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) depositing a precursor composition onto a substrate, the precursor composition comprising a binder and 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 photovoltaic conductive feature on the substrate, wherein the photovoltaic conductive feature has a minimum feature size of not greater than about 100 μm.
2 . The process of claim 1 , wherein the depositing comprises a lithographic printing.
3 . The process of claim 1 , wherein the depositing comprises a gravure printing.
4 . The process of claim 1 , wherein the depositing comprises a flexo printing.
5 . The process of claim 1 , wherein the depositing comprises a screen printing.
6 . The process of claim 1 , wherein the depositing comprises a photopatterning printing.
7 . The process of claim 1 , wherein the depositing comprises a drop on demand printing.
8 . The process of claim 1 , wherein the depositing comprises direct write printing.
9 . The process of claim 1 , wherein the depositing comprises syringe printing.
10 . The process of claim 1 , wherein the depositing comprises aerosol jetting.
11 . The process of claim 1 , wherein the depositing comprises ink jet printing.
12 . The process of claim 1 , wherein the binder limits spreading of the precursor composition after the printing.
13 . The process of claim 12 , wherein the binder is a solid at room temperature, but is flowable when heated to greater than 50° C.
14 . The process of claim 13 , wherein the printing employs a heated ink jet head.
15 . The process of claim 12 , wherein the binder is selected from the group consisting of wax, a styrene allyl alcohol, a polyalkylene carbonate, a polyvinyl acetal, a cellulose based material, tetradecanol, trimethylolpropane and tetramethylbenzene.
16 . The process of claim 12 , wherein the binder comprises DMAc.
17 . The process of claim 12 , wherein the binder comprises wax.
18 . The process of claim 12 , wherein the binder departs or decomposes during the heating.
19 . The process of claim 18 , wherein the departing or decomposing comprises vaporizing, subliming, unzipping, partial polymer chain breaking, combusting or chemically reacting.
20 . The process of claim 18 , wherein the binder leaves little or no residuals after the heating.
21 . The process of claim 12 , wherein the heating comprises heating the precursor composition to a temperature not greater than 225° C. to form the photovoltaic conductive feature on the substrate.
22 . The process of claim 12 , wherein the heating comprises heating the precursor composition to a temperature not greater than 185° C. to form the photovoltaic conductive feature on the substrate.
23 . The process of claim 12 , wherein the substrate has a softening point of not greater than about 225° C.
24 . The process of claim 12 , wherein the substrate comprises a polymer.
25 . The process of claim 12 , wherein the substrate comprises a ceramic.
26 . The process of claim 12 , wherein the conductive feature has a thickness greater than 1 μm.
27 . The process of claim 12 , wherein the conductive feature has a thickness greater than 5 μm.
28 . The process of claim 12 , wherein the conductive feature comprises a transparent conductive feature.
29 . The process of claim 28 , wherein the conductive feature comprises indium-tin oxide or antimony-tin oxide.
30 . The process of claim 12 , wherein the ink jet 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.
31 . The process of claim 30 , wherein the average droplet size is not greater than about 5 μm.
32 . The process of claim 12 , wherein the minimum feature size is not greater than about 75 μm.
33 . The process of claim 12 , wherein the minimum feature size is not greater than about 50 μm.
34 . The process of claim 12 , wherein the minimum feature size is not greater than about 25 μm.
35 . The process of claim 12 , wherein the conductive feature has a resistivity that is not greater than 4 times the resistivity of the equivalent pure metal.
36 . The process of claim 12 , wherein the conductive feature has a resistivity that is not greater than 2 times the resistivity of the equivalent pure metal.
37 . The process of claim 12 , wherein the precursor composition comprises the metal particles.
38 . The process of claim 37 , wherein the metal is selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
39 . The process of claim 12 , wherein the precursor composition comprises the metal precursor compound.
40 . The process of claim 39 , wherein the metal is selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
41 . The process of claim 12 , wherein the conductive feature comprises a set of finger lines and collector lines deposited essentially at a right angle to the finger lines.
42 . The process of claim 41 , wherein either or both the parallel finger lines or the collector lines have width less than 200 μm.
43 . The process of claim 41 , wherein either or both the parallel finger lines or the collector lines have width less than 100 μm.
44 . The process of claim 12 , wherein the precursor composition further comprises metal oxide particles.
45 . The process of claim 12 , wherein the precursor composition further comprises glass particles.
46 . The process of claim 12 , wherein the precursor composition comprises the metallic particles, the metallic particles having a volume median particle size of not greater than 100 nanometers.
47 . The process of claim 12 , wherein the precursor composition comprises the metallic particles, the metallic particles having a volume median particle size of not greater than 0.3 μm.
48 . The process of claim 47 , wherein the metallic particles comprise a cap or coating thereon.
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 silica.
51 . The process of claim 48 , wherein the cap or coating comprises glass.
52 . The process of claim 48 , wherein the cap or coating comprises an organic cap or coating.
53 . The process of claim 48 , wherein the cap or coating comprises a polymer.
54 . The process of claim 48 , 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.
55 . The process of claim 48 , wherein the cap or coating comprises PVP.
56 . The process of claim 12 , wherein the conductive feature comprises a metal-glass composition.
57 . The process of claim 12 , wherein the conductive feature is resistant to solder leaching.
58 . The process of claim 12 , wherein the process further comprises high shear mixing the precursor composition.
