Platinum ink compositions and methods for low temperature conductive coatings

Abstract

Conductive metal-organic decomposition (MOD) ink compositions comprising platinum are provided. Also provided are methods for preparing the conductive ink compositions, methods for forming conductive structures from the conductive ink compositions, and conductive structures formed from the conductive ink compositions, including high-density conductive platinum films. The conductive ink compositions preferably comprise platinum metal, a first bidentate complexing agent, and a solvent. The conductive platinum films can be formed from the ink compositions at low temperatures and are therefore suitable for use on a variety of substrates, including those optimal for electronic applications.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Application No. 63 / 402,341, filed August 30, 2022, the disclosure of which is incorporated herein by reference in its entirety.

[0002] FIELD OF THE INVENTION The present disclosure relates generally to novel ink compositions comprising platinum and methods for their preparation and use. More specifically, the present disclosure relates to metal-organic decomposition (MOD) platinum ink compositions suitable for use on low-temperature substrates. The present disclosure also describes methods for forming high-density conductive platinum films by applying the disclosed platinum ink compositions on substrates suitable for electronic applications, and the conductive platinum films formed by such methods. [Background technology]

[0003] BACKGROUND OF THE INVENTION The deposition of metallic platinum thin films on various substrates has attracted particular attention in the electronics industry. Such applications include the formation of contacts in microelectronic devices and high-temperature electrochemical and catalytic applications. Compared with more common noble metals such as gold and silver, the deposition of conductive platinum thin films is highly challenging, and related reports are scarce. Common deposition methods for platinum include vapor deposition and electrochemical and electroless deposition methods. However, these conventional processes are often impractical and difficult to adapt for large-scale production.

[0004] U.S. Patent No. 5,882,722 discloses thick conductive films formed from a mixture of metal powder and metal-organic decomposition complexes in an organic liquid vehicle. The mixture preferably contains metal flakes. However, only silver-containing mixtures are exemplified.

[0005] Choi et al. (2019) Adv. Mater. Interfaces 6 1901002 provides an overview of the status of metal-organic decomposition inks for printed electronics. However, examples of only silver, copper, and aluminum MOD inks are discussed.

[0006] Thus, there remains a need for conductive ink compositions comprising platinum that exhibit improved properties. Accordingly, it is an object of the present invention to provide particle-free conductive platinum ink compositions, particularly compositions that can form conductive structures at low temperatures, and methods for their preparation and use. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Patent No. 5,882,722 Summary of the Invention [Means for solving the problem]

[0008] (Summary of the Invention) The present disclosure addresses these and other considerations by providing, in some aspects, a particle-free conductive ink composition comprising platinum metal, a first bidentate complexing agent, and a solvent, wherein the composition forms a conductive metal film upon curing at or below 250°C.

[0009] In some aspects, the technology described herein relates to particle-free conductive ink compositions in which the platinum metal is platinum(II) metal ions.

[0010] In some aspects, the techniques described herein relate to particle-free conductive ink compositions in which the first bidentate complexing agent is an amine-containing organic complexing agent.

[0011] In some aspects, the technology described herein relates to particle-free conductive ink compositions in which the amine-containing organic complexing agent is a C3-C8 amino ether ligand.

[0012] In some aspects, the technology described herein relates to particle-free conductive ink compositions in which the amine-containing organic complexing agent is a primary aminoether ligand.

[0013] In some aspects, the technology described herein relates to particle-free conductive ink compositions in which the amine-containing organic complexing agent is a primary C3-C8 aminoether ligand.

[0014] In some aspects, the technology described herein relates to particle-free conductive ink compositions in which the amine-containing organic complexing agent is 2-methoxyethylamine.

[0015] In some aspects, the techniques described herein relate to particle-free conductive ink compositions in which the solvent comprises a terpene, a terpenoid, or a combination thereof.

[0016] In some aspects, the technology described herein relates to particle-free conductive ink compositions wherein the terpene is a purified terpene or the terpenoid is a purified terpenoid.

[0017] In some aspects, the technology described herein relates to a particle-free conductive ink composition in which the terpene is pinene or limonene.

[0018] In some aspects, the technology described herein relates to a particle-free conductive ink composition in which the terpenoid is terpineol.

[0019] In some aspects, the techniques described herein relate to particle-free conductive ink compositions in which the solvent comprises water.

[0020] In some aspects, the techniques described herein relate to particle-free conductive ink compositions that further include a second bidentate complexing agent.

[0021] In some aspects, the techniques described herein relate to particle-free conductive ink compositions in which the second bidentate complexing agent is a β-diketone.

[0022] In some aspects, the technology described herein relates to a particle-free conductive ink composition in which the β-diketone is an acetylacetonate.

[0023] In some aspects, the techniques described herein relate to a particle-free conductive ink composition in which the first bidentate complexing agent is 2-methoxyethylamine and the solvent comprises terpineol.

[0024] In some aspects, the techniques described herein relate to particle-free conductive ink compositions that further include a reducing ligand.

[0025] In some aspects, the techniques described herein relate to particle-free conductive ink compositions in which the reducing ligand is formic acid.

[0026] In some aspects, the techniques described herein relate to particle-free conductive ink compositions that further include a second bidentate complexing agent.

[0027] In some aspects, the techniques described herein relate to particle-free conductive ink compositions in which the second bidentate complexing agent is a β-diketone.

[0028] In some aspects, the technology described herein relates to a particle-free conductive ink composition in which the β-diketone is an acetylacetonate.

[0029] In some aspects, the techniques described herein relate to a particle-free conductive ink composition in which the first bidentate complexing agent is 2-methoxyethylamine and the solvent comprises terpineol.

[0030] In some aspects, the techniques described herein relate to particle-free conductive ink compositions that further include a glycol.

[0031] In some aspects, the technology described herein relates to particle-free conductive ink compositions in which the glycol is 1,2-propylene glycol, 1,3-propylene glycol, or a combination thereof.

[0032] In some aspects, the technology described herein relates to a particle-free conductive ink composition in which the first bidentate complexing agent is 2-methoxyethylamine and the solvent comprises water.

