POLYSILAZANE COATING FOR PHOTOVOLTAIC CELLS
A method of fabricating a photovoltaic cell, and a device produced by such a method, are described. The method includes providing a semiconductor substrate and electrically coupling an electrically conductive article to a top surface of the semiconductor substrate. An anti-reflective coating is formed over the semiconductor substrate and the electrically conductive article, in which the anti-reflective coating has a plurality of sub-layers. Each of the sub-layers comprises polysilazane and has a different index of refraction from the other sub-layers. A photovoltaic cell is formed from the semiconductor substrate, the electrically conductive article and the anti-reflective coating.
1 . A method of fabricating a photovoltaic cell, the method comprising:
providing a semiconductor substrate having a top surface;
electrically coupling an electrically conductive article to the top surface of the semiconductor substrate;
forming an anti-reflective coating over the electrically conductive article and the top surface of the semiconductor substrate, wherein the anti-reflective coating comprises a plurality of sub-layers, wherein each of the sub-layers comprises a polysilazane, and wherein the sub-layers have different indices of refraction from each other; and
forming a photovoltaic cell from the semiconductor substrate, the electrically conductive article and the anti-reflective coating.
2 . The method of claim 1 wherein the polysilazane comprises the structure:
wherein R 1 -R 5 , which can be the same or different, represent a hydrogen, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group side chain, and wherein n is an integer from 10 to 1000.
3 . The method of claim 2 wherein the side chain is a methyl, ethyl, vinyl, or allyl side chain.
4 . The method of claim 1 further comprising depositing a first layer on the semiconductor substrate prior to forming the anti-reflective coating, and wherein the electrically conductive article is electrically coupled to the semiconductor substrate through the first layer.
5 . The method of claim 4 wherein the first layer comprises silicon nitride, a transparent conductive oxide or an amorphous silicon.
6 . The method of claim 4 further comprising placing a second layer between the electrically conductive article and the first layer, wherein the second layer comprises silver.
7 . The method of claim 4 further comprising placing a cover element over the anti-reflective coating, wherein the first layer has a first index of refraction and the cover element has a second index of refraction, and wherein the sub-layers of the anti-reflective coating have indices of refraction that provide a graded change from the first index of refraction to the second index of refraction.
8 . The method of claim 7 wherein the cover element comprises glass.
9 . The method of claim 1 wherein the anti-reflective coating covers all exposed areas of the electrically conductive article.
10 . The method of claim 1 wherein the index of refraction of each sub-layer is after curing.
11 . The method of claim 1 further comprising placing a cover element over the anti-reflective coating, wherein the cover element has a bottom surface and a top surface, wherein the bottom surface faces the anti-reflective coating; and
wherein the method further comprises forming an outer anti-reflective coating comprising polysilazane on the top surface of the cover element.
12 . The method of claim 1 wherein the electrically conductive article is an electroformed article.
13 . The method of claim 1 wherein the electrically conductive article comprises copper.
14 . The method of claim 1 further comprising encapsulating the photovoltaic cell with an acid-producing encapsulant.
15 . The method of claim 14 wherein the acid-producing encapsulant comprises ethylene vinyl acetate.
16 . A photovoltaic cell comprising:
a semiconductor substrate having a top surface;
an electrically conductive article being electrically coupled to the top surface of the semiconductor substrate; and
an anti-reflective coating located over the electrically conductive article and the top surface of the semiconductor substrate, wherein the anti-reflective coating comprises a plurality of sub-layers, wherein each of the sub-layers comprises polysilazane, and wherein the sub-layers have different indices of refraction from each other.
17 . The photovoltaic cell of claim 16 wherein the polysilazane comprises the structure:
wherein R 1 -R 5 , which can be the same or different, represent a hydrogen, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group side chain; and wherein n is an integer from 10 to 1000.
18 . The photovoltaic cell of claim 17 wherein the side chain is a methyl, ethyl, vinyl, or allyl side chain.
19 . The photovoltaic cell of claim 16 further comprising a first layer between the semiconductor substrate and the anti-reflective coating, wherein the electrically conductive article is electrically coupled to the semiconductor substrate through the first layer.
20 . The photovoltaic cell of claim 19 wherein the first layer comprises silicon nitride, a transparent conductive oxide or an amorphous silicon.
21 . The photovoltaic cell of claim 19 further comprising a second layer between the electrically conductive article and the first layer, wherein the second layer comprises silver.
22 . The photovoltaic cell of claim 19 further comprising a cover element over the anti-reflective coating, wherein the first layer has a first index of refraction and the cover element has a second index of refraction, and wherein the sub-layers of the anti-reflective coating have indices of refraction that provide a graded change from the first index of refraction to the second index of refraction.
23 . The photovoltaic cell of claim 22 wherein the cover element comprises glass.
24 . The photovoltaic cell of claim 16 wherein the anti-reflective coating covers all exposed areas of the electrically conductive article.
25 . The photovoltaic cell of claim 16 wherein the index of refraction of each sub-layer is after curing.
26 . The photovoltaic cell of claim 16 further comprising:
a cover element over the anti-reflective coating, wherein the cover element has a bottom surface and a top surface, wherein the bottom surface faces the anti-reflective coating; and
an outer anti-reflective coating comprising polysilazane on the top surface of the cover element.
27 . The photovoltaic cell of claim 16 wherein the electrically conductive article is an electroformed article.
28 . The photovoltaic cell of claim 16 wherein the electrically conductive article comprises copper.
29 . The photovoltaic cell of claim 16 further comprising an acid-producing encapsulant encapsulating the photovoltaic cell.
30 . The photovoltaic cell of claim 29 wherein the acid-producing encapsulant comprises ethylene vinyl acetate.