Method for manufacturing vertical organic light-emitting transistor element, display device

Abstract

Provided is a method for manufacturing a vertical organic light-emitting transistor device capable of uniformly fixing a nanocarbon material over the entire region coated with a dispersant. 【Solution means】A method for manufacturing a vertical organic light-emitting transistor device, comprising: a step (A) of preparing a substrate on which a vertical organic light-emitting transistor device is formed on a main surface; a step (B) of applying an organic material containing a polymer having a hydrocarbon group on the main surface of the substrate; a step (C) of applying a dispersion liquid containing a dispersant and a carbon material on the organic material layer formed in step (B); a step (D) of drying the coating film formed in step (C); and a step (E) of applying a cleaning liquid and removing the dispersant after the implementation of step (D).

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a light-emitting element, and more particularly to a method for manufacturing a vertical organic light-emitting transistor element. The present invention also relates to a display device.

Background Art

[0002] A light-emitting transistor using a nanocarbon material as an electrode is known. For example, Patent Document 1 below discloses a vertical organic light-emitting transistor element using a nanocarbon material for a source electrode. According to such a technique, an additional driving horizontal transistor is not required as in a normal light-emitting diode, and since a channel is formed in the film thickness direction of the semiconductor layer, the channel length can be significantly shortened compared to a horizontal transistor in which a channel is formed parallel to the semiconductor layer surface. As a result, a current of a desired magnitude can be efficiently passed through the light-emitting transistor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the conductive layer provided in a semiconductor light-emitting element such as a light-emitting diode or a light-emitting transistor is not uniformly formed on a substrate, the current density in the semiconductor light-emitting element is biased, and bright and dark regions are formed in each pixel. Further, when viewed over the entire display area, there may be variations in luminance for each pixel. In particular, if there are variations in luminance that are recognizable by humans, it is related to the quality of the display device. Therefore, it is desirable that the conductive layer formed as part of the semiconductor light-emitting element be uniformly formed on the substrate. Further, particularly in the conductive layer provided in a vertical organic light-emitting transistor element, since transistor operation is performed by the electric field generated by the gate electrode of the light-emitting transistor, the conductive layer is formed thinly and most of the region must be voids.

[0005] A conductive layer made of a nanocarbon material used in a semiconductor device is formed by applying a dispersion liquid obtained by mixing the nanocarbon material in a predetermined dispersant onto a substrate, followed by drying treatment, baking treatment, and then a cleaning treatment for removing the dispersant.

[0006] However, when simply applying a dispersant mixed with a nanocarbon material onto a substrate and forming it through predetermined processes, in many cases, the formed conductive layer may not spread uniformly on the substrate but may be formed unevenly. Further, particularly in the process of forming a conductive layer that is thin and has most of the region as voids, which is required for a vertical organic light-emitting transistor element, uneven distribution of the conductive material is likely to occur, which may cause problems. Therefore, a semiconductor light-emitting element having a conductive layer made of a nanocarbon material may have luminance unevenness, and from the viewpoints of quality, reliability, etc., its active application to display devices has not been promoted.

[0007] In view of the above problems, an object of the present invention is to provide a method for manufacturing a vertical organic light-emitting transistor element capable of uniformly fixing a nanocarbon material over the entire region where the dispersant is applied.

Means for Solving the Problems

[0008] In order to achieve the above object, the present invention provides A method for manufacturing a vertical organic light-emitting transistor device, comprising: Step (A): preparing a substrate on which the vertical organic light-emitting transistor device is formed on a main surface; Step (B): applying an organic material containing a polymer having a hydrocarbon group on the main surface of the substrate; Step (C): applying a dispersion liquid containing a dispersant and a carbon material on the organic material layer formed in Step (B); Step (D): drying the coating film formed in Step (C); After carrying out Step (D), the method includes Step (E) of applying a cleaning liquid to remove the dispersant.

[0009] The above manufacturing method may be such that the content of the dispersant with respect to the carbon material in the dispersion liquid may be in the range of 1,000% by mass to 100,000% by mass.

[0010] The above manufacturing method may be such that the carbon material may be at least one selected from carbon nanotubes, graphene, and fullerenes. Preferably, the nanocarbon material is a carbon nanotube.

[0011] The above manufacturing method may be such that the dispersant is a polymer having a structural moiety represented by the following formula (1), and the dispersion liquid may be an organic solvent.

[0012] [Chemical formula] (In formula (1), R 1 is a tetravalent organic group constituting a tetracarboxylic acid, R 2 is a divalent organic group constituting a diamine, and n represents a positive integer.)

[0013] Furthermore, the above manufacturing method may be such that in the structural moiety represented by the above formula (1) which the dispersant has, R 1It may be a cyclobutane ring.

[0014] Also, in the above production method, the dispersant may contain an acid dissociable group.

[0015] In the above production method, the oxygen content in the organic material containing the polymer having the hydrocarbon group may be 1% by mass or less.

[0016] In the above production method, the step (C) may be a method in which the dispersion liquid is applied onto the organic material layer by any coating method such as a spin coating method, a slit coating method, a bar coating method, a spray coating method, or an inkjet method.

[0017] The above production method, the cleaning liquid may be an aqueous alkaline solution.

[0018] The display device of the present invention, comprises a vertical organic light-emitting transistor element manufactured by the above production method.

[0019] Regarding other features of the present invention, they will be clarified by the descriptions in the specification and drawings described later.

Effects of the Invention

[0020] According to the present invention, a method for manufacturing a vertical organic light-emitting transistor element capable of uniformly fixing a nanocarbon material over the entire region where the dispersant is applied is realized.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Mode for Carrying Out the Invention

[0022] Hereinafter, first, the configuration of a display device 1 equipped with a vertical organic light-emitting transistor element as one embodiment will be described, and then, details of one embodiment of the manufacturing method of the display device 1 according to the present invention will be described. And, since a verification evaluation experiment for confirming the effects of the present invention was conducted according to one example of the manufacturing method of the vertical organic light-emitting transistor element of the present invention, details of the verification evaluation experiment will be described last.

[0023] In the following description, the direction in which the data line 35 and the current supply line 36 are wired is defined as the X direction, the direction in which the gate line 34 is wired is defined as the Y direction, the direction orthogonal to this is defined as the Z direction, and the side facing away from the substrate 2 (+Z direction) is described as the upper layer side.

[0024] [Overall Configuration] The overall configuration of the display device 1 according to this embodiment will be described. FIG. 1 is a schematic diagram showing the overall configuration of the display device 1 according to this embodiment. The display device 1 has a substrate 2, and a display area 2a and a peripheral area 2b are provided on one surface of the substrate 2.

