JP5277675B2 - Method for producing organic thin film transistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic thin-film transistor which makes an off-state current low, and a method of manufacturing the organic thin-film transistor, and to provide an organic thin-film transistor array having the organic thin-film transistors, a display panel having the organic thin-film transistor array, and a display device having the display panel. <P>SOLUTION: In the organic thin-film transistor 10a, a gate electrode 12 is formed on a substrate 11, and a gate insulating film 13 is formed on the gate electrode 12. A source electrode 14 and a drain electrode 15 are formed with an air gap on the gate electrode 12 in which at least the gate insulating film 13 is formed. An organic semiconductor layer 16 is formed at a region including the air gap, and an interlayer insulating film 17 is formed so as to cover the organic semiconductor layer 16. A conductive layer 18 bonded to the drain electrode 15 is formed on the interlayer insulating film 17, and a part of the organic semiconductor layer 16 is formed on the interlayer insulating film 17. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

The present invention relates to a method of manufacturing a organic thin film transistor, an organic thin film transistor array, a display panel and a display unit.

  In recent years, organic thin film transistors using organic semiconductor materials have been intensively studied. At this time, the advantages of organic thin-film transistors are that they have high flexibility in the variety of material configurations, manufacturing methods, product forms, etc., can be easily increased in area, and can have a simple layer configuration. Can be manufactured using an inexpensive manufacturing apparatus.

  When manufacturing organic thin film transistors, it is possible to easily form thin films and circuits by using printing methods, spin coating methods, immersion methods, etc., which is orders of magnitude lower than conventional thin film transistors using Si semiconductor materials. Can be cheaply manufactured. In addition, when integrating an organic thin-film transistor, it becomes essential to pattern an organic-semiconductor layer. When transistors are integrated without patterning the organic semiconductor layer, off-current increases during operation of the transistors, and power consumption increases. Further, it causes crosstalk when displaying the display medium. In addition, when patterning a semiconductor layer using Si semiconductor material, photolithography and etching are used. Specifically, after applying a photoresist, exposing and developing a desired pattern to form a resist pattern, etching is performed using this as an etching mask, and the resist is peeled and patterned.

  On the other hand, when patterning the organic semiconductor layer, it is possible to use photolithography and etching as in the case of using the Si semiconductor material. However, when a polymer material is used as the organic semiconductor material, it is considered that transistor characteristics deteriorate if a pattern or the like is formed by applying a photoresist on the polymer organic semiconductor layer. In general, a photoresist in which a novolak resin having naphthoquinone diazide in a photosensitive group is dissolved in an organic solvent (for example, xylene, cellosolve solvent, etc.) is used, but a polymer material is included in the photoresist. This is because it often dissolves in an organic solvent. In addition, when a crystalline material such as pentacene is used as the organic semiconductor material, deterioration in transistor characteristics may be recognized although there is a difference in degree. Furthermore, it may be damaged by a stripping solution (for example, ethylene glycol monobutyl ether, monoethanolamine, etc.) used when stripping the resist. Further, the resist may be damaged by rinsing with pure water after peeling off.

  A method using a shadow mask is also known when patterning an organic semiconductor layer using a crystalline material such as pentacene. However, there is a limitation on the pattern size, which is not suitable for patterning of a large area. In addition, the shadow mask has a lifetime, and as a result, it is substantially difficult to manufacture it at orders of magnitude cheaper than a thin film transistor using a Si semiconductor material.

  On the other hand, it is promising to use an inkjet printing method when patterning the organic semiconductor layer. Patent Document 1 discloses a method for applying a charge to a predetermined position on a surface to be coated and for applying a charge having a polarity opposite to that of the charge to the coating material to guide the material to which the charge is imparted by Coulomb force to the predetermined position. A method of forming a recess in a predetermined position on the target surface and applying a coating material and depositing on the recess, or a method of forming a pattern by evaporating the solvent after applying the material and then irradiating the pattern with laser A method for producing an organic thin film transistor by appropriately combining the above is disclosed. Patent Document 2 discloses a patterning method by forming an indent region on the surface of a substrate and depositing a liquid material on the surface of a selected location adjacent to the indent region.

  The ink jet printing method can directly draw a pattern, so that the material usage rate can be significantly improved. By patterning the organic semiconductor layer by an ink jet printing method, there is a possibility that the manufacturing process can be simplified, the yield can be improved, and the cost can be reduced.

  In addition, when a polymer material that is soluble in an organic solvent is used as the organic semiconductor material, the organic semiconductor ink can be prepared by dissolving in an organic solvent, and thus can be patterned using an ink jet printing method. However, in consideration of printing accuracy, it is difficult to perform patterning at 50 μm or less, and it becomes difficult to achieve higher definition than photolithography. One solution is to make the ink droplets small, but it is technically difficult, and further has a problem of stability, and discharge clogging, discharge bending, etc. are likely to occur.

Furthermore, when the patterning area is large, it is very difficult to pattern all the transistors satisfactorily due to landing accuracy and the like. In particular, the physical properties (for example, viscosity, surface tension, and drying properties) of organic semiconductor ink vary depending on the physical properties (for example, purity, molecular weight, molecular weight distribution) of the polymer material used and the type of organic solvent. Difficult to adjust. For this reason, it is not always possible to discharge well from all the nozzles, and a discharge bend may occur or a discharge amount may change only for a certain nozzle. The same applies to the head characteristics, and not all nozzles have the same head characteristics. At this time, if there is a slight discharge bend in a certain nozzle, patterning may be impossible at a low resolution, but patterning may not be possible at a high resolution. As a result, even if the organic semiconductor layer is patterned into an island shape, a high-definition pattern (see FIG. 10A) is not formed, but an incomplete pattern (see FIG. 10B) is formed. In the organic thin film transistor array shown in FIG. 10, a gate electrode 2, a gate insulating film 3, a source electrode 4 / drain electrode 5, and an organic semiconductor layer 6 are sequentially stacked on a glass substrate (not shown).
JP 2004-297011 A JP 2004-141856 A

In view of the problem of the prior art described above it has for its object to provide a method for manufacturing organic thin film transistor capable of reducing the off current. The present invention also aims to provide a display device having an organic thin film transistor array having the organic thin film transistor manufactured by the manufacturing method of the organic thin film transistor, a display panel and the display panel having the organic thin film transistor array.

