WO2020136713A1

WO2020136713A1 - Method for manufacturing light-emitting device

Info

Publication number: WO2020136713A1
Application number: PCT/JP2018/047548
Authority: WO
Inventors: 惇佐久間; 康浅岡; 青森　繁
Original assignee: シャープ株式会社
Priority date: 2018-12-25
Filing date: 2018-12-25
Publication date: 2020-07-02

Abstract

This method for manufacturing a light-emitting device performs electrodeposition of functional particles (M1• M2) on a substrate electrode (U) formed on a substrate (C) and is provided with a first film forming step and a second film forming step next to the first film forming step. In the first film forming step, a first voltage is applied between a first substrate electrode in the substrate electrode and a facing electrode (8) to form a film of a first particle (M1) on the first substrate electrode. In the second film forming step, a second voltage is applied between a second substrate electrode in the substrate electrode and the facing electrode to form a film of a second particle (M2) on the second substrate electrode. The absolute value of the first voltage is smaller than the absolute value of the second voltage.

Description

Method for manufacturing light emitting device

The present invention relates to a method for manufacturing a light emitting device, in which a functional layer of the light emitting device is formed by electrodeposition.

Patent Document 1 discloses a method of forming an organic light emitting layer by an electrodeposition method in the production of an organic light emitting element.

Japanese Patent Laid-Open Publication "JP 2002-313565"

In the technique described in Patent Document 1, when forming a plurality of layers containing different materials, it is necessary to change the electrodeposition liquid each time the layers are formed. Therefore, an increase in takt time becomes a problem.

In order to solve the above problems, a method for producing a light emitting device of the present invention is a method for producing a light emitting device in which functional particles are electrodeposited on a substrate electrode formed on a substrate, the substrate and the substrate A substrate gripping step of sandwiching an electrodeposition liquid containing first particles and second particles different from the first particles as the functional particles between the counter electrodes arranged in parallel; A first film forming step of applying a first voltage between the first substrate electrode of the substrate electrodes and the counter electrode to form the first particles on the first substrate electrode; Subsequent to the first film forming step, a second voltage is applied between the second substrate electrode of the substrate electrodes and the counter electrode to form the second particles on the second substrate electrode. A second film forming step, wherein the absolute value of the first voltage is smaller than the absolute value of the second voltage.

With the above configuration, the tact time in manufacturing a light emitting device can be shortened.

6A to 6D are process cross-sectional views for explaining the method for manufacturing the light-emitting device according to the first embodiment of the present invention. It is a schematic diagram of a substrate concerning Embodiment 1 of the present invention. 1 is a schematic diagram of a light emitting device manufacturing apparatus according to a first embodiment of the present invention. FIG. 3 is a schematic view of the manufacturing apparatus of the light emitting device according to Embodiment 1 of the present invention in a state where the substrate is pressed against the electrodeposition tank. 3 is a flowchart illustrating a method of manufacturing the light emitting device according to the first embodiment of the invention. FIG. 3 is a schematic view of functional particles contained in the electrodeposition liquid according to the first embodiment of the present invention. 7 is a graph showing a relationship between applied voltage and elapsed time in an electrodeposition process using the light emitting device manufacturing apparatus according to the first embodiment and the modification of the present invention. FIG. 3 is a cross-sectional view of the light-emitting device manufacturing apparatus and the substrate for explaining the problems in the light-emitting device manufacturing method according to the first embodiment of the present invention. It is the schematic of the board|substrate which concerns on Embodiment 2 and Embodiment 3 of this invention. In the manufacturing apparatus of the light emitting device which concerns on Embodiment 2 of this invention, it is the schematic of the said manufacturing apparatus in the state which pressed the board|substrate to the electrodeposition tank. 6 is a flowchart illustrating a method for manufacturing a light emitting device according to a second embodiment of the invention. FIG. 6 is a process cross-sectional view for explaining an electrodeposition process according to Embodiment 2 of the present invention. FIG. 7 is a process cross-sectional view for explaining an electrodeposition process using the display device manufacturing apparatus according to the second embodiment of the present invention in comparison with an electrodeposition process using the display device manufacturing apparatus according to the comparative embodiment. 6 is a flowchart for explaining a method for manufacturing a light emitting device according to Embodiment 3 of the present invention. FIG. 6 is a process cross-sectional view for explaining an electrodeposition process according to Embodiment 3 of the present invention. It is a schematic sectional drawing which shows an example of the light emitting device which concerns on Embodiment 3 of this invention. It is a process sectional view for explaining the electrodeposition process concerning Embodiment 4 of the present invention. It is a schematic sectional drawing which shows an example of the light emitting device which concerns on Embodiment 4 of this invention.

[Embodiment 1]
In the present embodiment, a manufacturing apparatus and a manufacturing method for performing electrodeposition on the substrate C shown in FIG. 2 will be described. FIG. 2 is a schematic perspective view of the substrate C according to this embodiment. As shown in FIG. 2, the substrate C includes a single flat electrode U and an electrodeposition bath connection electrode D as substrate electrodes.

The flat electrode U is formed on the substrate C so as to be exposed on one of the surfaces of the substrate C. For example, the plane electrode U is formed in a rectangular shape on the substrate C.

The electrodeposition bath connecting electrode D is formed on any two sides of the substrate C orthogonal to each other on the surface of the substrate C on which the planar electrode U is formed. Since the flat electrode U and the electrodeposition bath connecting electrode D are electrically connected to each other, a voltage can be applied to the flat electrode U by applying a voltage to the electrodeposition bath connecting electrode D. As long as the electrodeposition bath connection electrode D is formed on the surface of the substrate C on which the planar electrode U is formed, the electrodeposition bath connection electrode D is not limited to be formed along two orthogonal sides of the substrate C, but also the substrate C. The shape is not particularly limited, such as being provided only along any one of the sides.

The flat electrode U and the electrodeposition bath connection electrode D are flush with the surface of the substrate C on which the flat electrode U and the electrodeposition bath connection electrode D are formed, and are exposed at the surfaces.

FIG. 3 is a schematic diagram of the light emitting device manufacturing apparatus 2 according to the present embodiment. FIG. 3A is a perspective view of the light emitting device manufacturing apparatus 2. FIG. 3B is a top view of the light emitting device manufacturing apparatus 2. 3C is a cross-sectional view taken along the line AA in FIG. It should be noted that FIG. 3A illustrates a state where the substrate C is installed in the light emitting device manufacturing apparatus 2. However, for simplicity of illustration, the illustration of the substrate C is omitted in FIGS. 3B and 3C.

In addition, in the present specification, the top view of the light-emitting device manufacturing apparatus 2 in each drawing is a top view at a position corresponding to (b) of FIG. 3 unless otherwise specified. Further, in the present specification, the cross-sectional view of the light-emitting device manufacturing apparatus 2 in each drawing is a cross-sectional view at a position corresponding to (c) of FIG. 3 unless otherwise specified.

As shown in FIG. 3, the light emitting device manufacturing apparatus 2 according to the present embodiment includes an electrodeposition tank 4, a bottom electrode 8, a pressing unit 10, and an electrodeposition power source 12.

The electrodeposition tank 4 includes an outer side surface 14 that defines the outer shape of the electrodeposition tank 4, and an inner side surface 16 and a bottom surface 18 that define the inside 4A of the electrodeposition tank 4. An edge portion 20 is defined between the outer side surface 14 and the inner side surface 16. A plurality of substrate connecting electrodes 22 are formed on the upper surface of the edge portion 20. That is, a plurality of substrate connecting electrodes 22 are formed on the outer periphery of the electrodeposition tank 4.

The bottom electrode 8 is formed on the bottom surface 18 of the electrodeposition tank 4. The bottom surface electrode 8 is flush with the bottom surface 18 and is exposed from the bottom surface 18. Further, when the substrate C is installed in the light emitting device manufacturing apparatus 2, the bottom surface electrode 8 serves as a counter electrode facing the flat electrode U formed on the substrate C.

The pressurizing unit 10 has a mechanism for moving at least one of the substrate C and the electrodeposition tank 4 to control the relative distance between the substrate C and the electrodeposition tank 4. In the present embodiment, it is assumed that the substrate C is placed in the manufacturing apparatus 2 for a light emitting device by disposing the substrate C in the pressure unit 10. When disposing the substrate C on the pressurizing unit 10, the substrate C is disposed so that the planar electrode U of the substrate C faces the bottom electrode 8 of the electrodeposition tank 4 in parallel.

The pressing unit 10 may be, for example, a vacuum chuck that holds the substrate C. In this case, the pressurizing unit 10 may control the relative distance between the substrate C and the electrodeposition tank 4 by moving the substrate C with respect to the electrodeposition tank 4.

The pressurizing unit 10 can bring the substrate C and the electrodeposition tank 4 close to each other until the substrate C and the electrodeposition tank 4 come close to each other. 4A and 4B are schematic diagrams corresponding to FIGS. 3A and 3C in a state where the substrate C and the electrodeposition tank 4 are pressed against each other. Shown respectively. 4B, the cross section of the substrate C is also illustrated.

