Conductive paste composition containing lithium, and articles made therefrom
View Patent ↗A paste composition contains an electrically conductive silver powder, one or more glass frits or fluxes, and a lithium compound dispersed in an organic medium. The paste is useful in forming an electrical contact on the front side of a solar cell device having an insulating layer. The lithium compound aids in establishing a low-resistance electrical contact between the front-side metallization and underlying semiconductor substrate during firing.
1. A paste composition comprising an inorganic solid portion comprising:
(a) about 75% to about 99% by weight based on solids of a source of an electrically conductive metal;
(b) about 0.1% to about 10% by weight based on solids of a glass component consisting essentially of:
5-30 wt. % of SiO 2 ;
50-95 wt. % of a lead oxide;
0-5 wt. % of Al 2 O 3 ;
0-10 wt. % of B 2 O 3 ;
0-5 wt. % of at least one of Li 2 O, Na 2 O, or K 2 O;
0-5 wt. % of at least one of MgO, CaO, SrO, or BaO;
0-5 wt. % of at least one oxide of Zn, Bi, Ta, Zr, Nb, Hf, Te, Cd, Mo, W, P, Gd, Ce, Ti, V, Mn, Sn, Ru, Cr, Co, Fe, Cu, Ag, or a mixture thereof; and
wherein the weight percentages are based on the total glass component; and
(c) about 0.1% to about 5% by weight based on solids of a lithium-containing additive;
wherein the inorganic solids portion is dispersed in an organic medium.
2. The paste composition of claim 1 , wherein the lead oxide is at least one of PbO 2 , Pb 3 O 4 , PbO, or a mixture thereof.
3. The paste composition of claim 1 , wherein the lithium-containing additive is at least one of lithium oxide, lithium hydroxide, a lithium salt of an inorganic or organic acid, or a mixture thereof.
4. The paste composition of claim 1 , wherein the lithium-containing additive is Li 2 CO 3 .
5. The paste composition of claim 1 , wherein the electrically conductive metal is at least one of gold, silver, copper, nickel, palladium, or an alloy or a mixture thereof.
6. The paste composition of claim 5 , wherein the electrically conductive metal is silver.
7. The paste composition of claim 1 , wherein the source of electrically conductive metal is finely divided silver particles.