# US 8,541,062 B2 · Multi-layer anti-reflective coatings and processes therefor

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- Number: US 8,541,062 B2
- Document ID: US8541062B2
- Status: Granted
- Kind: B2
- Application number: 12/567,880
- Filed: 2009-09-28
- Published: 2011-03-31
- Granted: 2013-09-24
- Earliest claimed: 2009-09-28
- Assignees: Guardian Industries Corp.
- Applicants: Desaraju V. Varaprasad
- Inventors: Desaraju V. Varaprasad
- Web page: https://patentgrep.com/patent/US8541062B2

## CPC

- H10F 77/315: {the coatings being antireflective or having enhancing optical properties}
- G02B 1/115: Multilayers
- Y02E 10/50: Photovoltaic [PV] energy
- Y10T 428/31855: Of addition polymer from unsaturated monomers
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Methods for making multi-layered anti-reflective coatings are disclosed. Un-solgel precursor compositions may be prepared having inorganic oxide precursors and UV curable acrylic monomer mixtures, deposited on a substrate, and subsequently the coated substrate may be cured by exposure to electromagnetic radiation, such as UV radiation. The coating layers may be heated using a temperature sufficient to burn off organic content and form a multi-layer anti-reflective coating. Substrates comprising such coatings and photovoltaic devices comprising such substrates and coatings are also disclosed.

## Claims

### Claim 1

A method of making a multi-layer anti-reflective coating, comprising:
preparing at least two un-solgel precursor compositions, wherein each of said at least two un-solgel precursor compositions comprises at least one inorganic oxide precursor and at least one UV curable monomer;
depositing a first coating layer of one of said un-solgel precursor compositions on a substrate;
curing said first coating layer by exposing said first coating layer to electromagnetic radiation;
depositing at least one additional coating layer of one of said un-solgel precursor compositions on said first cured coating layer;
curing said at least one additional coating layer by exposing said at least one additional coating layer to electromagnetic radiation; and
heating said cured coating layers to remove substantially all organic content and form a multi-layer anti-reflective coating.

### Claim 2 (depends on 1)

The method of claim 1, wherein at least two of said cured coating layers have different refractive indices after said heating step.

### Claim 3 (depends on 1)

The method of claim 1, wherein said inorganic oxide precursor is chosen from at least one titanium alkoxide, silicon alkoxide, and mixtures thereof.

### Claim 4 (depends on 3)

The method of claim 3, wherein said titanium alkoxide comprises titanium tetra n-butoxide.

### Claim 5 (depends on 3)

The method of claim 3, wherein said silicon alkoxide comprises gamma-methacryloxypropyl trimethoxy silane.

### Claim 6 (depends on 1)

The method of claim 1, wherein said at least one UV curable monomer is a UV curable acrylic monomer mixture.

### Claim 7 (depends on 1)

The method of claim 1, wherein said substrate comprises a glass substrate.

### Claim 8 (depends on 1)

The method of claim 1, wherein said exposure to electromagnetic radiation comprises exposure to ultraviolet (UV) radiation.

### Claim 9 (depends on 8)

The method of claim 8, wherein said exposure to ultraviolet (UV) radiation comprises exposing said coating layers to UV radiation for a period of time ranging from about 5 to 120 seconds.

### Claim 10 (depends on 1)

The method of claim 1, wherein said coated layers are heated at a temperature of from about 550 to 700° C. for a duration of from about 1 to 10 minutes.

### Claim 11 (depends on 1)

The method of claim 1, wherein said at least one inorganic oxide precursor is present in each of said un-solgel precursor compositions in an amount ranging from 0.1 to 20 wt % relative to the total weight of each of said un-solgel precursor composition.

### Claim 12 (depends on 1)

The method of claim 1, wherein said at least one UV curable monomer mixture is present in each of said un-solgel precursor compositions in an amount ranging from 10 to 99 wt % relative to the total weight of each of said un-solgel precursor composition.