first carrier transport are performed. Joins the layer 6. From the accuracy of alignment, it is desirable that the size of the anodized alumina template 19 in each pixel is smaller than the size of the first carrier transport layer 6. The bonding may be performed by bonding with the HTL layer by pressing pressure, or by baking and bonding the anodized alumina template 19 to the HTL layer after coating. Then, the support substrate 27 is peeled off from the anodized alumina template 19.

Next, as shown in FIG. 33, the resist 29 is formed only on the anodized alumina template 19 by the semiconductor process.

Then, as shown in FIG. 34, the edge cover material 30 is filled. The edge cover material 30 has an insulating polymer material such as polyimide that can be formed by coating, and an insulating property such as SiO ₂ that can be formed by a vacuum deposition method such as CVD (Chemical Vapor Deposition). Oxides can be mentioned.

Then, as shown in FIG. 35, the resist 29 is removed together with the excess edge cover material 30 by lift-off to form the edge cover 25.

Next, the through holes 4 are filled with the

quantum dots

5R, 5G, and 5B by the method described above in the first and second embodiments. Since the pixels of three colors of RGB are formed, the pixels other than the pixels of the desired color are protected by the resist 31 to avoid the filling of quantum dots of the undesired color. In FIG. 36, the quantum dots 5R are filled in the through holes 4 of the anodized alumina template 19 corresponding to red, and protected by a resist 31 to prevent the quantum dots 5R from being focused on the through holes 4 corresponding to green and blue. An example of doing this is shown.

After that, the through holes 4 are repeatedly filled with the

quantum dots

5R, 5G, and 5B of each color of RGB, and the

quantum dots

5R, 5G, and 5B of three colors are filled into the through holes 4 as shown in FIG. 37.

Then, as shown in FIG. 38, a second carrier transport layer 7 made of an ETL material and a cathode 13 made of Al are formed to manufacture a light emitting element 1D of a QLED element.

The light emitting element 1D of the QLED element produced in this manner does not have the anodized alumina template 19 between the RGB pixels, and can form an insulating edge cover 25.

(Embodiment 5)
FIG. 39 is a cross-sectional view of the light emitting element 1E according to the fifth embodiment. The same components as those described above are designated by the same reference numerals, and the detailed description thereof will not be repeated.

The light emitting element 1E according to the fifth embodiment includes an anodized alumina template 19E. The tubular oxide composed of the anodized alumina template 19E is formed both on the pixel pattern of three RGB colors and between the pixel patterns. That is, the tubular oxide is also present in the region of the edge cover 25E (pixel electrode partition wall, partition wall) that separates the pixel patterns.

In the above-described fourth embodiment, the purpose is to obtain good insulating properties by the edge cover 25, but since the anodized alumina template itself is also composed of insulating alumina, the anodized alumina template 19E according to the present embodiment is It has an insulator 35 (bulk partition) for a partition wall that acts as an edge cover at a position between the pixel patterns in which the

quantum dots

5R, 5G, and 5B are not filled in the through hole 4. As a result, the insulators 3 of the pixel patterns of each of the three RGB colors can be collectively treated as one member, so that the display device can be easily manufactured, and an inexpensive display device with a low manufacturing cost can be realized.

In FIG. 39, the scale of the three-color pixel pattern and the scale of the edge cover 25E between the pixel patterns are different in order to emphasize the thin through hole 4. The width of the region of the edge cover 25E is 100 nm or more, and the horizontal size per pixel is also 10 μm or more. Therefore, the number of through holes 4 existing directly above one pixel and the edge cover 25E is much larger than that shown in FIG. 39.

Further, in the present embodiment, as compared with the above-described fourth embodiment, the number of mask patterns is reduced by one and the support substrate is not required, so that the number of processes related to the fabrication of the light emitting element can be reduced and the cost can be reduced. ..

40 to 47 are cross-sectional views showing a method of manufacturing the light emitting element 1E. The same components as those described above are designated by the same reference numerals, and the detailed description thereof will not be repeated.

In the fifth embodiment, since the mask pattern is reduced and the support substrate is not required, the QLED element having the RGB3 color pixel pattern is produced while reducing the number of processes and the cost related to the production of the light emitting element. Can be done.