[0025] The substrate 2 is formed of a light-transmissive material. Specifically, for example, a glass substrate, a quartz substrate, or an organic resin substrate can be mentioned. Examples of the material of the organic resin substrate include polyimide and the like. The organic resin substrate can have a thickness of several micrometers to several tens of micrometers, and it is possible to realize a flexible sheet display.

[0026] The display area 2a is an area for displaying an image. In this embodiment, a plurality of pixels 3 are arranged in a matrix in the display area 2a. In the display area 2a, scanning signal lines 34 are provided for each pixel row, and video signal lines 35 and power potential lines 36 are provided for each pixel column. Although not shown in FIG. 1, common potential lines 37, which will be described later, are provided across the plurality of pixels 3.

[0027] The peripheral area 2b is an area outside the display area 2a. A drive circuit 4, an LSI chip 5, and a terminal portion 6 are provided in the peripheral area 2b. The drive circuit 4 is a circuit for driving a plurality of pixels 3 arranged in the display area 2a. The drive circuit 4 includes a scanning line drive circuit and a video line drive circuit (not shown). The LSI chip 5 controls the drive circuit 4. The terminal portion 6 is provided for connecting the display device 1 to an external terminal such as an FPC (Flexible Printed Circuit).

[0028] (Pixel Circuit) FIG. 2 is a diagram for explaining the circuit configuration of each of the plurality of pixels 3 according to this embodiment. Each of the plurality of pixels 3 has a selection transistor 30 and a light-emitting transistor 31.

[0029] The selection transistor 30 controls the conduction state between the video signal line 35 and the gate electrode 300 of the light-emitting transistor 31 by an on / off operation. The source electrode 301 of the selection transistor 30 is connected to the video signal line 35. The drain electrode 302 of the selection transistor 30 is connected to the gate electrode 300 (see FIG. 3) of the light-emitting transistor 31. The gate electrode 300 of the selection transistor 30 is connected to the scanning signal line 34.

[0030] The light-emitting transistor 31 emits light with a luminance corresponding to the voltage applied to the gate electrode 311. The source electrode 314 of the light-emitting transistor 31 is connected to the power supply potential line 36. The drain electrode 316 of the light-emitting transistor 31 is connected to the common potential line 37. The gate electrode 311 of the light-emitting transistor 31 is connected to the drain electrode 316 of the selection transistor 30.

[0031] (Drive Control) A predetermined power supply potential is applied to the source electrode 314 of the light-emitting transistor 31 via the power supply potential line 36. Also, a predetermined common potential is applied to the drain electrode 316 of the light-emitting transistor 31 via the common potential line 37. That is, a predetermined constant voltage is applied between the source and drain electrodes (314, 316) of the light-emitting transistor 31. When a voltage is applied to the gate electrode 311 of the light-emitting transistor 31, the electric field from the gate electrode 311 is controlled, and the current between the source and drain electrodes (314, 316) is controlled.

[0032] The scanning line drive circuit sequentially selects each of the rows of the plurality of pixels 3 in accordance with the timing signal input from the LSI chip 5. At this time, the scanning line drive circuit applies a voltage that turns on the selection transistor 30 to the scanning signal line 34 connected to the pixel 3 in the pixel row.

[0033] The video line driving circuit receives a video signal from the LSI chip 5, and in accordance with the selection of the scanning signal line 34 by the scanning line driving circuit, applies a voltage corresponding to the video signal of the row of the selected pixel 3 to each of the plurality of video signal lines 35. The voltage is applied to the gate electrode 311 of the light-emitting transistor 31 in the selected pixel row. As a result, a current corresponding to the voltage applied to the gate electrode 311 is supplied to the light-emitting layer 315 between the source and drain electrodes (314, 316) of the light-emitting transistor 31. Thereby, the light-emitting transistor 31 connected to the selected scanning signal line 34 emits light with a luminance corresponding to the current.

[0034] (Pixel configuration) FIG. 3 is a top view of one pixel among the plurality of pixels 3 provided in the display device 1 of the present embodiment. FIG. 4 is a cross-sectional view of one pixel taken along the line A-A' in FIG. 3. The display device 1 of the present embodiment is a so-called bottom emission type display device 1 in which the light emitted by the light-emitting transistor 31 is extracted toward the substrate 2 side. Each of the plurality of pixels 3 of the present embodiment includes a selection transistor 30, a light-emitting transistor 31, a protective layer 32, and a bank 33.

[0035] The selection transistor 30 includes a gate electrode 300, a source electrode 301, a drain electrode 302, a gate insulating layer 303, and a semiconductor layer 304. The selection transistor 30 of the present embodiment has a so-called bottom gate - top contact (BGTC) structure in which the gate electrode 300, the gate insulating layer 303, the semiconductor layer 304, and the source and drain electrodes (301, 302) are provided in this order from the substrate 2 side.

[0036] Note that the selection transistor 30 is not limited to the BGTC structure, and may be a bottom gate - bottom contact (BGBC) structure, a top gate - bottom contact (TGBC) structure, a top gate - top contact (TGTC) structure, or the like.

[0037] As the material of the semiconductor layer 304 of the selection transistor 30, a silicon-based semiconductor, an oxide-based semiconductor, an organic semiconductor, or the like can be used.

[0038] The protective layer 32 is provided to cover and protect the selection transistor 30, and has the role of electrically insulating between the source electrode 301 and the drain electrode 302 and the upper layer electrode. As the material of the protective layer 32, an inorganic insulating material can be used. As the inorganic insulating material, silicon nitride, silicon oxide, aluminum nitride, aluminum oxide, etc. can be used. The protective layer 32 is provided over the entire surface of the substrate 2. By providing the protective layer 32, the selection transistor 30 and the power supply potential line 36 are covered by the protective layer 32.

[0039] As shown in FIG. 3, most of the region constituting one pixel is occupied by the light-emitting transistor 31, and the selection transistor 30 is provided as small as possible at the corner of the region constituting one pixel. Further, the light-emitting transistor 31 is provided above the protective layer 32 in the cross-sectional view shown in FIG. 4.

[0040] The light-emitting transistor 31 includes a gate electrode 311, a gate insulating layer 312, an underlying layer 313, a source electrode 314, a light-emitting layer 315, and a drain electrode 316.

[0041] The gate electrode 311 is provided above the protective layer 32. The gate electrode 311 is provided across the outside of the region occupied by the selection transistor 30 in one pixel. Further, the gate electrode 311 is connected to the drain electrode 302 of the selection transistor 30 through a contact hole 32a provided in the protective layer 32.

