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Organic field-effect transistor, production method and intermediate structure therefor, and organic field-effect device

外国特許コード F110005406
整理番号 K02805WO
掲載日 2011年9月5日
出願国 アメリカ合衆国
出願番号 45842009
公報番号 20100051913
公報番号 8203138
出願日 平成21年7月10日(2009.7.10)
公報発行日 平成22年3月4日(2010.3.4)
公報発行日 平成24年6月19日(2012.6.19)
優先権データ
  • 特願2008-004629 (2008.1.11) JP
  • 特願2008-004630 (2008.1.11) JP
  • 2008JP065700 (2008.9.1) WO
発明の名称 (英語) Organic field-effect transistor, production method and intermediate structure therefor, and organic field-effect device
発明の概要(英語) An organic field-effect transistor normally includes: a source electrode and a drain electrode; an organic semiconductor layer in contact with the source electrode and the drain electrode; a gate insulating layer adjacent to the organic semiconductor layer; and a gate electrode in contact with the gate insulating layer.
The gate insulating layer according to the present invention is in a liquid state, constituted with a material containing no glue or thickener, a sole or main component of which is an ionic liquid.
Thus the capacitance of the ionic liquid corresponding to a gate voltage modulation frequency of 10 Hz is reduced to 1/10 at a frequency of 10 kHz of higher.
As a result, an organic field-effect transistor capable of operating at low voltage and assuring ample current gain and high-speed response (the capacitance of the ionic liquid corresponding to a gate voltage modulation frequency of 10 Hz is reduced to 1/10 at a frequency of 10 kHz of higher) is provided.
従来技術、競合技術の概要(英語) BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an organic field-effect transistor provided with an organic semiconductor layer and a gate insulating layer.
It also relates to a production method and an intermediate structure (structural body) for such an organic field-effect transistor as well as to an organic field-effect device.
More particularly, the present invention relates to an organic field-effect transistor that operates at a low drive voltage and yet assures a sufficiently high current gain and a high-speed response.
The transistor according to the present invention can be used as an amplifying element that amplifies current flowing between source and drain electrodes or a switching element that turns ON/OFF the flow of such current.
2. Description of Related Art
A field-effect transistor includes a source electrode, a drain electrode, a semiconductor layer in contact with the source and drain electrodes, a gate insulating layer adjacent to the semiconductor layer, and a gate electrode in contact with the gate insulating layer.
In recent years, extensive studies have been conducted on organic field-effect transistors with organic semiconductors instead of inorganic semiconductors and the gate insulating layers thereof constituted with electrolytes instead of dielectric materials.
Organic transistors are advantageous since they are not only light in weight but are also thin and flexible so that they can be bent.
Accordingly, the organic transistors are expected to expand applications of transistors.
Also, studies have been conducted on a polymer gel electrolyte comprised of polymer gel (polyethylene glycol) and Li ions (see. for example, J. Takeya et al., Appl. Phys. Lett. 88, 112102 (2006)) (hereafter referred to as "Polymer Gel Electrolyte I").
The polymer gel serves as glue or thickener.
The Polymer Gel Electrolyte I is not liquid but paste-like.
It has been observed that the application of a voltage to the Polymer Gel Electrolyte I causes ions to move, resulting in the formation of a layer in which positive ions are accumulated and a layer in which negative ions are accumulated over a region having a thickness of about 1 nm from the electrodes which, together, form layers in which the balance between positive and negative charges is lost (electric-double layers).
In these layers, the electric field is concentrated in a region with a thickness of about 1 nm from the surface of the semiconductor.
As a result, even when a voltage as low as 1 V is applied between the gate electrode and the source electrode (or the drain electrode), an electric field as strong as 10 MV/cm is applied in the layers.
Accordingly, when the Polymer Gel Electrolyte I is used as the gate insulating layer of a transistor, a stronger electric field can be applied to it at a lower voltage.
As a result, many carriers are injected into the gate insulating layer.
A high current gain can be achieved even at a low drive voltage in such a transistor.
In the meantime, there has been proposed an organic field-effect transistor with a gate insulating layer made of a polymer gel electrolyte comprised of a polymer gel and an ionic liquid (for example, 1-butyl-3-methylimidazolium hexafluorophosphate) (hereafter, referred to as "Polymer Gel Electrolyte II") (Jiyoul Lee et al., "Ion Gel Gated Polymer Thin-Film Transistor" J. Am. Chem. Soc. 129 (2007) 4532), instead of L1 ion.

特許請求の範囲(英語) [claim1]
1. A field-effect transistor comprising: a source electrode and a drain electrode;
an organic semiconductor layer in contact with the source electrode and the drain electrode;
a gate insulating layer adjacent to the organic semiconductor layer; and
a gate electrode in contact with the gate insulating layer, wherein:
the gate insulating layer is in a liquid state with a viscosity that is equal to 150 mPas (millipascals per second) or less at room temperature and is constituted of an ionic liquid as a sole or main component thereof.
[claim2]
2. The field-effect transistor according to claim 1, wherein: the gate electrode is separated from the organic semiconductor layer over a specific gap which is determined such that capillary force can be achieved.
[claim3]
3. The field-effect transistor according to claim 2, wherein: the ionic liquid is held within closed space formed at the field-effect transistor.
