JP2005005582A - Organic semiconductor field-effect transistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an organic semiconductor field-effect transistor by which the durability deterioration and oxidation deterioration of an organic semiconductor layer can be reduced. <P>SOLUTION: The organic semiconductor field-effect transistor is provided with the organic semiconductor layer 4, a source electrode 2 and a drain electrode 3 connected to the organic semiconductor layer 4, an insulating substrate 1, and a gate electrode 5. The organic semiconductor layer 4 contains at least one kind of compound of an antioxidant, a light stabilizer and an ultraviolet absorber. When the transistor is made to operate repeatedly, the durability deterioration and oxidation deterioration occurring in the organic semiconductor layer 4 due to flowing current can be reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic semiconductor field effect transistor, and more particularly to an organic semiconductor field effect transistor including an organic semiconductor layer coupled to a source electrode and a drain electrode, respectively.
[0002]
[Prior art and issues]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-94107
Conventionally, various organic semiconductor field effect transistors provided with an organic semiconductor layer respectively bonded to a source electrode and a drain electrode have been provided, and examples thereof include those described in Patent Document 1.
[0004]
This type of field effect transistor has a problem that when it is operated repeatedly, the organic semiconductor layer deteriorates in durability or oxidizes due to a flowing current. However, conventionally, no particularly effective coping method has been proposed for durability deterioration and oxidation deterioration of the organic semiconductor layer.
[0005]
SUMMARY OF THE INVENTION An object of the present invention is to provide an organic semiconductor field effect transistor that can reduce durability deterioration and oxidation deterioration of an organic semiconductor layer.
[0006]
Configuration, operation and effect of the invention
In order to achieve the above object, the present invention provides an organic semiconductor field effect transistor comprising at least an organic semiconductor layer, a source electrode, a drain electrode, and a gate electrode, wherein the source electrode and the drain electrode are respectively coupled to the organic semiconductor layer. The organic semiconductor layer contains at least one compound of an antioxidant, a light stabilizer and an ultraviolet absorber.
[0007]
In the organic semiconductor field effect transistor according to the present invention, when the organic semiconductor layer contains at least one compound of an antioxidant, a light stabilizer, and an ultraviolet absorber and is operated repeatedly, depending on a flowing current. Durability deterioration and oxidation deterioration occurring in the organic semiconductor layer are reduced.
[0008]
In the organic semiconductor field effect transistor according to the present invention, when an hindered phenol compound is used as an antioxidant, a hindered amine compound is used as a light stabilizer, and a benzotriazole compound is used as an ultraviolet absorber, the durability of the organic semiconductor layer Great effect on improvement.
[0009]
Moreover, it is preferable that content of at least 1 sort (s) of an antioxidant, a light stabilizer, and a ultraviolet absorber is 0.1 to 30 weight% of an organic-semiconductor layer. If the content is too small, a sufficient effect cannot be exhibited. If the content is too large, the speed at which the current flows decreases, or the resistance becomes too large.
[0010]
The organic semiconductor layer may be either a low-molecular organic polymer or a high-molecular organic semiconductor. When the organic semiconductor layer contains a high-molecular organic semiconductor, the organic semiconductor layer can be formed by itself and has the advantage of a high current flow rate. ing. Further, a low molecular or high molecular organic semiconductor may be combined, or a low molecular and / or high molecular organic semiconductor may be mixed with an insulating polymer.
[0011]
The organic semiconductor layer is a single layer film or a multilayer film, and the total film thickness thereof is in the range of 10 to 2000 nm, preferably in the range of 25 to 500 nm, more preferably in the range of 50 to 300 nm. If the film thickness is too thin, it is difficult to control the current, and if it is too thick, the switching voltage increases.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of an organic semiconductor field effect transistor according to the present invention will be described with reference to the accompanying drawings.
[0013]
(Basic structure and operation of organic semiconductor field effect transistor)
1 to 4 show a basic structure of an organic semiconductor field effect transistor according to the present invention.
[0014]
FIG. 1 shows a Brenner type, in which a source electrode 2 and a drain electrode 3 are provided on the surface of an insulating substrate 1, an organic semiconductor layer 4 is formed, a gate electrode 5 is provided on the back surface of the substrate 1, and a base substrate 6 Is installed.
[0015]
FIG. 2 shows an inverted stagger type, in which an organic semiconductor layer 4 is formed on the surface of an insulating substrate 1, a source electrode 2 and a drain electrode 3 are provided, a gate electrode 5 is provided on the back surface of the substrate 1, and a base substrate is provided. 6 is installed.
