JP2013177499A - Ink composition, printing method and method for manufacturing display device using the ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink composition, with which by a high-definition patterning, printing can be performed, and to provide a printing method and a method for manufacturing a display device.SOLUTION: An ink composition comprises: an organic material; and a solvent having a dipole moment of 1.3 or more and 3.0 or less and having a π covalent bond in a molecular frame.

Description

  The present disclosure relates to, for example, an ink composition used for forming an organic layer of an organic EL (Electro Luminescence) display device, a printing method using the same, and a method for manufacturing a display device.

  With the acceleration of the development of the information and communication industry, high performance display elements are required. For example, the organic EL display element is a spontaneous emission type display element and is excellent in terms of wide viewing angle, contrast, and response speed.

  Materials used for an organic layer such as a light emitting layer of an organic EL element are roughly classified into a low molecular material and a high molecular material. When an organic EL display device including the organic EL element as a pixel is manufactured, a dry method such as a vacuum evaporation method is used as a method for forming the organic layer when a low molecular material is used. On the other hand, when a polymer material is used, ejection printing methods such as spin coating, ink jet, and nozzle jet, or plate printing methods such as flexographic printing, screen printing, gravure printing, and reverse offset printing are used. .

  Among the plate printing methods, the reverse offset printing method forms an ink coating on an intermediate transfer body called a blanket, contacts the intaglio, and transfers the pattern remaining on the blanket to the substrate to be printed from the blanket. Printing is performed. As such reversal offset printing, those using a roll blanket (for example, see Patent Document 1) and those using a flat blanket (for example, see Patent Document 2) have been proposed.

JP 2004-327067 A JP 2010-158799 A

  However, since a soft material such as silicone rubber used on the surface of the blanket easily absorbs the ink solvent, the ink coating applied on the blanket is easily dried. For this reason, there has been a problem that so-called stringing occurs at the edge of the pattern, the ink coating film becomes a film, and all of the ink film is transferred to the plate side, the pattern accuracy is lowered, or patterning is impossible.

  The present technology has been made in view of such problems, and an object thereof is to provide an ink composition capable of printing with high-definition patterning, a printing method using the same, and a method for manufacturing a display device. .

  The ink composition according to the present technology includes an organic material and a solvent having a dipole moment of 1.3 or more and 3.0 or less and having a π covalent bond in the molecular skeleton.

  In the printing method according to the present technology, an organic material and a dipole moment of 1.3 or more and 3.0 or less, and an ink composition containing a solvent having a π covalent bond in a molecular skeleton is applied to a blanket to form a transfer layer. A step of pressing a plate having a predetermined pattern on the transfer layer to form a pattern layer on the blanket, and a step of transferring the pattern layer to the substrate to be printed.

  A display device manufacturing method according to the present technology uses the above-described printing method.

  In the ink composition, the printing method, or the manufacturing method of the display device according to the present technology, the dipole moment is 1.3 or more and 3.0 or less, and a solvent having a π covalent bond in the molecular skeleton is used. Solvent absorption is suppressed.

  According to the ink composition, printing method, and display device manufacturing method of the present technology, a dipole moment is 1.3 or more and 3.0 or less, and a solvent having a π covalent bond in the molecular skeleton is used. High-definition patterning printing becomes possible.

It is process drawing explaining the printing method flow which concerns on one embodiment of this indication. FIG. 3 is a process diagram following FIG. 2. It is a characteristic view showing the dipole moment of each solvent and the contact angle with respect to the blanket. 5 is a flowchart of a method for manufacturing a display device according to an embodiment of the present disclosure. FIG. 5 is a cross-sectional view illustrating an example of a configuration of the display device illustrated in FIG. 4. FIG. 5 is a cross-sectional view illustrating another example of the configuration of the display device illustrated in FIG. 4. FIG. 6 is a schematic diagram illustrating an example of a pixel drive circuit of the display device illustrated in FIG. 5. FIG. 8 is a circuit diagram illustrating an example of a pixel circuit illustrated in FIG. 7. It is a top view showing schematic structure of the module containing the display apparatus of the said embodiment. It is a perspective view showing the external appearance of the application example 1 of the display apparatus of the said embodiment. (A) is a perspective view showing the external appearance seen from the front side of the application example 2, (B) is a perspective view showing the external appearance seen from the back side. 12 is a perspective view illustrating an appearance of application example 3. FIG. 14 is a perspective view illustrating an appearance of application example 4. FIG. (A) is a front view of the application example 5 in an open state, (B) is a side view thereof, (C) is a front view in a closed state, (D) is a left side view, and (E) is a right side view, (F) is a top view and (G) is a bottom view. It is a characteristic view in Experimental Examples 1-5 of this indication. It is the schematic diagram showing the printing pattern in Experimental Examples 1-5.

Hereinafter, embodiments of the present technology will be described in detail with reference to the drawings. The description will be given in the following order.
1. Embodiment 1-1. Ink composition 1-2. Manufacturing method 1-3. 1. Configuration of organic EL display device Application example Example

<1. Embodiment>
(1-1. Ink composition)
The ink composition according to the embodiment of the present disclosure includes, for example, a light emitting layer 14C (see FIG. 5) composed of red (R), green (G), and blue (B) in an organic EL display device (display device 1, see FIG. 5). 5) is used when forming by a plate printing method using a plate. In the plate printing method, for example, reverse offset printing, as described above, the ink coating (transfer layer 22a) is formed on the blanket 21, and then the intaglio (reverse printing plate 23) is brought into contact therewith and remains on the blanket 21. Printing is performed by contact-transferring the pattern (pattern layer 22b) from the blanket 21 to the substrate to be printed (substrate 11) (see FIGS. 1 and 2). In the present embodiment, the configuration of the ink composition used in the plate printing method will be described in detail.

  The ink composition is composed of a material (solute) that constitutes a target object and a solvent that dissolves the material.

