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, the precursor composition comprising metallic nanoparticles comprising a metal; and
(b) heating the precursor composition to form the solar cell conductive feature on the substrate, wherein the conductive feature has a minimum feature size of not greater than about 200 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 direct printing comprises directing droplets of the precursor composition toward a surface of the substrate, the droplets having an average droplet size not greater than about 10 μm.
6 . The process of claim 5 , wherein the average droplet size is not greater than about 5 μm.
7 . The process of claim 4 , wherein the ink jet printing comprises depositing droplets onto the substrate at a rate of 1000 drops per second or higher.
8 . The process of claim 7 , wherein each droplet comprise from about 25 to 100 picoliters of the precursor composition.
9 . The process of claim 4 , wherein the minimum feature size is not greater than about 100 μm.
10 . The process of claim 4 , wherein the minimum feature size is not greater than about 50 μm.
11 . The process of claim 4 , wherein the minimum feature size is not greater than about 25 μm.
12 . The process of claim 4 , wherein the heating comprises heating the precursor composition to a temperature not greater than 300° C.
13 . The process of claim 4 , wherein the heating comprises heating the precursor composition to a temperature not greater than 225° C.
14 . The process of claim 4 , wherein the heating comprises heating the precursor composition to a temperature not greater than 185° C.
15 . The process of claim 4 , wherein the substrate has a softening point of not greater than about 225° C.
16 . The process of claim 4 , wherein the substrate comprises a polymer.
17 . The process of claim 4 , wherein the substrate comprises a ceramic.
18 . The process of claim 4 , wherein the conductive feature has a thickness greater than 1 μm.
19 . The process of claim 4 , wherein the conductive feature has a thickness greater than 5 μm.
20 . The process of claim 4 , wherein the conductive feature comprises a transparent conductive feature.
21 . The process of claim 4 , wherein the conductive feature comprises indium-tin oxide or antimony-tin oxide.
22 . The process of claim 4 , wherein the process further comprises surface modifying a surface on the substrate prior to the direct printing.
23 . The process of claim 22 , wherein the surface modifying comprises increasing or decreasing the hydrophilicity of the surface.
24 . The process of claim 22 , wherein the surface is modified by modifying chemicals.
25 . The process of claim 22 , wherein the surface modifying comprises laser patterning.
26 . The process of claim 25 , wherein the laser patterning increases or decreases the hydrophilicity of the substrate.
27 . The process of claim 22 , wherein the surface modifying comprises forming trenches in the surface by chemical etching or photochemical means.
28 . 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.
29 . 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.
30 . 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.
31 . The process of claim 4 , wherein the metal is selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
32 . The process of claim 4 , wherein the precursor composition further comprises metal oxide particles.
33 . The process of claim 4 , wherein the precursor composition further comprises glass particles.
34 . 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.
35 . The process of claim 34 , wherein either or both the parallel finger lines or the collector lines have width less than 200 μm.
36 . The process of claim 34 , wherein either or both the parallel finger lines or the collector lines have width less than 100 μm.
37 . The process of claim 4 , wherein the metallic nanoparticles have a volume median particle size of from about 10 to 80 nm.
38 . The process of claim 4 , wherein the metallic nanoparticles a volume median particle size of from about 25 to 75 nm.
39 . The process of claim 4 , wherein the metallic nanoparticles have a volume median particle size of not greater than 100 nm.
40 . The process of claim 39 , wherein the silver particles comprise a cap or coating thereon.
41 . The process of claim 40 , wherein the cap or coating comprises an inorganic cap or coating.
42 . The process of claim 40 , wherein the cap or coating comprises silica.
43 . The process of claim 40 , wherein the cap or coating comprises glass.
44 . The process of claim 40 , wherein the cap or coating comprises an organic cap or coating.
45 . The process of claim 40 , wherein the cap or coating comprises a polymer.
46 . The process of claim 40 , 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.
47 . The process of claim 40 , wherein the cap or coating comprises PVP.