The invention according to claim 13, in the manufacturing method of the organic thin film transistors, on a base plate, forming a Gate electrode on the gate electrode, and forming a Gate insulating film, at least on the gate insulating film is formed on the gate electrode, and forming a source over the source electrode及beauty drain electrode at a sky gap, on the substrate on which the source electrode及beauty drain electrodes are formed, a layer forming a part between the insulating film in a region including at least the gap, forming a organic semiconductor layer you contact with a portion of the interlayer insulating film, on at least the organic semiconductor layer, the layer It has a step of forming the remainder between the insulating film, and forming the remainder of part and the interlayer insulating film of the interlayer insulating film of the same material.

According to a second aspect of the present invention, in the method of manufacturing an organic thin film transistor according to the first aspect , a part of the interlayer insulating film is formed in a lattice shape or a line shape.
According to a third aspect of the present invention, in the method of manufacturing an organic thin film transistor according to the first or second aspect, a part of the interlayer insulating film and a remaining part of the interlayer insulating film are formed using a printing method. And
According to a fourth aspect of the present invention, in the method of manufacturing an organic thin film transistor according to the third aspect, a part of the interlayer insulating film and a remaining part of the interlayer insulating film are formed using a screen printing method. To do.
According to a fifth aspect of the present invention, in the method of manufacturing an organic thin film transistor according to any one of the first to fourth aspects, a part of the interlayer insulating film and a remaining part of the interlayer insulating film are formed of a binder resin and particles. It is characterized by containing.
A sixth aspect of the present invention is the method of manufacturing an organic thin film transistor according to any one of the first to fifth aspects, wherein a part of the interlayer insulating film and a remaining part of the interlayer insulating film are formed by the organic semiconductor layer. It is characterized by containing a material capable of absorbing light to be absorbed and / or a material capable of reflecting.
The invention according to claim 7 is the method for producing an organic thin film transistor according to claim 6, wherein the light absorbed by the organic semiconductor layer has a wavelength of 600 nm or less.
The invention according to claim 8 is the method of manufacturing an organic thin film transistor according to any one of claims 1 to 7, wherein a part of the interlayer insulating film and a remaining part of the interlayer insulating film are formed of the organic semiconductor layer. It contains a material that is soluble in a solvent that does not dissolve or swell.
According to a ninth aspect of the present invention, in the organic thin film transistor manufacturing method according to any one of the first to eighth aspects, the organic semiconductor layer is formed using a printing method.
According to a tenth aspect of the present invention, in the method of manufacturing an organic thin film transistor according to the ninth aspect, the organic semiconductor layer is formed using an ink jet printing method.
Invention of Claim 11 is a manufacturing method of the organic thin-film transistor as described in any one of Claim 1 thru | or 10, The said organic-semiconductor layer contains the organic-semiconductor material soluble in an organic solvent, It is characterized by the above-mentioned. And
The invention according to claim 12 is the method for producing an organic thin film transistor according to claim 11, wherein the organic semiconductor material is a polymer material having a triarylamine skeleton.

A thirteenth aspect of the present invention is an organic thin film transistor array, comprising the organic thin film transistor manufactured by the method of manufacturing an organic thin film transistor according to any one of the first to twelfth aspects.

The invention of claim 14 is a display panel, characterized by having an organic thin film transistor array according to claim 13.

According to a fifteenth aspect of the present invention, the display panel according to the fourteenth aspect has a memory property.

According to a sixteenth aspect of the present invention, in the display panel according to the fourteenth or fifteenth aspect , the display panel is flexible.

According to a seventeenth aspect of the present invention, in the display device, the display panel according to any one of the fourteenth to sixteenth aspects is provided.

According to the present invention, it is possible to provide a manufacturing method of the organic thin film transistor capable of reducing the off current. Further, according to the present invention, it is possible to provide a display device having an organic thin film transistor array having the organic thin film transistor manufactured by the manufacturing method of the organic thin film transistor, a display panel and the display panel having the organic thin film transistor array.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 shows an example of the organic thin film transistor array of the present invention. The organic thin film transistor array 10 includes an organic thin film transistor 10a. In the organic thin film transistor 10 a, a gate electrode 12 is formed on a glass substrate 11, and a gate insulating film 13 is formed on the gate electrode 12. Further, a source electrode 14 and a drain electrode 15 are formed on the gate insulating film 13 with a gap therebetween. At this time, a gap separating the source electrode 14 and the drain electrode 15 is formed on the gate electrode 12. An organic semiconductor layer 16 is formed so as to cover a gap separating the source electrode 14 and the drain electrode 15. Further, an interlayer insulating film 17 is formed so as to cover the organic semiconductor layer 16. At this time, a part of the organic semiconductor layer 16 is formed on the interlayer insulating film 17. A conductive layer 18 joined to the drain electrode 15 is formed on the interlayer insulating film 17.

