# US 2022/0045280 A1 · Ofets having multilayer organic semiconductor with high on/off ratio

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2022/0045280 A1
- Document ID: US20220045280A1
- Status: Published application
- Kind: A1
- Application number: 17/098,493
- Filed: 2020-11-16
- Published: 2022-02-10
- Earliest claimed: 2020-08-06
- Assignees: Facebook Technologies, LLC
- Applicants: Facebook Technologies, LLC
- Inventors: Tingling Rao; Lafe Purvis; Tanya Malhotra; Andrew John Ouderkirk
- Web page: https://patentgrep.com/patent/US20220045280A1

## CPC

- H10K 85/6572: {comprising only nitrogen in the heteroaromatic polycondensed ring system, e.g. phenanthroline or carbazole}
- H10K 10/484: {characterised by the channel regions}
- H10K 10/486: {the channel region comprising two or more active layers, e.g. forming pn heterojunctions}
- H10K 71/191: {characterised by provisions for the orientation or alignment of the layer to be deposited}
- H10K 85/10: Organic polymers or oligomers
- H10K 85/40: Organosilicon compounds, e.g. TIPS pentacene
- H10K 85/6574: {comprising only oxygen in the heteroaromatic polycondensed ring system, e.g. cumarine dyes}
- H10K 85/6576: {comprising only sulfur in the heteroaromatic polycondensed ring system, e.g. benzothiophene}
- Y02E 10/549: Organic PV cells
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

An organic field effect transistor includes a channel structure having a photoalignment layer and an organic semiconductor layer disposed directly over the photoalignment layer, where a charge carrier mobility varies along a thickness direction of the channel structure. The channel structure may define an active area between a source and a drain of the transistor and may include alternating layers of at least two photoalignment layers and at least two organic semiconductor layers. Each photoalignment layer is configured to influence an orientation of molecules within an overlying organic semiconductor layer and hence impact the mobility of charge carriers within the device active area while also advantageously decreasing the OFF current of the device.

## Claims

### Claim 1

An organic field effect transistor comprising:
a channel structure comprising a photoalignment layer and an organic semiconductor layer disposed directly over the photoalignment layer, wherein a charge carrier mobility varies along a thickness direction of the channel structure.

### Claim 2 (depends on 1)

The organic field effect transistor of claim 1, wherein the organic semiconductor layer is characterized by an intra layer gradient in charge carrier mobility.

### Claim 3 (depends on 1)

The organic field effect transistor of claim 1, wherein the photoalignment layer comprises a material selected from the group consisting of azo-compounds, polyimides, polysilanes, polystyrenes, polyesters, cinnamates, coumarins, chalconyls, tetrahydrophthalimides, and maleimides.

### Claim 4 (depends on 1)

The organic field effect transistor of claim 1, wherein the photoalignment layer is configured to influence an orientation of molecules within the organic semiconductor layer.

### Claim 5 (depends on 1)

The organic field effect transistor of claim 1, wherein the organic semiconductor layer comprises a polycrystalline layer or a single crystal layer.

### Claim 6 (depends on 1)

The organic field effect transistor of claim 1, wherein the organic semiconductor layer comprises a polycyclic aromatic hydrocarbon.

### Claim 7 (depends on 1)

The organic field effect transistor of claim 1, wherein the organic semiconductor layer comprises a molecule selected from the group consisting of naphthalene, anthracene, tetracene, pentacene, pyrene, polycene, fluoranthene, benzophenone, benzochromene, benzil, benzimidazole, benzene, hexachlorobenzene, nitropyridine-N-oxide, benzene-1,4-dicarboxylic acid, diphenylacetylene, N-(4-nitrophenyl)-(s)-prolinal, 4,5-dicyanoimidazole, benzodithiophene, cyanopyridine, thienothiophene, stilbene, and azobenzene.

### Claim 8 (depends on 1)

The organic field effect transistor of claim 1, further comprising a source located adjacent to a first region of the channel structure and a drain located adjacent to a second region of the channel structure, wherein the channel structure defines an active area located between the source and the drain.

### Claim 9 (depends on 1)

The organic field effect transistor of claim 1, wherein the channel structure comprises alternating layers of at least two photoalignment layers and at least two organic semiconductor layers.

### Claim 10 (depends on 9)

The organic field effect transistor of claim 9, wherein the organic semiconductor layers are characterized by an interlayer gradient in charge carrier mobility.

### Claim 11 (depends on 9)

The organic field effect transistor of claim 9, wherein a charge carrier mobility within the organic semiconductor layers progressively increases from a bottom of the channel structure to a top of the channel structure.

### Claim 12

A method comprising:
forming a first photoalignment layer;
illuminating the first photoalignment layer with polarized light to form a first oriented photoalignment layer;
forming a first organic semiconductor layer directly over the first oriented photoalignment layer;
forming a second photoalignment layer over the first organic semiconductor layer;
illuminating the second photoalignment layer with polarized light to form a second oriented photoalignment layer; and
forming a second organic semiconductor layer directly over the second oriented photoalignment layer.

### Claim 13 (depends on 12)

The method of claim 12, wherein the photoalignment layers each comprise a material independently selected from the group consisting of azo-compounds, polyimides, polysilanes, polystyrenes, polyesters, cinnamates, coumarins, chalconyls, tetrahydrophthalimides, and maleimides.

### Claim 14 (depends on 12)

The method of claim 12, wherein the organic semiconductor layers each comprise a polycyclic aromatic hydrocarbon.

### Claim 15 (depends on 12)

The method of claim 12, wherein the organic semiconductor layers each comprise a molecule independently selected from the group consisting of naphthalene, anthracene, tetracene, pentacene, pyrene, polycene, fluoranthene, benzophenone, benzochromene, benzil, benzimidazole, benzene, hexachlorobenzene, nitropyridine-N-oxide, benzene-1,4-dicarboxylic acid, diphenylacetylene, N-(4-nitrophenyl)-(s)-prolinal, 4,5-dicyanoimidazole, benzodithiophene, cyanopyridine, thienothiophene, stilbene, and azobenzene.

### Claim 16 (depends on 12)

The method of claim 12, further comprising:
forming a source adjacent to a first region of the first organic semiconductor layer; and
forming a drain adjacent to a second region of the first organic semiconductor layer, wherein a charge carrier mobility of the organic semiconductor layers within an active area between the source and the drain is characterized by an interlayer gradient.

### Claim 17

An organic field effect transistor comprising:
a first photoalignment layer disposed over a substrate;
a first organic semiconductor layer disposed directly over the first photoalignment layer;
a second photoalignment layer disposed over the first organic semiconductor layer; and
a second organic semiconductor layer disposed directly over the second photoalignment layer, wherein a charge carrier mobility within the first organic semiconductor layer is different than a charge carrier mobility within the second organic semiconductor layer.

### Claim 18 (depends on 17)

The organic field effect transistor of claim 17, wherein an orientation of molecules within the first organic semiconductor layer is different than an orientation of molecules within the second organic semiconductor layer.

### Claim 19 (depends on 17)

The organic field effect transistor of claim 17, further comprising:
a source disposed over a first region of the substrate; and
a drain disposed over a second region of the substrate, wherein the first and second organic semiconductor layers define an active area between the source and the drain.

### Claim 20 (depends on 19)

The organic field effect transistor of claim 19, further comprising a gate structure configured to control the conductivity of the first and second organic semiconductor layers within the active area.