When the substrate C and the electrodeposition tank 4 are pressed against each other, the bottom electrode 8 faces the flat electrode U of the substrate C via the inside 4A, as shown in FIG. 4(b). That is, when the substrate C and the electrodeposition tank 4 are pressed against each other, the inside 4A is sandwiched between the substrate C and the bottom electrode 8 that is parallel to the substrate C.

Further, when the substrate C and the electrodeposition bath 4 are pressed against each other, as shown in FIG. 4B, the electrode 22 for connecting the substrate of the electrodeposition bath 4 and the electrode D for connecting the electrodeposition bath of the substrate C And come into contact with each other and become electrically conductive with each other. As shown in (c) of FIG. 3 and (b) of FIG. 4, the electrodeposition bath 4 serves to assist the electrical continuity between the substrate connection electrode 22 and the electrodeposition bath connection electrode D. A spring 38 that pushes up the substrate connection electrode 22 may be provided below each substrate connection electrode 22.

Here, as shown in (c) of FIG. 3, the interior 4A defined by the side surface 16 and the bottom surface 18 has a distance d1 from the upper surface of the edge portion 20 to the upper surface of the bottom electrode 8. This distance d1 corresponds to the depth of the interior 4A, and as shown in FIG. 4B, when the substrate C and the electrodeposition bath 4 are pressed against each other, the bottom electrode 8 and the flat electrode U are separated from each other. Substantially equal to the distance between.

The electrodeposition power source 12 is a power source that applies at least a binary voltage to the bottom surface electrode 8 and the substrate connecting electrode 22. Further, the electrodeposition power source 12 may apply a voltage to the planar electrode U of the substrate C via the substrate connecting electrode 22 and the electrodeposition bath connecting electrode D. Therefore, the electrodeposition power source 12 may apply at least a binary voltage between the flat electrode U and the bottom electrode 8.

Here, when the substrate C and the electrodeposition bath 4 are pressed against each other, as long as a voltage can be applied to the planar electrode U via the substrate connection electrode 22 and the electrodeposition bath connection electrode D, the substrate connection electrode The shape of 22 is also not particularly limited. For example, when the electrodeposition bath connection electrode D is even formed along one side of the substrate C, the electrode 22 for substrate connection is the electrodeposition bath connection electrode when the substrate C and the electrodeposition bath 4 are pressed against each other. It may be formed along one side of the upper surface of the edge portion 20 that overlaps with D.

An example of performing film formation by electrodeposition on the planar electrode U of the substrate C using the light emitting device manufacturing apparatus 2 according to this embodiment will be described with reference to FIGS. 5 and 1. FIG. 5 is a flowchart for explaining an example of a manufacturing method using the light emitting device manufacturing apparatus 2 according to the present embodiment. FIG. 1 is a process cross-sectional view of a light emitting device manufacturing apparatus 2 and a substrate C in the manufacturing method shown in FIG.

In the method for manufacturing a light emitting device according to this embodiment, first, as shown in FIG. 1A, the substrate C is installed in the light emitting device manufacturing apparatus 2 (step S2). Step S2 is performed, for example, by placing the substrate C on the pressing unit 10 so that the planar electrode U of the substrate C faces the bottom electrode 8. In the present embodiment, the inside 4A is filled with the electrodeposition liquid L1 before the substrate C installed in the pressurizing unit 10 is brought close to the electrodeposition tank 4 in step S2.

In the present embodiment, the electrodeposition liquid L1 contains a plurality of functional particles. The functional particles contained in the electrodeposition liquid L1 are dispersed in the electrodeposition liquid L1 which is a solvent. Examples of the electrodeposition liquid L1 include water, alkyl alcohol, toluene, propylene glycol monomethyl ether acetate (PGMEA), alkane, and the like.

The functional particles contained in the electrodeposition liquid L1 may be, for example, the material of the functional layer of the light emitting element. Examples of the functional layer of the light emitting element include an electron transport layer, a light emitting layer, or a hole transport layer formed between electrodes of the light emitting element. In particular, when the functional particles are the material of the light emitting layer, the functional particles may be self-luminous particles. The functional particles in the present embodiment may include inorganic nanoparticles, and particularly may include semiconductor nanoparticles, that is, quantum dots.

When the functional particles in the present embodiment are the nanoparticle material of the light emitting layer, the functional particles may have a single core structure made of CdSe, ZnSe, InP or the like. Further, the functional particles in the present embodiment may have a core/shell structure composed of CdSe/ZnS, InP/ZnS, CdSe/CdS, ZnSe/ZnS, or the like. Further, the functional particles in the present embodiment may have a multi-shell structure composed of CdSe/ZnSe/ZnS or the like.

When the functional particles in the present embodiment are the nanoparticle material of the electron transport layer, even if the functional particles include ZnO, ZrO, MgZnO, AlZnO, TiO ₂ , Ta ₂ O ₃ , SrTiO ₃ or the like. Good. When the functional particles in the present embodiment are the nanoparticle material of the hole transport layer, the functional particles may include NiO, CuI, Cu ₂ O, CoO, Cr ₂ O ₃ or MoO _3. Good.

Further, in the present embodiment, the electrodeposition liquid L1 includes, as functional particles, first particles M1 and second particles M2 which are particles different from each other as functional particles, as shown in (a) of FIG. In particular, when the first particles M1 and the second particles M2 are materials for the light emitting layer, the first particles M1 and the second particles M2 may be self-luminous particles that emit different lights.

In the present embodiment, the functional particles contained in the electrodeposition liquid L1 may include a ligand that forms a coordinate bond with each of the functional particles. For example, as shown in (a) of FIG. 6, the first particles M1 may have a structure in which the first ligand R1 is coordinated around, and the second particles M2 are It may have a structure in which a second ligand R2 different from the one ligand R1 is coordinated. Examples of the ligand in the present embodiment include mercaptoalkanoic acid, alkanethiol, alkylamine, alkane, alkene, trioctylphosphine (TOP), trioctylphosphine oxide (TOPO), and the like.

Next, the pressurizing unit 10 is controlled to press the substrate C against the electrodeposition tank 4 (step S4). By executing step S4, as shown in FIG. 1B, the surface of the substrate C on which the planar electrode U is formed and the upper surface of the edge portion 20 are in contact with each other. As a result, the substrate gripping step of sandwiching the electrodeposition liquid L1 filled in the interior 4A between the substrate C and the bottom electrode 8 parallel to the substrate C is performed.

At this time, the surface of the flat electrode U exposed from the substrate C is immersed in the electrodeposition liquid L1 in the interior 4A. Therefore, the inside 4A is filled with the electrodeposition liquid L1, and the inside 4A is filled such that the liquid surface of the electrodeposition liquid L1 in the inside 4A is slightly higher than the upper surface of the edge portion 20 due to the surface tension. .. Thereby, even if the surface of the substrate C on which the planar electrode U is formed is flush, when the surface comes into contact with the upper surface of the edge portion 20, the surface of the planar electrode U is immersed in the electrodeposition liquid L1. It

In addition, in order to surely immerse the surface of the flat electrode U in the electrodeposition liquid L1 in step S4, the substrate C may be thinly formed only in the portion contacting the edge portion 20 in step S4. With this configuration, when the substrate C and the edge portion 20 are brought into contact with each other, the surface of the flat electrode U enters into the interior 4A more than the upper surface of the edge portion 20, so that the surface of the flat electrode U is more surely contacted. Be immersed in.

Since the substrate C is pressed against the upper surface of the edge portion 20 in step S4, as shown in FIG. 1B, the electrodeposition tank connection electrode D formed on the substrate C and the upper surface of the edge portion 20. The substrate connecting electrode 22 exposed from the abutment is brought into contact with and electrically connected.

After step S4, the electrodeposition process is performed.

In the present embodiment, the first particles M1 and the second particles M2 have polarities by having a specific functional group. Therefore, in the electrodeposition step, the first particles M1 and the second particles M2 migrate in the electrodeposition liquid L1 by Coulomb interaction due to the electric field generated between the bottom electrode 8 and the flat electrode U. Further, the first particles M1 and the second particles M2 have the same polarity. In the present embodiment, in the electrodeposition step, the voltage applied to each electrode is controlled so that the first particles M1 and the second particles M2 migrate toward the flat electrode U.

Further, each of the first particles M1 and the second particles M2 has a threshold voltage between the bottom electrode 8 and the plane electrode U, which is necessary for being adsorbed to the plane electrode U and forming a film on the plane electrode U. Each is different. The threshold voltage for each functional particle differs depending on the particle size of the functional particle, the type of ligand to be coordinated, or the number of coordinations to one functional particle.

In the present embodiment, the absolute value of the first threshold voltage V1 that is the threshold voltage for the first particles M1 is lower than the absolute value of the second threshold voltage V2 that is the threshold voltage for the second particles M2. That is, the first particles M1 are adsorbed to the flat electrode U to form a film under an electric field between the bottom electrode 8 and the flat electrode U, which are smaller than the second particles M2.

