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) providing a precursor composition comprising a powder, the powder comprising first metallic nanoparticles and having a bimodal particle size distribution, wherein the first metallic nanoparticles comprise a first metal;
(b) direct printing the precursor composition onto the substrate; and
(c) heating the precursor composition to form the solar cell conductive feature.
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 depositing.
4 . The process of claim 1 , wherein the direct printing comprises ink jet printing.
5 . The process of claim 4 , wherein the first metallic nanoparticles are spherical.
6 . The process of claim 4 , wherein the first metallic nanoparticles have an average particle size of not greater than 100 nanometers.
7 . The process of claim 4 , wherein the first metallic nanoparticles have an average particle size of from about 10 to 80 nanometers.
8 . The process of claim 4 , wherein the first metallic nanoparticles have an average particle size of from about 25 to 75 nanometers.
9 . The process of claim 4 , wherein the first metal is selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
10 . The process of claim 4 , wherein the precursor composition comprises a larger mode and a smaller mode.
11 . The process of claim 10 , wherein the larger mode and the smaller mode have different compositions.
12 . The process of claim 10 , wherein the larger mode comprises hollow or porous particles, and wherein the smaller mode comprises dense particles.
13 . The process of claim 10 , wherein the larger mode has an average particle size of from about 1 μm to 10 μm and the smaller mode has an average particle size of from about 10 to 100 nm.
14 . The process of claim 4 , wherein the powder further comprises second metallic nanoparticles comprising a metal oxide.
15 . The process of claim 14 , wherein the metal oxide acts as an adhesion promoter.
16 . The process of claim 14 , wherein the metal oxide comprises silica, copper oxide, aluminum oxide or titania.
17 . The process of claim 14 , wherein the metal oxide comprises silica, copper oxide, aluminum oxide or titania.
18 . The process of claim 14 , wherein the metal oxide comprises glass.
19 . The process of claim 14 , wherein the metal oxide comprises a conductive metal oxide.
20 . The process of claim 19 , wherein the conductive metal oxide comprises In 2 O 3 , indium-tin oxide, or antimony-tin oxide.
21 . The process of claim 14 , wherein the metal oxide comprises pyrogenous silica or surface modified silica.
22 . The process of claim 14 , wherein the metal oxide comprises aluminum borosilicate or lead borosilicate.
23 . The process of claim 4 , wherein the powder further comprises second metallic nanoparticles comprising a second metal.
24 . The process of claim 23 , wherein the second metal is selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
25 . The process of claim 23 , wherein the conductive feature comprises an alloy of the first metal and the second metal.
26 . The process of claim 4 , wherein the heating comprises heating the precursor composition to a temperature not greater than 225° C. to form the solar cell conductive feature on the substrate.
27 . The process of claim 4 , wherein the heating comprises heating the precursor composition to a temperature not greater than 185° C. to form the solar cell conductive feature on the substrate.
28 . The process of claim 4 , wherein the substrate has a softening point of not greater than about 225° C.
29 . The process of claim 4 , wherein the substrate comprises a polymer.
30 . The process of claim 4 , wherein the substrate comprises a ceramic.
31 . 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.
32 . The process of claim 31 , wherein either or both the parallel finger lines or the collector lines have a width not greater than 200 μm.
33 . The process of claim 31 , wherein either or both the parallel finger lines or the collector lines have a width not greater than 100 μm.
34 . The process of claim 4 , wherein the conductive feature has a thickness greater than 1 μm.
35 . The process of claim 4 , wherein the conductive feature has a thickness greater than 5 μm.
36 . The process of claim 4 , wherein the conductive feature comprises a transparent conductive feature.
37 . The process of claim 4 , wherein the conductive feature comprises indium-tin oxide or antimony-tin oxide.
38 . The process of claim 4 , wherein the first metallic nanoparticles have a volume median particle size of not greater than 100 nm.
39 . The process of claim 38 , wherein the first metallic nanoparticles comprise a cap or coating thereon.