[0042] As the material of the gate electrode 311, a material having translucency and conductivity is used in order to transmit the light emitted from the light-emitting layer 315 to the substrate 2 side. Specifically, as the material of the gate electrode 311, ITO (indium tin oxide), IZO (indium zinc oxide), etc. can be used. Alternatively, a metal material having a film thickness through which light can pass may be used as the material of the gate electrode 311.

[0043] The gate insulating layer 312 is provided above the gate electrode 311. The gate insulating layer 312 is provided over the entire surface of the substrate 2. As the material of the gate insulating layer 312, the same material as the gate insulating layer 303 of the selection transistor 30 can be used.

[0044] The underlayer 313 is an organic material layer provided above the gate insulating layer 312. The underlayer 313 has an opening 313a. The opening 313a is provided above the power potential line 36. The underlayer 313 is a material having dielectric properties. The underlayer 313 may also be composed of a material having radiation sensitivity and photosensitivity. The material of the underlayer 313 is an organic material containing an aromatic compound. For example, an aromatic polymer, a radiation-sensitive composition containing a polymer such as polyimide and a photosensitizer, a cinnamic acid group-containing polymer, a fluorine-based polymer having a crosslinkable group, etc. can be used. Note that the oxygen content of the organic material in the present embodiment is 1 mass% or less, but the oxygen content of the organic material may be 1% or more.

[0045] The source electrode 314 is provided in contact with the underlayer 313. The source electrode 314 is connected to the power potential line 36 provided below the underlayer 313 through the opening 313a of the underlayer 313.

[0046] The material of the source electrode 314 is a material containing a nanocarbon material. The nanocarbon material is graphene, fullerene, or a carbon nanotube, and contains at least one of these. The nanocarbon material is preferably a carbon nanotube. The carbon nanotube can be a single-walled carbon nanotube or a multi-walled carbon nanotube of two or more layers. The carbon nanotube is preferably a single-walled carbon nanotube. Hereinafter, the carbon nanotube may be abbreviated as "CNT".

[0047] The source electrode 314 is formed by applying a dispersion liquid containing a nanocarbon material such as carbon nanotubes and a dispersant. The dispersant is not particularly limited, but it is preferable to use a polyamic acid having a structural moiety represented by the formula (1) in terms of improving the dispersibility of carbon nanotubes. For the sake of caution, the formula (1) is reproduced below.

[0048] [Chemical formula] (In formula (1), R 1 is a tetravalent organic group constituting a tetracarboxylic acid, and R 2 is a divalent organic group constituting a diamine, and n represents a positive integer.)

[0049] R 1Specific examples of the tetravalent organic groups constituting the tetracarboxylic acids represented by include pyromellitic acid, 2,3,6,7-naphthalenetetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, 1,4,5,8-naphthalenetetracarboxylic acid, 2,3,6,7-anthracenetetracarboxylic acid, 1,2,5,6-anthracenetetracarboxylic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 2,3,3',4-biphenyltetracarboxylic acid, bis(3,4-dicarboxyphenyl) ether, 3,3'4,4'-benzophenonetetracarboxylic acid, bis(3,4-dicarboxyphenyl) sulfone, bis(3,4-dicarboxyphenyl) methane, 2,2-bis(3,4-dicarboxyphenyl) propane, 1,1,1,3,3,3-hexafluoro-2,2-bis(3,4-dicarboxyphenyl) propane, bis(3,4-dicarboxyphenyl) dimethylsilane, bis(3,4-dicarboxyphenyl) diphenylsilane, 2,3,4,5-pyridinetetracarboxylic acid, 2,6-bis(3,4-dicarboxyphenyl) pyridine and other aromatic tetracarboxylic acid dianhydrides, 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic acid, 2,3,5-tricarboxycyclopentylacetic acid, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalenesuccinic acid and other alicyclic tetracarboxylic acid dianhydrides, 1,2,3,4-butanetetracarboxylic acid and other aliphatic tetracarboxylic acid dianhydrides, and the like. These acid dianhydrides may be used alone or in combination of a plurality of compounds.

[0050] R 2Specific examples of the divalent organic group constituting the diamine represented by the following formula include p-phenylenediamine, m-phenylenediamine, 2,5-diaminotoluene, 2,6-diaminotoluene, 4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, diaminodiphenylmethane, diaminodiphenyl ether, 2,2'-diaminodiphenylpropane, bis(3,5-diethyl-4-aminophenyl)methane, diaminodiphenyl sulfone, diaminobenzophenone, diaminonaphthalene, 1,4-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenyl)benzene, 9,10-bis(4-aminophenyl)anthracene, 1,3-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)diphenyl sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane and other aromatic diamines, bis(4-aminocyclohexyl)methane, bis(4-amino-3-methylcyclohexyl)methane, cholestanyl 3,5-diaminobenzoate and other alicyclic diamines, 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,6-diaminohexane and other aliphatic diamines, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and other silicon diamines. These diamines may be used as a single compound, or a plurality of compounds may be used in combination.

[0051] Furthermore, R in the above formula (1) 1 is preferably a cyclobutane ring. The cyclobutane ring is preferably in that the ring structure is decomposed by light irradiation or heating, resulting in a structural change of the polyamic acid, which makes it easier to remove the dispersant. Also, the above dispersion may contain an organic solvent as the dispersion medium.

[0052] The light-emitting layer 315 is a layer containing an organic electroluminescence (organic EL) material. The light-emitting layer 315 is provided above the source electrode 314. The light-emitting layer 315 is provided so as to cover the vicinity of the edge portion of the opening 33a of the bank 33 described later. When electrons are injected into the light-emitting layer 315 from the source electrode 314 and holes are injected from the drain electrode 316, the electrons and holes recombine. The light-emitting molecules in the light-emitting layer 315 are excited by the surplus energy released thereby, and then emit light by de-excitation. The light-emitting layer 315 may include a hole transport layer, an electron transport layer, etc. so as to sandwich the layer of the organic EL material.

[0053] The drain electrode 316 is provided above the light-emitting layer 315. The drain electrode 316 corresponds to a partial region of the common potential line 37 shown in FIG. 2. The common potential line 37 is commonly provided in a plurality of pixels 3 and is all electrically connected.

[0054] As the material of the drain electrode 316, in order to reflect the light emitted by the light-emitting layer 315 toward the substrate 2 side, it is preferable to include a metal material with high reflectivity. As the metal material with high reflectivity, for example, aluminum, silver, etc. can be used.

[0055] The bank 33 is provided above the base layer 313 and the source electrode 314. The bank 33 has an opening 33a, and in a top view, the edge portion 33b of the opening 33a is provided so as to cover the vicinity of the peripheral portion of the source electrode 314. The material of the bank 33 is an insulating material. As the insulating material, an inorganic insulating material, an organic insulating material, or a combination thereof can be used. By providing the bank 33, a short circuit between the source electrode 314 and the drain electrode 316 can be prevented.