[0033] In some aspects, the techniques described herein relate to particle-free conductive ink compositions, where the compositions form a conductive metal film upon curing at or below 250°C.

[0034] In some aspects, the techniques described herein relate to particle-free conductive ink compositions, where the compositions form a conductive metal film upon curing at or below 200°C.

[0035] In some aspects, the techniques described herein relate to particle-free conductive ink compositions in which the conductive metal film exhibits a conductivity of at least 1% of the bulk metal conductivity.

[0036] In some aspects, the techniques described herein relate to methods of applying the above-described compositions to a substrate and curing the composition at an elevated temperature to form a conductive film.

[0037] In some aspects, the techniques described herein relate to methods wherein the applying step comprises printing.

[0038] In some aspects, the techniques described herein relate to methods wherein the printing is jet printing.

[0039] In some aspects, the techniques described herein relate to methods wherein the jet printing is aerosol jet printing.

[0040] In some aspects, the techniques described herein relate to methods in which the curing step is performed at 250° C. or less.

[0041] In some aspects, the techniques described herein relate to methods in which the curing step is performed at 200° C. or less.

[0042] In some aspects, the techniques described herein relate to conductive films formed by applying a particle-free conductive ink composition to a substrate and curing the composition at 250° C. or less to form the conductive film. [Brief explanation of the drawings]

[0043] [Figure 1] 1A-1C show coating and imaging using the platinum ink composition of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0044] (Detailed Description of the Invention) (Conductive Platinum Ink Composition) Provided herein are platinum-containing complex-based particle-free ink compositions that can be applied and cured at low temperatures to meet the current needs of the conductive printing industry.

[0045] The particle-free conductive ink composition is a stable formulation capable of depositing pure platinum metal on a variety of substrates at temperatures as low as 150°C or even lower. Most commercially produced conductive inks are specifically designed for inkjet, screen printing, or roll-to-roll processing methods to process large areas with fine-scale features in short time periods. These inks have different viscosities and compounding parameters. Particle-based inks are based on conductive metal particles, which are typically synthesized separately and then incorporated into the ink formulation. The resulting ink is then tailored for the specific particle process.

[0046] According to some aspects of the present disclosure, a platinum ink formulation may comprise platinum acetylacetonate as a precursor that is chelated by an amine ligand.

[0047] According to another aspect of the present disclosure, a platinum ink formulation can comprise a platinum complex combined with formic acid.

[0048] According to yet another aspect of the present disclosure, there is provided a particle-free conductive ink composition comprising platinum metal, a first bidentate complexing agent, and a solvent. The particle-free conductive ink composition preferably forms a conductive metal film upon curing at 250° C. or less. In a preferred embodiment, the platinum metal is platinum(II) metal ion.

[0049] As will be understood by those skilled in the art, a bidentate complexing agent is a ligand that contains two donor groups that can be bonded to the central metal atom in a coordination complex. In this composition, the central metal atom is a platinum metal atom, and the first bidentate complexing agent contains at least two heteroatoms. In a specific embodiment, the at least two heteroatoms of the first bidentate complexing agent are at least two nitrogen atoms, at least two oxygen atoms, or at least a nitrogen atom and at least an oxygen atom.

[0050] In some embodiments, the first bidentate complexing agent of the particle-free conductive ink composition is an amine-containing organic complexing agent. In some embodiments, the amine-containing organic complexing agent can be a C3-C8 alkylamine ligand. In other embodiments, the amine-containing organic complexing agent can be a primary aminoether ligand. In yet other embodiments, the amine-containing organic complexing agent can be a primary C3-C8 aminoether ligand. In a specific embodiment, the amine-containing organic complexing agent can be 2-methoxyethylamine.

[0051] The catalysts used in the present conductive ink compositions are ideally suited for use on an industrial scale in mass production. In some embodiments, it may therefore be advantageous for the solvent to be non-toxic to the environment and / or less harmful than is the case for many commonly used organic solvents. In some embodiments, it may also be advantageous for the solvent to have a higher flash point than is the case for many commonly used organic solvents. In some embodiments, it may also be advantageous for the solvent to be subject to less regulation than is the case for many commonly used organic solvents. For example, aromatic hydrocarbons such as xylene, toluene, mesitylene, and the like are highly regulated in most industrialized countries. Alternatives to these solvents may therefore be advantageous. Additionally, conductive inks formulated from aromatic hydrocarbons can have flash points below 60° C. and therefore typically unacceptable in mass production environments. Thus, in some embodiments, the solvent of the present conductive ink composition does not comprise an aromatic hydrocarbon, while in other embodiments, the solvent may comprise an aromatic solvent such as anisole, xylene, toluene, or the like.

[0052] In some embodiments, the solvent comprises a polar aprotic solvent. More specifically, the solvent can comprise a cyclic or acyclic ether solvent.

[0053] In a more specific embodiment, the cyclic ether solvent can be a furan, such as tetrahydrofuran.

[0054] In other more specific embodiments, the acyclic ether solvent can be a glycol ether, a dialkyl ether, or an ester.

[0055] For example, glycol ethers include ethylene glycol monomethyl ether (2-methoxyethanol, CHOCHCHOH), ethylene glycol monoethyl ether (2-ethoxyethanol, CHCHOCHCHOH), ethylene glycol monopropyl ether (2-propoxyethanol, CHCHCHOCHCHOH), ethylene glycol monoisopropyl ether (2-isopropoxyethanol, (CH)CHOCHCHOH), ethylene glycol monobutyl ether (2-butoxyethanol, CHCHCHCHOCHCHOH), ethylene glycol monophenyl ether (2-phenoxyethanol, CHOCHCHOH), ethylene glycol monobenzyl ether (2-benzyloxyethanol, CCHC H2OCH2CH2OH), propylene glycol methyl ether (1-methoxy-2-propanol, CH3OCH2CH(OH)CH3), diethylene glycol monomethyl ether (2-(2-methoxyethoxy)ethanol, methyl carbitol, CH3OCH2CH2OCH2CH2OH), diethylene glycol monoethyl ether (2-(2-ethoxyethoxy)ethanol, carbitol cellosolve, CH3CH2OCH2CH2OCH2CH2OH), diethylene glycol mono-n-butyl ether (2-(2-butoxyethoxy)ethanol, butyl carbitol, CH3CH2CH2CH2OCH2CH2OCH2CH2OH), dipropylene glycol methyl ether (CH3O(CH2CH(CH3)O)2H), or C12-15 Pareth-12 (CH3(CH2) n -(CH2CH2O) m -H (n=11-14 and m=12) (ethoxylated C 12-15(also called alcohol).