First, the anode 12 and the first carrier transport layer 6 are formed on the glass substrate 14 as shown in FIG. 40 by the same method as described above in FIGS. 24 to 27 of the fourth embodiment.

Then, as shown in FIG. 41, a pattern of a resist 32 having the same size as or smaller than that of the HTL is formed on the first carrier transport layer 6 of the HTL.

Next, as shown in FIG. 42, an edge cover material 33 made of an insulating oxide thin film such as _{SiO 2 having a film thickness similar to that of HTL is formed.} As a method for forming the edge cover material 33, a vacuum film forming method such as CVD with good film thickness controllability is used.

After that, as shown in FIG. 43, the excess edge cover material 33 on the first carrier transport layer 6 of the HTL is removed by lift-off to form the edge cover 25E.

Then, as shown in FIGS. 44 and 45, the large-area anodized alumina template 19E is bonded to the first carrier transport layer 6 of the HTL layer in the same manner as in the above-described fourth embodiment. At this time, since the pixels of the anodized alumina template 19E are not separated and do not form a pattern as in the fourth embodiment, the support substrate 27 is unnecessary by using the free-standing film of the anodized alumina template 19E. Become.

Next, each RGB pixel is filled with

quantum dots

5R, 5G, and 5B. FIG. 46 shows an embodiment in which the R pixel is filled with the quantum dots 5R. The anodized alumina template 19E is optically substantially transparent, and the arrangement of the anode 12 of the lower electrode can be confirmed, so that the mask pattern can be aligned. The

quantum dots

5R, 5G, and 5B are filled by the same method as described above in the first and second embodiments.

As a result, it is possible to reduce one mask pattern as compared with the fourth embodiment, and it is possible to reduce the cost by reducing the number of processes.

After that, as shown in FIG. 47, the second carrier transport layer 7 of the ETL layer and the cathode 13 of the Al electrode are formed on the front surface to produce the light emitting element 1E of the QLED element. At this time, in order to prevent the ZnO nanoparticles, which are ETL materials, from being filled in the narrow through holes 4 of the anodized alumina template 19E directly above the edge cover 25E, the particle size of the ZnO nanoparticles is set to the anodized alumina template 19E. It is desirable that it is larger than the size of the through hole 4 of.

The present invention 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 invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

1A Light emitting element 2 Light emitting layer 3 Insulator 4 Through hole 5 Quantum dot 6 1st carrier transport layer 7 2nd carrier transport layer 12 Anode 13 Cathode (common electrode)
14 Glass substrate 25 Edge cover (bulkhead)
25E edge cover (pixel electrode partition wall, partition wall)
35 Insulator for partition wall (bulkhead)