  Next, the manufacturing method of the organic thin-film transistor array 10 is demonstrated using FIG. First, a gate electrode 12, a gate insulating film 13, a source electrode 14 and a drain electrode 15 are sequentially stacked on a glass substrate 11 (see FIG. 2A). Next, a part 17a of the interlayer insulating film is formed on both sides of the gap separating the source electrode 14 and the drain electrode 15 (see FIG. 2B), and a part 17a of the interlayer insulating film is formed so as to cover the gap. The organic semiconductor layer 16 which contacts is formed (see FIG. 2C). Thereby, the patterning accuracy of the organic semiconductor layer 16 can be improved. At this time, a part 17 a of the interlayer insulating film may cover a part of the source electrode 14. Further, a remaining portion 17b of the interlayer insulating film is formed on the organic semiconductor layer 16 (see FIG. 2D), and a conductive layer 18 joined to the drain electrode 15 is formed on the interlayer insulating film 17 (FIG. 2 ( e)).

  The gate electrode 12, the source electrode 14, and the drain electrode 15 are preferably formed using a printing method such as a screen printing method, an ink jet printing method, a flexographic printing method, a gravure printing method, an offset printing method, and the like. The electrode 15 is preferably an inkjet printing method for reasons such as patterning accuracy, cost, and number of steps. At this time, it is preferable to use a metal ink in which metal particles are dispersed. Examples of the metal particles include Au, Ag, Cu, Pt, Pd, Ni, Ir, Rh, Co, Fe, Mn, Cr, Zn, Mo, W, Ru, In, and Sn. May be. Among these, Au, Ag, Cu, and Ni are preferable in terms of electrical resistance, thermal conductivity, and corrosion.

  In the metal ink, metal particles having an average particle diameter of several nanometers to several tens of nanometers are uniformly dispersed in a solvent. Such metal particles are sintered. This is because the influence of atoms on the surface having high activity increases as the particle size of the metal particles decreases. Therefore, an electrode can be drawn directly by carrying out inkjet printing of metal ink and sintering. At this time, the metal ink preferably has a surface tension of about 30 mN / m for inkjet printing. The metal ink preferably has a viscosity of 2 to 13 mPa · sec, and more preferably 7 to 10 mPa · sec. If the surface tension and viscosity of the metal ink are not suitable, ejection becomes impossible or defective, and it is difficult to form round droplets, and the ligament becomes longer. Further, the metal ink needs to have a drying property that does not cause the solvent to volatilize and the metal particles to solidify when ejected.

  Further, the gate electrode 12, the source electrode 14, and the drain electrode 15 may be formed of a conductive polymer. Examples of the conductive polymer include polythiophene, polyaniline, polypyrrole, polyparaphenylene, and polyacetylene. Also, those obtained by doping these polymers can be used as the conductive polymer. Among them, a complex of polyethylenedioxythiophene (PEDOT) and polystyrene sulfonic acid (PSS) (PEDOT / PSS) is preferable in terms of electrical conductivity, stability, heat resistance, and the like. The conductive polymer can adjust the electrical characteristics depending on the degree of polymerization and the structure, and further, does not require sintering, so that the electrode can be formed at a low temperature.

  In FIG. 2C, a part 17a of the interlayer insulating film is formed in a line shape substantially parallel to the channel as shown in FIG. Thereby, for example, when the organic semiconductor layer 16 is formed by using the ink jet printing method, even if the ink is not completely ejected, the landing deviation of the ink and the spread after the landing can be reduced. It can be controlled by the unit 17a. As a result, since the organic semiconductor layer 16 is formed in a region between the portions 17a of the interlayer insulating film, it is possible to suppress the occurrence of a leakage current via the organic semiconductor layer 16, thereby reducing the off-current and turning on / off The ratio can be improved. Furthermore, the patterning property of the organic semiconductor layer 16 is remarkably improved, and the influence on the adjacent organic thin film transistor can be suppressed. In addition, since the alignment accuracy in forming the organic semiconductor layer 16 is only in one direction, the throughput and yield can be improved.

  Further, as shown in FIG. 3B, the part 17a of the interlayer insulating film may be formed in a line shape substantially perpendicular to the channel. At this time, a portion 17a of the interlayer insulating film is formed in a region excluding the channel in the length direction. Thereby, for example, when the organic semiconductor layer 16 is formed by using the ink jet printing method, even if the ink is not completely ejected, the landing deviation of the ink and the spread after the landing can be reduced. It can be controlled by the unit 17a. As a result, since the organic semiconductor layer 16 is formed in a region between the portions 17a of the interlayer insulating film, it is possible to suppress the occurrence of a leakage current via the organic semiconductor layer 16, thereby reducing the off-current and turning on / off The ratio can be improved. Furthermore, the patterning property of the organic semiconductor layer 16 is remarkably improved, and the influence on the adjacent organic thin film transistor can be suppressed. In addition, since the alignment accuracy in forming the organic semiconductor layer 16 is only in one direction, the throughput and yield can be improved.

  Further, in FIG. 2 (c), as shown in FIG. 3 (c), a part 17a of the interlayer insulating film is a combination of a line shape substantially parallel to the channel and a line shape substantially perpendicular to the channel, ie, a lattice shape. It may be formed. This eliminates the need for a high degree of alignment accuracy when forming the organic semiconductor layer 16 and improves the throughput and yield. Such a portion 17a of the interlayer insulating film is preferably formed by one process, but may be formed by a plurality of processes. When forming the part 17a of the interlayer insulating film by a plurality of processes, after forming the first line, a second line orthogonal to the first line may be formed, or the first line After forming, dots may be formed between the first lines.