[0056] For example, the dialkyl ether can be ethylene glycol dimethyl ether (dimethoxyethane, CH3OCH2CH2OCH3), ethylene glycol diethyl ether (diethoxyethane, CH3CH2OCH2CH2OCH2CH3), or ethylene glycol dibutyl ether (dibutoxyethane, CH3CH2CH2CH2OCH2CH2OCH2CH2CH2CH3).

[0057] For example, the ester can be ethylene glycol methyl ether acetate (2-methoxyethyl acetate, CHOCHCHOCOCH), ethylene glycol monoethyl ether acetate (2-ethoxyethyl acetate, CHCHOCHCHOCOCH), ethylene glycol monobutyl ether acetate (2-butoxyethyl acetate, CHCHCHCHOCHCHOCOCH), or propylene glycol methyl ether acetate (1-methoxy-2-propanol acetate).

[0058] Other glycols suitable for inclusion in the present particle-free conductive ink composition include 1,2-propylene glycol, 1,3-propylene glycol, or a combination thereof.

[0059] In some embodiments, the solvent comprises water.

[0060] In some embodiments, the solvent comprises a terpene, a terpenoid, or a combination thereof. For example, in some embodiments, the solvent comprises pinene, limonene, particularly D-limonene, terpineol, or a combination thereof. In preferred embodiments, the solvent comprises limonene. In other preferred embodiments, the solvent comprises terpineol. In yet other preferred embodiments, the solvent comprises a combination of limonene and terpineol.

[0061] Not all terpenes and terpenoids may be suitable for use in the conductive ink compositions of the present disclosure. For example, in some embodiments, the solvent does not comprise alpha-terpinene, gamma-terpinene, terpinolene, or terpene-4-ol. Alternatively, or in addition, in some embodiments, it may be advantageous for the solvent to be in a purified form. For example, in some embodiments, the solvent is purified terpineol, purified limonene, or a combination of purified terpineol and purified limonene. A purified solvent is understood to be at least 95% pure, at least 97% pure, at least 98% pure, at least 99% pure, or even more pure.

[0062] In some embodiments, the conductive ink composition further comprises a second bidentate complexing agent. As is true for the first bidentate complexing agent, the second bidentate complexing agent comprises at least two heteroatoms. In specific embodiments, the at least two heteroatoms of the second bidentate complexing agent are at least two nitrogen atoms, at least two oxygen atoms, or at least a nitrogen atom and at least an oxygen atom.

[0063] In some embodiments, the second bidentate complexing agent comprises a ketone. In specific embodiments, the second bidentate complexing agent is a β-diketone. Even more specifically, the β-diketone is acetylacetonate.

[0064] In some embodiments, the conductive ink composition further comprises a reducing ligand. More specifically, the reducing ligand can be an organic acid, such as formic acid.

[0065] Conductive ink compositions can possess short viscosities that make them compatible with a wide range of patterning techniques, including slot die coating, spin coating, roll-to-roll printing (including gravure, flexography, and rotary screen printing), screen printing, aerosol jet printing, inkjet printing, airbrushing, Mayer rod coating, flood coating, 3D printing, and electrohydrodynamic printing. In particular, the inks are compatible with inkjet printing, dip coating, and spray coating. The patterned features can be highly conductive at room temperature and can achieve bulk conductivity upon decomposition at warm temperatures (e.g., in some cases below about 100°C). Finally, the ink compositions can remain stable at room temperature for several months without particle precipitation.

[0066] Thus, conductive ink compositions (also referred to as "conductive inks" or "inks") have been created for printing highly conductive features at low temperatures. Such inks are stable, particle-free, and can be suitable for a wide range of patterning techniques. In some embodiments, a "particle-free" ink is one that does not contain any particles with a diameter greater than about 10 nm. In some embodiments, a "particle-free" ink is one that has less than about 1% particles, preferably less than about 0.1% particles. Platinum salts are employed in the inks as precursor materials, which ultimately result in platinum in the platinum coating, lines, or patterns of structures formed in the printing process.

[0067] In some embodiments, the particle-free platinum ink composition is configured for application to a substrate. In some embodiments, the particle-free platinum ink composition is capable of converting to a conductive platinum structure at a temperature of about 250° C. or less. In some embodiments, the particle-free platinum ink composition is capable of converting to a conductive platinum structure at a temperature of 100° C. or less. In some embodiments, the particle-free platinum ink composition can be converted to a conductive platinum structure at temperatures of about 220°C or less, about 210°C or less, about 190°C or less, about 180°C or less, about 170°C or less, about 160°C or less, about 150°C or less, about 140°C or less, about 130°C or less, about 120°C or less, about 110°C or less, about 90°C or less, about 80°C or less, about 70°C or less, about 60°C or less, or even about 50°C or less.