40 . The process of claim 39 , wherein the cap or coating comprises an inorganic cap or coating.
41 . The process of claim 39 , wherein the cap or coating comprises silica.
42 . The process of claim 39 , wherein the cap or coating comprises glass.
43 . The process of claim 39 , wherein the cap or coating comprises an organic cap or coating.
44 . The process of claim 39 , wherein the cap or coating comprises a polymer.
45 . The process of claim 39 , 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.
46 . The process of claim 39 , wherein the cap or coating comprises PVP.
47 . The process of claim 4 , wherein the conductivity of the conductive feature is no less than 10 percent the conductivity of the pure silver.
48 . The process of claim 4 , wherein the conductive feature has a resistivity that is not greater than 4 times the resistivity of pure silver.
49 . The process of claim 4 , wherein the conductive feature has a resistivity that is not greater than 2 times the resistivity of pure silver.
50 . The process of claim 4 , wherein the conductive feature is resistant to solder leaching.
51 . The process of claim 4 , wherein the process further comprises high shear mixing the precursor composition.
52 . The process of claim 4 , wherein the process further comprises surface modifying the substrate with a laser.
53 . A precursor composition suitable for ink jet printing, the precursor composition comprising a powder and a liquid vehicle, wherein the powder comprises first metallic nanoparticles and has a bimodal particle size distribution, the first metallic nanoparticles comprising a first metal.
54 . The precursor composition of claim 53 , wherein the precursor composition has a viscosity not greater than about 100 centipoise.
55 . The precursor composition of claim 53 , wherein the precursor composition has a viscosity not greater than about 50 centipoise.
56 . The precursor composition of claim 53 , wherein the first metallic nanoparticles are spherical.
57 . The precursor composition of claim 53 , wherein the first metallic nanoparticles have an average particle size of not greater than 100 nanometers.
58 . The precursor composition of claim 53 , wherein the first metallic nanoparticles have an average particle size of from about 10 to 80 nanometers.
59 . The precursor composition of claim 53 , wherein the first metallic nanoparticles have an average particle size of from about 25 to 75 nanometers.
60 . The precursor composition of claim 53 , wherein the powder further comprises second metallic nanoparticles comprising a second metal or a metal oxide.
61 . The precursor composition of claim 60 , wherein the second metallic nanoparticles comprise the second metal.
62 . The precursor composition of claim 60 , wherein the second metal is selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
63 . The precursor composition of claim 60 , wherein the second metallic nanoparticles comprise the metal oxide.
64 . The precursor composition of claim 63 , wherein the metal oxide comprises silica, copper oxide, aluminum oxide or titania.
65 . The precursor composition of claim 63 , wherein the metal oxide comprises glass.
66 . The precursor composition of claim 63 , wherein the metal oxide comprises a conductive metal oxide.
67 . The precursor composition of claim 66 , wherein the conductive metal oxide comprises In 2 O 3 , indium-tin oxide, or antimony-tin oxide.
68 . The precursor composition of claim 63 , wherein the metal oxide comprises pyrogenous silica or surface modified silica.
69 . The precursor composition of claim 63 , wherein the metal oxide comprises aluminum borosilicate or lead borosilicate.
70 . The precursor composition of claim 53 , wherein the first metal is selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
71 . The precursor composition of claim 53 , wherein the first metallic particles comprise silver particles having a cap or coating thereon.
72 . The precursor composition of claim 71 , wherein the cap or coating comprises an inorganic cap or coating.
73 . The precursor composition of claim 71 , wherein the cap or coating comprises silica.
74 . The precursor composition of claim 71 , wherein the cap or coating comprises glass.
75 . The precursor composition of claim 71 , wherein the cap or coating comprises an organic cap or coating.
76 . The precursor composition of claim 71 , wherein the cap or coating comprises a polymer.
77 . The precursor composition of claim 71 , 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.
78 . The precursor composition of claim 71 , wherein the cap or coating comprises PVP.