  The organic semiconductor layer 16 is preferably formed using a printing method such as a screen printing method, an ink jet printing method, a flexographic printing method, a gravure printing method, an offset printing method, and the like, from the patterning accuracy, cost, solubility, etc. Ink jet printing is preferred. At this time, the organic semiconductor layer 16 preferably contains an organic semiconductor material soluble in an organic solvent. Thereby, the organic semiconductor layer 16 can be formed using the organic semiconductor ink in which the organic semiconductor material is dissolved in the organic solvent. Such an organic semiconductor material is not particularly limited, and a polymer material, an oligomer material, a low molecular material, or the like that is soluble in an organic solvent can be used. A polymer material having a triarylamine skeleton is preferable, and a chemical formula (1)

で表される化合物が特に好ましい。この材料は、無配向性の高分子材料であり、成膜形状や方法に関わらず、特性のバラツキが小さい。

Is particularly preferred. This material is a non-oriented polymer material and has little variation in characteristics regardless of the film formation shape and method.

  In the conventional organic thin film transistor array, when the organic semiconductor layer 16 is formed using the ink jet printing method, it is difficult to form a high-definition pattern as shown in FIG. It tends to be an incomplete pattern. In particular, when the patterning area is large, an incomplete pattern is likely to occur. Specifically, the organic semiconductor layer 16 is formed not only in the channel region but also between the source electrode 14 and the drain electrode 15 other than the channel region, and the organic semiconductor layer 16 constitutes each organic thin film transistor array. It is not separated by the thin film transistor, but affects the adjacent organic thin film transistor through the organic semiconductor layer 16. The incomplete patterning of the organic semiconductor layer 16 is due to the influence of variations in head characteristics, ejection bend from the nozzle, and the like. On the other hand, it is difficult to make all the nozzles uniformly in the same discharge state. Furthermore, the dry state after the droplets have landed also varies depending on the shape pattern, and the degree of spread of the droplets varies depending on the dry state. Further, when a polymer solution is used as the ink for the organic semiconductor layer, there is a possibility of variation in ejection speed due to a change in physical properties, and it is difficult to form a high-definition pattern.

  If the pattern of the organic semiconductor layer 16 is incomplete, a leakage current via the organic semiconductor layer 16 is generated, the leakage current increases the off current, and the on / off ratio decreases. Furthermore, when an image is displayed on the display medium using the organic thin film transistor array, crosstalk between pixels occurs. In particular, when organic thin film transistors are arranged at a high density, the influence of leakage current becomes significant.

  In the present invention, the organic semiconductor layer 16 can be physically separated because the organic semiconductor layer 16 in contact with the portion 17a of the interlayer insulating film is formed. As a result, the leakage current can be blocked by the part 17a of the interlayer insulating film, and an increase in off-current can be suppressed.

In addition, the organic semiconductor layer formed in an island shape by the ink jet printing method generally has a large film thickness unevenness due to the coffee stain phenomenon. The coffee stain phenomenon means that the solvent evaporates from the edge part of the droplet that has landed and spread, so the concentration of the solute at the edge part of the liquid droplet increases, the edge part becomes thick, and the central part becomes thin. It is a phenomenon. Unevenness of the film thickness due to this phenomenon increases the off-current or causes a shift in the threshold voltage _Vth , resulting in a large variation in transistor characteristics.

In the present invention, since the organic semiconductor layer 16 in contact with the part 17a of the interlayer insulating film is formed, the coffee stain phenomenon can be suppressed, and the uniformity of the film thickness of the organic semiconductor layer 16 is increased. As a result, the shift of _Vth is suppressed and variation in transistor characteristics is reduced.

  The remaining part 17b of the interlayer insulating film is formed on the organic semiconductor layer 16 as shown in FIG. 4 after the part 17a of the interlayer insulating film shown in FIG. 3C is formed. As a result, an interlayer insulating film having a through hole is formed. Even when the shape of the portion 17a of the interlayer insulating film is the shape shown in FIGS. 3A and 3B, the remaining portion 17b of the interlayer insulating film is also formed in a region other than on the organic semiconductor layer 16. Thus, an interlayer insulating film 17 having a through hole similar to that shown in FIG. 4 can be formed.

  In forming the part 17a and the remaining part 17b of the interlayer insulating film, it is preferable to use a printing method such as a screen printing method, an ink jet printing method, a flexographic printing method, a gravure printing method, an offset printing method, etc. The method is particularly preferred. Thereby, compared with the case where photolithography is used, throughput can be improved, the number of steps can be reduced, and cost can be reduced. At this time, the part 17a and the remaining part 17b of the interlayer insulating film may be formed using the same material, or may be formed using different materials.

  The interlayer insulating film 17 preferably contains a binder resin and particles. Examples of the binder resin include polyvinyl alcohol resin, polyvinyl acetal resin, acrylic resin, ethyl cellulose resin, polyethylene, polystyrene, polyamide, and the like, and two or more kinds may be used in combination.

  In addition, the particles may be either organic particles or inorganic particles as long as they can be present as particles in the interlayer insulating film 17, but the particle size can be easily controlled and dispersed in a solvent. Therefore, inorganic particles are preferable. Although it does not specifically limit as an organic particle, Carbon black, an azo pigment, a phthalocyanine pigment, a perylene pigment, etc. are mentioned, You may use 2 or more types together. In addition, the inorganic particles are not particularly limited, but include metal oxides such as silica, alumina, titanium oxide, zinc oxide, barium titanate, metal hydroxides, metal complexes, and the like. Good. Of these, materials having a low relative dielectric constant such as silica, alumina, and zinc oxide are preferable. The particles may be porous particles having mesopores or micropores, and examples thereof include mesoporous silica. In forming the interlayer insulating film 17, an insulating paste in which a binder resin, particles, and the like are mixed with a solvent, and a dispersant, a plasticizer, a viscosity modifier, and the like are added as necessary can be used. . Further, the mixing ratio of the binder resin and the particles is not particularly limited, and can be appropriately adjusted according to the pattern to be formed so as to obtain a paste having optimum physical properties, but the flexibility of the interlayer insulating film 17 is ensured. For this purpose, it is preferable that the binder resin is large.