  As the solute constituting the ink composition, for example, when forming the organic layer 14 (see FIG. 5) of the organic EL element 10 constituting the organic EL display device 1, an organic material is used. In the case of the plate printing method, it is necessary to increase the viscosity of the ink composition from the viewpoint of printability. For this reason, as the organic material (solute) of the ink composition, for example, a polymer or oligomer having a molecular weight of 5000 or more is preferably used. In particular, when forming the light emitting layer 14C, it is desirable to use an organic light emitting material having a π-conjugated system in the molecule in order to exhibit fluorescence or phosphorescence.

  As a solvent constituting the ink composition, a solvent having excellent solubility with respect to the organic material is preferably used. As a solvent having excellent solubility, it is preferable to use a solvent having a dipole moment within a predetermined range from the viewpoint of affinity with a solute. In addition, in the case of using an organic light emitting material having a π-conjugated system in the molecule in order to exhibit fluorescence or phosphorescence, the solvent having a π covalent bond in the molecular skeleton from the affinity with the solute, specifically, It is preferable to use a solvent having an oxygen atom or a nitrogen atom.

  The preferable value of the dipole moment of the solvent which comprises the ink composition in this Embodiment is demonstrated below.

  For example, the blanket 21 formed of silicone rubber tends to absorb the ink solvent when a solvent having high affinity for the silicone rubber is used as the ink solvent. For this reason, the ink applied on the blanket 21 is immediately dried, and it may be difficult to form a pattern. For this reason, it is preferable to use a solvent that has excellent solubility of the organic material and is not easily absorbed by the blanket 21 as the solvent constituting the ink composition in the present embodiment.

  The blanket, particularly the blanket 21 formed of the above-described silicone rubber, is generally formed using polydimethylsiloxane as a base (main component). Since this polymethylsiloxane is present on the surface of the blanket 21 and has almost no polarity, it is difficult to swell against a highly polar solvent. A dipole moment is generally used as an index representing polarity, but the dipole moment of polydimethylsiloxane is included in the range of 0 to 0.5.

  Therefore, as the solvent of the ink composition in the present embodiment, it is preferable to use a solvent having a higher dipole moment than polydimethylsiloxane, specifically, a solvent having a dipole moment larger than 0.5. Preferably it is 1.3 or more.

  On the other hand, in order to improve the coating property with respect to the blanket 21, it is preferable to use a solvent having a small contact angle of the solvent with respect to the blanket 21. As described above, the silicone blanket 21 is formed based on polydimethylsiloxane. For this reason, it becomes possible to improve paintability by using a solvent having a polarity, that is, a dipole moment close to that of polydimethylsiloxane, as an auxiliary solvent. In addition, when the difference between the dipole moment of polydimethylsiloxane and the dipole moment of the solvent constituting the ink composition is large, there is a possibility that the printing pattern cannot be maintained. For this reason, the dipole moment of the solvent is preferably 4 or less, more preferably 3.0 or less.

  From the above, it can be said that a preferable dipole moment value is 1.3 or more and 3.0 or less. FIG. 3 shows dipole moments of various solvents such as hexane, octane, xylene, tetralin, phenetole, diphenyl ether, anisole, acetophenone, cyclohexanone, N-methylpyrrolidone, 3-dimethyl-2-imidazolidinone, and contact angles with respect to the blanket 21. It represents. From FIG. 3, specific solvents constituting the ink composition in the present embodiment include phenol, 2-pentane, 3-pentane, 4-pentane, acetophenone, cyclohexanone, and N-methylpyrrolidone.

  In addition, the solvent of the ink composition in this Embodiment may combine several types of solvents. In that case, a solvent other than the range of the dipole moment may be used. For example, in order to improve the applicability to the blanket 21, a solvent having a small contact angle with respect to the blanket 21 as described above may be combined as an auxiliary solvent. The contact angle tends to be smaller as there is no conjugated system and the interaction between molecules is smaller. Specifically, a solvent having a polarity close to that of polydimethylsiloxane may be used as an auxiliary solvent, for example, a linear hydrocarbon type such as hexane or octane, an ether having no π bond, or an alcohol solvent. The contact angle of the ink composition with respect to the blanket 21 is preferably 30 ° or less.

(1-2. Manufacturing method)
1 and 2 show the reverse offset printing process. First, a blanket 21 is prepared as shown in FIG. The blanket 21 is formed by laminating a soft material layer made of silicone rubber on a base made of, for example, PET (polyethylene terephthalate) or metal. As shown in FIG. 1 (B), an ink composition 22 is applied onto the soft material layer of the blanket 21, and, for example, by spin coating, from the ink composition 22 as shown in FIG. 1 (C). A transfer layer 22a is formed.

  Subsequently, as shown in FIG. 1D, the reverse printing plate 23 is pressed against the blanket 21 on which the transfer layer 22a is formed. In this step, the blanket 21 and the reversal printing plate 23 are installed so as to be parallel, and by applying pressure to the back side of the blanket 21, uniform contact can be achieved.

  The reverse printing plate 23 is made of, for example, an inorganic material such as glass or silicon, or a metal such as stainless steel, copper, or nickel, and is provided with a concave portion having a pattern corresponding to a target printed matter. By bringing the reverse printing plate 23 and the blanket 21 into contact with each other so that the concave portion of the reverse printing plate 23 and the transfer layer 22a face each other, the reverse printing is performed on the blanket 21 side as shown in FIG. A pattern layer 22b made of the ink composition 22 having the same pattern as the concave pattern of the plate 23 is formed. On the reverse printing plate 23 side, a non-printing portion 22c made of an ink composition 22 having a reverse pattern to the concave portion (the same pattern as the convex portion) is formed. The contact between the reverse printing plate 23 and the blanket 21 is preferably performed within a short period of time, for example, within one minute after the transfer layer 22a is formed on the blanket 21. This is because if the time has passed, the solvent contained in the ink composition 22 volatilizes and the transfer layer 22a is dried.

