Transistor

• US 20070138463A1
• Filed: 11/09/2006
• Published: 06/21/2007
• Est. Priority Date: 11/09/2005
• Status: Active Grant

• Current Assignee: Goran Gustafsson, Lars Herlogsson, Magnus Berggren, Mats Sandberg, Nathaniel Robinson, Olle-Jonny Hagel, Xavier Crispin
• Original Assignee: Goran Gustafsson, Lars Herlogsson, Magnus Berggren, Mats Sandberg, Nathaniel Robinson, Olle-Jonny Hagel, Xavier Crispin
• Inventors: Crispin, Xavier, Berggren, Magnus, Sandberg, Mats, Robinson, Nathaniel, Gustafsson, Goran, Herlogsson, Lars, Hagel, Olle-Jonny
• Granted Patent: US 7,646,013 B2
• Time in Patent Office: Days
• US Class Current: 257/40
• CPC Class Codes: H10K 10/464 Lateral top-gate IGFETs comprising only a single gate
• CPC Class Codes: H10K 10/468 characterised by the gate dielectrics
• CPC Class Codes: H10K 71/30 Doping active layers, e.g. electron transporting layers

Abstract

A fast organic field effect transistor (100), which operates at low voltages, is achieved by the introduction of an oligomeric or polymeric electrolyte (131) between the gate electrode (141) and the organic semiconductor layer (121), which electrolyte (131) has a dissociation constant of at least 10−8. Said organic semiconductor layer (121) is in contact with the source electrode (111) and the drain electrode (112) of the transistor. In operation a potential (152) applied to said gate electrode (141) controls the current A between said source electrode (111) and said drain electrode (112).

Claims

1. A field-effect transistor device comprising:

an organic semiconductor layer;

a source electrode arranged in electronic contact with said organic semiconductor layer;

a drain electrode arranged in electronic contact with said organic semiconductor layer;

a gate electrode; and

an electrolyte layer, which is arranged between said gate electrode and said organic semiconductor layer, and which comprises an molecular, oligomeric, polymeric or dendrimetic electrolyte having a dissociation constant of at least 10<sup>−

8</sup>.

2. A device according to claim 1, which is arranged such that a current between said source and drain electrodes within said organic semiconductor layer is primarily controlled by means of a polarization of said electrolyte layer, which induces charge carriers in said semiconductor layer.

3. A device according to claim 1, wherein the electrolyte is arranged such that charge carriers are restrained from entering into said organic semiconductor layer from said electrolyte at least when a control voltage is applied to said gate electrode.

4. A device according to claim 1, wherein said electrolyte is dissociated into at least a small ion-complex having a first electric charge;

and a large ion-complex having an opposite electric charge to said first electric charge, wherein the large ion-complex is restricted from entering into said organic semiconductor layer, at least when a control voltage is applied to said gate electrode.

5. A device according to claim 4, wherein said large ion-complex is substantially immobile, at least when a control voltage is applied to said gate electrode.

6. A device according to claim 4, wherein said large ion-complex is an anion, and said small ion-complex is a cation.

7. A device according to claim 3, wherein said control voltage is between −

5 V and 0 V, preferably −

2 V and 0 V, more preferably between −

1.5 V and 0V and most preferably between −

1 and 0 V.

8. A field-effect transistor device according to claim 1, wherein said electrodes are arranged such that an application of a predetermined voltage between said gate electrode and said source and/or drain electrode forms an electric double layer at the interface of said organic semiconductor layer and said electrolyte layer.

9. A field-effect transistor device according to claim 1, wherein oligomeric or polymeric electrolyte having a dissociation constant of at least 10⁻

6 or even more preferred of at least 10<sup>−

3.5</sup>.

10. A field-effect transistor device according to claim 1, wherein said electrolyte layer comprises more than 4 mmol mobile cations per gram electrolyte.

11. A field-effect transistor device according to claim 10, wherein said electrolyte layer comprises more than 5 mmol mobile protons per gram dry electrolyte.