[0068] In some embodiments, the particle-free platinum conductive ink composition has a platinum concentration of about 1 to about 50 percent by weight of the conductive ink composition. In some embodiments, the particle-free platinum conductive ink composition has a platinum concentration of about 1 to about 40 percent by weight of the conductive ink composition. In some embodiments, the particle-free platinum conductive ink composition has a platinum concentration of about 1 to about 30 percent by weight of the conductive ink composition. In some embodiments, the particle-free platinum conductive ink composition has a platinum concentration of about 1 to about 20 percent by weight of the conductive ink composition. In some embodiments, the particle-free platinum conductive ink composition has a platinum concentration of about 1 to about 10 percent by weight of the conductive ink composition. In some embodiments, the particle-free platinum conductive ink composition has a platinum concentration of about 5 to about 15 percent by weight of the conductive ink composition. In some embodiments, the particle-free platinum conductive ink composition comprises about 1 weight percent, about 2 weight percent, about 3 weight percent, about 4 weight percent, about 5 weight percent, about 6 weight percent, about 7 weight percent, about 8 weight percent, about 9 weight percent, about 10 weight percent, about 11 weight percent, about 12 weight percent, about 13 weight percent, about 14 weight percent, about 15 weight percent, about 16 weight percent, about 17 weight percent, about 18 weight percent, about 19 weight percent, about 20 weight percent, about 21 weight percent, about 22 weight percent, about 23 weight percent, about 24 weight percent, about 25 weight percent, and having a platinum concentration of about 26 weight percent, about 27 weight percent, about 28 weight percent, about 29 weight percent, about 30 weight percent, about 31 weight percent, about 32 weight percent, about 33 weight percent, about 34 weight percent, about 35 weight percent, about 36 weight percent, about 37 weight percent, about 38 weight percent, about 39 weight percent, about 40 weight percent, about 41 weight percent, about 42 weight percent, about 43 weight percent, about 44 weight percent, about 45 weight percent, about 46 weight percent, about 47 weight percent, about 48 weight percent, about 49 weight percent, about 50 weight percent, or even higher weight percent.

[0069] In some embodiments, the particle-free platinum conductive ink composition of the present disclosure has a desired viscosity. In some embodiments, the desired viscosity is obtained using a micro-VISC viscometer. In some embodiments, the viscosity is measured at room temperature, such as at or about 22°C. In some embodiments, the conductive ink composition has a viscosity of about 50 centipoise to about 1,000 centipoise. In some embodiments, the conductive ink composition has a viscosity of about 0.5 centipoise to about 50 centipoise. In some embodiments, the conductive ink composition has a viscosity of about 1.0 centipoise to about 40 centipoise. In some embodiments, the conductive ink composition has a viscosity of about 2 centipoise to about 30 centipoise. In some embodiments, the conductive ink composition has a viscosity of about 0.5 centipoise to about 10 centipoise. In some embodiments, the conductive ink composition has a viscosity of about 1.0, about 2.0, or about 3.0 centipoise. In some embodiments, the conductive ink composition has a viscosity of at least about 0.5 centipoise, about 1.0 centipoise, about 2.0 centipoise, about 3.0 centipoise, about 4.0 centipoise, about 5.0 centipoise, about 6.0 centipoise, about 7.0 centipoise, about 8.0 centipoise, about 9.0 centipoise, about 10.0 centipoise, about 20.0 centipoise, about 30.0 centipoise, about 40.0 centipoise, about 50.0 centipoise, about 60.0 centipoise, about 70.0 centipoise, about 80.0 centipoise, or about 90.0 centipoise. In some embodiments, the conductive ink composition has a viscosity of at most about 100.0 centipoise, about 90.0 centipoise, about 80.0 centipoise, about 70.0 centipoise, about 60.0 centipoise, about 50.0 centipoise, about 40.0 centipoise, about 30.0 centipoise, about 20.0 centipoise, about 10.0 centipoise, about 9.0 centipoise, about 8.0 centipoise, about 7.0 centipoise, about 6.0 centipoise, about 5.0 centipoise, about 4.0 centipoise, about 3.0 centipoise, about 2.0 centipoise, or about 1.0 centipoise.

[0070] In some embodiments, the conductive ink composition has a viscosity of 0.8 to 1.3 centipoise at 22°C.

[0071] Methods for forming conductive structures In another aspect, a method of making a conductive structure, such as a conductive platinum film, is disclosed. In some embodiments, the method includes applying any of the conductive ink compositions described above to a substrate. In some embodiments, the method includes heating the conductive ink composition on the substrate at a decomposition temperature of about 250° C. or less to form the conductive structure. In some embodiments, the method includes heating the conductive ink composition on the substrate at a decomposition temperature of about 220°C or less, about 200°C or less, about 190°C, about 180°C or less, about 170°C or less, about 160°C, about 150°C or less, about 140°C or less, about 130°C or less, about 120°C or less, about 110°C or less, about 90°C or less, about 80°C or less, about 70°C or less, about 60°C or less, or about 50°C or less to form the conductive structure. In some embodiments, the conductive ink composition is heated using a heat source. Examples of heat sources include IR lamps, an oven, or a heated substrate.

[0072] In some embodiments, the conductivity of a conductive structure formed from the conductive ink composition is measured. In some embodiments, the conductivity of the conductive structure is measured to be about 2×10 -6 ohm-cm ~ approx. 1 × 10 -5 In some embodiments, the conductivity of the conductive structure is about 3×10 -6 ohm-cm ~ approx. 6 × 10 -6 In some embodiments, the conductivity of the conductive structure is at least about 2×10 -6 ohm-cm, approximately 3 × 10 -6 ohm-cm, approximately 4 × 10 -6 ohm-cm, approximately 5 × 10-6 ohm-cm, approximately 6 × 10 -6 ohm-cm, approximately 7 × 10 -6 ohm-cm, approximately 8 × 10 -6 ohm-cm, or approximately 9 × 10 -6 In some embodiments, the conductivity of the conductive structure is at most about 1×10 -5 ohm-cm, approximately 9 × 10 -6 ohm-cm, approximately 8 × 10 -6 ohm-cm, approximately 7 × 10 -6 ohm-cm, approximately 6 × 10 -6 ohm-cm, approximately 5 × 10 -6 ohm-cm, approximately 4 × 10 -6 ohm-cm, or approximately 3 × 10 -6 It is ohm-cm.

[0073] The conductivity of a conductive structure, in some embodiments, can be expressed in terms of sheet resistance (i.e., bulk resistivity divided by thickness) in units of ohms per square (also referred to as ohms / square or OPS). For example, in some embodiments, the resistance of a conductive structure is 5 ohms per square or less, 2 ohms per square or less, 1 ohm per square or less, 0.5 ohms per square or less, or even lower. Preferably, the resistance of a conductive structure is 1 ohm per square or less.

