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 metallic particles, a precursor compound to either a metal or a metal oxide, and a liquid vehicle;
(b) depositing the precursor composition onto a substrate; and
(c) converting the precursor compound to the metal or the metal oxide by heating the precursor composition to a conversion temperature and forming the solar cell conductive feature.
2 . The process of claim 1 , wherein the conductive feature comprises regions derived from the metallic particles dispersed in a matrix of the metal or the metal oxide formed from the metal. precursor compound.
3 . The process of claim 1 , wherein the precursor composition has a viscosity not greater than about 1000 centipoise.
4 . The process of claim 1 , wherein the precursor composition has a viscosity not greater than about 100 centipoise.
5 . The process of claim 1 , wherein the precursor composition has a viscosity not greater than about 50 centipoise.
6 . The process of claim 1 , wherein the precursor compound is a precursor compound to a metal.
7 . The process of claim 6 , wherein the metal is selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
8 . The process of claim 1 , wherein the precursor compound is a precursor compound to a metal oxide.
9 . The process of claim 8 , wherein the metal oxide comprises glass.
10 . The process of claim 8 , wherein the metal oxide comprises a conductive metal oxide.
11 . The process of claim 1 , wherein the depositing comprises syringe printing.
12 . The process of claim 1 , wherein the depositing comprises aerosol jet deposition.
13 . The process of claim 1 , wherein the depositing comprises lithographic printing.
14 . The process of claim 1 , wherein the depositing comprises gravure printing.
15 . The process of claim 1 , wherein the depositing comprises flexo printing.
16 . The process of claim 1 , wherein the depositing comprises screen printing.
17 . The process of claim 1 , wherein the depositing comprises photopatterning printing.
18 . The process of claim 1 , wherein the depositing comprises drop on demand printing.
19 . The process of claim 1 , wherein the depositing comprises ink jet printing.
20 . The process of claim 19 , wherein the conversion temperature is less than about 300° C.
21 . The process of claim 19 , wherein the conversion temperature is less than about 200° C.
22 . The process of claim 19 , wherein the substrate comprises a ceramic.
23 . The process of claim 19 , wherein the substrate comprises a polymer.
24 . The process of claim 19 , wherein the conductive feature comprises a set of finger lines and collector lines deposited essentially at a right angle to the finger lines.
25 . The process of claim 24 , wherein either or both the parallel finger lines or the collector lines have width less than 200 μm.
26 . The process of claim 24 , wherein either or both the parallel finger lines or the collector lines have width less than 100 μm.
27 . The process of claim 19 , wherein the conductive feature comprises a transparent conductive feature.
28 . The process of claim 27 , wherein the conductive feature comprises indium-tin oxide or antimony-tin oxide.
29 . The process of claim 19 , wherein the conductive feature has a thickness greater than 5 μm.
30 . The process of claim 19 , wherein the metallic particles comprise metal oxide particles.
31 . The process of claim 19 , wherein the process further comprises surface modifying the substrate with a laser.
32 . The process of claim 19 , wherein the metallic particles have a volume median particle size of not greater than 100 nanometers.
33 . The process of claim 19 , wherein the metallic particles have a volume median particle size of not greater than 0.3 μm.
34 . The process of claim 33 , wherein the metallic particles comprise a cap or coating thereon.
35 . The process of claim 34 , wherein the cap or coating comprises an inorganic cap or coating.
36 . The process of claim 34 , wherein the cap or coating comprises silica.
37 . The process of claim 34 , wherein the cap or coating comprises glass.
38 . The process of claim 34 , wherein the cap or coating comprises an organic cap or coating.
39 . The process of claim 34 , wherein the cap or coating comprises a polymer.
40 . The process of claim 34 , 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.
41 . The process of claim 34 , wherein the cap or coating comprises PVP.
42 . The process of claim 33 , wherein at least 80 volume percent of the metallic particles are not larger than twice the average particle size.
