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.

1 . A method of preparing a coating comprising Si on a substrate, the method comprising:
 (i) preparing a composition comprising a compound comprising Si and O, a polymeric glycol, a strong acid, at least a first alcohol, at least a second alcohol and water;   (ii) applying the composition onto a surface of a substrate to form a film;   (iii) evaporating the alcohols from the film; and   (iv) heating the film;   
       wherein at least one alcohol has a higher boiling point than at least the other alcohol and is miscible with at least the other alcohol and water. 
     
     
         2 . The method according to  claim 1 , wherein preparing the composition comprises mixing together to form a liquid composition:
 0.1 to 15 volume % of a compound comprising Si and O;   0.1 to 80 g of a polymeric glycol per liter of composition;   0.1 to 20 g of strong acid per liter of composition;   0.1 to 80 volume % of at least one alcohol having a higher boiling point than at least one other alcohol contained in the composition; and   a balance of the other alcohol contained in the composition.   
     
     
         3 . The method according to  claim 1 , wherein preparing the composition comprises mixing together to form a liquid composition:
 0.1 to 10 volume % of a compound comprising Si and O;   0.1 to 15 g of a polymeric glycol per liter of composition;   0.1 to 15 g of strong acid per liter of composition;   0.1 to 20 volume % of at least one alcohol having a higher boiling point than at least one other alcohol contained in the composition; and   a balance of the other alcohol contained in the composition.   
     
     
         4 . The method according to  claim 1 , wherein preparing the composition comprises mixing together to form a liquid composition:
 0.1 to 5 volume % of a compound comprising Si and O;   0.1 to 10 g of a polymeric glycol per liter of composition;   0.1 to 10 g of strong acid per liter of composition;   0.1 to 20 volume % of at least one alcohol having a higher boiling point than at least one other alcohol contained in the composition; and   a balance of the other alcohol contained in the composition.   
     
     
         5 . The method according to  claim 2 , wherein during the mixing, a ratio of a volume % of the polymeric glycol per liter of composition to the volume % of the compound comprising Si and O is at least 1. 
     
     
         6 . The method according to  claim 1 , wherein the compound comprising Si and O is selected from the group consisting of silanes, silicates, siloxanes and silanols. 
     
     
         7 . The method according to  claim 1 , wherein the compound comprising Si and O is tetraethyl orthosilicate. 
     
     
         8 . The method according to  claim 1 , wherein the polymeric glycol is selected from the group consisting of polyalkyl glycols and polyalkylene glycols. 
     
     
         9 . The method according to  claim 1 , wherein the polymeric glycol is polyethylene glycol. 
     
     
         10 . The method according to  claim 1 , wherein the strong acid is selected from the group consisting of nitric acid, hydrochloric acid, sulfuric acid and hydrobromic acid. 
     
     
         11 . The method according to  claim 1 , wherein the strong acid is hydrochloric acid. 
     
     
         12 . The method according to  claim 1 , wherein the strong acid is nitric acid. 
     
     
         13 . The method according to  claim 1 , wherein at least the first alcohol is ethanol. 
     
     
         14 . The method according to  claim 1 , wherein the first alcohol is ethanol, and the second alcohol has a boiling point that is higher than the boiling point of ethanol. 
     
     
         15 . The method according to  claim 1 , wherein the first alcohol is ethanol, and the second alcohol is selected from the group consisting of propanol, butanol and pentanol. 
     
     
         16 . The method according to  claim 1 , wherein the first alcohol is ethanol, and the second alcohol is n-butanol. 
     
     
         17 . The method according to  claim 1 , wherein applying the composition comprises dipping, brushing, spinning or spraying the composition onto the surface of the substrate. 
     
     
         18 . The method according to  claim 1 , wherein applying the composition comprises spraying the composition onto the substrate. 
     
     
         19 . The method according to  claim 1 , wherein the substrate is selected from plastic or glass. 
     
     
         20 . The method according to  claim 19 , wherein the substrate is photovoltaic glass having at least one smooth or patterned surface. 
     
     
         21 . The method according to  claim 1 , wherein, during the applying, the substrate is at room temperature and atmospheric pressure. 
     
     
         22 . The method according to  claim 1 , wherein, during the applying, the liquid composition is at room temperature. 
     