  In general, it is known that transistor characteristics of an organic thin film transistor are deteriorated with time due to absorption of light by an organic semiconductor material. For this reason, it is preferable that the interlayer insulating film 17 can block light absorbed by the organic semiconductor layer 16. At this time, the interlayer insulating film 17 preferably contains a material capable of absorbing such light and / or a material capable of reflecting.

  The material capable of absorbing the light absorbed by the organic semiconductor layer 16 is not particularly limited as long as the insulating property of the interlayer insulating film 17 can be maintained, and may be a metal oxide, a metal hydroxide, a metal complex, carbon black, Examples thereof include coloring pigments such as azo pigments, phthalocyanine pigments, and perylene pigments, and dyes such as aniline black and indigo, which may be used in combination of two or more.

  In addition, the material capable of reflecting the light absorbed by the organic semiconductor layer 16 is not particularly limited as long as the insulating property of the interlayer insulating film 17 can be maintained, and examples thereof include white pigments such as zinc oxide and titanium oxide. Two or more kinds may be used in combination.

  As an example of the organic semiconductor material, a compound represented by the chemical formula (1) will be described. First, FIG. 11 shows an ultraviolet-visible absorption spectrum of the compound represented by the chemical formula (1), measured using a thin film having a thickness of 40 nm. From FIG. 11, the compound represented by the chemical formula (1) tends to absorb light having a wavelength of 600 nm or less. Note that a polymer material having a triarylamine skeleton similarly absorbs light having a wavelength of 600 nm or less. For this reason, when a polymer material having a triarylamine skeleton is used as the organic semiconductor material, the interlayer insulating film 17 is preferably capable of blocking light having a wavelength of 600 nm or less. Thereby, the temporal deterioration of the transistor characteristics of the organic thin film transistor array 10 can be suppressed.

In general, it is known that the characteristics of the organic thin film transistor deteriorate over time due to the oxidation of the organic semiconductor material by oxygen in the air and the adsorption of water to the organic semiconductor material. For this reason, it is preferable that the interlayer insulating film 17 can block oxygen and moisture. At this time, the oxygen transmission rate and the water vapor transmission rate of the interlayer insulating film 17 can be appropriately selected according to the material constituting the organic semiconductor layer 16 and the like. For example, the organic EL panel having the organic thin film transistor array 10 has an oxygen transmission rate and a water vapor transmission rate of less than 10 ⁻² cc / m ² /day/atm/0.1 mm and 10 ⁻⁵ g / m ² / day / atm, respectively. / Less than 0.1 mm is preferable. Thereby, deterioration with time of the characteristics of the organic EL panel can be suppressed. By forming the organic semiconductor layer 16 using a polymer material having a triarylamine skeleton having excellent weather resistance, the upper limits of the oxygen transmission rate and the water vapor transmission rate of the organic EL panel can be increased.

  By forming the interlayer insulating film 17 as described above, it is possible to further suppress the deterioration of the characteristics of the organic thin film transistor array 10 over time due to photooxidation or the like.

  The interlayer insulating film 17 preferably contains a material that is soluble in a solvent that does not dissolve or swell the organic semiconductor layer 16. Thereby, when the interlayer insulating film 17 is formed, deterioration of the organic semiconductor layer 16 can be suppressed.

  When a polymer material having a triarylamine skeleton is used as the organic semiconductor material, the solvent that does not dissolve or swell the organic semiconductor layer 16 is not particularly limited, but ethylene glycol butyl ether, ethylene glycol hexyl ether, dipropylene glycol butyl ether, Dipropylene glycol methyl ether acetate, tripropylene glycol methyl ether, diethylene glycol butyl ether, α-terpineol, ethylene alcohol, isopropyl alcohol, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, etc. Two or more species may be used in combination.

  Examples of the binder resin that is soluble in these solvents include polyvinyl alcohol resin, polyvinyl acetal resin, acrylic resin, ethyl cellulose resin, polyethylene, polystyrene, polyamide, and the like. May be.

  Further, after the remaining portion 17b of the interlayer insulating film shown in FIG. 4 is formed, as shown in FIG. 5, the conductive layer bonded to the drain electrode 15 in the region including the through hole in the through hole and on the interlayer insulating film 17 18 is formed. At this time, the conductive layer 18 can be formed by patterning a thermosetting paste containing silver using a screen printing method.

  As described above, the organic thin film transistor array of the present invention can be produced with a low number of steps and a low cost.

  Furthermore, the organic thin film transistor array of the present invention is used as an active matrix substrate and combined with a display element such as an electrophoretic display element, a liquid crystal display element, or an organic EL display element, so that an electrophoretic panel, a liquid crystal panel, an organic EL panel, etc. A display panel can be manufactured.

  FIG. 12 shows an electrophoresis panel 20 as an example of the display panel of the present invention. Hereinafter, a method for manufacturing the display panel 20 will be described. First, as shown in FIG. 2, a gate electrode (scanning line) 12 is formed on a film substrate (or thin film SUS substrate) 11 using an Ag ink in which Ag particles are dispersed. Next, a polyamic acid is spin-coated on the gate electrode 12 and baked to form the gate insulating film 13. Further, ultraviolet rays are irradiated on the gate insulating film 13 through a photomask to form a high energy pattern on the surface. Next, inkjet printing is performed on the high energy pattern using Ag ink in which Ag particles are dispersed, and the source electrode (signal line) 14 and the drain electrode 15 are formed. Further, screen printing is performed using an insulating paste to form a part 17a of the interlayer insulating film. Next, ink-jet printing is performed using an organic semiconductor ink to form the organic semiconductor layer 16 that is in contact with the portion 17a of the interlayer insulating film. Further, screen printing is performed using an insulating paste, and the remaining portion 17 b of the interlayer insulating film is formed on the organic semiconductor layer 16. Next, the conductive layer 18 bonded to the drain electrode 15 is formed by screen printing using a conductive paste. The organic transistor array 10 can be produced as described above.