In the present embodiment, in the electrodeposition step, first, the first voltage whose absolute value is equal to or more than the absolute value of the first threshold voltage V1 and less than the absolute value of the second threshold voltage V2 is applied to the bottom electrode 8 The first film forming step of applying the voltage between the substrate and the flat electrode U is performed (step S6). In step S6, as shown in (c) of FIG. 1, among the functional particles contained in the electrodeposition liquid L1, only the first particles M1 migrate to the flat electrode U and are adsorbed on the flat electrode U.

By sufficiently applying the voltage in step S6, the first layer F1 including the first particles M1 shown in FIG. 1C is formed on the planar electrode U. In addition, step S6 is performed until almost all of the first particles M1 in the electrodeposition tank 4 are adsorbed on the flat electrode U for forming the first layer F1.

Subsequent to step S6, a second film forming step of applying a second voltage whose absolute value is greater than or equal to the absolute value of the second threshold voltage V2 between the bottom electrode 8 and the flat electrode U (step) is performed. S8). In step S8, the second particles M2 also migrate to the flat electrode U and are adsorbed on the flat electrode U. By sufficiently applying the voltage in step S8, the second layer F2 including the second particles M2 shown in (d) of FIG. 1 is formed on the first layer F1.

Since almost all the first particles M1 in the electrodeposition tank 4 are consumed in step S6, it is possible to reduce the mixing of the first particles M1 in the second layer F2 in step S8. The second layer F2 may contain a small amount of the first particles M1 as long as the density of the first particles M1 in the second layer F2 is lower than the standard of the defect as a final light emitting device. Therefore, in the present embodiment, a slight amount of the first particles M1 may be included in the electrodeposition tank 4 in step S8.

The present embodiment exemplifies a case where the functional material contained in the electrodeposition liquid L1 has a negative polarity. That is, a voltage of negative polarity is applied to the bottom electrode 8 and a voltage of positive polarity is applied to the plane electrode U. When the polarities of the functional material contained in the electrodeposition liquid L1 are reversed, the polarities of the voltages applied to the electrodes may be reversed.

Next, the voltage application between the bottom electrode 8 and the flat electrode U is released (step S10), and the electrodeposition process is completed. Next, as shown in FIG. 1E, the substrate C is pulled up from the electrodeposition bath 4 (step S12). Step S12 is executed by controlling the pressurizing unit 10 and separating the substrate C from the electrodeposition tank 4. Next, the substrate C is removed from the pressing unit 10 (step S14) to obtain the substrate C in which the first layer F1 and the second layer F2 are laminated on the flat electrode U from the lower layer. After that, the light emitting device may be manufactured by forming a counter substrate or the like on the upper layer of the second layer F2.

In the present embodiment, it is possible to perform electrodeposition of different functional particles without changing the electrodeposition liquid or the electrodeposition tank. For this reason, the tact time can be reduced even when a plurality of layers respectively containing different functional materials are formed.

In the present embodiment, the first substrate electrode, which is an electrode that applies the first voltage to the bottom electrode 8, and the second substrate electrode, which is the electrode that applies the second voltage to the bottom electrode 8. The case where and are the same plane electrode U has been described. According to this embodiment, a plurality of layers respectively containing different functional materials can be formed on the same plane electrode U by being laminated.

The mixing of the first particles M1 and the second particles M2 of the electrodeposition liquid L1 is preferably performed in step S6, that is, immediately before the first film forming step. When a long time has passed since the first particles M1 and the second particles M2 were mixed, adsorption and desorption of ligands may occur between the first particles M1 and the second particles M2. This is because ligand movement occurs equilibrium between the first particles M1 and the second particles M2. Therefore, when a long time has passed since the first particles M1 and the second particles M2 were mixed, as shown in FIG. 6B, both the first particles M1 and the second particles M2 Both the first ligand R1 and the second ligand R2 may change to a coordinated state.

By mixing the first particles M1 and the second particles M2 of the electrodeposition liquid L1 immediately before the first film forming step, the above-mentioned equilibration of the ligand is less likely to occur. For this reason, the ligand composition of the first particles M1 and the second particles M2 in the electrodeposition liquid L1 is more clearly different, so that the characteristics of the first particles M1 and the second particles M2 can be more clearly different. .. Therefore, the absolute values of the first threshold voltage V1 and the second threshold voltage V2 can be made to differ more clearly, and as a result, the yield of film formation of each functional particle is improved. Specifically, the mixing of the first particles M1 and the second particles M2 may be performed, for example, together with the filling of the electrodeposition liquid L1 into the electrodeposition tank 4.

The term "electrodeposition" in this specification includes an electrochemical film forming method for forming a thin film of a material in a solution by causing a potential difference between two electrodes in the solution. "Electrodeposition" in the present specification includes, for example, methods such as electrodeposition method, electrodeposition coating method, electrophoretic deposition method, dielectrophoretic deposition method, micelle electrolysis method, electroplating method and electroforming method. Good. Even when any one of these methods is selected as the electrodeposition step described above, it is possible to manufacture a light emitting device that achieves the effects described above.

[Modification]
A modified example of this embodiment will be described in detail with reference to FIG. 7. 7A to 7C, the vertical axis represents the voltage applied between the bottom electrode 8 and the flat electrode U in step S6, and the horizontal axis represents the elapsed time from the start of the application of the voltage. Is a graph illustrated in FIG.

The voltage application in step S6 is, for example, as shown in the graph of FIG. 7A, between the bottom electrode 8 and the plane electrode U, always higher than or equal to the first threshold voltage and lower than the second threshold voltage V2. It may be realized by continuing to apply the first voltage.

However, in the modified example of the present embodiment, the voltage application in step S6 is not limited to this, and the first voltage is applied between the bottom electrode 8 and the plane electrode U as shown in FIG. 7B. And the reverse voltage VR (eighth voltage) may be alternately applied. That is, step S6 is realized by alternately performing the forward voltage applying step of applying the first voltage and the reverse voltage applying step of applying the reverse voltage VR between the bottom electrode 8 and the flat electrode U. You may.

The reverse voltage VR has a polarity opposite to that of the first threshold voltage V1. The absolute value of the reverse voltage VR is smaller than the first threshold voltage V1 as shown in FIG. 7B. In addition, in step S6, as shown in FIG. 7B, the period of the reverse voltage applying step of applying the reverse voltage VR is shorter than the period of the forward voltage applying step of applying the first voltage. May be.

In step S6, as shown in the graph of FIG. 7A, when the first voltage is continuously applied between the bottom electrode 8 and the plane electrode U, the first particles M1 are always on the plane electrode side. It will continue to migrate. Further, although the second particles M2 are not adsorbed on the flat electrode U, they migrate in the direction of the flat electrode U, so that the density of the second particles M2 also increases on the flat electrode U side in the electrodeposition tank 4. ing.

Therefore, the second particles M2 caught in the first particles M1 may be adsorbed by the flat electrode U so as to be held by the first particles M1. Therefore, in the above-mentioned case, as shown in the process sectional view of the manufacturing apparatus 2 for a light emitting device at the time of completion of step S6 shown in FIG. There is.

In step S6, as shown in the graph of FIG. 7B, the forward voltage applying step and the reverse voltage applying step are alternately performed, so that the first particles M1 and the second particles M1 The particles M2 migrate toward the bottom electrode 8. Therefore, the first particles M1 and the second particles M2 repeat the migration to the bottom electrode 8 side and the migration to the flat electrode U side. Since the first voltage is applied in the forward voltage applying step, the first particles M1 gradually approach the flat electrode U while repeating the migration to the bottom electrode 8 side and the migration to the flat electrode U side. Finally, it is adsorbed on the flat electrode U.

Since the first particles and the second particles repeat the migration to the bottom electrode 8 side and the migration to the flat electrode U side, the second electrode M2 is held by the first particle M1 so that the flat electrode is held. The possibility of being adsorbed by U is reduced. Therefore, it is possible to reduce the occurrence of a film formation defect in which the second particles M2 are contained in the first layer F1. Since the absolute value of the reverse voltage VR is smaller than the absolute value of the first voltage V1, it is possible to reduce the adsorption of the first particles M1 to the bottom surface electrode 8.

Note that the method of alternately performing the forward voltage applying step and the reverse voltage applying step is not limited to the method of alternately applying the first voltage and the reverse voltage VR as shown in the graph of FIG. 7B. Absent. For example, as shown in FIG. 7C, the voltage may be applied so that the voltage between the bottom electrode 8 and the plane electrode U draws a sine wave with the elapsed time as the horizontal axis. In this case, the maximum value of the sine wave may be the first voltage and the minimum value may be the reverse voltage VR. Also in this case, the above-mentioned effects can be obtained similarly. As another example, the voltage between the bottom surface electrode 8 and the plane electrode U may draw a pseudo sine wave or a triangular wave with the elapsed time as the horizontal axis.

