Anti-reflective coating for photovoltaic glass panel

Abstract

A method of making an anti-reflective film comprises preparing a liquid composition with specific amounts of tetraethyl orthosilicate, polyethylene glycol, HCl, ethanol and at least one alcohol having a higher boiling point than ethanol and miscibility with both ethanol and water; applying the liquid composition onto a surface of a substrate to form a liquid film; evaporating the ethanol and the at least one alcohol from the liquid film to form a solid film; and heating the solid film to form a silica film.

Description

[0001]This application claims benefit of U.S. Provisional Application No. 60 / 894,001, filed Mar. 9, 2007, which is hereby incorporated by reference in its entirety into the present application.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to an anti-reflective coating. In particular, the present invention relates to an anti-reflective coating that can be used to increase the light transmission of glass used in the manufacture of solar modules, and to a method of making the anti-reflective coating.[0004]2. Discussion of the Background[0005]All United States patents and application Publications referred to herein are incorporated by reference in their entireties. In the case of conflict, the present specification, including definitions, will control.[0006]Solar modules have been developed that convert light into electricity. These modules typically include an outer layer of glass. The difference in the index of refraction between the gla...

AI Technical Summary

Benefits of technology

[0012]Methods in accordance with the present invention utilize a series of chemical moieties which, when applied to at least one surface of a substrate and heated, provide the inventive features described herein. The chemical moieties are preferably compounds that comprise both Si and O, polymeric glycols, strong acids and alcohols. Aqueous solutions of these compounds, when applied to at least one surface of a substrate, allow for the production of a thin film coating that increases the light transmission through a substrate as well as the anti-reflective coating efficiency.

[0013]One aspect of the present invention is found to be driven by the ratio of polymeric glycol to a compound comprising Si and O. Another aspect of the present invention is found to be driven by the evaporation rates of the solvents from the starting composition. When the solvent comprises more than one alcohol, the evaporation rate of the alcohols may be controlled in such a way as to improve the application process.

[0014]It has been found that when the solvent comprises more than one alcohol, wherein one alcohol has a higher boiling point than the other, a reduction in undesirable evaporation of the solvent during application to at least one surface of a substrate is observed. Such undesirable evaporation can increase costs for both materials and cleanup and can also produce uneven liquid films that do not adequately wet the substrate. Having more than one alcohol present in the starting composition enhances the anti-reflective coating efficiency.

Problems solved by technology

The difference in the index of refraction between the glass and air can lead to an undesirable partial reflection of light from the glass that reduces the amount of incident light that can be converted into electricity by the module.

However, silica coatings formed using liquid films containing tetraethyl orthosilicate, polyethylene glycol and ethanol have not shown a consistent improvement in transmission.

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