  Next, as shown in FIG. 2B, the substrate 11 is prepared, and alignment is performed so that the pattern layer 22b of the blanket 21 and the pattern formation position on the substrate 11 face each other. Subsequently, as shown in FIG. 2C, after the substrate 11 is pressed against the blanket 21 by, for example, the compressed gas pressurization method described above, the blanket 21 is removed from the substrate 11 as shown in FIG. When pulled apart, the pattern layer 22 b is printed on the substrate 11. The contact between the blanket 21 and the substrate 11 is preferably performed within 30 minutes after the pattern layer 22b is formed. This is because if the time has passed, the solvent of the ink composition 22 is volatilized and the pattern layer 22b is hardly transferred (peeled) from the blanket 21.

(1-3. Configuration of Organic EL Display Device)
FIG. 4 is a flowchart showing a method for manufacturing the display device 1 according to an embodiment of the present disclosure, and FIG. 5 shows an example of a cross-sectional configuration of the display device 1 obtained by this manufacturing method. The display device 1 includes a red organic EL element 10R, a green organic EL element 10G, and a blue organic EL element 10B each having a lower electrode 12, an organic layer 14, and an upper electrode 15 in this order on a substrate 11 arranged in a matrix. is there. This display device 1 has a red light emitting layer 14CR of the red organic EL element 10R, a green light emitting layer 14CG of the green organic EL element 10G, and a blue light emitting layer 14CB of the blue organic EL element 10B by the reverse offset printing shown in FIGS. Formed.

(Process of forming the lower electrode 12)
First, a transparent conductive film made of, for example, ITO (indium and tin oxide) is formed on the entire surface of the substrate 11 on which a pixel drive circuit (not shown) is formed, and this transparent conductive film is patterned to form a lower electrode. 12 is formed for each of the red organic EL element 10R, the green organic EL element 10G, and the blue organic EL element 10B (step S101). At this time, the lower electrode 12 is connected to the driving transistor of the pixel driving circuit. For the substrate 11, known materials such as quartz, glass, metal foil, or a resin film or sheet can be used, but quartz or glass is preferably used. For the lower electrode 12, a simple substance or an alloy of a metal element such as chromium (Cr), gold (Au), platinum (Pt), nickel (Ni), copper (Cu), tungsten (W) or silver (Ag), or A transparent conductive film such as an alloy of InZnO (indium zinc oxide) or zinc oxide (ZnO) and aluminum (Al) may be used.

(Step of forming partition wall 13)
Next, an inorganic insulating film such as SiO ₂ is formed on the lower electrode 12 and the substrate 11 by, for example, a CVD (Chemical Vapor Deposition) method, and is patterned using a photolithography technique and an etching technique. Thus, the partition wall 13 is formed (step S102). The partition wall 13 is used to ensure insulation between the lower electrode 12 and the upper electrode 15 and to form a light emitting region in a desired shape. Therefore, an opening corresponding to the light emitting region is provided. After the partition wall 13 is formed, oxygen plasma treatment is performed on the surface of the substrate 11 (the surface on the side where the partition wall 13 and the lower electrode 12 are formed) to clean the surface of the lower electrode 12.

(Step of forming hole injection layer 14A and hole transport layer 14B)
After the oxygen plasma treatment, the hole injection layer 14A and the holes common to the red organic EL element 10R, the green organic EL element 10G, and the blue organic EL element 10B in the organic layer 14 are formed on the lower electrode 12 and the partition wall 13. The transport layer 14B is formed in this order (steps S103 and S104).

  Although details will be described later for the hole injection layer 14A and the hole transport layer 14B, for example, the following materials can be used. Examples of the material of the hole injection layer 14A include polyaniline, polythiophene, polypyrrole, polyphenylene vinylene, polythienylene vinylene, polyquinoline, polyquinoxaline and derivatives thereof, and polymers containing an aromatic amine structure in the main chain or side chain. Conductive polymer, metal phthalocyanine (such as copper phthalocyanine) or carbon can be used. In addition, oligoaniline or polydioxythiophene such as poly (3,4-ethylenedioxythiophene) (PEDOT) may be used. It is also possible to use trade names such as Nafion (trademark) and trade name Liquion (trademark) manufactured by H.C. Starck, trade name Elsource (trademark) manufactured by Nissan Chemical, and conductive polymer verazol manufactured by Soken Chemical. it can.

  As the material of the hole transport layer 14B, for example, polyvinyl carbazole, polyfluorene, polyaniline, polysilane, a polysiloxane derivative having an aromatic amine in a side chain or a main chain, polythiophene and a derivative thereof, or a polymer material such as polypyrrole is used. can do.

(Step of forming red light emitting layer 14CR, green light emitting layer 14CG and blue light emitting layer 14CB)
After forming the hole transport layer 14B, the red light emitting layer 14CR of the red organic EL element 10R, the green light emitting layer 14CG of the green organic EL element 10G, and the blue light emitting layer 14CB of the blue organic EL element 10B are formed by reverse offset printing ( Step S105).

  Specifically, the red light emitting layer 14CR (green light emitting layer 14CG, blue light emitting layer 14CB) is formed by using the above-described reverse offset printing (FIGS. 1 and 2). First, as shown in FIG. 1A, a blanket 21 having a soft material layer on a substrate is prepared. Next, as shown in FIG. 1 (B), an ink composition 22 (for example, ink for the red light emitting layer 14CR) is applied on the soft material layer of the blanket 21. Subsequently, a transfer layer 22a made of the ink composition 22 is formed by spin coating as shown in FIG. In addition, if the red light emitting layer 14CR, the green light emitting layer 14CG, and the blue light emitting layer 14CB are formed in the atmosphere, the light emitting lifetime of the organic EL elements 10R, 10G, and 10B may be shortened. It is preferable to perform printing.

  After the transfer layer 22a made of the ink composition 22 for the red light emitting layer 14CR is formed on the blanket 21, the reverse printing plate 23 is pressed against the transfer layer 22a as shown in FIG. Hit it.