[0056] Further, although not shown in the drawings, a protective layer may be provided above the drain electrode 316 so as to cover the entire surface of the substrate 2. The protective layer suppresses moisture from entering the light-emitting layer 315 and deteriorating the characteristics of the light-emitting transistor 31. As the material of the protective layer, an inorganic insulating material can be used. As the inorganic insulating material, silicon nitride, silicon oxide, aluminum nitride, aluminum oxide, or a laminate of any combination of these materials can be used. Note that the protective layer is not provided at the positions of the LSI chip 5 and the terminal portion 6 in order to ensure electrical connection with the external terminals.

[0057] [Manufacturing Method] A method for manufacturing the light-emitting transistor 31 of the present embodiment, particularly a method for manufacturing a plurality of pixels 3 included in the display device 1, will be described. FIGS. 5 to 10 are top views showing the states during the manufacturing process of the light-emitting transistor 31 of the present embodiment.

[0058] First, as shown in FIG. 5, a substrate 2 on which the light-emitting transistor 31 is formed is prepared on the main surface (corresponding to step (A)).

[0059] Then, as shown in FIG. 6, a selection transistor 30 is formed on a part of one surface side of the substrate 2. The selection transistor 30 is formed through processes of film formation of materials, resist coating, exposure, development, and etching for each of the gate electrode 300, the gate insulating layer 303, the semiconductor layer 304, and the source / drain electrodes (301, 302). The selection transistor 30 may be manufactured by a general method, and detailed description thereof is omitted here.

[0060] In the present embodiment, as shown in FIG. 6, the power supply potential line 36 is formed simultaneously with the formation of the source / drain electrodes (301, 302) in the process of forming the selection transistor 30.

[0061] Next, as shown in FIG. 7, a protective layer 32 is formed. As the material of the protective layer 32, an inorganic insulating material is used. As the inorganic insulating material, silicon nitride, silicon oxide, aluminum nitride, aluminum oxide, etc. can be used. The protective layer 32 is formed by using a film forming method such as chemical vapor deposition method or sputtering method. The protective layer 32 is formed over the entire surface of the substrate 2. By forming the protective layer 32, the selection transistor 30 and the power potential line 36 are covered with the protective layer 32.

[0062] After forming the protective layer 32, as shown in FIG. 8, a contact hole 32a is formed in the region of the protective layer 32 above the drain electrode 302. The contact hole 32a is formed to connect the gate electrode 311 of the light-emitting transistor 31 and the drain electrode 302 of the selection transistor 30.

[0063] Next, the light-emitting transistor 31 is formed. First, as shown in FIG. 9, a gate electrode 311 is formed on the protective layer 32. The gate electrode 311 is also formed on the contact hole 32a formed in the protective layer 32 and is connected to the drain electrode 302 of the selection transistor 30.

[0064] As the material of the gate electrode 311, a material having translucency and conductivity is used. Specifically, as the material of the gate electrode 311, ITO (indium tin oxide), IZO (indium zinc oxide), etc. can be used. Alternatively, as the material of the gate electrode 311, a metal material having a film thickness through which light can pass may be used. The gate electrode 311 is formed by depositing a material by a sputtering method or the like and then removing unnecessary portions by etching.

[0065] After the gate electrode 311 is formed, as shown in FIG. 4, a gate insulating layer 312 is formed. Note that since the gate insulating layer 312 is formed over the entire surface of the substrate 2, the illustration of the gate insulating layer 312 during the manufacturing process is omitted.

[0066] As the material of the gate insulating layer 312, the same material as the gate insulating layer 312 of the selection transistor 30 can be used. The gate insulating layer 303 is formed by using a film formation method such as chemical vapor deposition method or sputtering method.

[0067] After forming the gate insulating layer 312, as shown in FIG. 10, the underlayer 313 is formed. The underlayer 313 is a material having dielectric properties.

[0068] After forming the underlayer 313, an opening 313a is formed by removing the layer in the region above the power supply potential line 36 in the underlayer 313. The opening 313a is formed by exposing and developing the underlayer 313.

[0069] Next, a contact hole 31a is formed in the region of the opening 313a. In this step, the contact hole 31a is formed by etching one surface side of the substrate 2 using the underlayer 313 in which the opening 313a is formed as a resist. At this time, one surface side of the substrate 2 is etched until the power supply potential line 36 is exposed. As a result, the regions of the gate insulating layer 312 and the protective layer 32 exposed by the opening 313a are removed, and the contact hole 31a is formed.

[0070] The etching method is not particularly limited. Any etching method can be used as long as a sufficient selectivity can be ensured between the etching rate for the underlayer 313 and the etching rates for the gate insulating layer 312 and the protective layer 32. As the etching method, either plasma etching or wet etching can be used.

[0071] Regarding the patterning methods of the underlying layer 313, the gate insulating layer 312, and the protective layer 32, in addition to the above method that utilizes the photosensitivity of the underlying layer 313, it is also possible to adopt a method in which, after forming the underlying layer 313 by performing film formation with the entire surface hardened by photosensitization or heating, etc., a photosensitive resist layer PR for patterning is separately formed on the underlying layer 313. In this case, when the photosensitive resist layer PR is, for example, a negative type, the solubility of the exposed area in the developer decreases. Therefore, the photomask M is formed so as to block the area where the opening 313a is to be formed.

[0072] In the step of developing the photosensitive resist layer PR, the photosensitive resist layer PR is immersed in the developer. The exposed area does not dissolve in the developer, and the area shielded during the exposure step dissolves. As a result, a resist opening PRa is formed.

[0073] Next, an opening 313a and a contact hole 31a are formed in the area of the resist opening PRa. In this step, by etching one surface side of the substrate 2 using the photosensitive resist layer PR in which the resist opening PRa is formed, the opening 313a and the contact hole 31a are formed. At this time, one surface side of the substrate 2 is etched until the power potential line 36 is exposed. As a result, the areas of the underlying layer 313, the gate insulating layer 312, and the protective layer 32 exposed by the resist opening PRa are removed, and the contact hole 31a is formed.

[0074] Note that the etching method is arbitrary and not particularly limited. Any etching method can be used as long as a sufficient selectivity ratio can be ensured between the etching rate for the photosensitive resist layer PR and the etching rates for the underlying layer 313, the gate insulating layer 312, and the protective layer 32. As the etching method, either plasma etching or wet etching can be used.

[0075] After the contact hole 31a is formed, the remaining photosensitive resist layer PR is removed (not shown). As described above, instead of using the photosensitivity of the underlying layer 313, the contact hole 31a may be formed using a separately patterned photosensitive resist layer PR.

