Layered Contact Structure For Solar Cells
Formulations and methods of making semiconductor devices and solar cell contacts are disclosed. The invention provides a method of making a semiconductor device or solar cell contact including ink jet printing onto a silicon wafer an ink composition, typically including a high solids loading (20-80 wt %) of glass frit and preferably a conductive metal such as silver. The wafer is then fired such that the glass frit fuses to form a glass, thereby forming a contact layer to silicon.
1 - 3 . (canceled)
4 . A method of making a solar cell contact including a contact layer and a bulk layer, the method comprising:
a. ink-jet printing, onto a silicon wafer, at least a portion of which bears an antireflective coating, a first ink layer having a solids loading of about 20 wt % to about 80 wt %, the ink comprising a silver plating solution and a glass frit, the glass frit having an average particle size of less than about 3 microns and a glass transition temperature of about 200° C. to about 700° C., and
b. firing the wafer, wherein the glass frit fuses to form a glass and forms a contact layer to silicon.
5 . The method of claim 4 , wherein the ink further comprises a phosphorus composition.
6 . The method of claim 5 , wherein the phosphorus composition comprises at least about 10 wt % elemental phosphorus, dry basis.
7 . The method of claim 4 , wherein the ink further comprises an etchant.
8 . The method of claim 4 , wherein the silver plating solution contains a silver compound selected from the group consisting of silver chloride, silver nitrate, silver sulfate, and combinations thereof.
9 . A method of making a solar cell contact including a contact layer and a bulk layer, the method comprising:
a. ink-jet printing, onto a silicon wafer, at least a portion of which bears an antireflective coating, a first conductive ink layer having a solids loading of about 20 wt % to about 80 wt %, the ink comprising glass frit, a silver plating solution, and a phosphorus composition including a phosphorus glass comprising at least 25 mol % P 2 O 5 , the glass frit having an average particle size of less than about 3 microns and a glass transition temperature of about 200° C. to about 700° C., and
b. firing the wafer, wherein the glass frit fuses to form a glass and forms a contact layer to silicon.
10 . The method of claim 9 , wherein the silver plating solution contains a silver compound selected from the group consisting of silver chloride, silver nitrate, silver sulfate, and combinations thereof.
11 . The method of claim 9 , wherein the ink further comprises an etchant.
12 . A method of making a solar cell contact including a contact layer and a bulk layer, the method comprising:
a. ink-jet printing, onto a silicon wafer, at least a portion of which bears an antireflective coating, a first conductive ink layer having a solids loading of about 20 wt % to about 80 wt %, the ink comprising a silver plating solution and phosphorus, wherein the phosphorus is present as a coating on silver, and glass frit having an average particle size of less than about 3 microns and a glass transition temperature of about 200° C. to about 700° C., and
b. firing the wafer, wherein the glass frit fuses to form a glass and forms a contact layer to silicon.
13 . The method of claim 12 , wherein the silver plating solution contains a silver compound selected from the group consisting of silver chloride, silver nitrate, silver sulfate, and combinations thereof.
14 . The method of claim 12 , wherein the ink further comprises an etchant.