[Embodiment 2]
In and after the present embodiment, a manufacturing apparatus and a manufacturing method for performing electrodeposition on the substrate C shown in FIG. 9 will be described. FIG. 9 is a schematic perspective view of the substrate C according to this embodiment. The substrate C shown in FIG. 9 differs from the substrate C shown in FIG. 1 only in that it includes a plurality of pixel electrodes E instead of the planar electrodes U and a plurality of electrodeposition bath connection electrodes D.

The pixel electrode E is patterned on the substrate C so as to be exposed on either surface of the substrate C. For example, the pixel electrodes E are formed in a matrix on the substrate C.

A plurality of electrodeposition bath connection electrodes D are formed on the surface of the substrate C on which the pixel electrodes E are formed, along any two sides of the substrate C orthogonal to each other. A voltage can be applied to each pixel electrode E by applying a voltage to each electrodeposition bath connecting electrode D. For this reason, a plurality of transistors (not shown) connected to each pixel electrode E may be formed on the substrate C, and each transistor is driven by applying a voltage to each electrodeposition tank connection electrode D. A voltage may be applied to each pixel electrode E.

The pixel electrode E and the electrodeposition bath connection electrode D are flush with the surface of the substrate C on which the pixel electrode E and the electrodeposition bath connection electrode D are formed, and are exposed on the surface.

Also in the present embodiment, electrodeposition on the substrate C is performed using the light emitting device manufacturing apparatus 2. The light emitting device manufacturing apparatus 2 in the present embodiment may have the same configuration as the light emitting device manufacturing apparatus 2 in the previous embodiment. 10A and 10 are schematic diagrams corresponding to FIGS. 3A and 3C in a state where the substrate C and the electrodeposition tank 4 are pressed against each other in the present embodiment. (B) of each.

In the present embodiment, when the substrate C and the electrodeposition bath 4 are pressed against each other, the plurality of substrate connection electrodes 22 of the electrodeposition bath 4 and the plurality of electrodeposition bath connection electrodes D of the substrate C are respectively Come into contact with each other and become electrically conductive with each other. The electrodeposition power source 12 can individually apply a voltage to each of the pixel electrodes E on the substrate C via the substrate connection electrode 22 and the electrodeposition bath connection electrode D. Therefore, the electrodeposition power source 12 applies at least a binary voltage between each pixel electrode E and the bottom electrode 8.

An example of performing film formation by electrodeposition on the pixel electrode E of the substrate C using the light emitting device manufacturing apparatus 2 according to this embodiment will be described with reference to FIGS. 11 and 12. FIG. 11 is a flowchart for explaining an example of a manufacturing method using the light emitting device manufacturing apparatus 2 according to the present embodiment. FIG. 12 is a process cross-sectional view of the light emitting device manufacturing apparatus 2 and the substrate C in the manufacturing method shown in FIG. 12 is an enlarged side view of the vicinity of the electrodeposition tank 4 in the electrodeposition process of this embodiment.

In the present embodiment, the substrate C includes, as pixel electrodes E, a plurality of first pixel electrodes E1, second pixel electrodes E2, and third pixel electrodes E3, as shown in the drawings of FIG. There is. In the present embodiment, a method of forming layers made of functional particles different from each other on each of the first pixel electrode E1, the second pixel electrode E2, and the third pixel electrode E3 will be described.

In the method for manufacturing a light emitting device according to the present embodiment, first, the substrate C is installed in the light emitting device manufacturing apparatus 2 (step S2). Step S2 is executed as in the previous embodiment. However, in the present embodiment, before the substrate C installed in the pressurizing unit 10 is brought close to the electrodeposition tank 4 in step S2, the inside 4A is filled with the electrodeposition liquid L2 different from the electrodeposition liquid L1. There is.

The electrodeposition liquid L2 may contain the same solvent as the solvent of the electrodeposition liquid L1. The electrodeposition liquid L2 contains, as functional particles, third particles M3 in addition to the first particles M1 and the second particles M2 described in the previous embodiment. Similar to the first particles M1 and the second particles M2, the third particles M3 may be the material of the functional layer of the light emitting element, or may be semiconductor nanoparticles, that is, quantum dots.

Also in this embodiment, the third particles M3 have the same polarity as the first particles M1 and the second particles M2. Also in the present embodiment, the bottom electrode 8 and the pixel electrode E, which are necessary for the first particles M1 and the second particles M2 to be adsorbed on any of the pixel electrodes E and to be deposited on the pixel electrodes E, The first threshold voltage V1 and the second threshold voltage V2 are respectively provided as the threshold voltages between the two. In addition, the absolute value of the third threshold voltage V3, which is the threshold voltage required for the third particles M3 to be adsorbed on any of the pixel electrodes E and to be formed on the pixel electrodes E, is the second threshold voltage. Greater than the absolute value of V2.

Next, similarly to the previous embodiment, the pressurizing unit 10 is controlled to press the substrate C against the electrodeposition tank 4, and the substrate holding step is performed (step S4). As a result, the pixel electrode E on the substrate C is immersed in the electrodeposition liquid L2. Following step S4, an electrodeposition step is performed.

In the present embodiment, in the electrodeposition step, first, the first voltage whose absolute value is equal to or more than the absolute value of the first threshold voltage V1 and less than the absolute value of the second threshold voltage V2 is applied to the bottom electrode 8 And a first pixel electrode E1 is applied between the first film forming step (step S16). In step S16, as shown in (a) of FIG. 12, among the functional particles contained in the electrodeposition liquid L2, only the first particles M1 migrate to the first pixel electrode E1, and the first particles M1 are deposited on the first pixel electrode E1. Adsorbed.

By sufficiently applying the voltage in step S16, the first layer F1 including the first particles M1 shown in FIG. 12B is formed on the first pixel electrode E1. Note that step S16 is performed until almost all of the first particles M1 in the electrodeposition tank 4 are adsorbed on the first pixel electrode E1 for forming the first layer F1.

Here, in the electrodeposition step, it may be difficult to apply a uniform voltage to all the pixel electrodes E on which film formation is desired. In particular, a voltage drop may occur in the specific pixel electrode E. The above will be described while comparing the present embodiment with the comparative embodiment.

FIGS. 13A and 13B are process cross-sectional views for explaining the electrodeposition process using the light emitting device manufacturing apparatus 2 according to the present embodiment. 13C and 13D are process cross-sectional views for explaining an electrodeposition process using the light emitting device manufacturing apparatus according to the comparative embodiment.

The light emitting device manufacturing apparatus according to the comparative embodiment is related to the present embodiment, except that, instead of the electrodeposition tank 4, it is provided with an electrodeposition tank 4C having a distance d2 larger than the distance d1 as a depth. The light emitting device manufacturing apparatus 2 has the same configuration.

Here, in the present embodiment and the comparative form, it is assumed that the voltage applied to the first pixel electrode E1B of the first pixel electrodes E1 is lower than the desired voltage with respect to the first pixel electrode E1A. In this case, the electric field generated between the bottom electrode 8 and the first pixel electrode E1B is weaker than the electric field generated between the bottom electrode 8 and the first pixel electrode E1A. The first layer F1 formed on each of the first pixel electrode E1A and the first pixel electrode E1B is referred to as a first layer F1A and a first layer F1B, respectively. In this case, the film formation rate of the first layer F1B becomes slower than the film formation rate of the first layer F1A.

However, the first particles M1 existing in the vicinity of a specific pixel electrode E decrease due to the film formation of the first layer F1, and the film formation rate of the first particles M1 on the pixel electrode E rapidly decreases. .. Here, in the film forming step, since the film forming rate of the first layer F1A is relatively high, the first particles M1 near the first pixel electrode E1A are consumed relatively quickly. Further, in the electrodeposition tank 4 having the depth of the relatively short distance d1 as in the present embodiment, the total amount of the first particles M1 in the electrodeposition tank 4 is relatively small. Therefore, in the film forming step, the first particles M1 in the vicinity of the first pixel electrode E1A rapidly decrease, and therefore, after the first layer F1A is continuously formed for a while, the film forming rate of the first layer F1A is Falls rapidly.

Further, since the film formation rate of the first layer F1B is relatively slow, the first particles M1 still remain in the vicinity of the first pixel electrode E1B even when the film formation rate of the first layer F1A rapidly decreases. ing. For this reason, as time further elapses, the film formation of the first layer F1B continues even after the film formation of the first layer F1A is substantially stopped. The film formation of the first layer F1B continues until the amount of the first particles M1 near the first pixel electrode E1B decreases.

Assuming that the first particles M1 are substantially evenly dispersed in the electrodeposition liquid L2, the total amount of the first particles M1 near each pixel electrode is substantially the same. That is, when the film formation takes a sufficient time, the amounts of the first particles M1 contained in the first layer F1A and the first layer F1B become substantially the same. Therefore, as shown in FIG. 13B, when the film thicknesses of the first layer F1A and the first layer F1B are set to the film thickness dF1 and the film thickness dF2, respectively, the film thickness dF1 and the film thickness dF2 are substantially the same. The film thickness is the same.

