JP2006165233A - Organic electronic device and organic electronic device creation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electronic device by a low-temperature process by realizing accurate attachment elasticity of an organic material droplet by an IJ process not using a photolithography process.
SOLUTION: A part or all of organic materials constituting an electronic device is ejected by an ink jet method capable of imparting charges to droplets, and a photoreactive charge inducing layer is provided on the landing electronic device to generate by light The droplet is attracted and attracted to the opposite charge portion to the droplet.
[Selection] Figure 1

Description

  The present invention relates to an electronic device using an organic material, and more particularly to an organic thin film electronic device using an IJ process.

  In recent years, research on electronic devices using organic materials has been active. By making organic materials into thin films and applying them to devices, it is expected to realize electronic devices with excellent process portability and low temperature.

  For example, research on electronic devices such as organic EL, organic ID tags, and organic FETs is active, but organic FETs are relatively weak bonds in which organic materials themselves are partially covalently bonded by molecular assemblies. Therefore, it can be expected to lower the temperature of the process and is excellent in portability because it is flexible and can be reduced in weight. For this reason, there is a possibility of application to liquid crystal displays as well as paper-like displays, and in recent years, research has become active rapidly. In such an electronic device field, there is an increasing demand for further lower process temperatures and superior portability in the future. One method for realizing this is an organic electronic device creation method using an IJ process, and application to next-generation low-temperature processes and highly portable electronic devices is expected.

For example, Patent Document 1 discloses a method for manufacturing an electronic device using an ink jet printing technique.
There are various methods for producing piezoelectric films. For example, Science 280, 2123 (2000), Tech Digest of IEDM, p.623 (2000), etc. A method for producing an organic TFT using surface mapping by energy control is described.
2004-141856 publication Science 280, 2123 (2000) Tech Digest of IEDM, p.623 (2000)

  There are several methods for the IJ process. The main methods are a method using a piezoelectric actuator (piezo method), a thermal method, an electrostatic attraction method, etc. Especially, the piezo method and the thermal method have made remarkable progress in recent years as printers for consumer use. Increasing droplet speed and speed. In addition, high precision landing elasticity is greatly advanced, but due to the principle of the IJ method, the smaller the droplet size, the more difficult it is to land the droplet due to external factors. The region where 3σ <10 μm is considered to be almost impossible. However, electronic devices such as FETs are required to have a high accuracy of 1 μm or less in channel length, which is a big barrier that prevents the application of the IJ method having various advantages.

  In order to solve such problems, it is effective to map the substrate surface energetically to induce fine droplets. As a method for mapping the substrate surface in terms of energy, mapping by surface free energy and electrostatic method can be raised. However, a thing using surface free energy requires a photolithography process to map, which increases cost and complexity of the process. Occurs. Further, since the droplets move after landing, there is a risk of contamination such as contamination. In the present invention, the surface of the substrate is subjected to electrostatic mapping with a very simple structure and means using a photoreactive charge inducing layer, and accurate landing elasticity of the droplet itself is realized by a direct IJ process without using a photolithography process. The objective is to realize various organic electronic devices with excellent portability through low-temperature processes.

  The configuration of the present invention for achieving the above object is as follows.

  A first aspect of the present invention resides in an electronic device using an organic material and having a photoreactive charge inducing layer as a part of its configuration in an electronic device excluding a self-luminous or power generation application. .

  A second aspect of the present invention is the electronic device according to the first aspect of the present invention, wherein the electronic device using the organic material is a transistor.

  According to a third aspect of the present invention, there is provided the electronic device according to the second aspect of the present invention, wherein the transistor using the organic material is a field effect transistor (FET).

  A fourth aspect of the present invention is the electronic device according to any one of the first to third aspects of the present invention, wherein the photoreactive charge inducing layer is composed of an organic material.

  A fifth aspect of the present invention is the electronic device according to any one of the first to fourth aspects of the present invention, wherein the electronic device has a charge transport layer adjacent to the photoreactive charge induction layer.

  A sixth aspect of the present invention is the electronic device according to the fifth aspect of the present invention, wherein the charge transport layer forms a channel of a transistor.