  As described above, the reverse printing plate 23 is provided with a concave portion of a pattern corresponding to a target pattern (for example, the red light emitting layer 14CR) on one surface. By bringing the reverse printing plate 23 and the blanket 21 into contact with each other so that the concave portion of the reverse printing plate 23 and the transfer layer 22a face each other, the reverse printing is performed on the blanket 21 side as shown in FIG. A pattern layer 22b made of the ink composition 22 having the same pattern as the recess pattern of the plate 23 (for example, a pattern corresponding to the red light emitting layer 14CR) is formed. On the reverse printing plate 23 side, a non-printing portion 22c made of an ink composition 22 having a reverse pattern to the concave portion (the same pattern as the convex portion) is formed.

  Next, as shown in FIG. 2B, the substrate 11 having the hole transport layer 14B formed thereon is prepared, and the alignment is performed so that the pattern layer 22b of the blanket 21 and the hole transport layer 14B face each other. Do. Here, the pattern layer 22b of the blanket 21 is adjusted to a position corresponding to the red organic EL element 10R. Next, as shown in FIG. 2C, after the substrate 11 is pressed against the blanket 21, the blanket 21 is pulled away from the substrate 11 as shown in FIG. A pattern layer 22b is printed thereon. The red light emitting layer 14CR is formed by heating the pattern layer 22b on the substrate 11 and completely removing the solvent. Thereafter, a new blanket 21 is used to form the green light emitting layer 14CG and the blue light emitting layer 14CB through the same process.

  Other methods for forming the red light emitting layer 14CR, the green light emitting layer 14CG, and the blue light emitting layer 14CB include an inkjet method and a nozzle printing method. However, in these methods, since the liquid ink must be retained in the formation region until the ink is dried, the partition wall 13 of the present embodiment is used as the lower partition wall, and the upper partition wall is formed thereon. There is a need. On the other hand, when the red light emitting layer 14CR, the green light emitting layer 14CG, and the blue light emitting layer 14CB are formed by reverse offset printing, an upper partition for holding ink is not necessary, and the display device 1 as shown in FIG. The structure can be simplified. Further, the red light emitting layer 14CR, the green light emitting layer 14CG, and the blue light emitting layer 14CB are not contaminated by the upper partition.

  Here, as described above, the ink composition 22 has a dipole moment of 1.3 or more and 3.0 or less, a solvent having a π covalent bond in the molecular skeleton, a red light emitting layer 14CR or a green light emitting layer 14CG. The polymer (light-emitting) material and the low-molecular material constituting the material are mixed.

  The organic material, particularly the polymer material, that is the solute of the ink composition 22 constitutes the red light emitting layer 14CR, the green light emitting layer 14CG, and the blue light emitting layer 14CB. Bonding occurs and generates light. Examples of the polymer material include polyfluorene polymer derivatives, (poly) paraphenylene vinylene derivatives, polyphenylene derivatives, polyvinyl carbazole derivatives, polythiophene derivatives, perylene dyes, coumarin dyes, rhodamine dyes, and the above polymers. What doped the organic EL material is mentioned. As the doping material, for example, rubrene, perylene, 9,10 diphenylanthracene, tetraphenylbutadiene, Nile red, coumarin 6 or the like can be used.

  In addition, the ink composition 22 may contain a low molecular material in addition to the polymer material. By using the low molecular material, the red light emitting layer 14CR, the green light emitting layer 14CG, and the blue light emitting layer 14CB can be formed with high definition on the substrate 11 by patterning, and the resolution of the display device 1 can be improved. .

  Specifically, when the transfer layer 22a is formed on the blanket 21 (FIG. 1C), or before the transfer of the pattern layer 22b from the blanket 21 described later to the substrate 11 (printed substrate) (FIG. 2A). , (B)), since this low molecular material suppresses the film formation of the ink composition 22 (transfer layer 22a, pattern layer 22b) on the blanket 21, high-definition patterning becomes possible. The conformation of the above polymer materials varies depending on the concentration and spin coating conditions. However, when the ink composition 22 does not contain a low molecular material, the molecules of these polymer materials are easily entangled, and the blanket It is estimated that the film is easily formed on the film 21. Since the low molecular weight material suppresses the film formation of the polymer material, the red light emitting layer 14CR and the green light emitting layer 14CG can be formed on the substrate 11 with fine line and space (line resolution). In the display device 1, this low molecular material constitutes a red light emitting layer 14CR, a green light emitting layer 14CG, and a blue light emitting layer 14CB together with the polymer material.

  The low molecular weight material of the ink composition 22 is other than a compound composed of a high molecular weight polymer or a condensate molecule produced by repeating the same reaction or a similar reaction in a low molecular weight compound, and has a molecular weight. Is substantially single. In addition, this low-molecular material does not form a new chemical bond between molecules by heating, and exists as a single molecule.

  The weight average molecular weight (Mw) of such a low molecular material is preferably 50,000 or less, and more preferably 15,000 or less. This is because a material having a large molecular weight, for example, a material having a molecular weight that is somewhat smaller than a material having a molecular weight of 50,000 or more has various characteristics, and therefore it is easy to adjust conditions such as solubility in a solvent and ink viscosity.

  The ratio of the polymer material to the low-molecular material is preferably polymer material: low-molecular material (weight ratio) = 10: 1 or more and 1: 2 or less, and preferably 21 or more and 1: 2 or less. More preferred. This is because when the polymer material: low molecular material (weight ratio) is less than 10: 1, the effect of the low molecular material is hardly exhibited, and when it exceeds 1: 2, film formation may be difficult.

  Examples of such low molecular weight materials include benzene, styrylamine, triphenylamine, porphyrin, triphenylene, azatriphenylene, tetracyanoquinodimethane, triazole, imidazole, carbazole, oxadiazole, polyarylalkane, phenylenediamine, It is possible to use arylamine, oxazole, anthracene, fluorenone, hydrazone, stilbene or derivatives thereof, or heterocyclic conjugated monomers or oligomers such as polysilane compounds, vinylcarbazole compounds, thiophene compounds or aniline compounds. .