59 . The process of claim 12 , wherein the process further comprises surface modifying the substrate with a laser.
60 . A process for forming a photovoltaic conductive feature, comprising:
(a) direct write printing a precursor composition onto a substrate, the precursor composition comprising at least one of metallic particles comprising a metal or a metal precursor compound to the metal;
(b) freezing the precursor composition as droplets of the precursor composition contact the substrate; and
(c) converting the precursor composition to the photovoltaic conductive feature on the substrate, wherein the conductive feature has a minimum feature size of not greater than about 100 μm.
61 . The process of claim 60 , wherein the direct write printing comprises syringe printing.
62 . The process of claim 60 , wherein the direct write printing comprises aerosol jet deposition.
63 . The process of claim 60 , wherein the direct write printing comprises ink jet printing.
64 . The process of claim 60 , wherein the melting point of the precursor composition is less than 25° C.
65 . The process of claim 60 , wherein the freezing comprises cooling the substrate to less than 10° C.
66 . The process of claim 60 , wherein the freezing limits spreading of the precursor composition after the printing.
67 . The process of claim 60 , wherein the process further comprises removing a solvent from the precursor composition after the freezing and converting the remaining components in the precursor composition to the photovoltaic conductive feature.
68 . The process of claim 60 , wherein the heating comprises heating the precursor composition to a temperature not greater than 225° C. to form the photovoltaic conductive feature on the substrate.
69 . The process of claim 60 , wherein the heating comprises heating the precursor composition to a temperature not greater than 185° C. to form the photovoltaic conductive feature on the substrate.
70 . The process of claim 60 , wherein the substrate has a softening point of not greater than about 225° C.
71 . The process of claim 60 , wherein the substrate comprises a polymer.
72 . The process of claim 60 , wherein the substrate comprises a ceramic.
73 . The process of claim 60 , wherein the conductive feature has a thickness greater than 1 μm.
74 . The process of claim 60 , wherein the conductive feature has a thickness greater than 5 μm.
75 . The process of claim 60 , wherein the conductive feature comprises a transparent conductive feature.
76 . The process of claim 60 , wherein the conductive feature comprises indium-tin oxide or antimony-tin oxide.
77 . The process of claim 63 , wherein the ink jet 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.
78 . The process of claim 77 , wherein the average droplet size is not greater than about 5 μm.
79 . The process of claim 60 , wherein the minimum feature size is not greater than about 75 μm.
80 . The process of claim 60 , wherein the minimum feature size is not greater than about 50 μm.
81 . The process claim 60 , wherein the minimum feature size is not greater than about 25 μm.
82 . The process claim 60 , wherein the conductive feature has a resistivity that is not greater than 4 times the resistivity of the equivalent pure metal.
83 . The process claim 60 , wherein the conductive feature has a resistivity that is not greater than 2 times the resistivity of the equivalent pure metal.
84 . The process claim 60 , wherein the precursor composition comprises the metal particles.
85 . The process of claim 84 , wherein the metal is selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
86 . The process claim 60 , wherein the precursor composition comprises the metal precursor compound.
87 . The process of claim 86 , wherein the metal is selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
88 . The process claim 60 , wherein the conductive feature comprises a set of finger lines and collector lines deposited essentially at a right angle to the finger lines.
89 . The process of claim 88 , wherein either or both the parallel finger lines or the collector lines have width less than 200 μm.
90 . The process of claim 88 , wherein either or both the parallel finger lines or the collector lines have width less than 100 μm.
91 . The process claim 60 , wherein the precursor composition further comprises metal oxide particles.
92 . The process claim 60 , wherein the precursor composition further comprises glass particles.
93 . The process claim 60 , wherein the precursor composition comprises silver nanoparticles having a volume median particle size of not greater than 100 nanometers.
94 . The process claim 60 , wherein the precursor composition comprises silver particles having a volume median particle size of not greater than 0.3 μm.
95 . The process of claim 94 , wherein the silver particles comprise a cap or coating thereon.
96 . The process of claim 95 , wherein the cap or coating comprises an inorganic cap or coating.
97 . The process of claim 95 , wherein the cap or coating comprises silica.
98 . The process of claim 95 , wherein the cap or coating comprises glass.
99 . The process of claim 95 , wherein the cap or coating comprises an organic cap or coating.
100 . The process of claim 95 , wherein the cap or coating comprises a polymer.
101 . The process of claim 95 , 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.
102 . The process of claim 95 , wherein the cap or coating comprises PVP.
103 . The process claim 60 , wherein the conductive feature comprises a metal-glass composition.
104 . The process claim 60 , wherein the conductive feature is resistant to solder leaching.
105 . The process claim 60 , wherein the process further comprises high shear mixing the precursor composition.
106 . The process claim 60 , wherein the process further comprises surface modifying the substrate with a laser.
107 . The process of claim 1 , wherein the photovoltaic conductive feature comprises a solar cell conductive feature.
108 . The process of claim 1 , wherein the precursor composition is deposited on the substrate in a non-contact printing process.
109 . The process of claim 1 , wherein the precursor composition is deposited on the substrate in an electrostatic printing process.
110 . The process of claim 60 , wherein the photovoltaic conductive feature comprises a solar cell conductive feature.
111 . The process of claim 60 , wherein the precursor composition is deposited on the substrate in an electrostatic printing process.