  A seventh aspect of the present invention is an electronic device forming method using an organic material, the step of providing a photoreactive charge inducing layer on a substrate, the step of applying a charge to a part of the photoreactive charge inducing layer by light, And a method of forming an electronic device, comprising at least a step of applying an electric charge to the organic material and discharging the organic material as droplets onto the photoreactive charge induction layer.

  The eighth of the present invention is the electronic device forming method according to claim 7, wherein the charge applied to the photoreactive charge inducing layer has a polarity opposite to that of the droplet.

  According to a ninth aspect of the present invention, there is provided the electronic device forming method according to claim 7, wherein the charge applied to the photoreactive charge induction layer has the same polarity as the charge of the droplet.

  As described above, according to the present invention, in the configuration of the organic FET, the photoreactive charge organic layer is formed on the substrate, the semiconductor layer is further formed thereon, the source / drain is further formed thereon, and the insulating film is formed thereon. By forming the gate electrode on top of it, it is possible to form an image by electrostatic attraction IJ method on the latent image written in the photoreactive charge induction layer when forming the source / drain Therefore, it becomes possible to directly form a very fine channel length. In addition, this configuration and production method makes it possible to attract droplets directly to a desired location without using surface energy, so that once a material adheres to a substrate, the material that may be contaminated can be directly removed without worrying about contamination. Drawing is possible, and an excellent organic FET can be realized. In addition to organic FETs, it is possible to accurately attract droplets to desired locations in various organic devices. Various devices using organic functional thin films, organic FETs, organic ID tags, organic EL, etc. Application to various devices can be expected.

  The inventor paid attention to electrostatic energy mapping by the photoreactive charge organic layer as energy mapping of the substrate surface. Photoreactive charge inducing layers include compound semiconductors such as InN, metals such as Si and Se, organic substances such as Alq3 (aluminum quinolinol complex) and azo pigments, but photoreactive charge inducing layers generate charges by light. It is possible to form an electrostatic latent image on the order of nm. On the other hand, an electrostatic attraction method is known as an IJ process. The electrostatic attraction method applies a static voltage to a droplet and attracts and deposits a meniscus by static electricity. Furthermore, this method can be easily combined with other IJ processes, for example, a piezo method and a thermal method, and it is also possible to apply a charge to the droplets discharged by other methods. The present inventor pays attention to these phenomena and adds structural ingenuity to accurately induce droplets by mapping by static electricity, enabling the realization of organic electronic devices that require high precision of landing accuracy. did. In other words, by providing a photoreactive charge inducing layer on the substrate, it becomes possible to form a latent image at the nm level, attracting charged fine droplets to the latent image with reverse charge, or latent image with the same charge. By avoiding this, it becomes possible to draw a fine pattern and to realize a high-performance organic electronic device. Further, since the photolithography process is not required, the cost can be greatly reduced, and the throughput can be greatly improved by simplifying the process.

  Hereinafter, the present invention will be described in detail. In the present invention, an organic film having various functions such as a conductive film, a semiconductor film, and an insulating film can be drawn using an IJ process, and an electronic device having various functions can be manufactured. In the comparative example, an example in which an organic FET is manufactured as an organic electronic device is shown.

  In the photoreactive charge induction layer in the present invention, a compound semiconductor such as InN, CdS, or a metal such as Si or Se, which forms a PN junction having an energy band that absorbs a specific light wavelength band and showing a photoelectric reaction, All known materials such as oxides such as ZnO can be used, but organic pigment materials such as azo pigments, phthalocyanine pigments, perylene pigments, quinacridone pigments, polycyclic quinone pigments, and organic materials such as Alq3 It is desirable to use There are various methods for applying the photoreactive charge inducing layer, which can be easily produced by spin coating, IJ, offset printing, screen printing, or the like. In the case of an inorganic material, it is possible to use physical vapor deposition means such as vapor deposition or sputtering. Any film forming method can form a thin film that sufficiently functions as the photoreactive charge inducing material layer of the present invention.