  On the other hand, a transparent conductive film 21b made of ITO (Indium Tin Oxide) is formed on the film substrate 21a by sputtering to produce a film substrate 21 with a transparent conductive film.

  Also, titanium oxide, silicone macromer / methacrylic acid copolymer, silicone polymer grafted carbon black, and silicone oil are mixed and dispersed by ultrasonic to prepare a black and white particle dispersion. From the obtained black and white particle dispersion, microcapsules 22a are produced using a gelatin-gum arabic complex coacervation method. Next, by using a wire blade method, a dispersion liquid in which microcapsules 22a are dispersed in a solution of urethane resin 22b is developed to form electrophoretic element 22 on film substrate 21 with a transparent electrode film. Furthermore, by joining the electrophoretic element 22 and the conductive layer 18 of the organic transistor array 10, the electrophoretic panel 20 having memory properties and flexibility can be manufactured.

  A liquid crystal panel is produced by joining the organic transistor array of the present invention and a substrate with a transparent electrode film having a rubbing alignment film through a silica spacer, and encapsulating a liquid crystalline material in the gap. can do.

  The organic EL panel can be produced by forming an organic EL element in the organic transistor array of the present invention and disposing an air shielding shield.

  FIG. 13 shows an example of the display device of the present invention. The display device 30 includes an electrophoretic panel 20, information input means 31 for inputting information of an image to be displayed to the electrophoretic panel 20, a housing 32, a drive circuit (not shown), an arithmetic circuit (not shown), an internal memory (not shown). ), Power supply means (not shown) for supplying power to the electrophoresis panel 20 and the information input means 31. The gate electrode (scanning line) 12 and the source electrode (signal line) 14 of the electrophoretic panel 20 form a dot matrix and display an image as a whole by displaying ON a designated dot. As the power supply means, internal power such as a battery may be provided, or a power receiving device such as an outlet receiving power from an external power source may be provided.

  The display device of the present invention is not particularly limited as long as it has the display panel of the present invention and means for supplying power to the display panel, and examples thereof include PDAs and portable terminals such as electronic book terminals.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not construed as being limited to the examples.

[Comparative Example 1]
An insulating film 19 having a thickness of 200 nm was formed on the glass substrate 11 by spin coating polyamic acid and heat-treating at 280 ° C. Next, using a UV lamp (irradiation amount: 7 J / cm ² ), ultraviolet rays were irradiated through a photomask to form a high energy pattern on the surface. Furthermore, by using an inkjet printing method, Ag ink in which Ag particles are dispersed on a high energy pattern is discharged and sintered at 280 ° C., thereby forming a gate electrode 12 having a thickness of 100 nm. Next, a polyamic acid was spin-coated on the gate electrode 12 and heat-treated at 280 ° C. to form a gate insulating film 13 having a thickness of 500 nm. Furthermore, a high energy pattern was formed on the surface through a photomask using a UV lamp (irradiation amount: 7 J / cm ² ). Next, by using an inkjet printing method, Ag ink was ejected onto the high energy pattern and sintered at 280 ° C., thereby forming a source electrode 14 and a drain electrode 15 having a thickness of 100 nm. At this time, the channel width was 140 μm and the channel length was 10 μm.

  Next, using an inkjet printing method, an organic semiconductor ink in which the compound represented by the chemical formula (1) is dissolved in tetralin is applied to form an island-shaped organic semiconductor layer 16 (see FIG. 10B). ). Furthermore, by using a screen printing method, an insulating paste containing a polyvinyl butyral resin, a silica filler, and ethylene glycol hexyl ether is printed and dried to form an interlayer insulating film 17 so as to cover the organic semiconductor layer 16. Formed. Next, by using a screen printing method, a thermosetting paste containing silver was printed and dried to form a conductive layer 18 to be joined to the drain electrode 15 to obtain an organic thin film transistor array (see FIG. 6). ).

[Example 1]
An insulating film 19 having a thickness of 200 nm was formed on the glass substrate 11 by spin coating polyamic acid and heat-treating at 280 ° C. Next, using a UV lamp (irradiation amount: 7 J / cm ² ), ultraviolet rays were irradiated through a photomask to form a high energy pattern on the surface. Furthermore, by using an inkjet printing method, Ag ink in which Ag particles are dispersed on a high energy pattern is discharged and sintered at 280 ° C., thereby forming a gate electrode 12 having a thickness of 100 nm. Next, a polyamic acid was spin-coated on the gate electrode 12 and heat-treated at 280 ° C. to form a gate insulating film 13 having a thickness of 500 nm. Furthermore, a high energy pattern was formed on the surface through a photomask using a UV lamp (irradiation amount: 7 J / cm ² ). Next, by using an inkjet printing method, Ag ink was ejected onto the high energy pattern and sintered at 280 ° C., thereby forming a source electrode 14 and a drain electrode 15 having a thickness of 100 nm. At this time, the channel width was 140 μm and the channel length was 10 μm.