48 . The process of claim 4 , wherein the conductive feature comprises a metal-glass composition.
49 . The process of claim 4 , wherein the conductive feature is resistant to solder leaching.
50 . The process of claim 4 , wherein the process further comprises high shear mixing the precursor composition.
51 . A process for forming a solar cell conductive feature, comprising heating an ink jet printed precursor composition on a substrate, the precursor composition comprising metallic nanoparticles comprising a metal, wherein the conductive feature has a minimum feature size of not greater than about 200 μm.
52 . The process of claim 51 , wherein the minimum feature size is not greater than about 100 μm.
53 . The process of claim 51 , wherein the minimum feature size is not greater than about 50 μm.
54 . The process of claim 51 , wherein the minimum feature size is not greater than about 25 μm.
55 . The process of claim 51 , wherein the heating comprises heating the precursor composition to a temperature not greater than 300° C.
56 . The process of claim 51 , wherein the heating comprises heating the precursor composition to a temperature not greater than 225° C.
57 . The process of claim 51 , wherein the heating comprises heating the precursor composition to a temperature not greater than 185° C.
58 . The process of claim 51 , wherein the substrate has a softening point of not greater than about 225° C.
59 . The process of claim 51 , wherein the substrate comprises a polymer.
60 . The process of claim 51 , wherein the substrate comprises a ceramic.
61 . The process of claim 51 , wherein the conductive feature has a thickness greater than 1 μm.
62 . The process of claim 51 , wherein the conductive feature has a thickness greater than 5 μm.
63 . The process of claim 51 , wherein the conductive feature comprises a transparent conductive feature.
64 . The process of claim 51 , wherein the conductive feature comprises indium-tin oxide or antimony-tin oxide.
65 . The process of claim 51 , wherein the conductivity of the conductive feature is no less than 10 percent the conductivity of the equivalent pure metal.
66 . The process of claim 51 , wherein the conductive feature has a resistivity that is not greater than 4 times the resistivity of the equivalent pure metal.
67 . The process of claim 51 , wherein the conductive feature has a resistivity that is not greater than 2 times the resistivity of the equivalent pure metal.
68 . The process of claim 51 , wherein the metal is selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
69 . The process of claim 51 , wherein the precursor composition further comprises metal oxide particles.
70 . The process of claim 51 , wherein the precursor composition further comprises glass particles.
71 . The process of claim 51 , wherein the conductive feature comprises a set of finger lines and collector lines deposited essentially at a right angle to the finger lines.
72 . The process of claim 71 , wherein either or both the parallel finger lines or the collector lines have width less than 200 μm.
73 . The process of claim 71 , wherein either or both the parallel finger lines or the collector lines have width less than 100 μm.
74 . The process of claim 51 , wherein the metallic nanoparticles have a volume median particle size of from about 10 to 80 nm.
75 . The process of claim 51 , wherein the metallic nanoparticles a volume median particle size of from about 25 to 75 nm.
76 . The process of claim 51 , wherein the metallic nanoparticles have a volume median particle size of not greater than 100 nm.
77 . The process of claim 76 , wherein the silver particles comprise a cap or coating thereon.
78 . The process of claim 77 , wherein the cap or coating comprises an inorganic cap or coating.
79 . The process of claim 77 , wherein the cap or coating comprises silica.
80 . The process of claim 77 , wherein the cap or coating comprises glass.
81 . The process of claim 77 , wherein the cap or coating comprises an organic cap or coating.
82 . The process of claim 77 , wherein the cap or coating comprises a polymer.
83 . The process of claim 77 , 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.
84 . The process of claim 77 , wherein the cap or coating comprises PVP.
85 . The process of claim 51 , wherein the conductive feature comprises a metal-glass composition.
86 . The process of claim 51 , wherein the conductive feature is resistant to solder leaching.
87 . The process of claim 51 , wherein the process further comprises high shear mixing the precursor composition.