[0076] After the contact hole 31a is formed by an etching process (or after the contact hole 31a is formed by an etching process and then the photosensitive resist layer PR is removed), a dispersion containing a nanocarbon material (carbon material) is applied onto the underlying layer 313 formed on the main surface of the substrate 2, and as shown in FIG. 10, a pattern of the source electrode 314 is formed on the underlying layer 313 (corresponding to step (C)).

[0077] In this step, a pattern of a coating film of a dispersion of a nanocarbon material is formed on the underlying layer 313 using a printing technique such as casting, screen printing, inkjet, etc. After the pattern is formed, the solvent is dried and removed, whereby the source electrode 314 is formed (corresponding to step (D)).

[0078] The pattern of the source electrode 314 is designed to overlap the opening 313a of the underlying layer 313 in a top view. Thereby, the pattern of the source electrode 314 is connected to the power potential line 36 through the contact hole 31a shown in FIG. 10.

[0079] After the solvent is dried and removed, a cleaning liquid is applied onto the source electrode 314 formed on the main surface of the substrate 2, and the dispersant is removed from the pattern formed by the coating film (corresponding to step (E)). Also, in this step, in addition to the above method of forming a pattern by printing in the formation of the pattern of the source electrode 314, a method may be adopted in which a dispersion is once applied over the entire underlying layer 313 formed on the main surface of the substrate 2, dried, washed, and then a photosensitive resist layer PR for separate patterning is formed on the source electrode 314. In this case, after the photosensitive resist layer PR is formed, the conductive layer is removed by etching, and the remaining photosensitive resist layer PR is removed (not shown).

[0080] Note that the combination of the dispersant and the cleaning solution is arbitrary. However, as the dispersant, an alkali-soluble polymer having a functional group that improves solubility in an alkaline aqueous solution is preferred, and as the cleaning solution, it is preferable to use an alkaline aqueous solution. By using an alkaline aqueous solution as the cleaning solution, it becomes possible to selectively leave the nanocarbon material that is difficult to disperse in the alkaline aqueous solution on the underlying layer 313. Further, by making the process use such an alkali-soluble polymer, it is possible to share the materials with other photosensitive resist layers PR that use an alkaline aqueous solution for development as well, greatly enhancing productivity. Further, as the alkaline aqueous solution, for example, KOH (potassium hydroxide), NaOH (sodium hydroxide), sodium carbonate, an aqueous solution of TMAH (tetramethylammonium hydroxide), etc. can be preferably used.

[0081] Furthermore, these dispersants may contain a molecular structure that can improve solubility in an alkaline aqueous solution by reacting to light or heat in the material and causing decomposition or a structural change. By using such a dispersant and applying light or heat after the formation of the source electrode 314 to improve solubility, and then applying the cleaning solution, it becomes possible to further improve the efficiency of removing the dispersant from the pattern by the coating film. As a molecular structure showing such a function, for example, the polyamic acid structure of the dispersant may contain a site that can be decomposed by light or heat such as cyclobutane and change the entire structure of the polyamic acid. Further, the dispersant may contain an acid dissociable group. The acid dissociable group is a group that generates an acidic group such as a carboxyl group or a phenolic hydroxyl group by the action of an acid. Examples of the acid dissociable group include a group having a t-butoxy structure and a group having an acetal structure. The acid acting on the acid dissociable group is the acid generated from an acid generator that generates an acid by the action of light or heat. Therefore, an acid generator is contained together with the dispersant having an acid dissociable group in the dispersion liquid.

[0082] Next, a bank 33 is formed. The material of the bank 33 is an insulating material. As the insulating material, an inorganic insulating material, an organic insulating material, or a combination thereof can be used. After forming the material of the bank 33, an opening 33a is formed by removing unnecessary portions.

[0083] Next, a light-emitting layer 315 is formed above the source electrode 314. In this step, a metal mask is installed above the substrate 2 and an organic material is vapor-deposited, so that the light-emitting layer 315 is formed in the vicinity of the opening 33a and the edge portion 33b of the bank 33 at least in the pixel region.

[0084] Next, a drain electrode 316 is formed above the light-emitting layer 315, and the light-emitting transistor 31 of the present embodiment as shown in FIG. 4 is completed. The material of the drain electrode 316 preferably contains a metal material with high reflectivity. As the metal material with high reflectivity, for example, aluminum, silver, etc. can be used.

[0085] Furthermore, although not shown, a protective layer may be formed above the drain electrode 316 so as to cover the entire surface of the substrate 2. As the material of the protective layer, an inorganic insulating material can be used. As the inorganic insulating material, silicon nitride, silicon oxide, aluminum nitride, aluminum oxide, or a laminate of any combination of these materials can be used. Note that in the positions of the LSI chip 5 and the terminal portion 6, the protective layer in this region is removed in order to ensure conduction with the external terminals.

[0086] As is clear from the above, the light-emitting transistor 31 of the present embodiment includes a gate electrode 311, a gate insulating layer 312 provided above the gate electrode 311, a base layer 313 provided above the gate insulating layer 312 and having dielectric properties, a source electrode 314 provided in contact with the base layer 313 and containing a nanocarbon material, a light-emitting layer 315 provided above the source electrode 314, and a drain electrode 316 provided above the light-emitting layer 315.

[0087] According to such a light-emitting transistor 31, since the underlying layer 313 has an adsorptivity to the nanocarbon material, the adhesion between the underlying layer 313 and the source electrode 314 becomes good. As a result, the processability of the source electrode 314, the resistance to the solvent during the application of the photosensitive resist layer in the subsequent process, and the resistance to the developer are enhanced. Further, by controlling the voltage applied to the gate electrode 311, it becomes easy to flow a current with a desired accuracy.

[0088] Also, in the light-emitting transistor 31, the underlying layer 313 has an opening 313a, and the source electrode 314 is connected to a power supply potential line 36 provided below the underlying layer 313 via the opening 313a. According to such a light-emitting transistor 31, a desired voltage can be applied to the source electrode 314 via the power supply potential line 36.

[0089] Also, in the light-emitting transistor 31, the underlying layer 313 has photosensitivity. According to such a light-emitting transistor 31, the opening 313a can be formed by exposing and developing the underlying layer 313. That is, the manufacturing process of the light-emitting transistor 31 can be simplified.

[0090] Also, in the light-emitting transistor 31, the nanocarbon material includes at least one of graphene or a carbon nanotube. According to such a light-emitting transistor 31, the adhesion between the underlying layer 313 and the source electrode 314 becomes even better.

[0091] Also, in the light-emitting transistor 31, the nanocarbon material is a carbon nanotube, and the carbon nanotube is a single-walled carbon nanotube. According to such a light-emitting transistor 31, the adhesion between the underlying layer 313 and the source electrode 314 becomes even better.