[0016]
FIG. 3 shows a staggered type, in which a gate electrode 5 is formed on the surface of an insulating substrate 1, a source electrode 2 and a drain electrode 3 are provided on the back surface of the substrate 1, an organic semiconductor layer 4 is formed, and a base substrate is formed. 6 is installed.
[0017]
FIG. 4 shows a vertical type in which a drain electrode 3 and a source electrode 2 are formed on the front and back surfaces of the organic semiconductor layer 4, and a gate electrode (grid electrode) 5 is provided in the organic semiconductor layer 4.
[0018]
In each of the organic semiconductor field effect transistors shown in FIGS. 1 to 4, when the organic semiconductor layer 4 has hole transport properties, when a negative voltage is applied to the gate electrode 5, the organic semiconductor layer 4 and the insulating layer of the substrate 1 Holes are accumulated near the interface to form a conduction channel, and a current flows between the source electrode 2 and the drain electrode 3 through the conduction channel. That is, it is in the “on” state. When the gate voltage is reversed, the holes in the storage zone disappear and the current stops. That is, the “off” state is entered.
[0019]
When the organic semiconductor layer 4 has an electron transporting property, when a positive voltage is applied to the gate electrode 5, hole depletion (electron accumulation) occurs in the vicinity of the interface between the organic semiconductor layer 4 and the insulating layer of the substrate 1. And a current flows between the source electrode 2 and the drain electrode 3 through the conduction channel. That is, it is in the “on” state. When the gate voltage is reversed, the electrons in the storage zone disappear and the current stops. That is, the “off” state is entered.
[0020]
As a material of the organic semiconductor layer 4, a π-electron conjugated aromatic compound, a chain compound, an organic pigment, an organic silicon compound, or the like can be used. Specific examples include pentacene, tetracene, thiophenoligoma derivatives, phenylene derivatives, phthalocyanine compounds, polyacetylene derivatives, polythiophene derivatives, polyphenylene derivatives, and cyanine dyes. However, materials that can be used as the organic semiconductor layer 4 are not limited to these.
[0021]
In the organic semiconductor field effect transistor according to the present invention, the organic semiconductor layer 4 includes at least one compound of an antioxidant, a light stabilizer (sometimes referred to as a light deterioration preventing agent), and an ultraviolet absorber. Is contained. By including these compounds, the organic semiconductor layer 4 is reduced in durability deterioration and oxidation deterioration due to repeated switching on and off. Hereinafter, Examples 1 to 6 and Comparative Example 1 manufactured by the present inventors will be described.
[0022]
(Example 1, Brenner type)
A silicon oxide film having a thickness of about 300 nm was formed on both surfaces of an n-type silicon substrate (3 × 3 cm, thickness 400 μm) having a conductivity of 6 S / cm by thermal oxidation. Next, using a positive photoresist on one surface of the silicon substrate, a metal film forming pattern that functions as a source electrode and a drain electrode was produced. The effective opening area of this pattern is 0.2 × 0.8 cm, and the distance between the openings is 6 μm.
[0023]
Thereafter, a chromium deposited film having a thickness of 20 nm was formed on the silicon substrate through the pattern by vacuum deposition, and a gold deposited film having a thickness of 30 nm was further formed thereon. Then, the photoresist was removed to form a source electrode and a drain electrode. On these electrodes, lead wires were connected with silver paste, and the connecting portions were fixed with epoxy resin.
[0024]
Next, 10 parts by weight of a polymer having a number average molecular weight of 70,000 (3-octylthiophene), 0.5 parts by weight of 4-hydroxy 3,5-diter-butyltoluene-based antioxidant (Sumitomo Chemical Co., Ltd .: Smither BHT) An organic semiconductor layer was formed using a spin coat method with a solution in which a part was dissolved in 190 parts by weight of chloroform and dried. This organic semiconductor layer covers the source and drain electrodes and the silicon oxide film of the silicon substrate, and the film thickness is 2 μm.
[0025]
On the other hand, the silicon oxide film opposite to the organic semiconductor layer forming surface of the silicon substrate is partially removed with a paper file, and n-type silicon is brought into ohmic contact with an indium gallium alloy. The lead wire was connected with silver paste, and the connecting portion was fixed with epoxy. Through this lead wire, an n-type silicon substrate (reference numerals 5 and 6 in FIG. 1) acts as a gate electrode.