Next, by using a screen printing method, an insulating paste containing polyvinyl butyral resin, silica filler, and ethylene glycol hexyl ether is printed and dried, so that the line-shaped interlayer insulating film parallel to the channel is obtained. A part 17a of the substrate was formed (see FIG. 2B and FIG. 3A). Further, an organic semiconductor ink in which the compound represented by the chemical formula (1) was dissolved in tetralin was applied using an ink jet printing method to form the organic semiconductor layer 16 in contact with a part 17a of the interlayer insulating film. Next, using the screen printing method, the same insulating paste as that of the part 17 a of the interlayer insulating film was printed, and the remaining part 17 b of the interlayer insulating film was formed on the organic semiconductor layer 16. At this time, the interlayer insulating film 17 had an oxygen transmission rate of 600 cc / m ² /day/atm/0.1 mm and a water vapor transmission rate of 50 g / m ² /day/atm/0.1 mm. Furthermore, by using a screen printing method, a thermosetting paste containing silver was printed and dried to form a conductive layer 18 joined to the drain electrode 15 to obtain an organic thin film transistor array (see FIG. 7). .

[Example 2]
An organic thin film transistor array was obtained in the same manner as in Example 1 except that a portion 17a of the line-shaped interlayer insulating film perpendicular to the channel was formed (see FIG. 3B).

[Example 3]
Example 1 is the same as Example 1 except that a part 17a of a line-like and perpendicular line-shaped, that is, a lattice-like interlayer insulating film is formed (see FIGS. 2B and 3C). Similarly, an organic thin film transistor array was obtained.

[Evaluation of transistor characteristics]
The transistor characteristics of the obtained organic thin film transistor array were measured in an atmosphere of less than 1 ppm oxygen and less than 1 ppm water. Specifically, the drain voltage _{V ds} and -20 V, was scanned gate voltage _{V g} from + 20V to -20 V. As a result, the drain current I _ds (on current) when V _g is −20 V and the drain current I _ds (off current) when V _g is +20 V are as shown in FIG. Specifically, the on-state currents of Comparative Example 1, Examples 1, 2, and 3 are −1.0 × 10 ⁻⁸ A, −9.0 × 10 ⁻⁹ A, and −1.0 × 10 ⁻⁸ A, respectively. And −9.0 × 10 ⁻⁹ A, and the off-state currents are −5.4 × 10 ⁻¹¹ A, −2.1 × 10 ⁻¹² A, −8.0 × 10 ⁻¹³ A, and −9, respectively. 0.0 × 10 ⁻¹³ A. Moreover, the threshold voltage _Vth of the comparative example 1, Example 1, 2, and 3 was 4.11V, 3.63V, 4.13V, and 1.82V, respectively (refer FIG. 9).

From this, it can be seen that the organic thin film transistors of Examples 1 and 2 have an improved on-off ratio due to a lower off-current than the organic thin film transistor of Comparative Example 1, and good transistor characteristics can be obtained. In addition, it can be seen that the organic thin film transistor of Example 3 has a smaller _Vth than the organic thin film transistors of Examples 1 and 2, and further excellent transistor characteristics can be obtained.

[Evaluation of degradation of transistor characteristics by light irradiation]
Using a light source and filter with an illuminance of 100,000 lux, the organic thin film transistor array of Example 3 was irradiated with light having a wavelength of 600 nm or less, 500 nm or less, and 450 nm or less blocked (referred to as samples A, B, and C, respectively). The mobility was measured. Note that mobility, the drain voltage _{V ds} and -20 V, by scanning a gate voltage _{V g} from + 20V to -20 V, was measured.

  FIG. 14 shows the evaluation results. The mobility of the organic thin film transistor array before irradiation with light was set to 100%. From FIG. 14, it can be seen that, except for sample A, the mobility decreases as the irradiation time increases. On the other hand, sample A shows that the transistor characteristics hardly deteriorate even when the irradiation time is increased.

[Example 4]
The organic thin film transistor array was formed in the same manner as in Example 1 except that an insulating paste containing polyvinyl butyral resin, silica filler, aniline black, and ethylene glycol hexyl ether was used when forming the interlayer insulating film 17. Obtained.

[Evaluation of degradation of transistor characteristics by light irradiation]
Using a light source with an illuminance of 100,000 lux, light having a wavelength of 300 to 1400 nm was irradiated to the organic thin film transistor array of Example 4, and the mobility was measured. Note that mobility, the drain voltage _{V ds} and -20 V, by scanning a gate voltage _{V g} from + 20V to -20 V, was measured.

  FIG. 14 shows the evaluation results. The mobility of the organic thin film transistor array before irradiation with light was set to 100%. From FIG. 14, it can be seen that the organic thin film transistor array of Example 4 is unlikely to deteriorate in transistor characteristics even when the irradiation time is increased as in Sample A.

[Comparative Example 2]
An organic thin film transistor array was obtained in the same manner as in Example 3 except that the remaining portion 17b of the interlayer insulating film was not formed on the organic semiconductor layer 16.

[Evaluation of deterioration of transistor characteristics by high humidity test]
Using the organic thin film transistor arrays of Example 3 and Comparative Example 2, a high humidity test was performed in an environment of 25 ° C. and 85% RH, and mobility was measured in the atmosphere. Note that mobility, the drain voltage _{V ds} and -20 V, by scanning a gate voltage _{V g} from + 20V to -20 V, was measured.

  FIG. 15 shows the evaluation results. The mobility of the organic thin film transistor array before the high humidity test was set to 100%. FIG. 13 shows that the mobility of the organic thin film transistor array of Comparative Example 2 decreases as the test time increases. On the other hand, it can be seen that the organic thin film transistor array of Example 3 maintains the transistor characteristics even when the test time is increased.

[Example 5]
A transparent conductive film 21b made of ITO (Indium Tin Oxide) was formed by sputtering on the film substrate 21a to produce a film substrate 21 with a transparent conductive film.

