# US 7,611,573 B2 · ZnS/Zn(O,OH)S-based buffer layer deposition for solar cells

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- Number: US 7,611,573 B2
- Document ID: US7611573B2
- Status: Granted
- Kind: B2
- Application number: 10/592,963
- Filed: 2004-04-02
- Published: 2009-07-30
- Granted: 2009-11-03
- Earliest claimed: 2004-04-02
- Assignees: Alliance for Sustainable Energy, LLC
- Inventors: Raghu N. Bhattacharya
- Web page: https://patentgrep.com/patent/US7611573B2

## CPC

- H10F 10/167: comprising Group I-III-VI materials, e.g. CdS/CuInSe2 [CIS] heterojunction photovoltaic cells
- H10F 77/123: comprising only Group II-VI materials, e.g. CdS, ZnS or HgCdTe
- Y02E 10/541: CuInSe2 material PV cells
- 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

## Abstract

The invention provides CBD ZnS/Zn(O,OH)S and spray deposited ZnS/Zn(O,OH)S buffer layers prepared from a solution of zinc salt, thiourea and ammonium hydroxide dissolved in a non-aqueous/aqueous solvent mixture or in 100% non-aqueous solvent. Non-aqueous solvents useful in the invention include methanol, isopropanol and triethyl-amine. One-step deposition procedures are described for CIS, CIGS and other solar cell devices.

## Claims

### Claim 1

A composition for deposition of a ZnS/Zn(O,OH)S film on a substrate comprising:
a zinc salt;
a source of sulfur;
an amine; and
a solvent comprising at least a portion of a non-aqueous material;
wherein the composition is deposited by a deposition process onto the substrate.

### Claim 2 (depends on 1)

The composition of claim 1 wherein the solvent is at least partially composed of an alcohol.

### Claim 3 (depends on 2)

The composition of claim 2 wherein the alcohol is selected from the group consisting of methanol, isopropanol, and mixtures thereof.

### Claim 4 (depends on 3)

The composition of claim 3 wherein the solvent contains at least 1% methanol.

### Claim 5 (depends on 4)

The composition of claim 4 wherein the non-aqueous/aqueous solvent contains at least 31% methanol.

### Claim 6 (depends on 4)

The composition of claim 4 wherein the solvent contains 100% methanol.

### Claim 7 (depends on 1)

The composition of claim 1 wherein the composition is deposited by chemical bath deposition.

### Claim 8 (depends on 1)

The composition of claim 1 wherein the composition is deposited by spray deposition.

### Claim 9 (depends on 1)

The composition of claim 1 wherein the amine is ammonium hydroxide.

### Claim 10 (depends on 1)

The composition of claim 1 wherein the solvent is at least partially composed of triethyl amine.

### Claim 11

A method for depositing a ZnS/Zn(O,OH)S film on a substrate comprising:
combining a zinc salt, an amine, and a sulfur source in a solvent comprising at least a potion of an organic material wherein the resultant solution is contacted to the substrate to fabricate a ZnS/Zn(O,OH)S film on the substrate.

### Claim 12 (depends on 11)

The method of claim 11 wherein the contacting step is accomplished by spraying.

### Claim 13 (depends on 11)

The method of claim 11 wherein the contacting step is accomplished by dipping.

### Claim 14 (depends on 11)

The method of claim 11 further comprising cleaning the deposited ZnS/Zn(O,OH)S film with ultrasound.

### Claim 15 (depends on 11)

The method of claim 11 wherein the ultrasound is performed on the ZnS/Zn(O,OH)S film for between ten and sixty seconds.

### Claim 16 (depends on 11)

The method of claim 11 wherein the ultrasound is performed during the deposition of ZnS/Zn(O,OH)S film.

### Claim 17 (depends on 11)

The method of claim 11 wherein the contact is performed once.

### Claim 18 (depends on 11)

The method of claim 11 wherein annealing is performed of the deposited ZnS/Zn(O,OH)S layer.

### Claim 19 (depends on 11)

The method of claim 11 wherein annealing at 200° C. for 10 minutes is performed on the deposited ZnS/Zn(O,OH)S layer.

### Claim 20 (depends on 11)

The method of claim 11 wherein as deposited ZnS/Zn(O,OH)S layer was used for final junction formation.