[0026]
In the organic semiconductor field effect transistor manufactured as described above, when the gate voltage is −15 V, the source-drain current when the source-drain voltage is −2 V is 1.2 × 10 ⁻⁷ A. Met.
[0027]
(Example 2, Brenner type)
In Example 2, 10 parts by weight of a polymer having a number average molecular weight of 60,000 (3-octylthiophene), 0.5 parts by weight of a hindered phenol antioxidant (manufactured by Nagase Sangyo Co., Ltd .: Irganox 1076), an ultraviolet absorber (Nagase Sangyo Co., Ltd .: Tinuvin 320) The organic-semiconductor layer was formed using the spin coat method in the solution which melt | dissolved 0.2 weight part in chloroform 190 weight part. Other processes were the same as in Example 1 to fabricate an organic semiconductor field effect transistor.
[0028]
In the organic semiconductor field effect transistor manufactured as described above, when the gate voltage is −15 V, the source-drain current when the source-drain voltage is −2 V is 1.2 × 10 ⁻⁷ A. Met.
[0029]
(Example 3, Brenner type)
In Example 3, 10 parts by weight of a polymer having a number average molecular weight of 50,000 (3-octylthiophene), 0.2 parts by weight of a hindered phenol antioxidant (Irganox 565 manufactured by Nagase Sangyo Co., Ltd.), hindered amine light An organic semiconductor layer was formed by spin coating using a solution in which 0.1 part by weight of a stabilizer (manufactured by Nagase Sangyo Co., Ltd .: Tinuvin 622LD) was dissolved in 190 parts by weight of chloroform. Other processes were the same as in Example 1 to fabricate an organic semiconductor field effect transistor.
[0030]
In the organic semiconductor field effect transistor manufactured as described above, when the gate voltage is −15 V, the source-drain current when the source-drain voltage is −2 V is 1.1 × 10 ⁻⁷ A. Met.
[0031]
(Example 4, Brenner type)
In Example 4, 10 parts by weight of a polymer having a number average molecular weight of 70,000 (3-octylthiophene), hindered phenol-based antioxidant (manufactured by Sumitomo Chemical Co .: Sumilizer MDP-S), 0.3 parts by weight, hindered amine Spin coating method using a solution prepared by dissolving 0.05 parts by weight of a light stabilizer (manufactured by Nagase Sangyo Co., Ltd .: Tinuvin 123) and 0.05 part by weight of an ultraviolet absorber (manufactured by Nagase Sangyo Co., Ltd .: Tinuvin 234) in 190 parts by weight of chloroform. Was used to form an organic semiconductor layer. Other processes were the same as in Example 1 to fabricate an organic semiconductor field effect transistor.
[0032]
In the organic semiconductor field effect transistor manufactured as described above, when the gate voltage is −15 V, the source-drain current when the source-drain voltage is −2 V is 1.2 × 10 ⁻⁷ A. Met.
[0033]
(Example 5, Brenner type)
A 50 nm thick silicon oxide film was formed on both surfaces of the p-type silicon substrate by thermal oxidation. Next, a source electrode and a drain electrode made of n-type silicon were formed in a comb shape with a channel length of 2.5 μm and a channel width of 2 mm on one surface of the silicon substrate.
[0034]
Next, 10 parts by weight of a polymer having a number average molecular weight of 60,000 (3-octylthiophene), 0.5 parts by weight of a hindered amine light stabilizer (manufactured by Nagase Sangyo Co., Ltd .: Chimassorb 119FL), an ultraviolet absorber (manufactured by Nagase Sangyo Co., Ltd .: Tinuvin 329) An organic semiconductor layer was formed by spin coating using a solution in which 0.5 part by weight was dissolved in 190 parts by weight of chloroform. Other processes were the same as in Example 1 to fabricate an organic semiconductor field effect transistor.
[0035]
In the organic semiconductor field effect transistor manufactured as described above, when the gate voltage is −15 V, the source-drain current when the source-drain voltage is −2 V is 1.3 × 10 ⁻⁷ A. Met.
[0036]
(Example 6, reverse stagger type)
A gold electrode was formed on a glass substrate by a vacuum evaporation method to obtain a gate electrode. Then, a silicon oxide film was formed as an insulating film over the gate electrode.
[0037]
Next, 5 parts of a solution in which 10 parts by weight of a polymer having a number average molecular weight of 90,000 (3-octylthiophene) and 0.1 parts by weight of an ultraviolet absorber (manufactured by Nagase Sangyo Co., Ltd .: Tinuvin 1577FF) were dissolved in 190 parts by weight of chloroform. An organic semiconductor layer was formed on the glass substrate by spin coating with a weight% chloroform solution. Further, a gold electrode was formed on the organic semiconductor layer by a vacuum vapor deposition method to form a source electrode and a drain electrode.
