Conductive Thick Film Paste For Solar Cell Contacts

Abstract

The present invention relates to an inorganic reaction system used in the manufacture of electroconductive pastes. The inorganic reaction system comprises a lead containing matrix forming composition and a tellurium oxide additive. Preferably the lead containing matrix forming composition is between 5-95 wt. % of the inorganic reaction system, and the tellurium oxide additive is between 5-95 wt. % of the inorganic reaction system. The lead containing matrix forming composition may be a glass frit, and may comprise lead oxide. Another aspect of the present invention relates to an electroconductive paste composition that comprises metallic particles, an inorganic reaction system as previously disclosed, and an organic vehicle. Another aspect of the present invention relates to an organic vehicle that comprises one or more of a binder, a surfactant, a solvent, and a thixatropic agent. Another aspect of the present invention relates to a solar cell printed with an electroconductive paste composition as disclosed, as well as an assembled solar cell module. Another aspect of the present invention relates to a method of producing a solar cell.

What is claimed: 
     
         1 . An inorganic reaction system for an electroconductive paste comprising a lead containing matrix forming composition and a tellurium oxide additive, wherein the lead containing composition is between 5-95 wt. % of the inorganic reaction system, and the tellurium oxide additive is between 5-95 wt. % of the inorganic reaction system. 
     
     
         2 . The inorganic reaction system of  claim 1 , wherein the lead containing matrix forming composition is between 10-90 wt. % of the inorganic reaction system, and the tellurium oxide additive is between 10-60 wt. % of the inorganic reaction system. 
     
     
         3 . The inorganic reaction system of  claim 1 , wherein the tellurium oxide additive comprises one or more of tellurium dioxide, tellurium trioxide, and any tellurium compound that would convert to tellurium oxide at temperature 200-1000° C. 
     
     
         4 . The inorganic reaction system of  claim 1 , wherein the tellurium oxide additive is of an average particle size of less than 10 μM. 
     
     
         5 . The inorganic reaction system of  claim 1 , wherein the tellurium oxide additive is of an average particle size of less than 1 μM. 
     
     
         6 . The inorganic reaction system of  claim 1 , wherein the lead containing matrix forming composition is a glass frit. 
     
     
         7 . The inorganic reaction system of  claim 1 , wherein the lead containing matrix forming composition comprises lead oxide. 
     
     
         8 . The inorganic reaction system of  claim 7 , wherein the lead containing matrix forming composition comprises between about 10-90 wt. %; lead oxide. 
     
     
         9 . The inorganic reaction system of  claim 7 , wherein the lead containing matrix forming composition comprises between about 5-45 wt. %; lead oxide. 
     
     
         10 . The inorganic reaction system of  claim 7 , wherein the inorganic reaction system has a lead oxide:Tellurium oxide additive weight percentage ratio of 95:5 to 5:95. 
     
     
         11 . An electroconductive paste composition comprising:
 metallic particles;   an inorganic reaction system as in  claim 1 ; and   an organic vehicle.   
     
     
         12 . The electroconductive paste as in  claim 11 , wherein the metallic particles are at least one of silver, gold, copper, and nickel. 
     
     
         13 . The electroconductive paste as in  claim 11 , wherein the metallic particles are silver. 
     
     
         14 . The electroconductive paste as in  claim 11 , wherein the metallic particles are about 50-95 wt. % of solid content of the paste. 
     
     
         15 - 22 . (canceled) 
     
     
         23 . A solar cell produced by applying an electroconductive paste according to  claim 11  to a silicon wafer and firing the silicon wafer. 
     
     
         24 . (canceled) 
     
     
         25 . (canceled) 
     
     
         26 . The solar cell of  claim 23 , wherein the silicon wafer is of sheet resistance above 70Ω/□. 
     
     
         27 . The solar cell of  claim 23 , wherein the silicon wafer is of sheet resistance above 90Ω/□. 
     
     
         28 . The solar cell of  claim 23 , wherein the silicon wafer is of sheet resistance above 95Ω/□. 
     
     
         29 - 32 . (canceled) 
     
     
         33 . The inorganic reaction system of  claim 5 , wherein the glass frit is at least partially crystalline. 
     
     
         34 . The inorganic reaction system of  claim 8 , wherein the lead containing matrix forming composition comprises between about 25-85 wt. % lead oxide. 
     
     
         35 . The inorganic reaction system of  claim 9 , wherein the lead containing matrix forming composition comprises between about 10-15 wt. % lead oxide. 
     
     
         36 . The inorganic reaction system of  claim 7 , wherein the inorganic reaction system has a lead oxide:Tellurium oxide additive weight percentage ratio of 10:1 to 1:10. 
     
     
         37 . The inorganic reaction system of  claim 7 , wherein the inorganic reaction system has a lead oxide:Tellurium oxide additive weight percentage ratio of 5:1 to 1:5.