  The photoreactive charge inducing layer in the present invention has no problem with any thickness, but is preferably 0.1 μm or more in order to ensure a sufficient carrier density. In order to maximize the effect of the generated charges, it is desirable to stack a charge transport layer on the photoreactive charge inducing material layer.

  In the organic FET provided with the photoreactive charge inducing material layer in the present invention, the thickness of the charge transport layer adjacent to the photoreactive charge inducing layer has a sharp change in potential at the edge of the electrostatic image due to the generated charge. For this purpose, it is preferable that the film is thin to some extent, and it is desirable that the thickness be about 50 μm or less. Since the charge transport layer is a semiconductor having charge mobility, the semiconductor layer forming the channel may be the same as the charge transport layer or a stacked body. Examples of the charge transport layer include various materials of low molecular weight and high molecular weight, and any known material can be used. Particularly, a low molecular weight compound having a triphenylamine skeleton or a benzidine skeleton, polycarbonate, polyester, polysilane, etc. These polymer materials are preferable because of their high mobility. A typical example of the material serving as the charge transport layer and the channel formation layer is phthalocyanine.

  In the case where a semiconductor layer for forming a channel is formed on the charge transport layer, the thickness of the semiconductor layer for forming a channel is preferably 0.1 μm or less in order to transmit light more. Although various films can be used for the semiconductor layer forming the channel, an organic material exhibiting high mobility is particularly desirable. For example, F8T2 (fluorene-bithiophene), P3HT (poly-3-hexylthiophene), and the like are typical examples of materials used by laminating with a charge transport layer. A low molecular material such as pentacene is also preferable as the material.

  The organic FET provided with the photoreactive charge induction layer in the present invention will be briefly described with reference to FIGS. FIG. 1 is an embodiment that best represents the present invention. As shown in FIG. 1, a conductive film 12 is formed on a sufficiently thick substrate 11, a pigment-based photoreactive charge organic layer 13 is further formed thereon, and a charge transport layer 14 is formed thereon. Then, a semiconductor layer 15 for forming a channel is formed. The charge transport layer 14 and the semiconductor layer 15 may be the same. A source / drain 16 is formed on the semiconductor layer 15 by the IJ method, an insulating film 17 is stacked on the source / drain 16, and a gate electrode 18 is formed. FIG. 2 shows a general structure of the organic FET used in the comparative example. As shown in FIG. 2, the semiconductor layer 15 is directly provided on a sufficiently thick substrate, and the photoreactive charge organic layer and the charge transport layer are not provided. A source / drain 16 is formed on the semiconductor layer 15 by the IJ method, an insulating film 17 is stacked on the source / drain 16, and a gate electrode 18 is formed. Specific examples are shown below.

(Example)
An example of producing an organic FET provided with a photoreactive charge organic layer by using the electrostatic attraction IJ method as a method of forming the source / drain and gate will be described. A 1 / m thick azo pigment as a photoreactive charge organic layer and a 20 μm thick hydrazone compound as a charge transport layer are formed by spin coating on an Al / PET substrate provided with an Al film as a conductive film on a PET substrate and dried. Went. On top of that, F8T2 was formed as a semiconductor layer by spin coating to a thickness of 0.1 μm and dried. Next, a source / drain layer was formed using the electrostatic attraction IJ method. After charging the entire semiconductor layer, use an argon ion laser to irradiate light with a wavelength of 514 nm so that the source and drain are spaced apart by 0.5 μm apart from the part where the source and drain are to be provided. The charge other than the desired part disappeared. When a metal nozzle with a nozzle diameter of 18 μm is positioned 400 μm above the substrate, filled with a PEDOT / PSS solution that becomes the source and drain, a rectangular wave opposite to charging is applied to drop the droplet onto the substrate, the laser A droplet with a diameter of about 1 μm was attracted to the charged part. The channel length was 0.5 μm. Further, a PVP layer serving as an insulating film was formed thereon by spin coating and dried. A gate electrode layer was formed thereon by a piezoelectric type IJ method. A PEDOT / PSS solution was used as the electrode material, and the droplet diameter was 10 μm.