[0038]
In the organic semiconductor field effect transistor manufactured as described above, when the gate voltage is −15 V, the source-drain current when the source-drain voltage is −2 V is 1.2 × 10 ⁻⁷ A. Met.
[0039]
(Comparative Example 1, Brenner type)
In Comparative Example 1, an organic semiconductor layer was formed using a spin coating method with a solution in which 10 parts by weight of a polymer having a number average molecular weight of 70,000 (3-octylthiophene) was dissolved in 190 parts by weight of chloroform. Other processes were the same as in Example 1 to fabricate an organic semiconductor field effect transistor.
[0040]
In the organic semiconductor field effect transistor manufactured as described above, when the gate voltage is −15 V, the source-drain current when the source-drain voltage is −2 V is 1.0 × 10 ⁻⁷ A. Met.
[0041]
(An endurance test)
In Examples 1 to 6 and Comparative Example 1, the source-drain voltage and the source-drain current with respect to the gate voltage were measured. Next, voltage switching was repeated 500 times, and then the source-drain voltage and the source-drain current with respect to the gate voltage were measured. The result after 500 times of switching is shown below.
[0042]
In Example 1, the source-drain current was 0.7 × 10 ⁻⁷ A when the gate voltage was −15 V and the source-drain voltage was −2 V.
[0043]
In Example 2, the source-drain current when the gate voltage was −15 V and the source-drain voltage was −2 V was 0.9 × 10 ⁻⁷ A.
[0044]
In Example 3, the source-drain current was 1.1 × 10 ⁻⁷ A when the gate voltage was −15 V and the source-drain voltage was −2 V.
[0045]
In Example 4, the source-drain current when the gate voltage was −15 V and the source-drain voltage was −2 V was 1.2 × 10 ⁻⁷ A.
[0046]
In Example 5, the source-drain current when the gate voltage was −15 V and the source-drain voltage was −2 V was 0.5 × 10 ⁻⁷ A.
[0047]
In Example 6, the source-drain current was 0.2 × 10 ⁻⁷ A when the gate voltage was −15 V and the source-drain voltage was −2 V.
[0048]
In Comparative Example 1, the source-drain current was 2.8 × 10 ⁻⁸ A when the gate voltage was −15 V and the source-drain voltage was −2 V.
[0049]
(Other embodiments)
The organic semiconductor field effect transistor according to the present invention is not limited to the above-described embodiments and examples, and it is needless to say that various modifications can be made within the scope of the gist.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a schematic configuration of an organic semiconductor field effect transistor (Brenner type) according to the present invention.
FIG. 2 is a cross-sectional view showing a schematic configuration of an organic semiconductor field effect transistor (inverted stagger type) according to the present invention.
FIG. 3 is a cross-sectional view showing a schematic configuration of an organic semiconductor field effect transistor (stagger type) according to the present invention.
4A and 4B show a schematic configuration of an organic semiconductor field effect transistor (vertical type) according to the present invention, in which FIG. 4A is a cross-sectional view and FIG. 4B is a perspective view.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Insulating substrate 2 ... Source electrode 3 ... Drain electrode 4 ... Organic-semiconductor layer 5 ... Gate electrode

Claims (5)

In an organic semiconductor field effect transistor comprising at least an organic semiconductor layer, a source electrode, a drain electrode, and a gate electrode, wherein the source electrode and the drain electrode are respectively coupled to the organic semiconductor layer.
Containing at least one compound of an antioxidant, a light stabilizer and an ultraviolet absorber in the organic semiconductor layer;
An organic semiconductor field effect transistor. 2. The organic semiconductor field effect transistor according to claim 1, wherein the antioxidant is a hindered phenol compound, the light stabilizer is a hindered amine compound, and the ultraviolet absorber is a benzotriazole compound. The content of at least one compound of the antioxidant, light stabilizer, and ultraviolet absorber is 0.1 to 30% by weight of the organic semiconductor layer, according to claim 1 or 2. Organic semiconductor field effect transistor. The organic semiconductor field effect transistor according to claim 1, wherein the organic semiconductor layer contains a polymer organic semiconductor. 5. The organic semiconductor field effect transistor according to claim 1, wherein the thickness of the organic semiconductor layer is 10 to 2000 nm.

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