Therefore, the light emitting device manufacturing apparatus 2 according to the present embodiment forms a film on each pixel electrode E even when a voltage drop occurs in a specific pixel electrode E when a voltage is applied to each pixel electrode E. The difference in film thickness between the formed layers can be reduced.

On the other hand, in the electrodeposition tank 4C having a relatively long distance d2 as the depth as in the comparative embodiment, the total amount of the first particles M1 in the electrodeposition tank 4C becomes relatively large. Therefore, even after the first layer F1A has been formed for a while, a relatively large number of first particles M1 near the first pixel electrode E1A remain. Therefore, the film formation rate of the first layer F1A does not decrease for a relatively long time, and the film formation of the first layer F1A is continuously performed. Therefore, in the comparative embodiment, film formation is continued not only on the first pixel electrode E1B but also on the first pixel electrode E1A while the voltage is being applied.

Therefore, the film thickness of the first layer F1A is larger than that of the first layer F1B due to the rapid film formation of the first layer F1A having a higher film formation rate than that of the first layer F1B. Become. That is, as shown in (d) of FIG. 13, when the film thicknesses of the first layer F1A and the first layer F1B are respectively set to the film thickness dFA and the film thickness dFB, the film thickness dFA is larger than the film thickness dFB. Become.

Therefore, when the voltage application is released when the film thickness of the first layer F1A reaches the target film thickness of the first layer F1, the film thickness of the first layer F1B is the target film thickness of the first layer F1B. It becomes thinner than the thickness. In addition, a relatively large amount of the first particles M1 in the vicinity of the first pixel electrode E1B, which were not formed as the first layer F1B, remain. Therefore, the remaining first particles M1 may be formed on the second pixel electrode E2 or the third pixel electrode E3 in a later step.

In the film forming process of the present embodiment, the distance d1 corresponding to the depth of the electrodeposition tank 4 is appropriately designed, and when the first particles M1 are all consumed, the target film thickness of the first layer F1 is set. It may be designed to have a film thickness. As a result, after the completion of the first film forming step, almost all of the first particles M1 in the electrodeposition liquid L2 are consumed, so that the above-mentioned film thickness difference can be reduced.

Subsequent to step S16, a second voltage whose absolute value is greater than or equal to the absolute value of the second threshold voltage V2 and less than the absolute value of the third threshold voltage V3 is applied to the bottom electrode 8 and the second pixel electrode E2. The second film forming process is applied during this period (step S18). In step S18, as shown in FIG. 12C, of the second particles M2 and the third particles M3, only the second particles M2 migrate to the second pixel electrode E2, and then on the second pixel electrode E2. Adsorbed. By sufficiently applying the voltage in step S18, the second layer F2 including the second particles M2 shown in FIG. 12D is formed on the second pixel electrode E2.

Since almost all the first particles M1 in the electrodeposition tank 4 are consumed in step S16, it is possible to reduce the mixing of the first particles M1 in the second layer F2 in step S18. The second layer F2 may contain a small amount of the first particles M1 as long as the density of the first particles M1 in the second layer F2 is lower than the standard of the defect as a final light emitting device. Therefore, in the present embodiment, a slight amount of the first particles M1 may be included in the electrodeposition tank 4 in step S18.

Subsequent to step S18, a third film forming step of applying a third voltage whose absolute value is equal to or more than the absolute value of the third threshold voltage V3 between the bottom electrode 8 and the third pixel electrode E3 is performed. (Step S20). In step S20, as shown in (e) of FIG. 12, the third particles M3 migrate to the third pixel electrode E3 and are adsorbed on the third pixel electrode E3. By sufficiently applying the voltage in step S20, the third layer F3 including the third particles M3 shown in FIG. 12F is formed on the third pixel electrode E3.

In step S16 and step S18, the first particles M1 and the second particles M2 in the electrodeposition tank 4 are almost completely consumed. Therefore, in step S20, the first particles M1 or the second particles M2 are contained in the third layer F3. Can be reduced. In addition, as long as the respective densities of the first particles M1 and the second particles M2 in the third layer F3 are lower than the standard of defectiveness as a final light emitting device, a small amount of the first particles M1 or the second particles M1 in the third layer F3 or Two particles M2 may be included. Therefore, in the present embodiment, a slight amount of the first particles M1 or the second particles M2 may be included in the electrodeposition tank 4 in step S20.

Next, the voltage application between the bottom electrode 8 and the pixel electrode E is released (step S22), and the electrodeposition process is completed. Then, step S12 and step S14 described above are performed in the same manner as in the previous embodiment. As a result, a substrate C including the first layer F1, the second layer F2, and the third layer F3 on the first pixel electrode E1, the second pixel electrode E2, and the third pixel electrode E3 is obtained. After that, a light emitting device may be manufactured by forming a counter substrate or the like on the first layer F1, the second layer F2, and the third layer F3.

In the present embodiment, the first substrate electrode, which is the electrode that applies the first voltage to the bottom electrode 8, is the first pixel electrode E1, and the electrode that applies the second voltage to the bottom electrode 8. A certain second substrate electrode is the second pixel electrode E2. That is, the first substrate electrode and the second substrate electrode are different from each other. According to this embodiment, it is possible to individually form a plurality of layers each containing a different functional material on the first pixel electrode E1 and the second electrode E2. Particularly, in the present embodiment, the first layer F1 containing the first particles M1 is formed on the first pixel electrode E1, and the second layer F2 containing the second particles M2 is formed on the second pixel electrode E2, respectively. it can.

Furthermore, in the present embodiment, the third substrate electrode that is an electrode that applies the third voltage between the bottom electrode 8 and the bottom electrode 8 is the third pixel electrode E3 that is different from the first pixel electrode E1 and the second pixel electrode E2. .. Therefore, in the present embodiment, the third layer F3 containing the third particles M3 can be separately formed on the third pixel electrode E3 independently of the first layer F1 and the second layer F2.

In the present embodiment, for example, the first particles M1, the second particles M2, and the third particles M3 may be quantum dots that emit blue light, green light, and red light, respectively. With this structure, it is possible to manufacture a light emitting device including a light emitting element that emits blue light, green light, and red light in each of the plurality of sub-pixels. In addition, this configuration is preferable in the following points because the quantum dots emitting blue light, the quantum dots emitting green light, and the quantum dots emitting red light are electrodeposited on the pixel electrode E in this order.

Generally speaking, the wavelength of light emitted by a quantum dot becomes longer as the diameter of the quantum dot becomes smaller. Furthermore, the smaller the quantum dot diameter, the more likely the quantum dot is to aggregate. Therefore, the quantum dots that emit blue light tend to aggregate more easily than the quantum dots that emit green light and red light, respectively. Furthermore, under the electric field of the same strength, particles that are more likely to aggregate are more likely to be adsorbed on the electrode by electrodeposition.

Therefore, the quantum dots that emit blue light tend to have a lower threshold voltage as compared with the quantum dots that emit green light and red light, respectively, because adsorption to the electrode by electrodeposition occurs. Similarly, a quantum dot that emits green light tends to have a lower threshold voltage required for adsorption to an electrode due to electrodeposition, as compared with a quantum dot that emits red light.

Therefore, in the present embodiment, it is preferable to electrodeposit the quantum dots emitting blue light before the quantum dots emitting green light and red light respectively. With this configuration, it is possible to more efficiently reduce mixing of the quantum dots emitting blue light into a layer including other quantum dots in a step subsequent to the step of electrodepositing the quantum dots emitting blue light.

Similarly, in the present embodiment, it is preferable that the quantum dots that emit green light be electrodeposited before the quantum dots that emit red light. With this configuration, it is possible to more efficiently reduce the mixing of the quantum dots emitting green light into the layer including the quantum dots emitting red light in a step subsequent to the step of electrodepositing the quantum dots emitting green light.

Also, generally, the shorter the wavelength of light emitted by a quantum dot, the greater the voltage required to cause the quantum dot to emit light. Therefore, as compared with the admissible amount of quantum dots having a shorter emission wavelength in a pixel having a longer emission wavelength, the admissible amount of quantum dots having a longer emission wavelength is smaller in a pixel having a shorter emission wavelength. In addition, in the present embodiment, the main quantum dots that are unintentionally electrodeposited in a certain electrodeposition process are not consumed in the electrodeposition process before the electrodeposition process and are not consumed in the electrodeposition tank 4. It is the quantum dot that remained in.

That is, when quantum dots emitting blue light, green light, and red light, respectively, are electrodeposited in this order, the main quantum dots that are unintentionally mixed in a certain electrodeposition process are the quantum dots to be electrodeposited. The quantum dots emit light of a wavelength shorter than the wavelength of the emitted light. Therefore, in the present embodiment, the quantum dots that emit blue light, green light, and red light, respectively, are electrodeposited in this order, and the mixing amount of the quantum dots that are unintentionally electrodeposited is an allowable amount. Can be reduced more efficiently.