  When forming the source / drain, it is also possible to apply an electric field having the same sign as the electric charge remaining by laser irradiation and discharge the droplet by electrostatic attraction IJ method. In this case, the charged charge is eliminated by generating a charge with a laser at the part where the source / drain is to be provided, and the droplet charged with the same sign as the surrounding charged charge is discharged to avoid the source / drain. The droplets land on the portion to be the drain, and the latent image formed by the laser becomes the source / drain.

  In addition, when forming the source / drain, it is also possible to leave the charge only in the channel length by laser irradiation, apply an electric field having the same sign as the remaining charge, and discharge the droplet by electrostatic attraction IJ method. It is. In this case, the liquid droplets land while avoiding the channel length portion, and the latent image portion becomes the channel length as it is.

  In this embodiment, F8T2 is used for the semiconductor layer, but other polymer semiconductors can also be used. It is also possible to form low molecular weight pentacene by vapor deposition.

  In this embodiment, the charge transport layer and the semiconductor layer for forming the channel are stacked, but one material may be used. For example, phthalocyanine-based copper phthalocyanine can be spin-coated with 20 μm and used as a charge transport layer and a semiconductor layer for channel formation.

  In this embodiment, PEDOT / PSS is used for the source / drain and gate conductive materials, but it is also possible to use a nano-dispersed material in which metal nanoparticles are dispersed.

  Wiring was performed on the gate, source and drain on the formed organic FET. When the characteristics of the organic FET formed using an impedance analyzer were measured, good FET characteristics were shown.

(Comparative example)
An organic FET was fabricated in the same manner as in Example 1 except that the conductive layer, photoreactive charge induction layer, and charge transport layer on the substrate were not provided. 1 μm of F8T2 was formed as a semiconductor layer on a PET substrate by spin coating and dried. Next, a source / drain layer was formed using the electrostatic attraction IJ method. A metal nozzle with a nozzle diameter of 18μm is positioned 400μm above the substrate, filled with the PEDOT / PSS solution that becomes the source and drain, and a droplet is dropped on the substrate by applying a negative rectangular wave, the channel length is 10μm Met. Further, a PVP layer serving as an insulating film was formed thereon by spin coating and dried. A gate electrode layer was formed thereon by a piezoelectric type IJ method. A PEDOT / PSS solution was used as the electrode material, and the droplet diameter was 10 μm.

  Wiring was performed on the gate, source and drain on the formed organic FET. When the characteristics of the organic FET formed using an impedance analyzer were measured, the channel length was large and sufficient FET characteristics could not be obtained.

It is sectional drawing of induction FET when the photoreactive charge induction layer is formed. It is sectional drawing of organic FET in case the photoreactive charge induction layer is not formed.

Explanation of symbols

11 Substrate on which organic FETs are formed
12 Conductive film
13 Photoreactive charge induction layer
14 Charge transport layer
15 Semiconductor layer
16 Source / Drain
17 Insulating film
18 Gate electrode

Claims (9)

  An electronic device using an organic material and excluding a self-light-emitting or power generation application, wherein the electronic device has a photoreactive charge inducing layer as a part of its configuration.   2. The electronic device according to claim 1, wherein the electronic device using the organic material is a transistor.   3. The electronic device according to claim 2, wherein the transistor using the organic material is a field effect transistor (FET).   4. The electronic device according to claim 1, wherein the photoreactive charge inducing layer is made of an organic material.   5. The electronic device according to claim 1, further comprising a charge transport layer adjacent to the photoreactive charge inducing layer.   6. The electronic device according to claim 5, wherein the charge transport layer forms a channel of a transistor.   An electronic device forming method using an organic material, the step of providing a photoreactive charge inducing layer on a substrate, the step of applying a charge to a part of the photoreactive charge inducing layer by light, and the applying of a charge to the organic material An electronic device forming method comprising at least a step of discharging the droplets to the photoreactive charge inducing layer as droplets.   8. The method of forming an electronic device according to claim 7, wherein the charge applied to the photoreactive charge inducing layer has a polarity opposite to that of the droplet.   8. The method of forming an electronic device according to claim 7, wherein the charge applied to the photoreactive charge inducing layer has the same polarity as the charge of the droplet.

Images