n-type thiophene semiconductors

• US 6,608,323 B2
• Filed: 07/24/2001
• Issued: 08/19/2003
• Est. Priority Date: 07/24/2000
• Status: Expired due to Term

• Current Assignee: Cambridge University (Government of United Kingdom), Northwestern University
• Original Assignee: Cambridge University (Government of United Kingdom), Northwestern University
• Inventors: Facchetti, Antonio, Sirringhaus, Henning, Marks, Tobin J., Friend, Richard H.
• Primary Examiner(s): Ho, Hoai
• Assistant Examiner(s): HO, TU TU V
• Application Number:
  US09/915,210
• Publication Number:
  US 20020053666A1
• Time in Patent Office: 756 Days
• Field of Search: 257/40, 257/213
• US Class Current: 257/40
• CPC Class Codes: C08G 61/126 with a five-membered ring containing one sulfur atom in the ring
• CPC Class Codes: H10K 10/462 Insulated gate field-effect transistors [IGFETs]
• CPC Class Codes: H10K 10/466 Lateral bottom-gate IGFETs comprising only a single gate
• CPC Class Codes: H10K 59/00 Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
• CPC Class Codes: H10K 59/125 including organic TFTs [OTFT]
• CPC Class Codes: H10K 71/16 using physical vapour deposition [PVD], e.g. vacuum deposition or sputtering
• CPC Class Codes: H10K 85/113 Heteroaromatic compounds comprising sulfur or selene, e.g. polythiophene
• CPC Class Codes: H10K 85/655 comprising only sulfur as heteroatom

Abstract

The new fluorocarbon-functionalized polythiophenes, in particular, α,ω-diperfluorohexylsexithiophene DFH-6T (1) can be straightforwardly prepared in high yield and purified by gradient sublimation. Introduction of perfluorocarbon chains on the thiophene core affords enhanced thermal stability and volatility, and increased electron affinity versus the fluorine-free analog 2. Evaporated films of 1, for example, behave as n-type semiconductors, and can be used to fabricate thin film transistors with FET mobilities on the order of ˜0.01 cm²/Vs—some of the highest reported to date for n-type organic semiconductors.

Claims

1. A field effect transistor device, comprising:

a gate electrode;

a source electrode and a drain electrode; and

an n-type conjugated organic semiconducting material between said source and drain electrodes and in electrical contact therewith, comprising at least one side chain that contains a fluoroalkyl group.

2. The field effect transistor device of claim 1 wherein said fluoroalkyl group is covalently attached to one of the conjugated units of the n-type organic semiconducting material.

3. The field effect transistor device of claim 1 wherein said n-type organic semiconducting material contains about four to about seven conjugated thiophene moieties.

4. The field effect transistor device of claim 3 wherein said n-type organic semiconducting material is di-substituted and at least one of said substituents comprises a fluoroalkyl moiety.

5. The field effect transistor device of claim 4 wherein said fluoroalkyl moiety is a C₅C₇ fluoroalkyl substituent.

6. The field effect transistor device of claim 1 wherein said n-type organic semiconducting material is a polythiophene polymer with more than seven conjugated thiophene moieties.

7. The field effect transistor of claim 6, where said polythiophene polymer contains fluoroalkyl substituents attached to the 3-position of the thiophene rings in a regioregular, head-to-tail configuration.

8. The field effect transistor of claim 7, where said polythiophene polymer is regioregular, head-to-tail poly-3-C_nF_2n+1-thiophene.

9. The field effect transistor of claim 7, wherein said polythiophene polymer is regioregular, head-to-tail poly-3-C_mH_2m+1C_nF_2n+1-thiophene.

10. A field effect transistor device of claim 1 wherein each of said source and drain electrodes have a work function less than about 5 eV.

11. The field effect transistor device of claim 10 wherein said electrodes comprise a material selected from the group consisting of silver and aluminum.

12. The field effect transistor device of claim 1 wherein said n-type semiconducting organic material has an electron affinity greater than about 3.0 eV.

13. The field effect transistor device of claim 12 wherein said electron affinity is greater than about 3.5 eV.

14. The field effect transistor device of claim 13 wherein said electron affinity is greater than about 4.0 eV.

15. The field effect transistor device of claim 1 further comprising a substrate with said n-type semiconducting material composition as a thin film thereon.

16. A field effect transistor device of claim 1 wherein said transistor is a thin film transistor.

17. A field effect transistor device of claim 1 wherein said transistor is a junction field-effect transistor.

18. The field-effect transistor of claim 17 wherein said gate electrode is in electrical contact with a p-type thiophene-based organic semiconductor.

19. A field-effect transistor device of claim 1 wherein said transistor is a pnp transistor.

20. A field-effect transistor device of claim 1 wherein said transistor is a npn transistor.

21. The organic transistor device of claim 1 wherein said n-type organic semiconducting material is in contact with a substrate coated with a fluorocarbon material.

22. The transistor device of claim 1 wherein said transistor is part of an integrated circuit.

23. A complementary logic circuit containing organic transistor devices as in any of the preceding claims.

24. An active matrix display containing an organic transistor device of claim 1.

25. An active matrix LED display containing an organic transistor device of claim 1.

26. A method of using an organic semiconductor material for n-type conduction in a field effect transistor, said method comprising:

providing a field effect transistor device having a gate electrode;

providing source and drain electrodes with an n-type semiconductor material therebetween and in electrical contact therewith, said n-type semiconductor material comprising a fluoroalkyl-substituted composition; and

operating said transistor for conduction with said composition to provide a positive source-drain current.

27. The method of claim 26 wherein a positive voltage is applied to said gate electrode to control conduction between said source and drain electrodes.

28. The method of claim 27 wherein the said gate electrode is in electrical contact with a p-type organic semiconductor.

29. The method of claim 28 wherein said n-type and p-type organic semiconductor materials are of polythiophene composition.

30. The method of claim 26 wherein said drain electrode is in electrical contact with a light emitting diode and said current injects electron into said diode, said applied gate voltage controlling said injection.

31. A complementary organic transistor circuit containing n- and p-type transistors in which the chemical structure of the n-type semiconducting material differs from that of the p-type semiconducting material only by the replacement of at least one alkyl side chain by a fluoroalkyl side chain.

32. A junction field-effect transistor in which the chemical structure of the n-type semiconducting material differs from that of the p-type semiconducting material only by the replacement of at least one alkyl side chain by a fluoroalkyl side chain.