  On the other hand, 20 parts by weight of titanium oxide, 1 part by weight of silicone macromer / methacrylic acid copolymer, 2 parts by weight of silicone polymer grafted carbon black, and 77 parts by weight of silicone oil are mixed and dispersed with an ultrasonic wave for 1 hour to disperse black and white particles. A liquid was prepared. From the obtained black and white particle dispersion, microcapsules 22a were produced using a gelatin-gum arabic complex coacervation method. At this time, the microcapsule 22a had an average particle size of about 60 μm. Next, the electrophoretic element 22 was formed on the film substrate 21 with the transparent electrode film by developing a dispersion liquid in which the microcapsules 22a were dispersed in the urethane resin 22b solution using a blade coating method. Furthermore, the electrophoretic element 22 and the conductive layer 18 of the organic transistor array 10 of Example 1 were joined to obtain an electrophoretic panel (see FIG. 16).

It is sectional drawing which shows an example of the organic thin-film transistor array of this invention. It is sectional drawing explaining the manufacturing method of the organic thin-film transistor array of FIG. It is a top view which shows the shape of a part of interlayer insulation film. It is a top view which shows the shape of the remainder of an interlayer insulation film. It is a top view which shows the shape of a conductive layer. It is sectional drawing which shows the organic thin-film transistor array of the comparative example 1. 1 is a cross-sectional view showing an organic thin film transistor array of Example 1. FIG. It is a figure which shows the ON current and OFF current of an organic thin-film transistor. It is a figure which shows the threshold voltage of an organic thin-film transistor. It is a top view which shows the conventional organic thin-film transistor. It is a figure which shows the ultraviolet visible absorption spectrum of the compound represented by Chemical formula (1). It is sectional drawing which shows an example of the display panel of this invention. It is a perspective view which shows an example of the display apparatus of this invention. It is a figure which shows deterioration of the transistor characteristic by light irradiation. It is a figure which shows deterioration of the transistor characteristic by a high humidity test. 10 is a cross-sectional view showing a display panel of Example 5. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Organic thin-film transistor array 10a Organic thin-film transistor 11 Glass substrate 12 Gate electrode (scanning line)
13 Gate insulating film 14 Source electrode (signal line)
DESCRIPTION OF SYMBOLS 15 Drain electrode 16 Organic-semiconductor layer 17 Interlayer insulating film 17a Part 17b The remainder 18 Conductive layer 19 Insulating film 20 Electrophoretic panel 21 Film substrate with a transparent conductive film 21a Film substrate 21b Transparent conductive film 22 Electrophoretic element 22a Microcapsule 22b Urethane resin 30 Display Device 31 Information Input Means 32 Housing

Claims (17)

On a base plate, forming a Gate electrode,
On the gate electrode, and forming a Gate insulating film,
At least the gate insulating film is formed on the gate electrode, and forming a source over the source electrode及beauty drain electrode at a sky gap,
On the substrate on which the source electrode及beauty drain electrodes are formed, forming a part of the layer insulating film,
In a region including at least the gap, forming a organic semiconductor layer you contact with a portion of the interlayer insulating film,
At least on the organic semiconductor layer, it has a step of forming the remainder of the layer insulating film,
A method of manufacturing an organic thin film transistor, wherein a part of the interlayer insulating film and a remaining part of the interlayer insulating film are formed of the same material . 2. The method of manufacturing an organic thin film transistor according to claim 1 , wherein a part of the interlayer insulating film is formed in a lattice shape or a line shape. Using printing method, a manufacturing method of an organic thin film transistor according to claim 1 or 2, characterized in that to form the remainder of part and the interlayer insulating film of the interlayer insulating film. Scan using a screen printing method, a manufacturing method of an organic thin film transistor according to claim 3, characterized in that to form the remainder of part and the interlayer insulating film of the interlayer insulating film. The interlayer remainder part and the interlayer insulating film of the insulating film, method of manufacturing an organic thin film transistor according to any one of claims 1 to 4, characterized in that it contains a binder resin and particles. A part of the interlayer insulating film and a remaining part of the interlayer insulating film contain a material capable of absorbing and / or reflecting a light absorbed by the organic semiconductor layer. The manufacturing method of the organic thin-film transistor as described in any one of Claims 1 thru | or 5 . The method of manufacturing an organic thin film transistor according to claim 6 , wherein the light absorbed by the organic semiconductor layer has a wavelength of 600 nm or less. The part of the interlayer insulating film and the remaining part of the interlayer insulating film contain a material soluble in a solvent that does not dissolve or swell the organic semiconductor layer. The manufacturing method of the organic thin-film transistor of description. Using printing method, a manufacturing method of an organic thin film transistor according to any one of claims 1 to 8, characterized by forming the organic semiconductor layer. With Lee inkjet printing method, a manufacturing method of an organic thin film transistor according to claim 9, characterized in that to form the organic semiconductor layer. The method of manufacturing an organic thin film transistor according to any one of claims 1 to 10, wherein the organic semiconductor layer contains an organic semiconductor material soluble in an organic solvent. 12. The method of manufacturing an organic thin film transistor according to claim 11 , wherein the organic semiconductor material is a polymer material having a triarylamine skeleton. The organic thin film transistor array, characterized by having an organic thin film transistor manufactured by the manufacturing method of an organic thin film transistor according to any one of claims 1 to 12. Display panel characterized in that it comprises an organic thin film transistor array according to claim 13. The display panel according to claim 14 , which has a memory property. Display panel according to claim 14 or 15, characterized in that it has a flexibility. Display device characterized by having a display panel according to any one of claims 14 to 16.

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