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 particles comprising a core comprising a metal and having a cap or coating disposed thereon; and
(b) heating the precursor composition to form the solar cell conductive feature on the substrate, wherein the conductivity of the solar cell conductive feature is no less than 10 percent the conductivity of the equivalent pure metal.
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 cap or coating comprises an inorganic cap or coating.
6 . The process of claim 4 , wherein the cap or coating comprises a metal oxide.
7 . The process of claim 4 , wherein the cap or coating comprises lead oxide, molybdenum oxide or vanadium oxide.
8 . The process of claim 4 , wherein the cap or coating comprises an elemental metal.
9 . The process of claim 4 , wherein the cap or coating comprises silica.
10 . The process of claim 4 , wherein the cap or coating comprises glass.
11 . The process of claim 4 , wherein the cap or coating comprises an organic compound.
12 . The process of claim 4 , wherein the cap or coating comprises a polymer.
13 . The process of claim 4 , wherein the cap or coating comprises a conductive polymer.
14 . The process of claim 4 , wherein the cap or coating comprises PVP.
15 . The process of claim 4 , wherein the cap or coating comprises a compound selected from the group consisting of: sulfonated perfluorohydrocarbon polymer, polystyrene, polystyrene/methacrylate, sodium bis(2-ethylhexyl) sulfosuccinate, tetra-n-octyl-ammonium bromide and alkane thiolates.
16 . The process of claim 4 , wherein the cap or coating comprises multiple caps or coatings.
17 . The process of claim 4 , wherein the metal is selected from the group consisting of copper, nickel, gold, platinum and palladium.
18 . The process of claim 4 , wherein core comprises a conductive metal oxide.
19 . The process of claim 4 , wherein the metal is selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
20 . The process of claim 19 , wherein the cap or coating comprises silica.
21 . The process of claim 19 , wherein the cap or coating comprises glass.
22 . The process of claim 4 , wherein the metallic particles have a volume median particle size of not greater than 100 nm.
23 . The process of claim 4 , wherein the metallic particles have a volume median particle size of not greater than 0.3 μm.
24 . The process of claim 4 , wherein the cap or coating has a thickness of not greater than about 100 nm.
25 . The process of claim 4 , wherein the cap or coating has a thickness of not greater than about 50 nm.
26 . The process of claim 4 , wherein the cap or coating has a thickness of not greater than about 5 nm.
27 . 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.
28 . 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.
29 . The process of claim 4 , wherein the substrate has a softening point of not greater than about 225° C.
30 . The process of claim 4 , wherein the substrate comprises a polymer.
31 . The process of claim 4 , wherein the substrate comprises a ceramic.
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 has a resistivity that is not greater than 4 times the resistivity of the equivalent pure metal.
35 . 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.
36 . The process of claim 4 , wherein the heating sinters adjacent particles to one another.
37 . 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.
38 . The process of claim 37 , wherein either or both the parallel finger lines or the collector lines have width less than 200 μm.
39 . The process of claim 37 , wherein either or both the parallel finger lines or the collector lines have width less than 100 μm.
40 . The process of claim 4 , wherein the conductive feature has a thickness greater than 1 μm.
41 . The process of claim 4 , wherein the conductive feature has a thickness greater than 5 μm.
42 . The process of claim 4 , wherein the conductive feature comprises a transparent conductive feature.
43 . The process of claim 4 , wherein the conductive feature comprises indium-tin oxide or antimony-tin oxide.
44 . The process of claim 4 , wherein the conductive feature comprises a metal-glass composition.
45 . The process of claim 4 , wherein the conductive feature is resistant to solder leaching.
46 . The process of claim 4 , wherein the process further comprises high shear mixing the precursor composition.
47 . The process of claim 4 , wherein the process further comprises surface modifying the substrate with a laser.
48 . A process for forming a solar cell conductive feature, the process comprising heating an ink jet printed precursor composition to form the solar cell conductive feature on a substrate, wherein the precursor composition comprises metallic particles having a core comprising a metal and a cap or coating disposed on the core, and wherein the conductivity of the conductive feature is no less than 10 percent the conductivity of the equivalent pure metal.