Specific examples of the low molecular weight material include α-naphthylphenylphenylenediamine, porphyrin, metal tetraphenylporphyrin, metal naphthalocyanine, hexacyanoazatriphenylene, 7,7,8,8-tetracyanoquinodimethane (TCNQ), 7 , 7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (F4-TCNQ), tetracyano 4,4,4-tris (3-methylphenylphenylamino) triphenylamine, N,
N, N ′, N ′,-tetrakis (p-tolyl) p-phenylenediamine, N, N, N ′, N ′,
-Tetraphenyl-4,4'-diaminobiphenyl, N-phenylcarbazole, 4-di-p-tolylaminostilbene, poly (paraphenylene vinylene), poly (thiophene vinylene), poly (2,2'-thienylpyrrole) However, it is not limited to these.

  More preferably, it is preferable to use low molecular weight materials represented by the following formulas (1) to (3).

（Ａ１〜Ａ３は芳香族炭化水素基、複素環基またはそれらの誘導体である。）

(A1 to A3 are aromatic hydrocarbon groups, heterocyclic groups, or derivatives thereof.)

（但し、式（１）に含まれる化合物を除く。Ｚ１は含窒素炭化水素基あるいはその誘導体である。Ｌ１は２価の芳香族環基が１乃至４個結合した基、具体的には、２〜４個の芳香族環が連結した２価の基、またはその誘導体である。Ａ４およびＡ５は、芳香族炭化水素基、またはその誘導体である。但し、Ａ４およびＡ５は互いに結合して環状構造を形成してもよい。）

(However, the compound included in Formula (1) is excluded. Z1 is a nitrogen-containing hydrocarbon group or a derivative thereof. L1 is a group in which 1 to 4 divalent aromatic ring groups are bonded, specifically, A divalent group in which 2 to 4 aromatic rings are linked, or a derivative thereof A4 and A5 are aromatic hydrocarbon groups or a derivative thereof, provided that A4 and A5 are bonded to each other to form a ring A structure may be formed.)

（但し、式（１）および式（２）に含まれる化合物を除く。Ｚ２は含窒素炭化水素基あるいはその誘導体である。Ｌ２は２価の芳香族環基が２乃至６個結合した基である。具体的には、２〜６個の芳香族環が連結した２価の基、またはその誘導体である。Ａ６〜Ａ９は、芳香族炭化水素基あるいは複素環基、またはその誘導体が１〜１０個結合した基である。）

(However, the compounds included in the formula (1) and the formula (2) are excluded. Z2 is a nitrogen-containing hydrocarbon group or a derivative thereof. L2 is a group in which 2 to 6 divalent aromatic ring groups are bonded. Specifically, it is a divalent group in which 2 to 6 aromatic rings are linked, or a derivative thereof A6 to A9 are aromatic hydrocarbon groups or heterocyclic groups, or derivatives thereof are 1 to 10 groups bonded together.)

  Specific examples of the compound represented by the formula (1) include compounds such as the following formula (1-1) to formula (1-48).

  Specific examples of the compound represented by the formula (2) include compounds such as the following formula (21) to formula (2163).

  Specific examples of the compound represented by the formula (3) include compounds such as the following formulas (3-1) to (3-45).

  Note that the blue light emitting layer 14CB may be formed as a common layer as shown in FIG. In that case, after forming the red light emitting layer 14CR and the green light emitting layer 14CG, the blue light emitting layer 14CB is formed on the entire surface of the red light emitting layer 14CR, the green light emitting layer 14CG and the hole transport layer 14B by vapor deposition. As a material of the blue light emitting layer 14CB serving as the common layer, for example, a guest material of a blue or green fluorescent dye is used for doping an anthracene compound as a host material. Thereby, blue or green emission light is generated.

  In addition, when the blue light emitting layer 14CB is used as a common layer, the ink composition 22 constituting the red light emitting layer 14CR and the green light emitting layer 14CG contains a low molecular material, so that the red light emitting layer 14CR and The injection efficiency of holes and electrons from the blue light emitting layer 14CB laminated on the green light emitting layer 14CG to the light emitting layers 14CR and 14CG can be improved. That is, the characteristics of the red organic EL element 10R and the green organic EL element 10G are improved.

  When the red light emitting layer 14CR and the green light emitting layer 14CG do not contain the low molecular weight material, there is a difference between the energy level of the blue light emitting layer 14CB and the energy level of the red light emitting layer 14CR and the green light emitting layer 14CG. growing. That is, the efficiency of hole or electron injection between the blue light-emitting layer 14CB, the red light-emitting layer 14CR, and the green light-emitting layer 14CG is lowered, and there is a possibility that desired characteristics cannot be obtained. On the other hand, when the red light emitting layer 14CR and the green light emitting layer 14CG are formed of a low molecular material together with a high molecular material, the difference in energy level is reduced, and the above hole and electron injection efficiency can be improved. It becomes.

(Step of forming electron transport layer 14D, electron injection layer 14E, and upper electrode 15)
After forming the blue light emitting layer 14CB, the electron transport layer 14D, the electron injection layer 14E, and the upper electrode 15 are formed in this order on the entire surface of the blue light emitting layer 14CB by vapor deposition (steps S106, S107, S108).

The electron transport layer 14D increases the efficiency of electron transport to the red light emitting layer 14CR, the green light emitting layer 14CG, and the blue light emitting layer 14CB. Examples of the material for the electron transport layer 14D include quinoline, perylene, phenanthroline, bisstyryl, pyrazine, triazole, oxazole, fullerene, oxadiazole, fluorenone, and derivatives and metal complexes thereof. Specifically, tris (8-hydroxyquinoline) aluminum (abbreviation Alq3), anthracene, naphthalene, phenanthrene, pyrene, perylene, butadiene, coumarin, C _60, acridine, stilbene, 1,10-phenanthroline or a derivative thereof or a metal Complex and the like.

The electron injection layer 14E is for increasing the electron injection efficiency. As a material of the electron injection layer 14E, for example, lithium oxide (Li ₂ O) which is an oxide of lithium (Li), cesium carbonate (Cs ₂ CO ₃ ) which is a composite oxide of cesium (Cs), or these Mixtures can be used. Further, as a material of the electron injection layer 14E, for example, an alkaline earth metal such as calcium (Ca) or barium (Ba), an alkali metal such as lithium or cesium, a work function such as indium (In) or magnesium (Mg) is small. Metals, oxides of these metals, composite oxides, fluorides, and the like may be used alone, or as a mixture or alloy.