43 . The process of claim 33 , wherein the metal precursor compound is a precursor to a metal selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
44 . The process of claim 43 , wherein the conductivity of the conductive feature is no less than 10 percent the conductivity of the equivalent pure metal.
45 . The process of claim 43 , wherein the conductive feature has a resistivity that is not greater than 4 times the resistivity of the equivalent pure metal.
46 . The process of claim 43 , wherein the conductive feature has a resistivity that is not greater than 2 times the resistivity of the equivalent pure metal.
47 . The process of claim 19 , wherein the conductive feature comprises a metal-glass composition.
48 . The process of claim 19 , wherein the conductive feature is resistant to solder leaching.
49 . The process of claim 19 , wherein the process further comprises high shear mixing the. precursor composition.
50 . The process of claim 19 , wherein the metallic particles comprise a second metal different from the metal formed from the metal precursor compound.
51 . The process of claim 19 , wherein the metallic particles comprise the same metal as the metal formed from the metal precursor compound.
52 . 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.
53 . 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.
54 . 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.
55 . A process for forming a solar cell conductive feature, the process comprising the steps of:
(a) providing a precursor composition comprising a metal precursor compound to a metal, a liquid vehicle, and metal oxide particles;
(b) depositing the precursor composition onto a substrate; and
(c) converting the metal precursor compound to the metal by heating the precursor composition to a conversion temperature and forming the solar cell conductive feature.
56 . The process of claim 55 , wherein the metal oxide particles comprise glass.
57 . The process of claim 55 , wherein the metal oxide particles comprise a conductive metal oxide.
58 . The process of claim 55 , wherein the precursor composition has a viscosity not greater than about 1000 centipoise.
59 . The process of claim 55 , wherein the precursor composition has a viscosity not greater than about 100 centipoise.
60 . The process of claim 55 , wherein the precursor composition has a viscosity not greater than about 50 centipoise.
61 . The process of claim 55 , wherein the conductive feature comprises metal oxide regions derived from the particles dispersed in a matrix of the metal formed from the metal precursor compound.
62 . The process of claim 55 , wherein the metal oxide particles have a volume average particle size of not greater than 0.3 μm.
63 . The process of claim 55 , wherein the metal oxide particles comprise metal oxide nanoparticles.
64 . The process of claim 63 , wherein the nanoparticles comprise glass nanoparticles.
65 . The process of claim 55 , wherein the depositing comprises syringe printing.
66 . The process of claim 55 , wherein the depositing comprises aerosol jet deposition.
67 . The process of claim 55 , wherein the depositing comprises lithographic printing.
68 . The process of claim 55 , wherein the depositing comprises gravure printing.
69 . The process of claim 55 , wherein the depositing comprises flexo printing.
70 . The process of claim 55 , wherein the depositing comprises screen printing.
71 . The process of claim 55 , wherein the depositing comprises photopatterning printing.
72 . The process of claim 55 , wherein the depositing comprises syringe printing.
73 . The process of claim 55 , wherein the depositing comprises aerosol jet deposition.
74 . The process of claim 55 , wherein the depositing comprises ink jet printing.
75 . The process of claim 55 , wherein the substrate comprises a ceramic.
76 . The process of claim 55 , wherein the substrate comprises a polymer.
77 . The process of claim 55 , wherein the process further comprises surface modifying the substrate with a laser.
78 . The process of claim 55 , wherein the conductive feature comprises a set of finger lines and collector lines deposited essentially at a right angle to the finger lines.
79 . The process of claim 78 , wherein either or both the parallel finger lines or the collector lines have a width less than 200 μm.
80 . The process of claim 78 , wherein either or both the parallel finger lines or the collector lines have a width less than 100 μm.
81 . The process of claim 55 , wherein the metal is selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
82 . The process of claim 55 , wherein the conductive feature comprises a metal-glass composition.
83 . The process of claim 55 , wherein the process further comprises high shear mixing the precursor composition.