Low viscosity precursor compositions and methods for the deposition of conductive electronic features
A precursor composition for the deposition and formation of an electrical feature such as a conductive feature. The precursor composition advantageously has a low viscosity enabling deposition using direct-write tools. The precursor composition also has a low conversion temperature, enabling the deposition and conversion to an electrical feature on low temperature substrates. A particularly preferred precursor composition includes silver metal for the formation of highly conductive silver features.
1 . A process for forming a solar cell conductive feature, comprising:
(a) direct printing a precursor composition onto a substrate in multiple passes, the precursor composition comprising at least one of metallic particles comprising a metal or a metal precursor compound to the metal; and
(b) heating the precursor composition to form the solar cell conductive feature on the substrate, wherein the conductive feature has a thickness greater than 1 μm.
2 . The process of claim 1 , wherein the direct printing comprises syringe printing.
3 . The process of claim 1 , wherein the direct printing comprises aerosol jet deposition.
4 . The process of claim 1 , wherein the direct printing comprises ink jet printing.
5 . The process of claim 4 , wherein the conductive feature has a thickness greater than 5 μm.
6 . The process of claim 4 , wherein the heating occurs between the multiple passes.
7 . The process of claim 4 , wherein the heating occurs after the multiple passes
8 . The process of claim 4 , wherein the heating comprises heating the precursor composition to a temperature not greater than 300° C.
9 . The process of claim 4 , wherein the heating comprises heating the precursor composition to a temperature not greater than 225° C.
10 . The process of claim 4 , wherein the heating comprises heating the precursor composition to a temperature not greater than 185° C.
11 . The process of claim 4 , wherein the substrate has a softening point of not greater than about 225° C.
12 . The process of claim 4 , wherein the substrate comprises a ceramic.
13 . The process of claim 4 , wherein the substrate comprises a polymer.
14 . The process of claim 4 , wherein the conductivity of the conductive feature is no less than 10 percent the conductivity of the equivalent pure metal.
15 . The process of claim 4 , wherein the conductive feature has a resistivity that is not greater than 4 times the resistivity of the equivalent pure metal.
16 . The process of claim 4 , wherein the conductive feature has a resistivity that is not greater than 2 times the resistivity of the equivalent pure metal.
17 . The process of claim 4 , wherein the conductive feature comprises a transparent conductive feature.
18 . The process of claim 4 , wherein the conductive feature comprises indium-tin oxide or antimony-tin oxide.
19 . The process of claim 4 , wherein the precursor composition comprises the metallic particles.
20 . The process of claim 19 , wherein the metal is selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
21 . The process of claim 4 , wherein the precursor composition comprises the metal precursor composition.
22 . The process of claim 21 , wherein the metal is selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
23 . The process of claim 4 , wherein the metal is selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
24 . The process of claim 4 , wherein the conductive feature comprises a set of finger lines and collector lines deposited essentially at a right angle to the finger lines.
25 . The process of claim 24 , wherein either or both the parallel finger lines or the collector lines have width less than 200 μm.
26 . The process of claim 24 , wherein either or both the parallel finger lines or the collector lines have width less than 100 μm.
27 . The process of claim 4 , wherein the precursor composition further comprises metal oxide particles.
28 . The process of claim 4 , wherein the precursor composition further comprises glass particles.
29 . The process of claim 4 , wherein the precursor composition comprises metallic nanoparticles having a volume median particle size of not greater than 100 nanometers.
30 . The process of claim 4 , wherein the precursor composition comprises metallic particles having a volume median particle size of not greater than 0.3 μm.
31 . The process of claim 30 , wherein the metallic particles comprise a cap or coating thereon.
32 . The process of claim 31 , wherein the cap or coating comprises an inorganic cap or coating.
33 . The process of claim 31 , wherein the cap or coating comprises silica.
34 . The process of claim 31 , wherein the cap or coating comprises glass.
35 . The process of claim 31 , wherein the cap or coating comprises an organic cap or coating.
36 . The process of claim 31 , wherein the cap or coating comprises a polymer.
37 . The process of claim 31 , wherein the cap or coating comprises PVP.
38 . The process of claim 4 , wherein the conductive feature comprises a metal-glass composition.
39 . The process of claim 4 , wherein the conductive feature is resistant to solder leaching.
40 . The process of claim 4 , wherein the process further comprises high shear mixing the precursor composition.
41 . The process of claim 4 , wherein the process further comprises surface modifying the substrate with a laser.