[0092] In addition, in the above light-emitting transistor 31, the underlayer 313 can be formed through the following steps using a radiation-sensitive composition for forming the underlayer. The underlayer 313 formed by this forming method exhibits specific electrical characteristics, has excellent adhesion to carbon nanotubes, and also has good chemical resistance and flatness. Further, according to this forming method, since heating is performed at 140°C or lower, thermal degradation of the substrate and the elements provided on the substrate is suppressed. Hereinafter, each step will be described in detail.

[0093] [Step (1)] In this step, a coating film is formed on the gate insulating layer 312 using the radiation-sensitive composition. Specifically, a coating film of the radiation-sensitive composition is formed by applying the radiation-sensitive composition onto the surface of the gate insulating layer 312. In order to remove the solvent contained in the coating film, it is preferable to perform a pre-bake treatment in this step.

[0094] Elements such as a selection transistor are provided in the lower layer of the gate insulating layer 312. As described above, according to this forming method, deterioration of these elements due to heating can be suppressed.

[0095] As the coating method, for example, an appropriate method such as a spray method, a roll coating method, a spin coating method, a slit die coating method, a bar coating method, an inkjet method, etc. can be adopted. Among these, as the coating method, the inkjet method is preferable. The conditions for pre-bake vary depending on the type and usage ratio of each component, etc., but for example, it can be set to 60°C to 130°C for about 30 seconds to 10 minutes. The film thickness of the formed coating film, as the value after pre-bake, is preferably 0.1 μm to 5 μm, more preferably 0.1 μm to 1 μm, and even more preferably 0.2 μm to 0.4 μm.

[0096] [Step (2)] In this process, a part of the coating film is irradiated (exposed) with radiation. Specifically, the coating film formed in step (1) is irradiated with radiation through a mask having a predetermined pattern. Depending on the pattern of the mask used, it is possible to form patterns such as contact hole formation and line and space formation. Examples of the radiation used at this time include ultraviolet rays, far ultraviolet rays, X-rays, charged particle beams, etc. Also, the mask used may be a multi-tone mask such as a half-tone mask or a gray-tone mask.

[0097] Examples of ultraviolet rays include g-line (wavelength 436 nm), i-line (wavelength 365 nm), KrF excimer laser light (wavelength 248 nm), etc. Examples of X-rays include synchrotron radiation, etc. Examples of charged particle beams include electron beams, etc. Among these radiations, ultraviolet rays are preferred, and ultraviolet rays with a wavelength of 200 nm or more and 380 nm or less are more preferred. The exposure amount of the radiation is preferably 1,000 J / m 2 ~20,000 J / m 2 is preferred.

[0098] Also, in some cases, post-exposure baking (PEB) can be performed after exposure.

[0099] [Step (3)] In this step, the coating film irradiated with radiation is developed. Specifically, the coating film irradiated with radiation in step (2) is developed with a developer to remove the irradiated portion of the radiation. As the developer, for example, an alkaline aqueous solution in which potassium hydroxide, sodium carbonate, triethanolamine, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, etc. are dissolved in water, or organic solvents such as ethanol, isopropyl alcohol, acetone, ethyl acetate, butyl acetate can be used.

[0100] As the development method, for example, an appropriate method such as a puddle method, a dipping method, a rocking dipping method, a shower method, etc. can be adopted. The development time varies depending on the composition of the radiation-sensitive composition, but it can be, for example, 30 seconds to 120 seconds.

[0101] [Step (4)] In this step, the coating film after the above step (3) can be heated. The coating film is heat-treated (post-baked) and cured by a heating device such as a hot plate or an oven.

[0102] The upper limit of the heating temperature in this step is 140 °C, and the heating temperature may be 130 °C, may be 125 °C, or may be 115 °C. According to the formation method, the coating film can be made into a good shape even by heating at such a relatively low temperature.

[0103] Also, in the above light-emitting transistor 31, the source electrode 314 formed on the organic material layer can be formed through the steps shown below using a composition containing a nanocarbon material.

[0104] As the coating method of the composition containing a nanocarbon material, for example, an appropriate method such as a spray coating method, a roll coating method, a spin coating method, a slit die coating method (slit coating method), a bar coating method (bar coating method), a solution dipping method, an inkjet method, etc. can be adopted. The nanocarbon material layer is formed with a certain thickness by a predetermined method. In addition, in order to improve the purity, it is preferable to perform a step of removing the solvent by a baking process and a solution dipping process for removing the dispersant on the nanocarbon material layer. Among the above-described coating methods, the slit die coating method or the inkjet method is preferable from the viewpoints of the film thickness uniformity of the coating film and the liquid saving property. Also, from the viewpoint that the patterning of the electrode can be performed only by coating, the inkjet method is more preferable.

[0105] By adopting the method for forming the underlying layer 313, the source electrode 314 formed on the upper layer of the underlying layer 313 exhibits specific electrical characteristics, has excellent adhesion to the underlying layer 313, and also has good chemical resistance and flatness.

[0106] The display device 1 of the present embodiment includes a substrate 2 and a plurality of pixels 3 arranged on one surface of the substrate 2. Each of the plurality of pixels 3 has any one of the above light-emitting transistors 31.

[0107] According to such a display device 1, since the underlying layer 313 of the light-emitting transistor 31 has dielectric properties, the adhesion between the underlying layer 313 and the source electrode 314 is improved. As a result, when a voltage corresponding to a video signal is applied to the gate electrode 311, it becomes easy to pass a current through the light-emitting transistor 31 with desired accuracy. Therefore, in order to pass a current through the light-emitting transistor 31 with desired accuracy, there is no need to provide a compensation circuit or separately provide transistors and capacitors for each pixel 3.

[0108] The manufacturing method of the light-emitting transistor 31 of the present embodiment includes forming a gate electrode 311 on one surface side of the substrate 2, forming a gate insulating layer 312 on one surface side after forming the gate electrode 311, forming a dielectric underlying layer 313 on one surface side after forming the gate insulating layer 312, forming a source electrode 314 containing a nanocarbon material on the underlying layer 313, forming a light-emitting layer 315 above the source electrode 314, and forming a drain electrode 316 above the light-emitting layer 315.

[0109] According to such a manufacturing method of the light-emitting transistor 31, since the underlying layer 313 has dielectric properties, a light-emitting transistor 31 with good adhesion between the underlying layer 313 and the source electrode 314 can be formed. Also, thereby, the manufacturing yield is improved.