[0074] The conductive ink compositions of the present disclosure can be used to form conductive structures with high levels of bulk platinum. Specifically, in some embodiments, the conductive structures have a bulk platinum content of at least 1%. In more specific embodiments, the conductive structures have a bulk platinum content of at least 2%, at least 5%, at least 10%, at least 15%, at least 20%, or even higher.

[0075] (Application of Conductive Ink Composition) The conductive ink compositions of the present disclosure can be used in a variety of printing applications, including slot die coating, spin coating, roll-to-roll printing (including gravure, flexography, and rotary screen printing), screen printing, aerosol jet printing, inkjet printing, airbrushing, Mayer rod coating, flood coating, 3D printing, dispensers, and electrohydrodynamic printing. In particular, the inks can be used in inkjet printing, dip coating, and spray coating.

[0076] Additionally, patterns can be created using photolithography to create a mask and etch the silver from an area, thereby creating high fidelity features. Both positive and negative patterning processes may be used to create the patterns.

[0077] In some embodiments, the particle-free platinum conductive ink composition is applied to a polymer substrate. In some embodiments, the particle-free platinum conductive ink composition is applied to a non-polar polymer substrate. In some embodiments, the particle-free platinum conductive ink composition is applied to a glass substrate. In some embodiments, the particle-free platinum conductive ink composition is applied to a ceramic substrate.

[0078] Additionally, elastomers and particularly 3D substrates with non-planar structural features can be used in conjunction with the conductive structures. In some embodiments, the particle-free platinum conductive ink composition is applied to an elastomer. In some embodiments, the particle-free platinum conductive ink composition is applied to a 3D substrate.

[0079] In some embodiments, the particle-free platinum conductive ink composition of the present method has a platinum concentration of about 0.1 to 50 percent by weight of the ink composition. In some embodiments, the particle-free platinum conductive ink composition of the present method has a platinum concentration of about 0.1 to 40 percent by weight of the ink composition. In some embodiments, the ink composition has a platinum concentration of about 1 to 30 percent by weight of the ink composition. In some embodiments, the ink composition has a platinum concentration of about 1 to 20 percent by weight of the ink composition. In some embodiments, the ink composition has a platinum concentration of about 1 to 10 percent by weight of the ink composition. In some embodiments, the ink composition has a platinum concentration of about 5 to 15 percent by weight of the ink composition. In some embodiments, the ink composition has a platinum concentration of about 0.1 weight percent, about 0.2 weight percent, about 0.3 weight percent, about 0.4 weight percent, about 0.5 weight percent, about 0.6 weight percent, about 0.7 weight percent, about 0.8 weight percent, about 0.9 weight percent, about 1 weight percent, about 2 weight percent, about 3 weight percent, about 4 weight percent, about 5 weight percent, about 6 weight percent, about 7 weight percent, about 8 weight percent, about 9 weight percent, about 10 weight percent, about 11 weight percent, about 12 weight percent, about 13 weight percent, about 14 weight percent, about 15 weight percent, about 16 weight percent, about 17 weight percent, about 18 weight percent, about 19 weight percent, or about 20 weight percent of the ink composition.

[0080] In some embodiments, the ink composition of the present method has a concentration of metal salt of at least about 0.1 weight percent, about 0.2 weight percent, about 0.3 weight percent, about 0.4 weight percent, about 0.5 weight percent, about 0.6 weight percent, about 0.7 weight percent, about 0.8 weight percent, about 0.9 weight percent, 1 weight percent, about 2 weight percent, about 3 weight percent, about 4 weight percent, about 5 weight percent, about 6 weight percent, about 7 weight percent, about 8 weight percent, about 9 weight percent, about 10 weight percent, about 11 weight percent, about 12 weight percent, about 13 weight percent, about 14 weight percent, about 15 weight percent, about 16 weight percent, about 17 weight percent, about 18 weight percent, about 19 weight percent, or about 20 weight percent of the ink composition. In some embodiments, the ink composition has a platinum concentration of up to about 40 weight percent, about 39 weight percent, about 38 weight percent, about 37 weight percent, about 36 weight percent, about 35 weight percent, about 34 weight percent, about 33 weight percent, about 32 weight percent, 31 weight percent, about 30 weight percent, about 29 weight percent, about 28 weight percent, about 27 weight percent, about 26 weight percent, about 25 weight percent, about 24 weight percent, about 23 weight percent, about 22 weight percent, about 21 weight percent, about 20 weight percent, about 19 weight percent, about 18 weight percent, about 17 weight percent, about 16 weight percent, about 15 weight percent, about 14 weight percent, about 13 weight percent, or about 12 weight percent of the ink composition.

[0081] In some embodiments, the ink composition of the present method has a platinum concentration of about 0.1 to 50 percent by weight of the ink composition. In some embodiments, the ink composition of the present method has a platinum concentration of about 0.1 to 40 percent by weight of the ink composition. In some embodiments, the ink composition has a platinum concentration of about 1 to 30 percent by weight of the ink composition. In some embodiments, the ink composition has a platinum concentration of about 1 to 20 percent by weight of the ink composition. In some embodiments, the ink composition has a platinum concentration of about 1 to 10 percent by weight of the ink composition. In some embodiments, the ink composition has a platinum concentration of about 5 to 15 percent by weight of the ink composition. In some embodiments, the ink composition has a platinum concentration of about 0.1 weight percent, about 0.2 weight percent, about 0.3 weight percent, about 0.4 weight percent, about 0.5 weight percent, about 0.6 weight percent, about 0.7 weight percent, about 0.8 weight percent, about 0.9 weight percent, 1 weight percent, about 2 weight percent, about 3 weight percent, about 4 weight percent, about 5 weight percent, about 6 weight percent, about 7 weight percent, about 8 weight percent, about 9 weight percent, about 10 weight percent, about 11 weight percent, about 12 weight percent, about 13 weight percent, about 14 weight percent, about 15 weight percent, about 16 weight percent, about 17 weight percent, about 18 weight percent, about 19 weight percent, or about 20 weight percent of the ink composition.