     
         23 . The method according to  claim 1 , wherein, during the applying, the substrate is at a temperature of 50° C. or above. 
     
     
         24 . The method according to  claim 1 , wherein, during the applying, the liquid composition is at a temperature of 50° C. or above. 
     
     
         25 . The method according to  claim 1 , wherein the evaporation of the alcohols takes 60 seconds or more. 
     
     
         26 . The method according to  claim 1 , wherein the heating is at a temperature in a range of from 500° C. to 800° C. 
     
     
         27 . The method according to  claim 1 , wherein after heating, the film is between 700 and 1400 Å thick. 
     
     
         28 . The method according to  claim 1 , wherein after heating, the film is porous. 
     
     
         29 . A method of increasing the transmission of light through a substrate, the method comprising:
 (i) preparing a composition comprising a compound comprising Si and O, a polymeric glycol, a strong acid, at least two alcohols and water;   (ii) applying the composition onto a surface of a substrate to form a film on the substrate;   (iii) evaporating the alcohols from the film; and   (iv) heating the film;   
       wherein at least one alcohol has a higher boiling point than the other and is miscible with both the other alcohol and water; and wherein, after heating, the transmission of light through the substrate comprising said film is increased by at least 0.5% when compared to the transmission of light through the substrate not comprising said film. 
     
     
         30 . A method of making a coating comprising Si on a substrate, the method comprising:
 (i) preparing a composition comprising tetraethyl orthosilicate, polyethylene glycol, HCl, ethanol, at least one alcohol having a higher boiling point than ethanol, and water;   (ii) applying the composition onto a surface of a substrate to form a film;   (iii) evaporating the at least one alcohol and the ethanol from the film; and   (iv) heating the film;   wherein the at least one alcohol having a higher boiling point than ethanol is miscible with both ethanol and water.   
     
     
         31 . The method according to  claim 30 , wherein preparing the composition comprises mixing together to form a liquid composition:
 0.1 to 10 volume % of tetraethyl orthosilicate,   0.1 to 20 volume % of a solution of 30 g polyethylene glycol in 100 ml water,   0.1 to 2 volume % of a solution of 37 weight % HCl in water,   0.1 to 80 volume % of at least one alcohol having a higher boiling point than ethanol, and   a balance of ethanol.   
     
     
         32 . The method according to  claim 31 , wherein during the mixing, a ratio of the volume % of the solution of 30 g polyethylene glycol in 100 ml water to the volume % of tetraethyl orthosilicate is at least 0.5. 
     
     
         33 . The method according to  claim 30 , wherein the at least one alcohol comprises a monohydric alcohol. 
     
     
         34 . The method according to  claim 30 , wherein the at least one alcohol comprises n-butanol. 
     
     
         35 . The method according to  claim 30 , wherein the composition comprises 1 to 3 volume % of tetraethyl orthosilicate. 
     
     
         36 . The method according to  claim 30 , wherein the composition comprises 4.6 to 6.9 g of polyethylene glycol per liter of the composition. 
     
     
         37 . The method according to  claim 30 , wherein the composition comprises 1.78 to 2.66 g of HCl per liter of the composition. 
     
     
         38 . The method according to  claim 30 , wherein the composition comprises 1 to 20 volume % of the at least one alcohol having a higher boiling point than ethanol. 
     
     
         39 . The method according to  claim 30 , wherein the substrate is selected from the group consisting of plastic and glass. 
     
     
         40 . The method according to  claim 30 , wherein the substrate is photovoltaic glass having at least one smooth or patterned surface. 
     
     
         41 . The method according to  claim 30 , wherein, during the applying, the substrate is at room temperature and atmospheric pressure. 
     
     
         42 . The method according to  claim 30 , wherein, during the applying, the liquid composition is at room temperature. 
     
     
         43 . The method according to  claim 30 , wherein, during the applying, the substrate is at a temperature of 50° C. or above. 
     
     
         44 . The method according to  claim 30 , wherein, during the applying, the liquid composition is at a temperature of 50° C. or above. 
     
     
         45 . The method according to  claim 30 , wherein the applying comprises spraying the composition onto the surface of the substrate. 
     