[0110] In the above manufacturing method, the underlying layer 313 has photosensitivity. Before forming the gate insulating layer 312, a power supply potential line 36 is formed on one surface side. After forming the underlying layer 313, the underlying layer 313 is exposed and developed, and thereby, the layer in the region above the power supply potential line 36 in the underlying layer 313 is removed. Using the underlying layer 313 as a resist, the contact hole 31a is formed by etching one surface side until the power supply potential line 36 is exposed. Through the contact hole 31a, a source electrode 314 connected to the power supply potential line 36 is formed.

[0111] According to such a manufacturing method of the light-emitting transistor 31, since the underlying layer 313 has photosensitivity, it functions as a resist. Therefore, when forming the contact hole 31a, it is not necessary to go through complicated processes such as resist coating, exposure, development, etching, and resist stripping on the underlying layer 313. Thus, the manufacturing process is simplified.

[0112] In the above manufacturing method, the nanocarbon material includes at least one of graphene or carbon nanotubes. According to such a manufacturing method of the light-emitting transistor 31, a light-emitting transistor 31 with better adhesion between the underlying layer 313 and the source electrode 314 can be formed. Also, the manufacturing yield becomes even better.

[0113] In the above manufacturing method, the nanocarbon material is a carbon nanotube, and the carbon nanotube is a single-walled carbon nanotube. According to such a manufacturing method of the light-emitting transistor 31, a light-emitting transistor 31 with better adhesion between the underlying layer 313 and the source electrode 314 can be formed. Also, the manufacturing yield becomes even better.

[0114] The manufacturing method of the light-emitting transistor 31 of this embodiment includes forming a plurality of pixels 3 each including a light-emitting transistor 31 on one surface of the substrate 2, and forming the light-emitting transistor 31 by the above method.

[0115] According to the manufacturing method of such a light-emitting transistor 31, since the underlying layer 313 of the light-emitting transistor 31 constituting the pixel 3 has dielectric properties, a light-emitting transistor 31 with good adhesion between the underlying layer 313 and the source electrode 314 can be formed. Also, thereby, the manufacturing yield is improved.

[0116] Furthermore, according to the manufacturing method of such a light-emitting transistor 31, since the underlying layer 313 has photosensitivity, the underlying layer 313 can function as a resist. Therefore, when forming the contact hole 31a, it is not necessary to go through complicated processes such as resist coating, exposure, development, etching, and resist stripping on the underlying layer 313. Thus, the manufacturing process is simplified.

[0117] [Verification and Evaluation Experiment] Finally, a verification and evaluation experiment was conducted to confirm the extent of the effect obtained by the manufacturing method of the present invention on the dispersibility of carbon nanotubes, which are nano-carbon materials applied on a substrate. This will be described below.

[0118] 1. Synthesis of Polymer [Synthesis Example 1: Synthesis of Polyamic Acid] By the synthesis method described in the above Patent Document 2, a polyamic acid having a hydrocarbon group in the side chain (hereinafter referred to as "polymer (paa-1)") was obtained.

[0119] [Synthesis Example 2: Synthesis of Polyamic Acid] By the synthesis method described in the above Patent Document 3, a photodegradable polyamic acid having a hydrocarbon group in the side chain (hereinafter referred to as "polymer (paa-2)") was obtained.

[0120] [Comparative Synthesis Example 1: Polyimide Synthesis] N-methyl-2-pyrrolidone (NMP) was added to the polyamic acid solution obtained in the same manner as in Synthesis Example 1 above. A predetermined imidizing agent was added to the solution, and the solution was heated at 110°C and reacted for a predetermined time to obtain polyimide (hereinafter referred to as "polymer (PI-1)"). The imidization rate of the obtained polymer (PI-1) was 50%.

[0121] 2. Preparation and Evaluation of CNT-Containing Dispersion Compositions (1) Preparation of Dispersion Compositions To a container containing 10 parts by mass of single-walled carbon nanotubes (SWNTs) and 50 parts by mass of the polymer (paa-1) obtained in Synthesis Example 1 as a dispersant, 100,000 parts by mass of NMP was added as a solvent. Subsequently, ultrasonic dispersion was carried out for 60 minutes to prepare a dispersion composition (S-1).

[0122] Next, to a container containing 10 parts by mass of single-walled carbon nanotubes (SWNTs) and 100 parts by mass of the polymer (paa-1) obtained in Synthesis Example 1 as a dispersant, 100,000 parts by mass of NMP was added as a solvent. Subsequently, ultrasonic dispersion was carried out for 60 minutes to prepare a dispersion composition (S-2).

[0123] Next, to a container containing 10 parts by mass of single-walled carbon nanotubes (SWNTs) and 500 parts by mass of the polymer (paa-1) obtained in Synthesis Example 1 as a dispersant, 100,000 parts by mass of NMP was added as a solvent. Subsequently, ultrasonic dispersion was carried out for 60 minutes to prepare a dispersion composition (S-3).

[0124] Next, to a container containing 10 parts by mass of single-walled carbon nanotubes (SWNTs) and 1,000 parts by mass of the polymer (paa-1) obtained in Synthesis Example 1 as a dispersant, 100,000 parts by mass of NMP was added as a solvent. Subsequently, ultrasonic dispersion was carried out for 60 minutes to prepare a dispersion composition (S-4).

[0125] Next, to a container containing 10 parts by mass of single-walled carbon nanotubes (SWNTs) and 5,000 parts by mass of the polymer (paa-1) obtained in Synthesis Example 1 as a dispersant, 100,000 parts by mass of NMP was added as a solvent. Subsequently, ultrasonic dispersion was carried out for 60 minutes to prepare a dispersion composition (S-5).

[0126] Next, 10 parts by mass of single-walled carbon nanotubes (SWNTs) and 500 parts by mass of the polymer (paa-2) obtained in Synthesis Example 2 as a dispersant were placed in a container, and 100,000 parts by mass of NMP was added as a solvent. Then, ultrasonic dispersion was performed for 60 minutes to prepare a dispersion composition (S-6).

[0127] Next, 10 parts by mass of single-walled carbon nanotubes (SWNTs) and 500 parts by mass of the polymer (PI-1) obtained in Comparative Synthesis Example 1 as a dispersant were placed in a container, and 100,000 parts by mass of NMP was added as a solvent. Then, ultrasonic dispersion was performed for 60 minutes to prepare a dispersion composition (C-1).

[0128] (2) Evaluation of CNT dispersibility The dispersion compositions (S-1) to (C-1) obtained in (1) above were allowed to stand on a flat surface at 25°C. The evaluation was as follows: "Best (A)" if the CNTs maintained the initial dispersion state without sedimentation after one week; "Good (B)" if the CNTs maintained the initial dispersion state without sedimentation until three days later; "Fair (C)" if the CNTs maintained the initial dispersion state without sedimentation until one day later; "Passable (D)" if the CNTs maintained the initial dispersion state without sedimentation until three hours later; and "Poor (E)" if sedimentation or aggregation of the CNTs was observed within three hours. As a result, the CNT dispersibility of the dispersion compositions (S-1) to (S-6) and (C-1) was "Best (A)".