[claim4]
4. The field-effect transistor according to claim 1, wherein: the ionic liquid is held in the field-effect transistor by capillary force.
[claim5]
5. The field-effect transistor according to claim 1, wherein: the ionic liquid is held within closed space formed at the field-effect transistor.
[claim6]
6. The field-effect transistor according to claim 1, wherein: a capacitance of the ionic liquid corresponding to a gate voltage modulation frequency of 10 Hz is reduced to 1/10 at a frequency of 10 kHz or higher.
[claim7]
7. The field-effect transistor according to claim 6, wherein: the ionic liquid is free of glue and thickener.
[claim8]
8. The field-effect transistor according to claim 7, wherein: the organic semiconductor is either a rubrene or a pentacene.
[claim9]
9. The field-effect transistor according to claim 1, wherein: the organic semiconductor is either a rubrene or a pentacene.
[claim10]
10. The field-effect transistor according to claim 1, wherein: the ionic liquid is free of glue and thickener.
[claim11]
11. The field-effect transistor according to claim 1, wherein: the ionic liquid contains nano particles of an inorganic oxide.
[claim12]
12. The field-effect transistor according to claim 1, wherein: the gate insulating layer in the liquid state contains inorganic ions.
[claim13]
13. The field-effect transistor according to claim 1, wherein: a cation constituting the ionic liquid is selected from
imidazolium cations, pyrrolidinium cations, piperidinium cations, ammonium cations, and pyrazolium cations.
[claim14]
14. The field-effect transistor according to claim 1, wherein: the ionic liquid is constituted with a cation selected from
1-methyl-3-methylimidazolium, 1-ethyl-3-methylimidazolium, 1-propyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1-pentyl-3-methylimidazolium, 1-hexyll-3-methylimidazolium, 1-octyl-3-methylimidazolium, 1,2-dimethyl-3-propylimidazolium, 1-methyl-1-propylpyrrolidinium, 1-methyl-1-butylpyrrolidinium, 1-butyl-1-methylpyrrolidinium, 1-methyl-1-propylpiperidinium, trimethyl propyl ammonium, trimethyl octyl ammonium, trimethyl hexyl ammonium, trimethyl pentyl ammonium, and trimethyl butyl ammonium, 1-ethyl-2,3,5-trimethylpyrazolium, 1-butyl-2,3,5-trimethylpyrazolium and 1-propyl-2,3,5-trimethylpyrazolium; and
an anion selected from
bis(trifluoromethanesulfonyl)imide, bis(fluorosulfonyl)imide, bis(perfluoroethylsulfonyl)imide, tetrafluoroborate, hexafluorophosphate, and dicyanoamine.
[claim15]
15. The field-effect transistor according to claim 14, wherein: the ionic liquid is selected from;
1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-ethyl-3-methylimidazolium bis(perfluoroethylsulfonyl)imide, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium dicyanoamine, 1-methyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-propylpyrrolidinium bis(fluorosulfonyl)imide, 1-methyl-1-propylpiperidinium bis(trifluoromethanesulfonyl)imide, trimethylbutylammonium bis(trifluoromethanesulfonyl)imide, and trimethylpentylammonium bis(trifluoromethanesulfonyl)imide.
[claim16]
16. The field-effect transistor according to claim 15, wherein: the ionic liquid is selected from;
1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide.
[claim17]
17. The field-effect transistor according to claim 1, further comprising: a substrate upon which the source electrode, the drain electrode, and the gate electrode are disposed.
[claim18]
18. The field-effect transistor according to claim 1, wherein: the substrate is elastic.
[claim19]
19. An organic field-effect device that includes an field-effect transistor according to claim 1.
[claim20]
20. An intermediate structural body for producing an organic field-effect transistor, comprising: a source electrode;
a drain electrode;
an organic semiconductor layer in contact with the source electrode and the drain electrode; and
a gate electrode in contact with the gate insulating layer, wherein:
the gate insulating layer is in a liquid state with a viscosity that is equal to 150 mPas (millipascals per second) or less at room temperature and is constituted of an ionic liquid as a sole or main component thereof, and
a gate electrode separated from the organic semiconductor layer over a specific gap which is determined such that capillary force can be obtained for a liquid electrolyte constituted of an ionic liquid.
[claim21]
21. An intermediate structural body, comprising: a substrate with a depressed area of a predetermined depth on a surface thereof which is determined such that capillary force can be achieved in a liquid electrolyte with a viscosity that is equal to 150 mPas (millipascals per second) or less at room temperature and having an ionic liquid as a sole or main component thereof;
a source electrode and a drain electrode formed on a surface of the substrate so as to face opposite each other across the depressed area; and
a gate electrode formed on a bottom surface of the depressed area.
[claim22]
22. The intermediate structural body according to claim 21, wherein: the substrate is elastic.
  • 発明者/出願人(英語)
  • TAKEYA JUNICHI
  • ONO SHIMPEI
  • SEKI SHIRO
  • JAPAN SCIENCE AND TECHNOLOGY AGENCY
  • CENTRAL RESEARCH INSTITUTE OF ELECTRIC POWER INDUSTRY
国際特許分類(IPC)
米国特許分類/主・副
  • 257/40
  • 257/E51.001
参考情報 (研究プロジェクト等) PRESTO Structures and control of interfaces AREA
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