Solution process for fabricating high-performance organic thin-film transistors

• US 10,454,033 B2
• Filed: 03/20/2017
• Issued: 10/22/2019
• Est. Priority Date: 01/08/2016
• Status: Active Grant

• Current Assignee: Hong Kong Baptist University
• Original Assignee: Hong Kong Baptist University
• Inventors: Ong, Beng Soon, Lei, Yanlian
• Primary Examiner(s): Higgins, Gerard
• Application Number:
  US15/464,336
• Publication Number:
  US 20170200896A1
• Time in Patent Office: 946 Days
• CPC Class Codes: B32B 3/10 characterised by a discontinuous layer, i.e. formed of separate pieces of material
• CPC Class Codes: C08G 2261/124 alternating
• CPC Class Codes: C08G 2261/1412 Saturated aliphatic units
• CPC Class Codes: C08G 2261/212 Regioregularity
• CPC Class Codes: C08G 2261/3223 containing one or more sulfur atoms as the only heteroatom, e.g. thiophene
• CPC Class Codes: C08G 2261/3243 containing one or more sulfur atoms as the only heteroatom, e.g. benzothiophene
• CPC Class Codes: C08G 2261/334 containing heteroatoms
• CPC Class Codes: C08G 2261/344 containing heteroatoms
• CPC Class Codes: C08G 2261/364 containing hetero atoms
• CPC Class Codes: C08G 2261/51 Charge transport
• CPC Class Codes: C08G 2261/92 TFT applications
• CPC Class Codes: C08G 61/126 with a five-membered ring containing one sulfur atom in the ring
• CPC Class Codes: C08L 23/06 Polyethene
• CPC Class Codes: C08L 27/06 Homopolymers or copolymers of vinyl chloride
• CPC Class Codes: C08L 33/06 of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
• CPC Class Codes: C08L 33/12 Homopolymers or copolymers of methyl methacrylate
• CPC Class Codes: C08L 33/20 Homopolymers or copolymers of acrylonitrile C08L55/02 takes precedence
• CPC Class Codes: C08L 65/00 Compositions of macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain C08L7/00 - C08L57/00, C08L61/00 take precedence; Compositions of derivatives of such polymers
• CPC Class Codes: C09D 11/106 containing macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: C09D 11/107 from unsaturated acids or derivatives thereof
• CPC Class Codes: C09D 11/108 : Hydrocarbon resins
• CPC Class Codes: C09D 11/12 : based on waxes or bitumen
• CPC Class Codes: C09D 11/52 : Electrically conductive inks
• CPC Class Codes: C09D 123/06 : Polyethene
• CPC Class Codes: C09D 125/06 : Polystyrene
• CPC Class Codes: C09D 127/06 : Homopolymers or copolymers of vinyl chloride
• CPC Class Codes: C09D 133/12 : Homopolymers or copolymers of methyl methacrylate
• CPC Class Codes: C09D 133/20 : Homopolymers or copolymers of acrylonitrile C09D155/02 takes precedence
• CPC Class Codes: C09D 165/00 : Coating compositions based on macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain C09D107/00 - C09D157/00, C09D161/00 take precedence; Coating compositions based on derivatives of such polymers
• CPC Class Codes: C09D 5/24 : Electrically-conducting paints conductive materials H01B1/00
• CPC Class Codes: C09D 7/65 : macromolecular C09D7/41-C09D7/48 take precedence
• CPC Class Codes: H10K 10/464 : Lateral top-gate IGFETs comprising only a single gate
• CPC Class Codes: H10K 10/466 : Lateral bottom-gate IGFETs comprising only a single gate
• CPC Class Codes: H10K 10/476 : comprising at least one organic layer and at least one inorganic layer
• CPC Class Codes: H10K 10/484 : characterised by the channel regions
• CPC Class Codes: H10K 10/488 : the channel region comprising a layer of composite material having interpenetrating or embedded materials, e.g. a mixture of donor and acceptor moieties, that form a bulk heterojunction
• CPC Class Codes: H10K 71/12 : using liquid deposition, e.g. spin coating
• CPC Class Codes: H10K 71/13 : using printing techniques, e.g. ink-jet printing or screen printing
• CPC Class Codes: H10K 71/40 : Thermal treatment, e.g. annealing in the presence of a solvent vapour
• CPC Class Codes: H10K 85/111 : comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
• CPC Class Codes: H10K 85/113 : Heteroaromatic compounds comprising sulfur or selene, e.g. polythiophene
• CPC Class Codes: H10K 85/141 : comprising aliphatic or olefinic chains, e.g. poly N-vinylcarbazol, PVC or PTFE
• CPC Class Codes: H10K 85/151 : Copolymers
• CPC Class Codes: H10K 85/621 : Aromatic anhydride or imide compounds, e.g. perylene tetra-carboxylic dianhydride or perylene tetracarboxylic di-imide
• CPC Class Codes: Y10T 428/24802 : Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]

