# US 2018/0323362 A1 · System and method for work function reduction and thermionic energy conversion

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

- Number: US 2018/0323362 A1
- Document ID: US20180323362A1
- Status: Published application
- Kind: A1
- Application number: 15/969,027
- Filed: 2018-05-02
- Published: 2018-11-08
- Earliest claimed: 2017-05-02
- Assignees: Spark Thermionics, Inc.
- Applicants: Spark Thermionics, Inc.
- Inventors: Jared William Schwede; Lucas Heinrich Hess
- Web page: https://patentgrep.com/patent/US20180323362A1

## CPC

- H10N 10/13: characterised by the heat-exchanging means at the junction
- H01J 45/00: Discharge tubes functioning as thermionic generators {(structural combination of fuel element with thermoelectric element G21C3/40; nuclear power plants using thermionic converters G21D7/04; structural combination of a radioactive source with a thermionic converter, e.g. radioisotope batteries G21H1/10; generators in which thermal or kinetic energy is converted into electrical energy by ionisation of a fluid and removal of the charge therefrom H02N3/00)}
- H10N 10/851: comprising inorganic compositions
- H10N 10/853: comprising arsenic, antimony or bismuth (H10N10/852 takes precedence)
- H10N 10/855: comprising compounds containing boron, carbon, oxygen or nitrogen
- H10N 10/8556: {comprising compounds containing germanium or silicon}
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

A thermionic energy converter, preferably including an anode and a cathode. An anode of a thermionic energy converter, preferably including an n-type semiconductor, one or more supplemental layers, and an electrical contact. A method for work function reduction and/or thermionic energy conversion, preferably including inputting thermal energy to a thermionic energy converter, illuminating an anode of the thermionic energy converter, thereby preferably reducing a work function of the anode, and extracting electrical power from the system.

## Claims

### Claim 1

A method for operating a thermionic energy converter (TEC), the method comprising:
reducing a work function of an anode of the TEC, comprising:
illuminating the anode with a plurality of photons; and
at an n-type semiconductor of the anode, absorbing the plurality of photons; and
substantially concurrent with reducing the work function, generating a thermionic current, comprising:
at a cathode of the TEC, thermionically emitting a plurality of electrons;
at the anode, substantially concurrent with absorbing the plurality of photons, capturing the plurality of electrons; and
at the anode, providing the plurality of electrons as electrical power;
wherein the anode comprises:
the n-type semiconductor;
a work function reduction layer; and
an intermediary layer arranged between the n-type semiconductor and the work function reduction layer.

### Claim 2 (depends on 1)

The method of claim 1, wherein the intermediary layer comprises a transition metal oxide.

### Claim 3 (depends on 2)

The method of claim 2, wherein the transition metal oxide is titanium oxide.

### Claim 4 (depends on 1)

The method of claim 1, wherein the n-type semiconductor is selected from the group consisting of: n-type silicon, n-type silicon carbide, n-type germanium, and an n-type III-V semiconductor.

### Claim 5 (depends on 1)

The method of claim 1, wherein illuminating the anode comprises, at the cathode, emitting the plurality of photons.

### Claim 6 (depends on 1)

The method of claim 1, wherein:
reducing the work function of the anode comprises achieving an illuminated work function at the anode; and
a dark work function of the anode when substantially not illuminated is greater than the illuminated work function by at least 50 meV.

### Claim 7 (depends on 1)

The method of claim 1, wherein the work function reduction layer comprises at least one of: an alkali metal and an alkaline earth metal.

### Claim 8

A method for operating a thermionic energy converter (TEC), the method comprising:
reducing a work function of an anode of the TEC, comprising:
illuminating the anode with a plurality of photons; and
at an n-type semiconductor of the anode, absorbing the plurality of photons; and
substantially concurrent with reducing the work function, generating a thermionic current, comprising:
at a cathode of the TEC, thermionically emitting a plurality of electrons;
at the anode, substantially concurrent with absorbing the plurality of photons, capturing the plurality of electrons; and
at the anode, providing the plurality of electrons as electrical power;
wherein the anode comprises:
the n-type semiconductor;
an electrical contact; and
a layer opposing the electrical contact across the n-type semiconductor, wherein the layer does not comprise an alkali metal and does not comprise an alkaline earth metal.

### Claim 9 (depends on 8)

The method of claim 8, wherein the layer comprises an oxide.

### Claim 10 (depends on 8)

The method of claim 8, wherein the anode further comprises a work function reduction layer, wherein the layer is arranged between the n-type semiconductor and the work function reduction layer.

### Claim 11 (depends on 8)

The method of claim 8, wherein:
reducing the work function of the anode comprises achieving an illuminated work function at the anode; and
a dark work function of the anode when substantially not illuminated is greater than the illuminated work function by at least 50 meV.

### Claim 12

A thermionic energy converter (TEC) comprising:
an anode comprising:
an n-type semiconductor;
a work function reduction layer; and
an intermediary layer arranged between the n-type semiconductor and the work function reduction layer;
a cathode, wherein the TEC defines a gap between the anode and the cathode;
an enclosure isolating the gap from an ambient environment proximal the TEC; and
an electrical load electrically coupling the cathode to the anode.

### Claim 13 (depends on 12)

The TEC of claim 12, wherein the intermediary layer comprises a transition metal oxide.

### Claim 14 (depends on 13)

The method of claim 13, wherein the transition metal oxide is titanium oxide.

### Claim 15 (depends on 13)

The method of claim 13, wherein the intermediary layer has a thickness between 2 nm and 50 nm.

### Claim 16 (depends on 12)

The method of claim 12, wherein the n-type semiconductor is selected from the group consisting of: n-type silicon, n-type silicon carbide, n-type germanium, and an n-type III-V semiconductor.

### Claim 17 (depends on 12)

The method of claim 12, wherein the n-type semiconductor comprises silicon.

### Claim 18 (depends on 17)

The method of claim 17, further comprising a silicon oxide layer arranged between the n-type semiconductor and the intermediary layer.

### Claim 19 (depends on 17)

The method of claim 17, further comprising an oxide layer arranged between the n-type semiconductor and the intermediary layer, wherein the oxide layer comprises at least one of: molybdenum and manganese.

### Claim 20 (depends on 12)

The method of claim 12, wherein the n-type semiconductor comprises gallium arsenide.