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 photovoltaic conductive feature, comprising:
(a) printing a precursor composition onto a substrate by a printing process selected from the group consisting of lithographic printing, gravure printing, flexo printing, and drop on demand printing, wherein the precursor composition comprises metallic nanoparticles comprising a metal; and
(b) heating the precursor composition to form the photovoltaic conductive feature on the substrate, wherein the conductivity of the photovoltaic conductive feature is no less than 10 percent the conductivity of the equivalent pure metal.
2 . The process of claim 1 , wherein the printing process comprises lithographic printing.
3 . The process of claim 1 , wherein the printing process comprises gravure printing.
4 . The process of claim 1 , wherein the printing process comprises flexo printing.
5 . The process of claim 1 , wherein the printing process comprises drop on demand printing.
6 . The process of claim 1 , wherein the heating comprises heating the precursor composition to a temperature not greater than 300° C. to form the photovoltaic conductive feature.
7 . The process of claim 1 , wherein the heating comprises heating the precursor composition to a temperature not greater than 225° C. to form the photovoltaic conductive feature.
8 . The process of claim 1 , wherein the heating comprises heating the precursor composition to a temperature not greater than 185° C. to form the photovoltaic conductive feature.
9 . The process of claim 1 , wherein the metallic nanoparticles have an average particle size of not greater than about 100 nanometers.
10 . The process of claim 1 , wherein the metallic nanoparticles have an average particle size of from about 10 to 80 nm.
11 . The process of claim 1 , wherein the metallic nanoparticles have an average particle size of from about 25 to 75 nm.
12 . The process of claim 1 , wherein at least about 70 volume percent of the nanoparticles are not larger than twice the average particle size.
13 . The process of claim 1 , wherein the conductive feature has a resistivity that is not greater than 4 times the resistivity of the equivalent pure metal.
14 . The process of claim 1 , wherein the conductive feature has a resistivity that is not greater than 2 times the resistivity of the equivalent pure metal.
15 . The process of claim 1 , wherein the heating sinters adjacent nanoparticles to one another.
16 . The process of claim 1 , wherein the nanoparticles are spherical.
17 . The process of claim 1 , wherein the precursor composition further comprises metal oxide particles.
18 . The process of claim 1 , wherein the precursor composition further comprises glass particles.
19 . The process of claim 1 , wherein the precursor composition further comprises a metal precursor compound.
20 . The process of claim 1 , wherein the metal is selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
21 . The process of claim 20 , wherein the metallic nanoparticles comprise a cap or coating thereon.
22 . The process of claim 21 , wherein the cap or coating comprises an inorganic cap or coating.
23 . The process of claim 21 , wherein the cap or coating comprises silica.
24 . The process of claim 21 , wherein the cap or coating comprises glass.
25 . The process of claim 21 , wherein the cap or coating comprises an organic cap or coating.
26 . The process of claim 21 , wherein the cap or coating comprises a polymer.
27 . The process of claim 21 , wherein the cap or coating comprises an intrinsically conductive polymer, a sulfonated perfluorohydrocarbon polymer, polystyrene, polystyrene/methacrylate, sodium bis(2-ethylhexyl)sulfosuccinate, tetra-n-octyl-ammonium bromide or an alkane thiolate.
28 . The process of claim 21 , wherein the cap or coating comprises PVP.
29 . The process of claim 1 , wherein the conductive feature comprises a set of finger lines and collector lines deposited essentially at a right angle to the finger lines.
30 . The process of claim 29 , wherein either or both the parallel finger lines or the collector lines have width less than 200 μm.
31 . The process of claim 29 , wherein either or both the parallel finger lines or the collector lines have width less than 100 μm.
32 . The process of claim 1 , wherein the conductive feature has a thickness greater than 5 μm.
33 . The process of claim 1 , wherein the conductive feature comprises a transparent conductive feature.
34 . The process of claim 1 , wherein the conductive feature comprises indium-tin oxide or antimony-tin oxide.
35 . The process of claim 1 , wherein the conductive feature comprises a metal-glass composition.
36 . The process of claim 1 , wherein the conductive feature is resistant to solder leaching.
37 . The process of claim 1 , wherein the process further comprises high shear mixing the precursor composition.
38 . The process of claim 1 , wherein the process further comprises surface modifying the substrate with a laser.
39 . The process of claim 1 , wherein the substrate comprises a ceramic.
40 . The process of claim 1 , wherein the substrate comprises a polymer.
41 . The process of claim 1 , wherein the photovoltaic conductive feature comprises a solar cell conductive feature.