  The upper electrode 15 is formed in the form of a solid film on the substrate 11 while being insulated from the lower electrode 12 by the partition wall 13 and the organic layer 14, and includes the red organic EL element 10R, the green organic EL element 10G, and the blue organic EL element 10B. Functions as a common electrode. The upper electrode 15 is formed of a metal conductive film such as aluminum, magnesium, calcium, or sodium (Na). It is preferable that the upper electrode 15 is formed of an alloy of magnesium and silver (Mg—Ag alloy) having good conductivity in a thin film and low light absorption. The ratio of magnesium and silver in the Mg-Ag alloy is not particularly limited, but is preferably in the range of Mg: Ag = 20: 1 to 1: 1 in terms of film thickness ratio. An alloy of aluminum and lithium (Al—Li alloy) may be used as the material of the upper electrode 15.

  The upper electrode 15 may be formed of a mixed layer containing an organic light emitting material such as an aluminum quinoline complex, a styrylamine derivative, or a phthalocyanine derivative. In this case, a light-transmitting layer such as an Mg—Ag alloy may be further formed as the third layer.

  After the upper electrode 15 is formed, a protective layer 16 made of amorphous silicon nitride having low water permeability is formed by, for example, vapor deposition or CVD. After the protective layer 16 is formed, finally, a sealing substrate 17 provided with a light shielding film and a color filter (not shown) is bonded onto the protective layer 16 with an adhesive layer (not shown) interposed therebetween. . Thus, the display device 1 shown in FIG. 5 is completed.

  FIG. 7 illustrates a planar configuration of the display device 1 including the organic EL element 10 of the present embodiment. The display device 1 is used as an organic EL television device or the like. For example, a plurality of organic EL elements 10 (for example, a red organic EL element 10R, a green organic EL, etc.) are formed on a substrate 11 as a display region 110. Elements 10G and blue organic EL elements 10B) are arranged in a matrix. Around the display area 110, a signal line driving circuit 120 and a scanning line driving circuit 130, which are drivers for displaying images, are provided. A combination of adjacent organic EL elements 10 constitutes one pixel (pixel).

  A pixel drive circuit 140 is provided in the display area 110. FIG. 8 illustrates an example of the pixel driving circuit 140. The pixel drive circuit 140 is an active drive circuit formed below the lower electrode 12. That is, the pixel drive circuit 140 includes a drive transistor Tr1 and a write transistor Tr2, a capacitor (holding capacitor) Cs between the transistors Tr1 and Tr2, a first power supply line (Vcc), and a second power supply line (GND). ), The organic EL element 10 (for example, 11R, 11G, 11B) connected in series to the drive transistor Tr1. The drive transistor Tr1 and the write transistor Tr2 are configured by general TFTs, and the configuration thereof may be, for example, an inverted staggered structure (so-called bottom gate type) or a staggered structure (top gate type), and is not particularly limited.

  In the pixel driving circuit 140, a plurality of signal lines 120A are arranged in the column direction, and a plurality of scanning lines 130A are arranged in the row direction. An intersection between each signal line 120A and each scanning line 130A corresponds to one of the organic EL elements 10 (subpixel). Each signal line 120A is connected to the signal line drive circuit 120, and an image signal is supplied from the signal line drive circuit 120 to the source electrode of the write transistor Tr2 via the signal line 120A. Each scanning line 130A is connected to the scanning line driving circuit 130, and a scanning signal is sequentially supplied from the scanning line driving circuit 130 to the gate electrode of the writing transistor Tr2 via the scanning line 130A.

  In the display device 1, a scanning signal is supplied from the scanning line driving circuit 130 to the pixel via the gate electrode of the writing transistor Tr 2, and an image signal is held from the signal line driving circuit 120 via the writing transistor Tr 2. The capacitance Cs is held. That is, the drive transistor Tr1 is controlled to be turned on / off in accordance with the signal held in the holding capacitor Cs, whereby the drive current Id is injected into the red organic EL element 10R, the green organic EL element 10G, and the blue organic EL element 10B. The holes and electrons recombine to emit light. This light is transmitted through the lower electrode 12 and the substrate 11 in the case of bottom emission (bottom emission), and is transmitted through the upper electrode 15, the wavelength converter and the sealing substrate 17 in the case of top emission (top emission). And then taken out.

  In the plate printing method, after an ink coating is formed on a blanket, the intaglio is brought into contact, and the pattern remaining on the blanket is printed by contact transfer from the blanket to the substrate to be printed. The blanket 21 is required to have releasability to transfer all of the contact surface when the organic film (transfer layer 22a) formed on the blanket 21 comes into contact with the substrate to be printed. As a material for the blanket 21 having excellent releasability, a silicone rubber based on polydimethylsiloxane is generally used.

  However, a soft material such as silicone rubber used on the surface of the blanket easily absorbs the ink solvent, and the ink coating applied on the blanket tends to dry. For this reason, as described above, there is a problem that stringing occurs at the edge of the pattern, the ink coating film is formed into a film, the pattern accuracy is lowered, or patterning cannot be performed.

  As a method for solving this problem, a method of adding a mechanism for swelling the blanket 21 in advance (Japanese Patent Laid-Open No. 2007-90698) or a mechanism for removing a solvent (Japanese Patent Laid-Open No. 2007-95517) is proposed. Has been. However, there is a problem that the process becomes complicated and the cost increases. Further, when a phenomenon in which the solvent cannot be completely removed occurs, a reverse diffusion phenomenon of the solvent occurs with respect to the organic substance patterned on the blanket 21, so that the pattern shrinks with the drying process. As a result, there has been a problem that dimensional variation occurs and the definition is lowered, and the brightness of the display device is uneven.