Abstract

The present invention relates to a solution or ink composition for fabricating high-performance thin-film transistors. The solution or ink comprises an organic semiconductor and a mediating polymer such as polyacrylonitrile, polystyrene, or the like or mixture thereof, in an organic solvent such as chlorobenzene or dichlorobenzene. The percentage ratio by weight of semiconductor:mediating polymer ranges from 5:95 to 95:5, and preferably from 20:80 to 80:20. The solution or ink is used to fabricate via solution coating or printing a semiconductor film, followed by drying and thermal annealing if necessary to provide a channel semiconductor for organic thin-film transistors (OTFTs). The resulting OTFT device with said channel semiconductor has afforded OTFT performance, particularly field-effect mobility and current on/off ratio that are superior to those OTFTs with channel semiconductors fabricated without a mediating polymer.

Claims

1. A solution-based method of fabricating a channel semiconductor for organic thin-film transistors at room temperature comprising:

dissolving at least one organic semiconductor and at least one hydrocarbon binder in at least one solvent to produce a solution;

coating or printing said solution on a substrate to produce a coated substrate; and

drying said coated substrate at room temperature to produce a channel semiconductor;

wherein the at least one organic semiconductor comprises a diketopyrrolopyrrole-based polymer.

2. The method according to claim 1, wherein the at least one hydrocarbon binder is selected from straight-chain aliphatic hydrocarbons or branched-chain aliphatic hydrocarbons.

3. The method according to claim 1, wherein the at least one hydrocarbon binder is an aliphatic hydrocarbon including aromatic substituents selected from phenyl and tolyl.

4. The method according to claim 1 wherein the solution further comprises other additives selected from other hydrocarbon derivatives, aromatic compounds, or polymer additives other than the at least one hydrocarbon binder.

5. The method according to claim 1 wherein the at least one hydrocarbon binder comprises paraffin wax, household candle wax, or polyethylene wax.

6. The method according to claim 1 wherein the at least one hydrocarbon binder has a melting point above room temperature.

7. The method according to claim 1 wherein the proportion of the at least one hydrocarbon binder in the channel semiconductor ranges from 10% to 90% by weight.

8. The method according to claim 7 wherein the proportion of the at least one hydrocarbon binder in the channel semiconductor ranges from 45% to 70% by weight.

9. The method according to claim 1 wherein the at least one organic semiconductor comprises a polymer represented by the following formula:

10. The method according to claim 1 wherein the at least one solvent comprises chlorobenzene or dichlorobenzene.

11. A solution-based method of fabricating a channel semiconductor for organic thin-film transistors comprising:

dissolving an organic semiconductor in a solvent with a mediating polymer or hydrocarbon binder at a percentage ratio by weight of organic semiconductor;

mediating polymer ranging from 5;

95 to 95;

5 or a hydrocarbon binder loading from 10 to 90 weight percent to produce a solution; and

spin casting or printing said solution on a substrate to produce a channel semiconductor;

wherein the resulting organic thin-film transistor with said channel semiconductor exhibits increased field effect mobility as compared to an organic thin-film transistor with a channel semiconductor formed from a solution without a mediating polymer, and wherein the organic semiconductor comprises a diketopyrrolopyrrole-based polymer.

12. The method according to claim 11, wherein the percentage ratio by weight of organic semiconductor:

mediating polymer ranges from 20;

80 to 80;

20.

13. The method according to claim 11, wherein the resulting organic thin-film transistor with said channel semiconductor has a field effect mobility of greater than or equal to 2 cm²V⁻

1s<sup>−

1</sup> and a current on/off ratio of greater than or equal to 10⁵.

14. The method according to claim 11, wherein the mediating polymer comprises polyacrylonitrile, polystyrene, poly(methyl methacrylate), poly(methyl methacrylate-alt-styrene), polyvinyl chloride, or mixtures thereof.

15. The method according to claim 11, wherein the organic semiconductor comprises a polymer represented by the following formula:

16. The method according to claim 11, further comprising drying with thermal annealing after the spin casting or printing of the solution on a substrate.