[0082] (decomposition) In another aspect, the particle-free platinum conductive ink composition of the present disclosure is decomposed on a substrate to form conductive structures on the substrate, hi some embodiments, the particle-free platinum conductive ink composition is decomposed by heating the composition at a temperature of about 270°C or less. In some embodiments, the conductive ink composition is decomposed by heating the composition at a temperature of about 260° C. or less, about 250° C. or less, about 240° C. or less, about 230° C. or less, about 220° C. or less, about 210° C. or less, about 200° C. or less, about 190° C. or less, about 180° C. or less, about 170° C. or less, about 160° C. or less, about 150° C. or less, about 140° C. or less, about 130° C. or less, about 120° C. or less, about 110° C. or less, about 100° C. or less, about 90° C. or less, about 80° C. or less, or about 70° C. In some embodiments, the conductive ink composition is heated by a heat source. Examples of heat sources include an IR lamp, an oven, or a heated substrate.

[0083] In some embodiments, the conductive ink composition is decomposed by exposing the composition to a light source at a wavelength of about 100 nm to about 1,500 nm. In some embodiments, the conductive ink composition is decomposed by exposing the composition to a light source at a wavelength of about 100 nm to about 1,000 nm, such as a xenon lamp or an IR lamp. In some embodiments, the conductive ink composition is decomposed by exposing the composition to a light source at a wavelength of about 100 nm to about 700 nm. In some embodiments, the conductive ink composition is decomposed by exposing the composition to a light source at a wavelength of about 100 nm to about 500 nm. In some embodiments, the conductive ink composition is decomposed by exposing the composition to a light source at a wavelength of about 100 nm to about 300 nm. In some embodiments, the conductive ink composition is degraded by exposing the composition to a light source at a wavelength of about 100 nm, about 200 nm, about 300 nm, about 400 nm, about 500 nm, about 600 nm, about 700 nm, about 800 nm, about 900 nm, or about 1,000 nm.

[0084] In some embodiments, the conductive ink composition is decomposed by a combination of heating the reducible metal complex, e.g., at any of the temperatures listed above, and exposing the composition to a light source, e.g., at any of the wavelengths listed above.

[0085] In some embodiments, the conductivity of the conductive structure is measured. In some embodiments, the conductivity of the conductive structure is measured to be about 1×10 -6 In some embodiments, the conductivity of the conductive structure is about 1×10 ohm-cm or greater. -6 ohm-cm ~ approx. 8 × 10 -4 In some embodiments, the conductivity of the conductive structure is about 3×10 -6 ohm-cm ~ approx. 6 × 10 -6 In some embodiments, the conductivity of the conductive structure is at least about 1×10 -6 ohm-cm, approximately 2 × 10 -6 ohm-cm, approximately 3 × 10-6 ohm-cm, approximately 4 × 10 -6 ohm-cm, approximately 5 × 10 -6 ohm-cm, approximately 6 × 10 -6 ohm-cm, approximately 7 × 10 -6 ohm-cm, approximately 8 × 10 -6 ohm-cm, approximately 9 × 10 -6 ohm-cm, approximately 1 x 10 -5 ohm-cm, approximately 2 × 10 -5 ohm-cm, approximately 3 × 10 -5 ohm-cm, approximately 4 × 10 -5 ohm-cm, approximately 5 × 10 -5 ohm-cm, approximately 6 × 10 -5 ohm-cm, approximately 7 × 10 -5 ohm-cm, approximately 8 × 10 -5 ohm-cm, approximately 9 × 10 -5 ohm-cm, approximately 1 x 10 -4 ohm-cm, approximately 2 × 10 -4 ohm-cm, approximately 3 × 10 -4 ohm-cm, approximately 4 × 10 -4 ohm-cm, approximately 5 × 10 -4 ohm-cm, approximately 6 × 10 -4 ohm-cm, or approximately 7 × 10 -4 In some embodiments, the conductivity of the conductive structure is at most about 8×10 -4 ohm-cm, 7 × 10 -4 ohm-cm, approximately 6 × 10 -4 ohm-cm, approximately 5 × 10 -4 ohm-cm, approximately 4 × 10 -4 ohm-cm, approximately 3 × 10 -4 ohm-cm, approximately 2 × 10 -4 ohm-cm, or approximately 1×10 -4 ohm-cm, approximately 9 × 10 -5 ohm-cm, approximately 8 × 10 -5 ohm-cm, approximately 7 × 10 -5 ohm-cm, approximately 6 × 10 -5 ohm-cm, approximately 5 × 10 -5 ohm-cm, approximately 4 × 10 -5 ohm-cm, approximately 3 × 10 -5 ohm-cm, approximately 2 × 10 -5ohm-cm, approximately 1 x 10 -5 ohm-cm, approximately 9 × 10 -6 ohm-cm, approximately 8 × 10 -6 ohm-cm, approximately 7 × 10 -6 ohm-cm, approximately 6 × 10 -6 ohm-cm, approximately 5 × 10 -6 ohm-cm, approximately 4 × 10 -6 ohm-cm, approximately 3 × 10 -6 ohm-cm, or approximately 2 × 10 -6 It is ohm-cm.

[0086] (Application of ink composition) The ink compositions of the present disclosure can be used in a variety of printing applications, including slot die coating, spin coating, roll-to-roll printing (including gravure, flexography, and rotary screen printing), screen printing, aerosol jet printing, inkjet printing, airbrushing, Mayer rod coating, flood coating, 3D printing, and electrohydrodynamic printing. In particular, the inks can be used in inkjet printing, dip coating, and spray coating. Additionally, patterns can be generated using photolithography to create masks and etch platinum from certain areas, thereby creating high-fidelity features.

[0087] In a preferred embodiment, the ink composition is used to print conductive structures comprising platinum metal in an aerosol jet printing application. This method, also known as maskless mesoscale material deposition (M3D) (see, e.g., U.S. Pat. No. 7,485,345), involves atomization of a particle-free ink composition via ultrasonic or pneumatic techniques to generate micrometer-scale droplets. The aerosolized ink is combined with a carrier gas and directed through a flow head onto a substrate where the ink ultimately hardens into conductive structures.