Claims

It has a light emitting layer and
The light emitting layer is
An insulator in which a plurality of through holes penetrating in the thickness direction of the light emitting layer are formed,
A light emitting device having at least one quantum dot inserted into each of the plurality of through holes.
The light emitting element according to claim 1, wherein the same number of quantum dots are inserted into each of the plurality of through holes.
The light emitting element is
The first carrier transport layer, which is in contact with the lower end of the insulator and is one of the electron transport layer and the hole transport layer,
It is in contact with the upper end of the insulator and is provided with a second carrier transport layer which is the other of the electron transport layer and the hole transport layer.
The light emitting layer is
A first light emitting row in which n quantum dots are inserted into the through holes so as to be tightly packed in the thickness direction of the light emitting layer between the first carrier transport layer and the second carrier transport layer.
A second light emitting row in which p quantum dots are inserted into the through holes without being packed in the thickness direction of the light emitting layer between the first carrier transport layer and the second carrier transport layer is included. Ori,
The light emitting element according to claim 1, wherein n is larger than p.
The second carrier transport layer is composed of a plurality of particles.
The light emitting element according to claim 3, wherein the diameter of the particles is larger than the diameter of the through hole.
The light emitting element is
The first carrier transport layer, which is in contact with the lower end of the insulator and is one of the electron transport layer and the hole transport layer,
It is in contact with the upper end of the insulator and is provided with a second carrier transport layer which is the other of the electron transport layer and the hole transport layer.
The light emitting layer is
A first light emitting row in which n quantum dots are inserted into the through holes so as to be tightly packed in the thickness direction of the light emitting layer between the first carrier transport layer and the second carrier transport layer.
The space between the first carrier transport layer and the second carrier transport layer is tightly packed in the thickness direction of the light emitting layer, and includes a second light emitting row in which p quantum dots are inserted into the through holes. And
The light emitting element according to claim 1, wherein n is larger than p.
The second carrier transport layer is composed of a plurality of particles.
The light emitting element according to claim 5, wherein the diameter of the particles is smaller than the diameter of the through hole.
The light emitting element according to any one of claims 1 to 6, wherein the insulator contains aluminum oxide.
The light emitting device according to any one of claims 1 to 7, wherein the diameter of the through hole is 1 times or more and less than 2 times the diameter of the quantum dot.
The light emitting device according to any one of claims 1 to 8, wherein the length of the through hole is 10 times or less the diameter of the quantum dot.
The light emitting element according to any one of claims 1 to 9, wherein the thickness of the light emitting layer is 5 nm or more and 100 nm or less.
A plurality of quantum dots are inserted into each of the plurality of through holes, and a plurality of quantum dots are inserted.
The light emitting element according to claim 1, wherein one of the plurality of quantum dots inserted into each of the plurality of through holes and the other one are laminated in the thickness direction of the light emitting layer so as to be in contact with each other.
The light emitting element is
The first carrier transport layer, which is in contact with the lower end of the insulator and is one of the electron transport layer and the hole transport layer,
It is in contact with the upper end of the insulator and is provided with a second carrier transport layer which is the other of the electron transport layer and the hole transport layer.
The second carrier transport layer is composed of a plurality of particles.
The light emitting device according to claim 1, wherein one of the plurality of particles in the second carrier transport layer is in contact with one quantum dot and is in contact with another plurality of particles among the plurality of particles.
A plurality of pixels including the light emitting element according to any one of claims 1 to 12 are provided.
A display device including a partition wall that separates light emitting elements included in the plurality of pixels for each pixel.
It is equipped with an insulator for partition walls that is integrally formed with the insulator of each light emitting element.
The display device according to claim 13, wherein the partition wall insulator functions as at least a part of the partition wall.
Multiple pixel electrodes arranged in an island shape corresponding to each light emitting layer,
Further, a common electrode commonly arranged in the plurality of light emitting elements so as to sandwich each light emitting layer with each pixel electrode is provided.
The display device according to claim 13, wherein the partition wall is formed so as to reach the common electrode through the plurality of pixel electrodes.
Multiple pixel electrodes arranged in an island shape corresponding to each light emitting layer,
Further, a common electrode commonly arranged in the plurality of light emitting elements so as to sandwich each light emitting layer with each pixel electrode is provided.
The partition wall is a pixel electrode partition wall that separates the plurality of pixel electrodes.
The display device according to claim 13, further comprising a partition wall insulator integrally formed with an insulator of each light emitting element in order to separate the light emitting elements of the plurality of pixels.
As a step of forming a light emitting layer,
An insulator forming step of forming an insulator having a plurality of through holes penetrating in the thickness direction of the light emitting layer, and an insulator forming step.
A method for manufacturing a light emitting device, which includes a quantum dot insertion step of inserting at least one quantum dot into each of the plurality of through holes.
The method for manufacturing a light emitting element according to claim 17, wherein at least one quantum dot is inserted into each of the plurality of through holes based on a capillary phenomenon or electrophoresis in the quantum dot insertion step.
The method for manufacturing a light emitting element according to claim 17, wherein at least one quantum dot is inserted into each of the plurality of through holes by a printing method in the quantum dot insertion step.
Any one of claims 17 to 19, which includes a sticking step of sticking the insulator to a carrier transport layer which is either an electron transport layer or a hole transport layer after the insulator forming step. The method for manufacturing a light emitting element according to.
A light emitting element forming step of forming a light emitting element by the method for manufacturing a light emitting element according to any one of claims 17 to 20 for each of a plurality of pixels.
A method for manufacturing a display device, which includes a partition wall forming step of forming a partition wall that separates light emitting elements of a plurality of pixels for each pixel.
The insulator of each light emitting element is integrally formed with the partition wall insulator.
The method for manufacturing a display device according to claim 21, wherein the partition wall insulator functions as at least a part of the partition wall.