Multi-layer anti-reflective coatings and processes therefor
View Patent ↗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.
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.
2. The method of claim 1 , wherein at least two of said cured coating layers have different refractive indices after said heating step.
3. The method of claim 1 , wherein said inorganic oxide precursor is chosen from at least one titanium alkoxide, silicon alkoxide, and mixtures thereof.
4. The method of claim 3 , wherein said titanium alkoxide comprises titanium tetra n-butoxide.
5. The method of claim 3 , wherein said silicon alkoxide comprises gamma-methacryloxypropyl trimethoxy silane.
6. The method of claim 1 , wherein said at least one UV curable monomer is a UV curable acrylic monomer mixture.
7. The method of claim 1 , wherein said substrate comprises a glass substrate.
8. The method of claim 1 , wherein said exposure to electromagnetic radiation comprises exposure to ultraviolet (UV) radiation.
9. 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.
10. 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.
11. 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.
12. 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.