[0088] In some embodiments, the ink composition is compatible with many non-polar polymeric, glass, and ceramic substrates that polar complexes do not wet very well. In some embodiments, the ink composition is applied to a polymeric substrate. In some embodiments, the ink composition is applied to a non-polar polymeric substrate. In some embodiments, the ink composition is applied to a glass substrate. In some embodiments, the ink composition is applied to a ceramic substrate.

[0089] Additionally, elastomers and particularly 3D substrates with non-planar structural features can be used in conjunction with conductive structures. In some embodiments, the ink composition is applied to an elastomer. In some embodiments, the ink composition is applied to a 3D substrate.

[0090] It will be readily apparent to those skilled in the art that other suitable modifications and adaptations to the compositions and methods described herein can also be made without departing from the scope of the invention or any embodiment thereof. Having now described the invention in detail, the same will be more clearly understood by reference to the following examples, which are included herein for illustrative purposes only and are not intended to be limiting of the invention.

[0091] (Example) Characterization of Porous Platinum Ink Formulations and Corresponding Films 1.500 grams (5.000 mmol) of tetraamineplatinum(II) hydroxide hydrate (Pt(NH2)4(OH)2·HO) was dissolved in 4.500 grams (250.000 mmol) of water under ambient conditions and mechanically vortexed until complete solubility was achieved. Once a one-phase solution was achieved, 0.768 grams (10.093 mmol) of 1,2-propylene glycol (C3H8O2) was pipetted into the mixture via dropwise addition, followed by vortexing to ensure adequate mixing. Following a second vortexing step, an equimolar amount of 0.768 grams (10.093 mmol) of 1,3-propylene glycol (C3H8O2) was added to the resulting mixture and mechanically vortexed a third time. The final component, 0.359 grams (4.780 mmol) of 2-methoxyethylamine (CHOCHCHNH), was added to the entire solution and vortexed. A clear, colorless solution was obtained and filtered using an 8 mL Luer-lock syringe fitted with a 0.22 μm PTFE filter into a glass vial deemed suitable for ink printing characterization.

[0092] Upon depositing a 100 μL droplet onto a glass or wafer substrate, the film was heat-treated on a hotplate at 80 °C for 10 minutes, causing it to turn off-white. The film was then annealed in a binder oven at 200 °C for 30 minutes and exhibited a transition sequence from white to red to metallic gray, indicating the decomposition of the platinum complex into a metallic conductive structure. Using a multimeter for resistance measurements, the platinum film had electrical resistances of 178 to 400 ohms at diameters of 1.1 to 1.9 cm after 30 minutes, respectively. Resistivity may vary depending on the printing method and pyrolysis equipment used to characterize the porous platinum ink.

[0093] Characterization of High-Density Platinum Ink Formulations and Corresponding Films Under ambient conditions, 5.027 grams of 2-methoxyethylamine (CH3OCH2CH2NH2) was pipetted into a glass vial and 1.267 grams (8.213 mmol) of terpineol (C 10 H 18 The resulting mixture was then treated with 0.706 grams (1.800 mmol) of platinum(II) acetylacetonate (PtC5H7O2)2, resulting in a yellow, biphasic solution. The two-part stirring method required to dissolve the precursor involved 12-16 hours of ambient stirring, followed by stirring at 65°C for 2 hours. After all was said and done, the ink was a clear, red solution due to complete solvation of the platinum precursor. It was filtered using an 8 mL Luer-Lock syringe fitted with a 0.22 μm PTFE filter, and was ready for immediate ink printing demand.

[0094] Upon blade coating with a desired wet thickness of 15 μm, the ink was annealed at 230°C for 1 hour in a binder oven and at 200°C on a hot plate, exhibiting a red to black to metallic gray color transition sequence, indicating complete decomposition of the platinum complex into a native conductive platinum network. Using a four-point probe apparatus, the platinum film had an electrical sheet resistance of 19 ohms per square (OPS) after 1 hour at 230°C in a binder oven and 48 OPS after 1 hour on a hot plate at 200°C. Electrical resistance can vary depending on the printing method and pyrolysis apparatus used to characterize the high-density platinum ink.

[0095] Typical Ink Formulations with Platinum(II) Acetylacetonate, Cure Profiles, and Electrical Properties (Ink formulation method 1) 1.627 g (46 wt%) of 2-methoxyethylamine and 0.175 g (5 wt%) of terpineol were mixed under ambient conditions. The resulting mixture was then treated with 0.706 g (20 wt%) of platinum(II) acetylacetonate, resulting in a yellow suspension. The resulting mixture was then stirred under ambient conditions for 12-16 hours, followed by stirring at 65°C for 2 hours. After this period, complete dissolution of the precursor was observed. The resulting solution was passed through a 0.22 μm PTFE filter to obtain a clear, stable red solution. To this, 0.998 g (28 wt%) of 1-hexanol was added. The viscosity of the ink was determined to be 3.7 centipoise and the solids content was 10 wt%.

[0096] The prepared ink can be blade / bar coated onto various substrates, such as glass or polyimide. Alternatively, the ink can be aerosol-sprayed onto the substrate of choice depending on the application. Typical annealing methods include heating at 230°C for 1 hour in a convection oven or at 200°C on a hot plate for 1 hour. The ink leaves a smooth, reflective surface during the annealing sequence and undergoes a transition from red to black to a metallic gray color, indicating the platinum complex is converting to its metallic form. Figure 1A shows the camera reflection photographing a 3 x 2 inch glass slide coated with platinum ink using a 20 μm blade cured at 200°C for 1 hour. Using a four-point probe apparatus, the platinum film had an electrical sheet resistance of 19 ohms per square (Ω / □) after 1 hour at 230°C in a binder oven and 48 Ω / □ after 1 hour at 200°C on a hot plate. The electrical resistance can vary depending on the printing method and pyrolysis equipment used to characterize the dense platinum ink. Scanning microscope imaging of the surface (Fig. 1B, optical image at 25K magnification) and edge (Fig. 1C, SEM image at 10.5K magnification) reveals the tightly packed structure that forms the dense film.