[0129] (3) Evaluation of CNT dispersion stability (durability) A dispersion composition was prepared in the same manner as in (1) above. The obtained dispersion composition was left standing at a flat location in an environment of 40°C, and the dispersion state over time was observed. The evaluation was as follows: if the CNT did not settle after one week and maintained the initial dispersion state, it was rated "excellent (A)"; if the CNT did not settle until three days later and maintained the initial dispersion state, it was rated "good (B)"; if the CNT did not settle until one day later and maintained the initial dispersion state, it was rated "fair (C)"; if the CNT did not settle until three hours later and maintained the initial dispersion state, it was rated "passable (D)"; if sedimentation or aggregation was observed three hours later, it was rated "poor (E)". As a result, the CNT dispersion stabilities of this dispersion composition (S-1) to (S-6) and (C-1) were "excellent (A)".

[0130] (4) Evaluation of CNT (carbon nanotube) coatability The dispersion compositions (S-1) to (C-1) obtained in (1) above were spin-coated onto a glass substrate on which an underlayer 313 was formed, and dried on a hot plate at 80°C for 10 minutes to form a coating film with a film thickness of 0.1 μm at the center of the substrate. This coating film was observed with a microscope at a magnification of 50 times to examine the presence or absence of film thickness unevenness and pinholes in the coating film. The evaluation was as follows: when neither film thickness unevenness nor pinholes were observed, the coatability was rated "excellent (A)"; when at least one of film thickness unevenness and pinholes was slightly observed, the coatability was rated "good (B)"; when at least one of film thickness unevenness and pinholes was clearly observed, the coatability was rated "poor (C)". As a result, in (S-3) to (S-5) and (C-1), neither film thickness unevenness nor pinholes were observed, and the coatability was "excellent (A)". In (S-1) and (S-2), slight film thickness unevenness was observed, and the coatability was "good (B)".

[0131] (5) Evaluation of dispersant removability From the dispersion composition (S-1) obtained in the above (1), (C-1) was applied onto a glass substrate on which the underlayer 313 was formed by spin coating, and dried on a hot plate at 80 °C for 10 minutes to form a coating film with a film thickness of 0.1 μm at the center of the substrate. Also, for (S-6), ultraviolet rays including a wavelength of 260 nm were irradiated onto the coating film using a UV lamp at 1 J. This coating film was immersed in an aqueous sodium hydroxide solution for 1 minute, and the surface was observed with an AFM (atomic force microscope, manufactured by Hitachi High-Technologies Corporation).

[0132] Both Fig. 11 and Fig. 12 are photographs of the surface of the substrate taken with an AFM. Fig. 11 is an example of a photograph of the substrate surface where the unevenness of CNTs is observed, and Fig. 12 is an example of a photograph of the substrate surface where the unevenness of CNTs is not observed with an AFM, that is, the CNTs are covered with a resin and a dispersant. When the dispersant on the surface is removed and the exposure of CNTs (carbon nanotubes) is seen as shown in Fig. 11, it is rated as "good (A)". When a part of the CNTs is exposed as shown in Fig. 12, it is rated as "acceptable (B)". When the surface is covered with a resin and no exposure of CNTs is seen, or when it is impossible to determine due to poor film formation, it is rated as "poor (C)".

[0133] As a result, in (S-2) to (S-4) and (S-6), the dispersant on the surface was removed and the exposure of CNTs (carbon nanotubes) was seen, so the judgment was "good (A)". In (S-1), although CNTs were exposed, aggregation of CNTs was seen, so the judgment was "acceptable (B)". In (S-5), although CNTs were exposed, a part of the CNT surface was covered with a resin, so the judgment was "acceptable (B)". In (C-1), the surface was covered with a dispersant and no exposure of CNTs was seen, so it was rated as "poor (C)".

[0134] Summarizing the above results, it is as shown in Table 1 below.

[0135]

Table 1

Claims

1. A method for manufacturing a vertical organic light-emitting transistor device, comprising: preparing a substrate on which the vertical organic light-emitting transistor device is formed on a main surface (step A); applying an organic material containing a polymer having a hydrocarbon group on the main surface of the substrate (step B); applying a dispersion liquid containing a dispersant and a carbon material on the organic material layer formed in step (B) (step C); drying the coating film formed in step (C) (step D); a method for manufacturing a vertical organic light-emitting transistor device, comprising, after the implementation of step (D), applying a cleaning liquid to remove the dispersant (step E).

2. The method for manufacturing a vertical organic light-emitting transistor device according to claim 1, wherein the content of the dispersant in the dispersion liquid with respect to the carbon material is in the range of 1,000% by mass to 100,000% by mass.

3. The method for manufacturing a vertical organic light-emitting transistor device according to claim 1 or 2, wherein the carbon material is at least one selected from carbon nanotubes, graphene, and fullerenes.

4. The method for manufacturing a vertical organic light-emitting transistor device according to claim 3, wherein the carbon material is a carbon nanotube.

5. The method for manufacturing a vertical organic light-emitting transistor device according to any one of claims 1 to 4, wherein the dispersant is a polymer having a structural moiety represented by the following formula (1), and the dispersion liquid is an organic solvent. 【Chemical 1】 (In formula (1), R 1 is a tetravalent organic group constituting a tetracarboxylic acid, R 2 is a divalent organic group constituting a diamine, and n is a positive integer.

6. In the structural part represented by the above formula (1) that the dispersant has, R 1 The manufacturing method of the vertical organic light-emitting transistor element according to claim 5, wherein is a cyclobutane ring.

7. The method for manufacturing a vertical organic light-emitting transistor device according to claim 5 or 6, wherein the dispersant contains an acid dissociable group.

8. The method for manufacturing a vertical organic light-emitting transistor device according to any one of claims 1 to 7, wherein the oxygen content in the organic material containing the polymer having a hydrocarbon group is 1% by mass or less.

9. The method for manufacturing a vertical organic light-emitting transistor device according to any one of claims 1 to 8, wherein in step (C), the dispersion liquid is applied on the organic material layer by any one of a spin coating method, a slit coating method, a bar coating method, a spray coating method, and an inkjet method.

10. The method for manufacturing a vertical organic light-emitting transistor device according to any one of claims 1 to 9, wherein the cleaning liquid is an aqueous alkali solution.

11. A display device comprising a vertical organic light-emitting transistor device manufactured by the manufacturing method according to any one of claims 1 to 10.

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