[Embodiment 3]
FIG. 14 is a flowchart for explaining an example of a manufacturing method using the light emitting device manufacturing apparatus 2 according to the present embodiment. FIG. 15 is a process cross-sectional view of the light emitting device manufacturing apparatus 2 and the substrate C in the manufacturing method shown in FIG. In each figure of FIG. 15, an enlarged side view of the vicinity of the electrodeposition tank 4 in the electrodeposition step of the present embodiment is shown. An example of performing film formation by electrodeposition on the pixel electrode E of the substrate C using the light emitting device manufacturing apparatus 2 according to this embodiment will be described with reference to FIGS. 14 and 15.

The light emitting device manufacturing apparatus 2 and the substrate C in the present embodiment have the same configurations as the light emitting device manufacturing apparatus 2 and the substrate C in the previous embodiment, respectively.

In the method for manufacturing a light emitting device according to the present embodiment, first, the substrate C is installed in the light emitting device manufacturing apparatus 2 (step S2). Step S2 is executed as in the previous embodiment. However, in the present embodiment, before the substrate C installed in the pressurizing unit 10 in step S2 is brought close to the electrodeposition tank 4, the electrodeposition liquid L1 and the electrodeposition liquid L2 different from the electrodeposition liquid L1 are provided in the interior 4A. It is filled with L3.

The electrodeposition liquid L3 may contain the same solvent as the solvent of the electrodeposition liquid L1 and the electrodeposition liquid L2. The electrodeposition liquid L3 contains, as functional particles, fourth particles M4 and fifth particles M5 in addition to the first particles M1, the second particles M2, and the third particles M3 described in the above embodiment. The fourth particles M4 and the fifth particles M5 may be the material of the functional layer of the light emitting device, like the first particles M1, the second particles M2, and the third particles M3. It may be a dot.

Also in this embodiment, the fourth particles M4 and the fifth particles M5 have the same polarity as the first particles M1, the second particles M2, and the third particles M3. Also in the present embodiment, the first particles M1, the second particles M2, and the third particles M3 are the first threshold voltage V1 and the second threshold voltage, respectively, as the threshold voltages between the bottom electrode 8 and the pixel electrode E. V2 and a third threshold voltage V3. Further, the absolute value of the fourth threshold voltage V4, which is the threshold voltage required for the fourth particles M4 to be adsorbed on any of the pixel electrodes E and to be formed on the pixel electrodes E, is the first threshold voltage. It is smaller than the absolute value of V1. In addition, the absolute value of the fifth threshold voltage V5, which is the threshold voltage required for the fifth particles M5 to be adsorbed on any of the pixel electrodes E and to be formed on the pixel electrodes E, is the third threshold. It is larger than the absolute value of the voltage V3.

Next, similarly to the previous embodiment, the pressurizing unit 10 is controlled to press the substrate C against the electrodeposition tank 4, and the substrate holding step is performed (step S4). As a result, the pixel electrode E on the substrate C is immersed in the electrodeposition liquid L3. Following step S4, an electrodeposition step is performed.

In the present embodiment, in the electrodeposition process, first, a fourth voltage whose absolute value is equal to or more than the absolute value of the fourth threshold voltage V4 and less than the absolute value of the first threshold voltage V1 is applied to the bottom electrode 8 And a fourth film forming step of applying the voltage between all the pixel electrodes E (step S24). In step S24, as shown in FIG. 15A, among the functional particles contained in the electrodeposition liquid L3, only the fourth particles M4 migrate to each of the pixel electrodes E and are adsorbed on the pixel electrodes E. It

By sufficiently applying the voltage in step S24, the fourth layer F4 including the fourth particles M4 shown in FIG. 15B is formed on all the pixel electrodes E. Note that step S24 is performed until almost all of the fourth particles M4 in the electrodeposition tank 4 are adsorbed on the pixel electrode E for forming the fourth layer F4.

Then, step S16, step S18, and step S20 are executed by the same method as in the previous embodiment. FIG. 15C shows a state in which the first voltage is applied between the first pixel electrode E1 and the bottom electrode 8 in step S16. Here, in the present embodiment, in step S16, the fourth layer F4 at the position overlapping the first pixel electrode E1 adsorbs the first particles M1.

By executing step S16, step S18, and step S20 in the present embodiment, as shown in FIG. 15D, the first layer F1, the second layer F2, and the third layer F3 are formed. Is obtained. Here, the first layer F1 is formed on the fourth layer F4 at a position overlapping with the first pixel electrode E1. In addition, the second layer F2 is formed on the fourth layer F4 at a position overlapping with the second pixel electrode E2. Further, the third layer F3 is formed on the fourth layer F4 at a position overlapping with the third pixel electrode E3.

In step S24, almost all of the first particles M1 in the electrodeposition tank 4 are consumed, so in step S16, step S18, and step S20, respectively, in the first layer F1, the second layer F2, and the second layer F2. Mixing of the fourth particles M4 in the three-layer F3 can be reduced. In addition, as long as the density of the fourth particles M4 in the first layer F1, the second layer F2, or the third layer F3 is lower than the standard of the defect as a final light emitting device, A minute amount of the fourth particles M4 may be included in the second layer F2 or the third layer F3. Therefore, in the present embodiment, a small amount of the fourth particles M4 may be included in the electrodeposition tank 4 in each of step S16, step S18, and step S20.

Subsequent to step S20, a fifth film forming step of applying a fifth voltage whose absolute value is equal to or more than the absolute value of the fifth threshold voltage V5 between the bottom electrode 8 and all the pixel electrodes E is performed. (Step S26). In step S26, as shown in (e) of FIG. 15, the fifth particles M5 migrate to and are adsorbed on each of the first layer F1, the second layer F2, and the third layer F3. By sufficiently performing the voltage application in step S26, the fifth layer M5 shown in (f) of FIG. 15 is formed on each of the first layer F1, the second layer F2, and the third layer F3. The layer F5 is deposited.

Before step S26, almost all the functional particles other than the fifth particles M5 in the electrodeposition tank 4 are consumed, so that the functional particles other than the fifth particles M5 are mixed in the fifth layer F5 in step S26. Can be reduced. In addition, as long as the density of the functional particles excluding the fifth particles M5 in the fifth layer F5 is lower than the standard of the defect as a final light emitting device, the functional particles excluding the fifth particles M5 are included in the fifth layer F5. , May be contained in a very small amount. Therefore, in the present embodiment, a small amount of functional particles other than the fifth particles M5 may be included in the electrodeposition tank 4 in step S26.

Next, the voltage application between the bottom electrode 8 and the pixel electrode E is released (step S22), and the electrodeposition process is completed. Then, step S12 and step S14 described above are performed in the same manner as in the previous embodiment. As a result, the substrate C is obtained by stacking the fourth layer F4, the first layer F1, the second layer F2, the third layer F3, and the fifth layer F5 on the pixel electrode E in this order. ..

An example of a light emitting device including the substrate C obtained in the present embodiment will be described with reference to FIG. Each drawing of FIG. 16 is a sectional side view of the light emitting device LD according to the present embodiment. The light emitting device LD shown in FIG. 16A is obtained by forming the counter substrate CC on the fifth layer F5 of the substrate C described above.

The counter substrate CC has a single common electrode CE as a substrate electrode. The common electrode CE is formed on the counter substrate CC so as to be exposed on one surface of the counter substrate CC.

In the light emitting device LD, the counter substrate CC and the common electrode CE face each other via the fourth layer F4 to the fifth layer F5 of the substrate C. Here, the common electrode CE overlaps all the pixel electrodes E on the substrate C and is in contact with all the fifth layers F5. The configuration of the light emitting device LD shown in each drawing of FIG. 16 is an example in this embodiment. Alternatively, for example, in the light emitting device LD, the common electrode CE may be directly provided on the upper layer of the layer electrodeposited on the substrate C (for example, the upper layer of the fifth layer). In addition to this, for example, in the light emitting device LD, instead of the counter substrate CC, the common electrode CE and the sealing glass held with a space between the common electrode CE and the common electrode CE are electrodeposited on the substrate C. It may be provided on the upper layer of the layer.

In the light emitting device LD, the first layer F1, the second layer F2, and the third layer F3 may be a blue light emitting layer, a green light emitting layer, and a red light emitting layer, respectively. Further, each of the fourth layer F4 and the fifth layer F5 may be a hole transport layer or an electron transport layer.

In this case, in the light emitting device LD, between the substrate C and the counter substrate CC, the blue light emitting element is arranged at a position overlapping with the first layer F1, the green light emitting element is arranged at a position overlapping with the second layer F2, and the third layer is formed. The light emitting device may include a red light emitting element at a position overlapping with F3. The light emitting device LD may function as a display device by providing the blue light emitting element in the blue sub pixel, the green light emitting element in the green sub pixel, and the red light emitting element in the red sub pixel.

