Metal Inks
Self-reducing metal inks and systems and methods for producing and using the same are disclosed. In an exemplary embodiment, a method may comprise selecting a metal-organic (MO) precursor, selecting a reducing agent, and dissolving the MO precursor and the reducing agent in an organic solvent to produce a metal ink that remains in a liquid phase at room temperature. Metal inks, including self-reducing and fire-through metal inks, are also disclosed, as are various applications of the metal inks.
1 . A method comprising:
selecting a metal-organic (MO) precursor;
selecting a reducing agent; and
dissolving the MO precursor and the reducing agent in an organic solvent to produce a metal ink that remains in a liquid phase at room temperature.
2 . The method of claim 1 , wherein the MO precursor and the reducing agent are non-reacting at room temperature.
3 . The method of claim 1 , further comprising selecting the organic solvent from organic solvents that have a sufficiently high boiling point so as to remain in a liquid phase at room temperature.
4 . The method of claim 1 , further comprising selecting the organic solvent from organic solvents that provide viscosity and wetting properties for inkjet printing.
5 . The method of claim 1 , wherein selecting the MO precursor is from MO precursors having a metal ion that is reduced to a pure metallic state at a potential positive of a reduction potential of the reducing agent.
6 . The method of claim 5 , wherein the reducing agent includes formate ions.
7 . The method of claim 1 , further including reacting the MO precursor and the reducing agent at an activating temperature.
8 . The method of claim 7 , further including reacting the MO precursor and the reducing agent at temperatures in the range of about 150-250° C.
9 . The method of claim 8 , wherein reacting the MO precursor and the reducing agent produces substantially pure metal deposits on a substrate.
10 . The method of claim 1 , further comprising
elevating the temperature of the metal ink;
reacting the reducing agent with the MO precursor; and
producing a substantially uncontaminated metal deposit on a substrate.
11 . A metal ink produced according to the process of claim 1 .
12 . The metal ink of claim 11 , wherein the metal ink forms metal deposits at elevated temperatures.
13 . The metal ink of claim 12 , wherein the metal deposits consist of copper (Cu), gold (Au), silver (Ag), lead (Pb), palladium (Pd), platinum (Pt), cobalt (Co), iron (Fe), Tin (Sn), and metal alloys.
14 . A self-reducing metal ink produced according to the process of claim 1 .
15 . A fire-through metal ink produced according to the process of claim 1 .
16 . The fire-through metal ink of claim 15 further comprising a soluble metal complex and soluble organo-metallic reagent in a solution containing a particulate metal or metal organic precursor at room temperature.
17 . A method comprising:
providing a metal ink in a liquid phase at room temperature; and
applying the metal ink to a substrate at an elevated temperature, wherein the metal ink reacts in a single step at the elevated temperature to produce substantially pure metal deposits on the substrate.
18 . The method of claim 17 wherein applying the metal ink to the substrate is by at least one of the following processes: spraying, dipping, spinning, direct-write deposition, and inkjet printing.
19 . A method comprising:
providing a fire-through metal ink in a liquid phase at room temperature; and
applying the fire-through metal ink to a coated surface of a solar cell, wherein the fire-through metal ink reacts with the coated surface of the solar cell to produce electrical contacts with a p-n layer beneath the coated surface of the solar cell.
20 . The method of claim 19 wherein applying the metal ink to the substrate is by at least one of the following processes: spraying, dipping, spinning, direct-write deposition, and inkjet printing.