12. A field-effect transistor device according to claim 1, wherein said electrolyte is an oligomeric or polymeric acid having at least one acid-functional group, or a salt thereof.

13. A field-effect transistor device according to claim 12, wherein the most acidic acid-functional group of said oligomeric or polymeric acid has a pK_a value of less than 6.

14. A field-effect transistor device according to claim 13, wherein said oligomeric or polymeric acid is a oligomer or polymer of monomer units having phosphonic acid, sulphonic acid, carboxylic acid or phosphoric acid groups.

15. A field-effect transistor device according to claim 14, wherein said monomer units have phosphonic acid groups, said monomer units preferably being vinylphosphonic acid.

16. A field-effect transistor device according to claim 14, wherein said monomer units have sulphonic acid groups, said monomer units preferably being styrene-4-sulphonic acid or a salt thereof.

17. A field-effect transistor device according to claim 14, wherein said oligomeric or polymeric acid is a cooligomer or copolymer of first comonomer units having phosphonic acid, sulphonic acid, carboxylic acid or phosphoric acid groups, and second comonomer units having phosphonic acid, sulphonic acid, carboxylic acid or phosphoric acid groups, the first and second comonomer units being different.

18. A field-effect transistor device according to claim 17, wherein said first comonomer units have phosphonic acid groups, said first comonomer units preferably being vinylphosphonic acid.

19. A field-effect transistor device according to claim 17, wherein said second comonomer units have carboxylic acid groups, said second comonomer units preferably being acrylic acid.

20. A field-effect transistor device according to claim 17, wherein said first comonomer units are vinylphosphonic acid and said second comonomer units are acrylic acid, preferably being present in the cooligomer or copolymer at a molar ratio of vinylphosphonic acid to acrylic acid of higher than 50:

50.

21. A field-effect transistor device according to claim 8, wherein said electrolyte is a composition of two or more oligomeric or polymeric acids, each defined as in any one of claims 6 to 14.

22. A field-effect transistor device according to claim 21, wherein said electrolyte is a composition of a polymer of vinylphosphonic acid and a polymer of acrylic acid, preferably at a molar ratio of vinylphosphonic acid to acrylic acid of higher than 70:

30.

23. A field-effect transistor device according to claim 12, wherein said oligomeric or polymeric acid is cross-linked.

24. A field-effect transistor device according to claim 23, wherein said oligomeric or polymeric acid is cross-linked by an external cross-linker.

25. A field-effect transistor device according to claim 24, wherein the external cross-linker has two or more glycidyl groups.

26. A field-effect transistor device according to claim 25, wherein the external cross-linker is polyethylene glycol diglycidyl ether.

27. A field-effect transistor device according to claim 1, wherein said organic semiconductor layer comprises an oligomeric or polymeric semiconductor.

28. A field-effect transistor device according to claim 17, wherein said oligomeric or polymeric semiconductor is selected from the group consisting of polyalkylthiophenes, naphthalene, anthracene, tetracene, pentacene, hexacene and derivatives thereof.

29. A field-effect transistor device according to claim 1, wherein said source electrode comprises a material selected from the group consisting of chromium, titanium, copper, aluminium, molybdenum, tungsten, nickel, gold, palladium, platinum, conducting polymers and oligomers, carbon nanotubes, carbon paste, silver paste and combination thereof.

30. A field-effect transistor device according to claim 21, wherein said oligomeric or polymeric acid is cross-linked.

31. A field-effect transistor device according to claim 1, wherein said drain electrode comprises a material selected from the group consisting of chromium, titanium, copper, aluminium, molybdenum, tungsten, nickel, gold, palladium, platinum, conducting polymers and oligomers, carbon nanotubes, carbon paste, silver paste and combination thereof.

32. A method of controlling an organic field-effect transistor, comprising the step of primarily controlling a current within an organic semiconductor layer by polarizing an electrolyte layer such that charge carriers are induced in said semiconductor layer.