Either one of the substrate C and the counter substrate CC may be a transparent substrate provided with a transparent electrode. In this case, the light emitting device LD may take out the light from each light emitting element from the transparent substrate side.

The light emission of each light emitting element may be realized by driving each pixel electrode E. In this case, the electrodeposition tank connection electrode D may function as a terminal for inputting a signal for driving each pixel electrode E.

Here, another example of the light emitting device LD according to the present embodiment will be described with reference to FIG.

Ideally, in the light emitting device LD, as shown in (a) of FIG. 16, each of the first layer F1, the second layer F2, and the third layer F3 has a first particle M1, a second particle M2, And it is preferable that it consists of only the third particles M3.

However, in the manufacturing method of the present embodiment, for the reasons described above, as shown in FIG. 16B, the first particles M1 are formed in the second layer F2 and the first particles M1 are formed in the third layer F3. The second particles M2 may be contained in a small amount.

Here, the first particles M1 in the second layer F2 tend to be formed on the pixel electrode E side in the second layer F2, as shown in (b) of FIG. This is because immediately before the second film forming step, the remaining first particles M1 have already migrated to the pixel electrode E side in the electrodeposition tank 4, so that in the subsequent second film forming step, This is because one particle M1 tends to be preferentially adsorbed. For the same reason, the first particles M1 and the second particles M2 in the third layer F3 tend to be formed on the pixel electrode E side in the third layer F3, as shown in (b) of FIG. ..

By the way, in a light emitting device including a plurality of quantum dots stacked between a hole transporting layer and an electron transporting layer, in general, the light emission of the light emitting device is near the interface of the light emitting layer on the hole transporting layer side. Tend to occur in. This is because when the light emitting layer is composed of quantum dots, the mobility of holes in the light emitting layer is lower than the mobility of electrons in the light emitting layer.

From the above circumstances, in the present embodiment, it is preferable that the pixel electrode E of the substrate C is the cathode of the light emitting element described above, and the common electrode CE of the counter substrate CC is the anode of the light emitting element described above. In this case, it is preferable that the fourth layer F4 function as an electron transport layer and the fifth layer F5 function as a hole transport layer.

With the above configuration, the first particles M1 in the second layer F2 and the first particles M1 and the second particles M2 in the third layer F3 are on the fourth layer F4 of each layer, that is, on the electron transport layer side. It is easily formed. Therefore, even when each light emitting element of the light emitting device LD is driven, the first particles M1 in the second layer F2 and the first particles M1 and the second particles M2 in the third layer F3 emit light. Hard to do. Therefore, so-called color mixing, in which different light is emitted from the light emitting element that emits light of a specific color, is reduced, and display quality is improved.

[Embodiment 4]
FIG. 17 is a process cross-sectional view of the light-emitting device manufacturing apparatus 2 and the substrate C for explaining an example of the manufacturing method using the light-emitting device manufacturing apparatus 2 according to the present embodiment. 17 is an enlarged side view of the vicinity of the electrodeposition tank 4 in the electrodeposition process of this embodiment.

The light emitting device manufacturing apparatus 2 and the substrate C in the present embodiment have the same configurations as the light emitting device manufacturing apparatus 2 and the substrate C in the previous embodiment, respectively. Further, the method for manufacturing the light emitting device according to the present embodiment can be realized by the same method as the method for manufacturing the light emitting device according to the previous embodiment, except for steps S24 and S26 in each step of the flowchart shown in FIG. .. An example of performing film formation by electrodeposition on the pixel electrodes E of the substrate C using the light emitting device manufacturing apparatus 2 according to this embodiment will be described with reference to FIGS. 14 and 17.

In the method for manufacturing a light emitting device according to the present embodiment, first, the substrate C is installed in the light emitting device manufacturing apparatus 2 (step S2). Step S2 is executed as in the previous embodiment. However, in the present embodiment, before the substrate C installed in the pressurizing unit 10 in step S2 is brought close to the electrodeposition tank 4, the electrodeposition solution L1, the electrodeposition solution L2, and the electrodeposition solution L2 are placed in the interior 4A. An electrodeposition liquid L4 different from L3 is filled.

The electrodeposition liquid L4 may contain the same solvent as the solvent of the electrodeposition liquid L1, the electrodeposition liquid L2, and the electrodeposition liquid L3. The electrodeposition liquid L4 contains, as functional particles, the first particles M1, the second particles M2, and the third particles M3 described in the previous embodiment. Furthermore, the electrodeposition liquid L4 includes fourth particles M4A, fourth particles M4B, and fourth particles M4C instead of the fourth particles M4, and instead of the fifth particles M5, as compared with the electrodeposition liquid L3. , Fifth particles M5A, fifth particles M5B, and fifth particles M5C.

The fourth particles M4A, the fourth particles M4B, the fourth particles M4C, the fifth particles M5A, the fifth particles M5B, and the fifth particles M5C may have the same configuration as the functional particles up to the previous embodiment, In particular, they have the same polarity. Here, the absolute values of the threshold voltages of the fourth particles M4A, the fourth particles M4B, and the fourth particles M4C are smaller than the absolute values of the threshold voltages of the first particles M1 and are different from each other. The absolute values of the threshold voltages of the fifth particles M5A, the fifth particles M5B, and the fifth particles M5C are larger than the absolute values of the threshold voltages of the third particles M3, and are different from each other.

In particular, in the present embodiment, the absolute value of the threshold voltage of the fourth particles M4B is larger than the absolute value of the threshold voltage of the fourth particles M4A and smaller than the absolute value of the threshold voltage of the fourth particles M4C. Further, in the present embodiment, the absolute value of the threshold voltage of the fifth particles M5B is larger than the absolute value of the threshold voltage of the fifth particles M5A and smaller than the absolute value of the threshold voltage of the fifth particles M5C.

In the present embodiment, in step S24, first, a voltage whose absolute value is larger than the absolute value of the threshold voltage of the fourth particles M4A and smaller than the absolute value of the threshold voltage of the fourth particles M4B is set as the bottom electrode 8. The voltage is applied to the first pixel electrode E1. Thereby, as shown in FIG. 17A, only the fourth particles M4A migrate to each of the first pixel electrodes E1 and are adsorbed on the first pixel electrodes E1.

By sufficiently performing the above voltage application, the fourth layer F4A containing the fourth particles M4A shown in FIG. 17B is formed on the first pixel electrode E1. The voltage application is performed until almost all of the fourth particles M4A in the electrodeposition tank 4 are adsorbed on the pixel electrode E for forming the fourth layer F4A.

As described above, the absolute values of the threshold voltages of the fourth particles M4A, the fourth particles M4B, and the fourth particles M4C are different from each other. Therefore, as described above, the fourth layer F4A can be formed by adsorbing only the fourth particles M4A only on the first pixel electrode E1.

By applying the same method to the fourth particles M4B, the fourth layer F4B containing the fourth particles M4B can be formed on the second pixel electrode E2 as shown in (c) of FIG. Further, by applying the same method to the fourth particles M4C, as shown in FIG. 17C, the fourth layer F4C including the fourth particles M4C is separately formed on the third pixel electrode E3. can do. As a result, the fourth layer F4 including the fourth layer F4A, the fourth layer F4B, and the fourth layer F4C shown in (c) of FIG. 17 is provided on different pixel electrodes E, respectively.

Then, Step S16, Step S18, and Step S20 are carried out in the same manner as in the previous embodiment to form the first layer F1, the second layer F2, and the third layer F3 shown in FIG. 17D. .. Here, in the present embodiment, as shown in FIG. 17D, the first layer F1 is placed on the fourth layer F4A, the second layer F2 is placed on the fourth layer F4B, and the third layer F3 is placed on the fourth layer F4B. A film is formed on the four-layer F4C.

Next, in the present embodiment, in step S26, first, a voltage whose absolute value is larger than the absolute value of the threshold voltage of the fifth particles M5A and smaller than the absolute value of the threshold voltage of the fifth particles M5B is set to the bottom surface. The voltage is applied between the electrode 8 and the first pixel electrode E1. As a result, as shown in (e) of FIG. 17, only the fifth particles M5A migrate to each of the first layers F1 and are adsorbed on the first layers F1.

By sufficiently performing the voltage application described above, the fifth layer F5A including the fifth particles M5A shown in (f) of FIG. 17 is formed on the first layer F1. The voltage application is performed until almost all of the fifth particles M5A in the electrodeposition tank 4 are adsorbed on the pixel electrode E for forming the fifth layer F5A.

As described above, the absolute values of the threshold voltages of the fifth particles M5A, the fifth particles M5B, and the fifth particles M5C are different from each other. Therefore, as described above, the fifth layer F5A can be formed by adsorbing only the fifth particles M5A only on the first layer F1.

