# US 7,078,261 B2 · Increased mobility from organic semiconducting polymers field-effect transistors

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- Number: US 7,078,261 B2
- Document ID: US7078261B2
- Status: Granted
- Kind: B2
- Application number: 10/320,933
- Filed: 2002-12-16
- Published: 2004-06-17
- Granted: 2006-07-18
- Earliest claimed: 2002-12-16
- Assignees: The Regents of the University of California
- Inventors: Alan J. Heeger; Daniel Moses; Guangming Wang; James S. Swensen
- Web page: https://patentgrep.com/patent/US7078261B2

## CPC

- H10K 10/466: {Lateral bottom-gate IGFETs comprising only a single gate}
- H10K 85/113: {Heteroaromatic compounds comprising sulfur or selene, e.g. polythiophene}
- H10K 71/12: using liquid deposition, e.g. spin coating
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES

## Abstract

Organic FETs are produced having high mobilities in the accumulation mode and in the depletion mode. Significantly higher mobility is obtained from FETs in which RR-P3HT film is applied by dip-coating to a thickness of only about 20 Å to 1 μm. It was found that the structural order of the semiconducting polymer at the interface between the semiconducting polymer and the SiO2 gate-insulator is important for achieving high carrier mobility. Heat-treatment under an inert atmosphere also was found to increase the on/off ratio of the FET.

## Claims

### Claim 1

A process for constructing an organic field effect transistor, comprising the steps of:
a) providing a substrate having a gate electrode;
b) providing the substrate with source and drain electrodes; and
c) providing upon the substrate directly from solution, a layer of regioregular, head-to-tail poly 3-hexylthiophene semiconducting polymer, characterized in that said transistor has a high mobility correlating to an improved structural order of the semiconducting polymer layer, said layer having the improved structural order demonstrated by an absorbance of a 0—0 absorption band in an optical spectrum.

### Claim 2 (depends on 1)

The process of claim 1, further comprising the step of: d) heat treating the layered substrate at about 150° C. to 170° C. for about three minutes in an inert atmosphere.

### Claim 3 (depends on 1)

The process of claim 1, wherein the layer is about 20 Å to 1 μm.

### Claim 4 (depends on 1)

The process of claim 1, wherein the mobility is about 0.2 cm2V−1s−1.

### Claim 5 (depends on 1)

The process of claim 1, wherein the layer of semiconducting polymer is provided upon the substrate by dip-coating.

### Claim 6 (depends on 1)

The process of claim 1, wherein the 0-0 absorption band is greater than about 86% of that of a maximum absorbance for regioregular poly 3-hexylthiophene.

### Claim 7

A process for constructing an organic field effect transistor, comprising the steps of:
a) providing a substrate having a gate electrode;
b) providing the substrate with source and drain electrodes; and
c) depositing upon the substrate directly from solution, a layer of semiconducting regioregular head-to-tail poly 3-hexylthiophene, characterized in that said transistor has a high mobility of about 0.2 cm2V−1s−1 correlating to an improved structural order of the regioregular head-to-tail poly 3-hexylthiophene layer, said layer having the improved structural order demonstrated by an absorbance of a 0—0 absorption band in an optical spectrum, wherein the 0-0 absorption band is greater than about 86% of that of a maximum absorbance for regioregular poly 3-hexylthiophene; and
d) heat treating the layered substrate at about 150° C. to 170° C. for about three minutes in an inert atmosphere.

### Claim 8 (depends on 7)

The process of claim 7, wherein the layer is about 20 Å to 1 μm.

### Claim 9 (depends on 1)

A field effect transistor fabricated from the process of claim 1.