Conductive Paste And Conductive Track Or Coating

Abstract

The present invention relates to a conductive paste for forming a conductive track or coating on a substrate, particularly suitable for use in solar cells. The paste comprises a solids portion dispersed in an organic medium, the solids portion comprising electrically conductive material and an inorganic particle mixture wherein the inorganic particle mixture comprises substantially crystalline particles. The present invention also relates to a method of preparing a conductive paste, a method for the manufacture of a surface electrode of a solar cell, an electrode for a solar cell and a solar cell.

What is claimed: 
     
         1 . A conductive paste for forming a conductive track or coating on a substrate, the paste comprising a solids portion dispersed in an organic medium,
 the solids portion comprising electrically conductive material and an inorganic particle mixture;   wherein the inorganic particle mixture comprises substantially crystalline particles of two or more different metal compounds and is substantially lead free;   wherein the glass content of the solids portion is less than 0.05 wt %,   wherein two or more of the different metal compounds contain only one metal element, and   wherein the particles of the inorganic particle mixture have a particle size distribution in which one or more of the following conditions applies:   (a) D 10 ≤0.41 μm;   (b) D 50 ≤1.6 μm;   (c) D 90 ≤4.1 μm;   (d) (D 50 −D 10 )≤1.15 μm;   (e) (D 90 −D 10 )≤2.5 μm;   (f) (D 90 −D 10 )≤3.7 μm; or   (g) (D 50 /D 10 )≤3.85.   
     
     
         2 . A conductive paste according to  claim 1 , wherein three or more, four or more, five or more, or six or more of the different metal compounds contain only one metal element. 
     
     
         3 . A conductive paste according to  claim 1 , wherein the glass content of the solids portion is less than 0.01 wt %. 
     
     
         4 . A conductive paste according to  claim 1 , wherein the solids portion is substantially glass free. 
     
     
         5 . A conductive paste according to  claim 1 , wherein the inorganic particle mixture includes less than 0.1 wt % PbO, preferably less than 0.05 wt %, more preferably less than 0.01 wt %, most preferably less than 0.005 wt % PbO. 
     
     
         6 . A conductive paste according to  claim 1 , wherein the solids portion includes 0.1 to 15 wt % of inorganic particle mixture. 
     
     
         7 . A conductive paste according to  claim 1 , wherein the solids portion includes 80 to 99.9 wt % of electrically conductive material. 
     
     
         8 . A conductive paste according to  claim 1 , wherein the particles of the inorganic particle mixture satisfy D 90 ≤2.2 μm. 
     
     
         9 . A conductive paste according to  claim 1 , wherein the particles of the inorganic particle mixture satisfy D 50 ≤1.05 μm. 
     
     
         10 . A conductive paste according to  claim 1 , wherein the particles of the inorganic particle mixture satisfy D 10 ≤0.4 μm. 
     
     
         11 . A conductive paste according to  claim 1 , wherein the particles of the inorganic particle mixture satisfy D 90 −D 10 ≤1.8 μm. 
     
     
         12 . A conductive paste according to  claim 1 , wherein the particles of the inorganic particle mixture satisfy D 90 −D 50 ≤1.15 μm. 
     
     
         13 . A conductive paste according to  claim 1 , wherein the particles of the inorganic particle mixture satisfy D 50 −D 10 ≤0.6 μm. 
     
     
         14 . A method for the manufacture of a surface electrode of a solar cell, the method comprising applying a conductive paste according to  claim 1  to a semiconductor substrate, and firing the applied conductive paste. 
     
     
         15 . Use of a conductive paste according to  claim 1  in the manufacture of a surface electrode of a solar cell.