  In contrast, the ink composition of the present embodiment uses a solvent having a dipole moment of 1.3 or more and 3.0 or less and having a π covalent bond in the molecular skeleton. The polydimethylsiloxane on the surface of the blanket 21 has almost no polarity. For this reason, by using a solvent having higher polarity than dimethylsiloxane, solvent absorption into the blanket 21 can be suppressed, and swelling of the blanket 21 is suppressed. Therefore, it is suppressed that the transfer layer and the pattern layer are formed into a film on the blanket 21.

  As described above, according to the present embodiment, a solvent having a dipole moment of 1.3 or more and 3.0 or less and having a π covalent bond in the molecular skeleton is used. Thereby, high-definition pattern printing can be performed without adding a new process for suppressing the swelling of the silicone rubber blanket 21. Therefore, a display device with high display quality can be provided.

<2. Application example>
(Modules and application examples)
Hereinafter, application examples of the display devices 1 and 2 described in the above embodiment will be described. The display device according to the above embodiment is an image signal that is input from the outside or is generated internally, such as a television device, a digital camera, a notebook personal computer, a mobile terminal device such as a mobile phone, or a video camera. Alternatively, the present invention can be applied to display devices for electronic devices in various fields that display images.

(module)
The display devices 1 and 2 described in the above embodiment are incorporated into various electronic devices such as application examples 1 to 5 described later, for example, as modules as illustrated in FIG. In this module, for example, a region 210 exposed from the protective layer 16 and the sealing substrate 17 is provided on one side of the substrate 11, and wirings of the signal line driving circuit 120 and the scanning line driving circuit 130 are provided in the exposed region 210. An external connection terminal (not shown) is formed by extending. The external connection terminal may be provided with a flexible printed circuit (FPC) 220 for signal input / output.

(Application example 1)
FIG. 10 illustrates an appearance of a television device to which the display devices 1 and 2 described in the above embodiment are applied. This television apparatus has, for example, a video display screen unit 300 including a front panel 310 and a filter glass 320, and the video display screen unit 300 is configured by the display device according to the above embodiment.

(Application example 2)
FIG. 11 illustrates an appearance of a digital camera to which the display devices 1 and 2 described in the above embodiment are applied. The digital camera includes, for example, a flash light emitting unit 410, a display unit 420, a menu switch 430, and a shutter button 440, and the display unit 420 is configured by the display device according to the above embodiment. .

(Application example 3)
FIG. 12 shows the appearance of a notebook personal computer to which the display devices 1 and 2 described in the above embodiment are applied. The notebook personal computer has, for example, a main body 510, a keyboard 520 for inputting characters and the like, and a display unit 530 for displaying an image. The display unit 530 is a display device according to the above embodiment. It is comprised by.

(Application example 4)
FIG. 13 shows an appearance of a video camera to which the display devices 1 and 2 described in the above embodiment are applied. This video camera has, for example, a main body 610, a subject photographing lens 620 provided on the front side surface of the main body 610, a start / stop switch 630 at the time of photographing, and a display 640. Reference numeral 640 denotes the display device according to the above embodiment.

(Application example 5)
FIG. 14 shows an appearance of a mobile phone to which the display devices 1 and 2 described in the above embodiment are applied. For example, the mobile phone is obtained by connecting an upper housing 710 and a lower housing 720 with a connecting portion (hinge portion) 730, and includes a display 740, a sub-display 750, a picture light 760, and a camera 770. Yes. The display 740 or the sub-display 750 is configured by the display device according to the above-described embodiment or the like.

  Furthermore, specific examples of the present technology will be described.

<3. Example>
The light emitting layer 14C of the organic EL element 10 was formed using the plate printing method described above. Table 1 and FIG. 15 show the solvent composition, the dipole moment, and the weight increase rate after 1 minute constituting the ink composition in each experimental example. Moreover, the schematic diagram of the printing pattern in each Experimental example 1-5 was shown to FIG. 16 (A)-(E). The weight increase rate after 1 minute is the weight increase rate of the silicone rubber when the solvent is immersed in the blanket for 1 minute.

  In Experimental Example 4 (Comparative Example 1) using 100% xylene as a solvent, xylene was absorbed into the silicone blanket and a film was formed on the surface of the blanket. For this reason, patterning could not be performed as shown in FIG. In order to perform patterning using xylene, as described above, the solvent absorption from the organic film formed on the blanket can be suppressed by swelling the solvent in the blanket in advance. However, in that case, since the solvent is reversely diffused from the blanket to the organic film, the obtained pattern may be shrunk or distorted with the volatilization of the solvent.

  In Experimental Example 5 (Comparative Example 2) using NMP: octane (50:50) as a solvent, the ink was repelled from the magnitude of the dipole moment (dipole moment 4.09), and the coating film could not be formed. As shown in FIG. 16 (E), the partial liquid was in a state where a puddle was generated.

  In contrast, in Experimental Examples 1 to 3 (Examples 1 to 3) using a solvent having a dipole moment in the range of 1.3 to 3.0, the results are shown in FIGS. Thus, it can be seen that the patterning is accurate.

  From the above results, it was confirmed that high-definition patterning printing was possible by using a solvent having a dipole moment of 1.2 or more and 3.0 or less as a solvent constituting the ink composition. From the characteristic diagram of FIG. 15, the solvent constituting the ink composition is a solvent in which the weight increase rate of the solvent with respect to the polymer constituting the blanket is 1% or more and 6% or less when the solvent is immersed in the blanket for 1 minute. Can be said to be preferable.

  While the present disclosure has been described with reference to the embodiments and examples, the present disclosure is not limited to the above-described embodiments and the like, and various modifications can be made. For example, in the above-described embodiment and the like, an example in which the red light emitting layer 14CR or the green light emitting layer 14CG is formed using the ink composition 22 has been described, but a light emitting layer other than the red light emitting layer 14CR and the green light emitting layer 14CG, or Other organic layers 14 such as the hole injection layer 14A and the hole transport layer 14B may be formed by patterning. In particular, if the hole injection layer 14A is formed by patterning, leakage current can be suppressed.