[0097] Low-Temperature Platinum Ink Formulation with Platinum(II) Acetylacetonate and Formic Acid (Ink formulation method 2) 1.696 g (33.9 wt%) of 2-methoxyethylamine and 0.250 g (5 wt%) of terpineol were mixed under ambient conditions. The resulting mixture was then treated with 0.740 g (14.8 wt%) of platinum(II) acetylacetonate, resulting in a yellow suspension. The resulting mixture was then stirred under ambient conditions for 12-16 hours, followed by stirring at 65°C for 2 hours. After this period, complete dissolution of the precursor was observed. The resulting solution was passed through a 0.22 μm PTFE filter to obtain a clear, stable red solution. To this, 2.227 g (44.5 wt%) of 1-hexanol was added, followed by 0.087 g (1.7 wt%, 1:1 ratio with Pt) of formic acid, forming a clear solution. The viscosity of the ink was determined to be --- centipoise and ---% solids content.

[0098] The prepared ink can be blade / bar coated onto various substrates, such as glass or polyimide. Alternatively, the ink can also be aerosol-sprayed onto the substrate of choice depending on the application. The low-cure ink was blade-coated onto a glass slide and annealed inside a convection oven at 150°C for 1 hour to form a dense film of metallic platinum. Electrical resistance can vary depending on the printing method and pyrolysis equipment used to characterize the dense platinum ink.

[0099] All patents, patent publications, and other published references mentioned herein are hereby incorporated by reference in their entirety to the same extent as if each was individually and specifically incorporated by reference.

[0100] While specific examples have been provided, the above description is illustrative and not restrictive. Any one or more of the features of the above-described embodiments may be combined in any manner with one or more features of any other embodiment of the present invention. Moreover, many variations of the present invention will become apparent to those skilled in the art upon review of this specification. The scope of the present invention should therefore be determined by reference to the appended claims, along with their full scope of equivalents.

Claims

1. 1. A particle-free conductive ink composition comprising: Platinum metal, a first bidentate complexing agent; and Solvent and Equipped with A particle-free conductive ink composition, wherein the composition forms a conductive metal film upon curing at 250°C or less.

2. The particle-free conductive ink composition of claim 1 , wherein the platinum metal is platinum(II) metal ion.

3. 10. The particle-free conductive ink composition of claim 1, wherein the first bidentate complexing agent is an amine-containing organic complexing agent.

4. The amine-containing organic complexing agent is C ３ -C ８ The particle-free conductive ink composition of claim 3, wherein the ligand is an aminoether ligand.

5. The particle-free conductive ink composition of claim 3 , wherein the amine-containing organic complexing agent is a primary aminoether ligand.

6. The amine-containing organic complexing agent is a primary C ３ -C ８ The particle-free conductive ink composition of claim 3, wherein the ligand is an aminoether ligand.

7. 4. The particle-free conductive ink composition of claim 3, wherein the amine-containing organic complexing agent is 2-methoxyethylamine.

8. The particle-free conductive ink composition of claim 1 , wherein the solvent comprises a terpene, a terpenoid, or a combination thereof.

9. The particle-free conductive ink composition of claim 8 , wherein the terpene is a purified terpene or the terpenoid is a purified terpenoid.

10. The particle-free conductive ink composition of claim 8 , wherein the terpene is pinene or limonene.

11. The particle-free conductive ink composition of claim 8 , wherein the terpenoid is terpineol.

12. The particle-free conductive ink composition of claim 1 , wherein the solvent comprises water.

13. The particle-free conductive ink composition of claim 1 further comprising a second bidentate complexing agent.

14. 14. The particle-free conductive ink composition of claim 13, wherein the second bidentate complexing agent is a β-diketone.

15. 15. The particle-free conductive ink composition of claim 14, wherein the β-diketone is an acetylacetonate.

16. 16. The particle-free conductive ink composition of claim 15, wherein the first bidentate complexing agent is 2-methoxyethylamine and the solvent comprises terpineol.

17. The particle-free conductive ink composition of claim 1 further comprising a reducing ligand.

18. 18. The particle-free conductive ink composition of claim 17, wherein the reducing ligand is formic acid.

19. 20. The particle-free conductive ink composition of claim 17, further comprising a second bidentate complexing agent.

20. 20. The particle-free conductive ink composition of claim 19, wherein the second bidentate complexing agent is a β-diketone.

21. 21. The particle-free conductive ink composition of claim 20, wherein the β-diketone is an acetylacetonate.

22. 22. The particle-free conductive ink composition of claim 21, wherein the first bidentate complexing agent is 2-methoxyethylamine and the solvent comprises terpineol.

23. The particle-free conductive ink composition of claim 1 further comprising a glycol.

24. 24. The particle-free conductive ink composition of claim 23, wherein the glycol is 1,2-propylene glycol, 1,3-propylene glycol, or a combination thereof.

25. 25. The particle-free conductive ink composition of claim 24, wherein the first bidentate complexing agent is 2-methoxyethylamine and the solvent comprises water.

26. 26. The particle-free conductive ink composition of any one of claims 1-25, wherein the composition forms a conductive metal film upon curing at 250°C or less.

27. 27. The particle-free conductive ink composition of claim 26, wherein the composition forms a conductive metal film upon curing at 200°C or less.

28. The particle-free conductive ink composition of any one of claims 1-25, wherein the conductive metal film exhibits a conductivity of at least 1% of the bulk metal conductivity.

29. 1. A method of forming a conductive film, comprising: Providing a particle-free conductive ink composition according to any one of claims 1 to 25; applying the composition to a substrate; curing the composition at an elevated temperature to form the conductive film; A method comprising:

30. 30. The method of claim 29, wherein the applying step comprises printing.

31. The method of claim 30, wherein the printing is jet printing.

32. The method of claim 31 , wherein the jet printing is aerosol jet printing.

33. 30. The method of claim 29, wherein the curing step occurs at 250°C or less.

34. 34. The method of claim 33, wherein the curing step occurs at 200°C or less.

35. 26. A conductive film formed by applying the particle-free conductive ink composition of any one of claims 1 to 25 to a substrate and curing the composition at 250°C or less to form the conductive film.

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