# US 9,520,513 B2 · Photovoltaic devices including heterojunctions

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- Number: US 9,520,513 B2
- Document ID: US9520513B2
- Status: Granted
- Kind: B2
- Application number: 13/969,007
- Filed: 2013-08-16
- Published: 2014-01-09
- Granted: 2016-12-13
- Earliest claimed: 2007-09-25
- Assignees: First Solar, Inc.
- Applicants: First Solar, Inc
- Inventors: David Eaglesham
- Web page: https://patentgrep.com/patent/US9520513B2

## CPC

- H10F 10/16: Photovoltaic cells having only PN heterojunction potential barriers
- H10F 71/125: {The active layers comprising only Group II-VI materials, e.g. CdS, ZnS or CdTe}
- H10F 71/127: {The active layers comprising only Group III-V materials, e.g. GaAs or InP}
- Y02E 10/543: Solar cells from Group II-VI materials
- Y02E 10/544: Solar cells from Group III-V materials
- Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A photovoltaic cell including a first semiconductor layer that includes a III-V compound semiconductor, the first semiconductor layer positioned over a transparent conductive layer, and a second semiconductor layer that includes a II-VI compound semiconductor, the second semiconductor layer positioned between the first semiconductor layer and a back metal contact. The photovoltaic cell further includes an interfacial layer between the first and second semiconductor layers that enhances a rectifying junction formed between the III-V and II-VI compound semiconductor materials.

## Claims

### Claim 1

A photovoltaic device comprising:
a transparent conductive layer on a substrate;
a first semiconductor layer including an n-type III-V compound semiconductor, the first semiconductor layer positioned over the transparent conductive layer;
a second semiconductor layer including a p-type II-VI compound semiconductor, the second semiconductor layer positioned between the first semiconductor layer and a back metal contact, wherein a rectifying heterojunction is formed between the III-V and II-VI compound semiconductors; and
an interfacial layer between the first semiconductor layer and the second semiconductor layer that enhances the rectifying heterojunction between the III-V and II-VI compound semiconductors,
wherein the interfacial layer comprises an oxide or doped composition thereof, wherein the oxide or doped composition thereof is selected from the group consisting of mercury oxide, nickel oxide, palladium oxide, silver oxide, strontium oxide, titanium oxide, and vanadium oxide.

### Claim 2 (depends on 1)

The device of claim 1, wherein the II-VI compound is a cadmium telluride.

### Claim 3 (depends on 1)

The device of claim 1, wherein the III-V compound is a gallium nitride.

### Claim 4 (depends on 3)

The device of claim 3, wherein the gallium nitride is a gallium aluminum nitride.

### Claim 5 (depends on 1)

The device of claim 1, wherein the interfacial layer includes an oxide.

### Claim 6 (depends on 1)

The device of claim 1, wherein the first semiconductor layer is a window layer of the device and the second semiconductor layer is an absorber layer of the device.

### Claim 7 (depends on 1)

The photovoltaic device of claim 1, wherein the n-type III-V compound semiconductor comprises a compound with a chemical formula XY, wherein X is selected from a group including boron, aluminum, gallium, indium, and thallium, and Y is selected from a group including nitrogen, phosphorus, arsenic, antimony, and bismuth.

### Claim 8 (depends on 1)

The photovoltaic device of claim 1, wherein the p-type II-VI compound semiconductor comprises a compound with a chemical formula X′Y′, wherein X′ is selected from a group including zinc, cadmium, and mercury, and Y′ is selected from a group including oxygen, sulfur, selenium, tellurium, and polonium.

### Claim 9 (depends on 1)

The device of claim 1, wherein the interfacial layer further comprises amphiphilic molecules for altering electrical performance through creation of a dipole.

### Claim 10

A system for generating electrical energy comprising:
a multilayered photovoltaic cell including
a transparent conductive layer on a substrate,
a first semiconductor layer including an n-type III-V compound semiconductor, the first semiconductor layer positioned over the transparent conductive layer,
a second semiconductor layer including a p-type II-VI compound semiconductor, the second semiconductor layer positioned between the first semiconductor layer and a back metal electrode, wherein a rectifying heterojunction is formed between the III-V and II-VI compound semiconductors, and
an interfacial layer that enhances the rectifying heterojunction between the III-V and II-VI compound semiconductors;
a first electrical connection connected to the transparent conductive layer; and
a second electrical connection connected to the back metal electrode, the back metal electrode being adjacent to the second semiconductor layer,
wherein the interfacial layer comprises an oxide or doped composition thereof, wherein the oxide or doped composition thereof is selected from the group consisting of mercury oxide, copper oxide, iron oxide, nickel oxide, palladium oxide, silver oxide, strontium oxide, titanium oxide, and vanadium oxide.

### Claim 11 (depends on 10)

The system of claim 10, wherein the II-VI compound is a cadmium telluride and the III-V compound is a gallium nitride.

### Claim 12 (depends on 10)

The system of claim 10, wherein the first semiconductor layer is a window layer of the device and the second semiconductor layer is an absorber layer of the device.

### Claim 13 (depends on 10)

The system of claim 10, wherein the n-type III-V compound semiconductor comprises a compound with a chemical formula XY, wherein X is selected from a group including boron, aluminum, gallium, indium, and thallium, and Y is selected from a group including nitrogen, phosphorus, arsenic, antimony, and bismuth.

### Claim 14 (depends on 10)

The system of claim 10, wherein the p-type II-VI compound semiconductor comprises a compound with a chemical formula X′Y′, wherein X′ is selected from a group including zinc, cadmium, and mercury, and Y′ is selected from a group including oxygen, sulfur, selenium, tellurium, and polonium.

### Claim 15 (depends on 10)

The system of claim 10, wherein the interfacial layer further comprises amphiphilic molecules for altering electrical performance through creation of a dipole.