By applying the same method to the fifth particles M5B, the fifth layer F5B including the fifth particles M5B can be formed in the second layer F2 as shown in (f) of FIG. Further, by applying the same method to the fifth particles M5C, as shown in (f) of FIG. 17, the fifth layer F5C including the fifth particles M5C is separately formed on the third layer F3. be able to. Thus, the fifth layer F5A, the fifth layer F5B, and the fifth layer F5C shown in (f) of FIG. 17 are provided on the first layer F1, the second layer F2, and the third layer F3, respectively. In addition, the fifth layer F5 is obtained.

Next, step S22, step S12, and step S14 are performed in the same manner as in the previous embodiment. As a result, in the present embodiment, as compared with the substrate C of the previous embodiment, the substrates C individually formed at the positions overlapping the pixel electrodes E are also formed for the fourth layer F4 and the fifth layer F5. can get.

An example of a light emitting device including the substrate C obtained in the present embodiment will be described with reference to FIG. FIG. 18 is a sectional side view of the light emitting device LD according to this embodiment. The light emitting device LD shown in FIG. 18 is obtained by forming the counter substrate CC on the fifth layer F5 of the substrate C described above. The counter substrate CC has the same configuration as the counter substrate CC in the previous embodiment.

The light emitting device LD in the present embodiment is individually formed for each pixel electrode E in the fourth layer F4 and the fifth layer F5 as compared with the light emitting device LD in the previous embodiment. Therefore, the functional particles contained in the fourth layer F4 with which the first layer F1, the second layer F2, and the third layer F3 are in contact are different from each other. Similarly, the functional particles contained in the fifth layer F5 with which the first layer F1, the second layer F2, and the third layer F3 are in contact are different from each other.

Therefore, in the present embodiment, the fourth layer F4 and the fifth layer F5 suitable for the first layer F1, the second layer F2, and the third layer F3 can be individually formed. In particular, when the first layer F1, the second layer F2, and the third layer F3 of the light emitting device LD according to the present embodiment are light emitting layers that emit light of different colors, respectively, a hole transport layer suitable for the respective light emitting layers and The electron transport layer may be different for each color emitted.

In the present embodiment, for example, when the fourth layer F4 is an electron transport layer and the fifth layer F5 is a hole transport layer, an appropriate electron transport layer and hole transport layer are separately formed for each color to be emitted. be able to. Therefore, according to the manufacturing method of the present embodiment, it is possible to provide the light emitting device LD including the light emitting element with further improved light emitting efficiency.

In addition, in step S16 in each of the above-described embodiments, the sixth voltage may be applied between the bottom electrode 8 and the second pixel electrode E2 and the third pixel electrode E3 that do not adsorb the first particles M1. Good. Here, the absolute value of the sixth voltage is smaller than the absolute value of the first voltage.

According to the configuration, the first particles M1 migrate toward the first pixel electrode E1 also by the electric field generated between the second pixel electrode E2 and the third pixel electrode E3 and the first pixel electrode E1. Therefore, the film formation rate of the first layer F1 on the first pixel electrode E1 is improved. Since the absolute value of the sixth voltage is smaller than the absolute value of the first voltage, adsorption of the first particles M1 by the second pixel electrode E2 or the third pixel electrode E3 is reduced.

Furthermore, the sixth voltage may have a polarity opposite to that of the first voltage. With this configuration, it is possible to further reduce the adsorption of the first particles M1 by the second pixel electrode E2 and the third pixel electrode E3. Since the absolute value of the sixth voltage is smaller than the absolute value of the first voltage as described above, adsorption of the first particles M1 by the bottom surface electrode 8 is also reduced in the above configuration.

Similarly, in step S18 in each of the above-described embodiments, the seventh voltage is applied between the bottom electrode 8 and the first pixel electrode E1 and the third pixel electrode E3 that do not adsorb the second particles M2. Good. Here, the absolute value of the seventh voltage is smaller than the absolute value of the second voltage.

According to the configuration, the second particles M2 migrate toward the second pixel electrode E2 also by the electric field generated between the first pixel electrode E1 and the third pixel electrode E3 and the second pixel electrode E2. Therefore, the film formation rate of the second layer F2 on the second pixel electrode E2 is improved. Since the absolute value of the seventh voltage is smaller than the absolute value of the second voltage, the adsorption of the second particles M2 by the first pixel electrode E1 or the third pixel electrode E3 is reduced.

Furthermore, the seventh voltage may have a polarity opposite to that of the second voltage. With this configuration, it is possible to more efficiently reduce the adsorption of the second particles M2 by the first pixel electrode E1 and the third pixel electrode E3. Since the absolute value of the seventh voltage is smaller than the absolute value of the second voltage as described above, adsorption of the second particles M2 by the bottom surface electrode 8 is also reduced in the above configuration.

The present invention is not limited to the above-described embodiments, but various modifications can be made within the scope of the claims, and 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 of the embodiments.

2 Light Emitting Device Manufacturing Equipment 4 Electrodeposition Tank 8 Bottom Electrode C Substrate E Pixel Electrode U Planar Electrode LD Light Emitting Device L1, L2, L3 Electrodeposition Solution M1 First Particle M2 Second Particle M3 Third Particle M4 Fourth Particle M5 5 particles

Claims

A method for manufacturing a light-emitting device, which comprises electrodepositing functional particles on a substrate electrode formed on a substrate,
A substrate gripping step of sandwiching an electrodeposition liquid containing first particles and second particles different from the first particles as the functional particles between the substrate and a counter electrode arranged in parallel with the substrate. When,
After the substrate holding step, a first voltage is applied between the first substrate electrode of the substrate electrodes and the counter electrode to form the first particles on the first substrate electrode. Film formation process,
Subsequent to the first film forming step, a second voltage is applied between the second substrate electrode of the substrate electrodes and the counter electrode to form the second particles on the second substrate electrode. A second film forming step,
The method for manufacturing a light emitting device, wherein the absolute value of the first voltage is smaller than the absolute value of the second voltage.
The said 1st board|substrate electrode and the said 2nd board|substrate electrode are the same electrodes, The said 2nd particle|grain is formed in the upper layer of the layer of the said 1st particle|grain in the said 2nd film-forming process. Manufacturing method of light emitting device.
The method for manufacturing a light emitting device according to claim 1, wherein the first substrate electrode and the second substrate electrode are electrodes different from each other.
The electrodeposition liquid further contains, as the functional particles, third particles different from the first particles and the second particles,
Subsequent to the second film forming step, a third voltage is applied between the third substrate electrode of the substrate electrodes and the counter electrode to form the third particles on the third substrate electrode. Further comprising a third film forming step,
The method for manufacturing a light emitting device according to claim 3, wherein the absolute value of the second voltage is smaller than the absolute value of the third voltage.
The electrodeposition liquid further contains, as the functional particles, fourth particles different from the first particles, the second particles, and the third particles,
Prior to the first film forming step, a fourth voltage is applied between the first substrate electrode, the second substrate electrode, the third substrate electrode, and the counter electrode to remove the fourth particles. Further comprising a fourth film forming step of forming a film on the first substrate electrode, the second substrate electrode, and the third substrate electrode,
The method for manufacturing a light emitting device according to claim 4, wherein the absolute value of the fourth voltage is smaller than the absolute value of the first voltage.
The electrodeposition liquid further contains, as the functional particles, fifth particles different from the first particles, the second particles, and the third particles,
Next to the third film forming step, a fifth voltage is applied between the first substrate electrode, the second substrate electrode, the third substrate electrode and the counter electrode to remove the fifth particles from each other. Further comprising a fifth film forming step of forming a film on the first substrate electrode, the second substrate electrode, and the third substrate electrode,
The method for manufacturing a light emitting device according to claim 4, wherein the absolute value of the third voltage is smaller than the absolute value of the fifth voltage.
7. The first particle is a quantum dot emitting blue light, the second particle is a quantum dot emitting green light, and the third particle is a quantum dot emitting red light. Item 6. A method for manufacturing a light emitting device according to item.
In the first film forming step, a sixth voltage is applied between the substrate electrode different from the first substrate electrode and the counter electrode,
The method for manufacturing a light emitting device according to claim 3, wherein an absolute value of the sixth voltage is smaller than an absolute value of the first voltage.
In the second film forming step, a seventh voltage is applied between the counter electrode and the substrate electrode different from the second substrate electrode,
The method for manufacturing a light emitting device according to claim 3, wherein the absolute value of the seventh voltage is smaller than the absolute value of the second voltage.
In the first film forming step, a forward voltage applying step of applying the first voltage between the first substrate electrode and the counter electrode, and between the first substrate electrode and the counter electrode The reverse voltage applying step of applying an eighth voltage having a polarity opposite to that of the first voltage and having an absolute value smaller than that of the first voltage is alternately executed. Item 1. A method of manufacturing a light emitting device according to item 1.
The method for manufacturing a light emitting device according to claim 1, wherein the first particles and the second particles are mixed in the electrodeposition liquid immediately before the first film forming step.
The method for manufacturing a light emitting device according to claim 1, wherein the functional particles are a material for a functional layer of a light emitting element.
The method for manufacturing a light emitting device according to claim 12, wherein the substrate electrode is a cathode of the light emitting element.