     
         46 . The method according to  claim 30 , wherein the evaporation of the at least one alcohol and the ethanol takes 60 seconds or more. 
     
     
         47 . The method according to  claim 30 , wherein the heating is at a temperature in a range of from 500° C. to 800° C. 
     
     
         48 . The method according to  claim 30 , wherein after heating, the film is between 700 Å and 2000 μm thick. 
     
     
         49 . The method according to  claim 30 , wherein after heating, the film is porous. 
     
     
         50 . A method of making an anti-reflective coating, the method comprising preparing a liquid composition comprising
 0.1 to 5 volume % of tetraethyl orthosilicate,   0.231 to 20 g of polyethylene glycol per liter of the liquid composition,   0.444 to 8.88 g of HCl per liter of the liquid composition,   0.1 to 20 volume % of at least one alcohol having a higher boiling point than ethanol and miscibility with both ethanol and water, and a balance of ethanol;   applying the liquid composition onto a surface of a substrate to form a liquid film;   evaporating the at least one alcohol and the ethanol from the liquid film to form a solid film; and   heating the solid film to form a silica film.   
     
     
         51 . The method according to  claim 50 , wherein the liquid composition is prepared by mixing together
 0.1 to 5 volume % of tetraethyl orthosilicate,   0.1 to 5 volume % of a solution of 30 g polyethylene glycol in 100 ml water,   0.1 to 2 volume % of a solution of 37 weight % HCl in water,   0.1 to 20 volume % of at least one alcohol having a higher boiling point than ethanol and miscibility with both ethanol and water, and   a balance of ethanol.   
     
     
         52 . The method according to  claim 51 , wherein during the mixing a ratio of the volume % of the solution of 30 g polyethylene glycol in 100 ml water to the volume % of tetraethyl orthosilicate is at least 0.5. 
     
     
         53 . The method according to  claim 50 , wherein the at least one alcohol comprises a monohydric alcohol. 
     
     
         54 . The method according to  claim 50 , wherein the at least one alcohol comprises n-butanol. 
     
     
         55 . The method according to  claim 50 , wherein the liquid composition comprises 1 to 3 volume % of tetraethyl orthosilicate. 
     
     
         56 . The method according to  claim 50 , wherein the liquid composition comprises 4.6 to 6.9 g of polyethylene glycol per liter of the liquid composition. 
     
     
         57 . The method according to  claim 50 , wherein the liquid composition comprises 1.78 to 2.66 g of HCl per liter of the liquid composition. 
     
     
         58 . The method according to  claim 50 , wherein the liquid composition comprises 1 to 20 volume % of the at least one alcohol having a higher boiling point than ethanol and miscibility with both ethanol and water. 
     
     
         59 . The method according to  claim 50 , wherein the substrate is selected from the group consisting of plastic and glass. 
     
     
         60 . The method according to  claim 50 , wherein the substrate is photovoltaic glass having at least one smooth or patterned surface. 
     
     
         61 . The method according to  claim 50 , wherein during the applying the substrate is at room temperature and atmospheric pressure. 
     
     
         62 . The method according to  claim 50 , wherein during the applying the liquid composition is at room temperature. 
     
     
         63 . The method according to  claim 50 , wherein during the applying the substrate is at a temperature of 50° C. or above. 
     
     
         64 . The method according to  claim 50 , wherein during the applying the liquid composition is at a temperature of 50° C. or above. 
     
     
         65 . The method according to  claim 50 , wherein the applying comprises spraying the liquid composition onto the surface of the substrate. 
     
     
         66 . The method according to  claim 50 , wherein the evaporation of the at least one alcohol and the ethanol from the liquid film to form the solid film takes 60 seconds or more. 
     
     
         67 . The method according to  claim 50 , wherein the heating is at a temperature in a range of from 500° C. to 800° C. 
     
     
         68 . The method according to  claim 50 , wherein the silica film is between 700 Å and 2000 μm thick. 
     
     
         69 . The method according to  claim 50 , wherein the silica film is porous. 
     
     
         70 . A coating on a substrate made by the method of  claim 1 . 
     
     
         71 . A coating on a substrate made by the method of  claim 29 . 
     
     
         72 . A coating on a substrate made by the method of  claim 30 . 
     
     
         73 . A coating on a substrate made by the method of  claim 50 .