Glass compositions used in conductors for photovoltaic cells

Abstract

The invention relates to zinc-containing glass compositions useful in conductive pastes for silicon semiconductor devices and photovoltaic cells.

1 . A composition comprising:
 (a) electrically conductive material;   (b) glass frit, wherein the glass frit comprises SiO 2 , 27-45 wt % ZnO, and 0.5-3 wt % P 2 O 5 ; and   (c) organic medium.   
     
     
         2 . The composition of  claim 1 , wherein the glass frit comprises 35-42 wt % ZnO, and 1-2 wt % P 2 O 5 . 
     
     
         3 . The composition of  claim 1 , wherein the glass frit comprises 8-25 wt % SiO 2 . 
     
     
         4 . The composition of  claim 1 , wherein the glass frit further comprises Al 2 O 3 , PbO, ZrO 2 , and PbF 2 . 
     
     
         5 . The composition of  claim 3 , wherein the glass frit comprises 8-25 wt % SiO 2 , 35-42 wt % ZnO, 1-2 wt % P 2 O 5 , 0.1-4 wt % Al 2 O 3 , 8-40 wt % PbO, 0.5-4 wt % ZrO 2 , and 8-35 wt % PbF 2 . 
     
     
         6 . The composition of  claim 1 , wherein the electrically conductive material comprises one or more of the following: (1) Al, Cu, Au, Ag, Pd and Pt; (2) alloy of Al, Cu, Au, Ag, Pd and Pt; and (3) mixtures thereof. 
     
     
         7 . The composition of  claim 1 , wherein the electrically conductive material comprises Ag. 
     
     
         8 . The composition of  claim 1 , wherein the electrically conductive material is 70-90 wt % of the composition. 
     
     
         9 . The composition of  claim 1 , wherein the glass frit is 3-7 wt % of the composition. 
     
     
         10 . The composition of  claim 1  further comprising one or more additives selected from the group consisting of: (a) a metal wherein said metal is selected from Zn, Pb, Bi, Gd, Ce, Zr, Ti, Mn, Sn, Ru, Co, Fe, Cu, and Cr; (b) a metal oxide of one or more of the metals selected from Zn, Pb, Bi, Gd, Ce, Zr, Ti, Mn, Sn, Ru, Co, Fe, Cu and Cr; (c) any compounds that can generate the metal oxides of (b) upon firing; and (d) mixtures thereof. 
     
     
         11 . A method of making a semiconductor device including the steps of:
 (a) providing a semiconductor substrate, one or more insulating films, and the composition of  claim 1 ;   (b) applying the insulating film to the semiconductor substrate;   (c) applying the composition to the insulating film on the semiconductor substrate, and   (d) firing the semiconductor, insulating film and composition.   
     
     
         12 . The method of  claim 10  wherein the insulating film includes one or more components selected from the group consisting of: titanium oxide, silicon nitride, SiNx:H, silicon oxide, and silicon oxide/titanium oxide. 
     
     
         13 . A semiconductor device made by the method of  claim 10 . 
     
     
         14 . A semiconductor device wherein, prior to firing, the front-side electrode comprises the composition of  claim 1 . 
     
     
         15 . The semiconductor device of  claim 12 , wherein the semiconductor device is a solar cell. 
     
     
         16 . The semiconductor device of  claim 13 , wherein the semiconductor device is a solar cell.