  Moreover, in the said embodiment etc., although the case where the printing pattern layer as a part of functional layer was the light emitting layer 14C was illustrated, it is not limited to this, Other organic layers 14, for example, hole injection layer 14A, One or more of the hole transport layer 14B, the electron transport layer 14D, and the electron supply layer 14E may be formed by offset printing as a print pattern layer.

  Furthermore, in the said embodiment etc., although the structure of organic EL element 10R, 10G, 10B was mentioned concretely and demonstrated, it is not necessary to provide all the layers and you may further provide another layer. In the above-described embodiment and the like, a display device including red and green organic EL elements as organic EL elements other than blue has been described. However, the present disclosure is not limited thereto, and a functional layer is formed using a printing method. The present invention can be applied to all display devices that can be formed. For example, application to a display device composed of a blue organic EL element and a yellow organic EL element is also possible.

  Furthermore, in the above-described embodiments and the like, the case of the active matrix display devices 1 and 2 has been described, but the present disclosure can also be applied to a passive matrix display device. Furthermore, the configuration of the pixel driving circuit for active matrix driving is not limited to that described in the above embodiment, and a capacitor or a transistor may be added as necessary. In that case, a necessary driving circuit may be added in addition to the signal line driving circuit 120 and the scanning line driving circuit 130 described above in accordance with the change of the pixel driving circuit.

  Further, in the above-described embodiment and the like, the case where the display devices 1 and 2 are the top emission type or the bottom emission type has been described. However, the present disclosure also discloses the display devices 1 and 2 that extract light from both the upper surface and the lower surface. Is applicable.

In addition, this technique can also take the following structures.
(1) An ink composition comprising an organic material and a solvent having a dipole moment of 1.3 or more and 3.0 or less and having a π covalent bond in the molecular skeleton.
(2) The ink composition according to (1), which contains 50% or more of the solvent.
(3) The ink composition according to (1) or (2), wherein the organic material includes a polymer or oligomer having a molecular weight of 5000 or more.
(4) The ink composition according to any one of (1) to (3), wherein a weight of the organic material in a solution composed of the organic material and a solvent is 80% or more and 99.5% or less. .
(5) The solvent is at least one of anisole, phenetole, diphenyl ether, 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, acetophenone, cyclohexanone, 2-pentanone, 3-pentanone and 4-pentanone. The ink composition according to any one of (1) to (4).
(6) The solvent is at least one of 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, acetophenone, cyclohexanone, 2-pentanone, 3-pentanone, and 4-pentanone. The ink composition according to any one of (5).
(7) a step of applying an ink composition containing an organic material and a dipole moment of 1.3 or more and 3.0 or less and having a π covalent bond in the molecular skeleton to a blanket to form a transfer layer; A printing method comprising: pressing a plate having a predetermined pattern onto the transfer layer to form a pattern layer on the blanket; and transferring the pattern layer to a substrate to be printed.
(8) The printing method according to (7), wherein a weight increase rate of the solvent with respect to a polymer constituting the blanket is 1% or more and 6% or less when the solvent is immersed in the blanket for 1 minute.
(9) The printing method according to (7) or (8), wherein the blanket is formed of silicone rubber.
(10) including a step of forming a display element on a substrate, wherein the step of forming the display element has an organic material and a dipole moment of 1.3 to 3.0, and a π covalent bond is attached to the molecular skeleton. A step of applying an ink composition containing a solvent having a blanket to form a transfer layer, a step of pressing a plate having a predetermined pattern on the transfer layer to form a pattern layer on the blanket, and the pattern And a step of transferring the layer to the substrate to be printed.

DESCRIPTION OF SYMBOLS 1, 2 ... Display apparatus, 10R ... Red organic EL element, 10G ... Green organic EL element, 10B ... Blue organic EL element, 11 ... Substrate, 12 ... Lower electrode, 13 ... Lower partition, 14 ... Organic film, 14A ... Positive Hole injection layer, 14B ... hole transport layer, 14CR ... red light emitting layer, 14CG ... green light emitting layer, 14CB ... blue light emitting layer, 14D ... electron transport layer, 14E ... electron injection layer, 15 ... upper electrode, 16 ... protective layer 17 ... sealing substrate, 21 ... blanket, 22 ... ink composition for reverse printing, 22a ... transfer layer, 22b ... pattern layer, 22c ... non-printing part.

Claims (10)

Organic materials,
An ink composition comprising: a dipole moment of 1.3 or more and 3.0 or less and a solvent having a π covalent bond in the molecular skeleton.   The ink composition according to claim 1, comprising 50% or more of the solvent.   The ink composition according to claim 1, comprising a polymer or oligomer having a molecular weight of 5000 or more as the organic material.   The ink composition according to claim 1, wherein the weight of the organic material in the solution composed of the organic material and a solvent is 80% or more and 99.5% or less.   The solvent is at least one of anisole, phenetole, diphenyl ether, 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, acetophenone, cyclohexanone, 2-pentanone, 3-pentanone and 4-pentanone. The ink composition according to 1.   The ink composition according to claim 1, wherein the solvent is at least one of 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, acetophenone, cyclohexanone, 2-pentanone, 3-pentanone, and 4-pentanone. object. A step of applying an ink composition containing an organic material and a dipole moment of 1.3 or more and 3.0 or less and having a π covalent bond in the molecular skeleton to a blanket to form a transfer layer;
Pressing a plate having a predetermined pattern on the transfer layer to form a pattern layer on the blanket;
Transferring the pattern layer to a substrate to be printed.   The printing method according to claim 7, wherein a weight increase rate of the solvent with respect to a polymer constituting the blanket when the solvent is immersed in the blanket for 1 minute is 1% or more and 6% or less.   The printing method according to claim 7, wherein the blanket is formed of silicone rubber. Forming a display element on a substrate;
The step of forming the display element includes:
A step of applying an ink composition containing an organic material and a dipole moment of 1.3 or more and 3.0 or less and having a π covalent bond in the molecular skeleton to a blanket to form a transfer layer;
Pressing a plate having a predetermined pattern on the transfer layer to form a pattern layer on the blanket;
And transferring the pattern layer to a substrate to be printed.

Images