49 . The process of claim 48 , wherein the cap or coating comprises an inorganic cap or coating.
50 . The process of claim 48 , wherein the cap or coating comprises a metal oxide.
51 . The process of claim 48 , wherein the cap or coating comprises lead oxide, molybdenum oxide or vanadium oxide.
52 . The process of claim 48 , wherein the cap or coating comprises an elemental metal.
53 . The process of claim 48 , wherein the cap or coating comprises silica.
54 . The process of claim 48 , wherein the cap or coating comprises glass.
55 . The process of claim 48 , wherein the cap or coating comprises an organic compound.
56 . The process of claim 48 , wherein the cap or coating comprises a polymer.
57 . The process of claim 48 , wherein the cap or coating comprises a conductive polymer.
58 . The process of claim 48 , wherein the cap or coating comprises PVP.
59 . The process of claim 48 , wherein the cap or coating comprises a compound selected from the group consisting of: sulfonated perfluorohydrocarbon polymer, polystyrene, polystyrene/methacrylate, sodium bis(2-ethylhexyl) sulfosuccinate, tetra-n-octyl-ammonium bromide and alkane thiolates.
60 . The process of claim 48 , wherein the cap or coating comprises multiple caps or coatings.
61 . The process of claim 48 , wherein the metal is selected from the group consisting of copper, nickel, gold, platinum and palladium.
62 . The process of claim 48 , wherein core comprises a conductive metal oxide.
63 . The process of claim 48 , wherein the metal is selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
64 . The process of claim 63 , wherein the cap or coating comprises silica.
65 . The process of claim 63 , wherein the cap or coating comprises glass.
66 . The process of claim 48 , wherein the metallic particles have a volume median particle size of not greater than 100 nm.
67 . The process of claim 48 , wherein the metallic particles have a volume median particle size of not greater than 0.3 μm.
68 . The process of claim 48 , wherein the cap or coating has a thickness of not greater than about 100 nm.
69 . The process of claim 48 , wherein the cap or coating has a thickness of not greater than about 50 nm.
70 . The process of claim 48 , wherein the cap or coating has a thickness of not greater than about 5 nm.
71 . The process of claim 48 , 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.
72 . The process of claim 48 , 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.
73 . The process of claim 48 , wherein the substrate has a softening point of not greater than about 225° C.
74 . The process of claim 48 , wherein the substrate comprises a polymer.
75 . The process of claim 48 , wherein the substrate comprises a ceramic.
76 . The process of claim 48 , wherein the precursor composition further comprises metal oxide particles.
77 . The process of claim 48 , wherein the precursor composition further comprises glass particles.
78 . The process of claim 48 , wherein the conductive feature has a resistivity that is not greater than 4 times the resistivity of the equivalent pure metal.
79 . The process of claim 48 , wherein the conductive feature has a resistivity that is not greater than 2 times the resistivity of the equivalent pure metal.
80 . The process of claim 48 , wherein the heating sinters adjacent particles to one another.
81 . The process of claim 80 , wherein the conductive feature comprises a set of finger lines and collector lines deposited essentially at a right angle to the finger lines.
82 . The process of claim 81 , wherein either or both the parallel finger lines or the collector lines have width less than 200 μm.
83 . The process of claim 81 , wherein either or both the parallel finger lines or the collector lines have width less than 100 μm.
84 . The process of claim 48 , wherein the conductive feature has a thickness greater than 1 μm.
85 . The process of claim 48 , wherein the conductive feature has a thickness greater than 5 μm.
86 . The process of claim 48 , wherein the conductive feature comprises a transparent conductive feature.
87 . The process of claim 48 , wherein the conductive feature comprises indium-tin oxide or antimony-tin oxide.
88 . The process of claim 48 , wherein the conductive feature comprises a metal-glass composition.
89 . The process of claim 48 , wherein the conductive feature is resistant to solder leaching.
90 . The process of claim 48 , wherein the substrate has been surface modified with a laser.