Photosensitive Silver Complexes for Room-Temperature Conductive Patterns

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Solution Overview

Problem

Current methods for fabricating electrically-conductive silver patterns and grids in electronic devices are time-consuming and expensive, particularly when using nanoparticle-based inks, and require high-temperature sintering processes that are not compatible with polymeric substrates, limiting their application in flexible electronics.

Innovation Solution

A non-hydroxylic-solvent soluble silver complex comprising reducible silver ions complexed with an α-oxy carboxylate and a 5- or 6-membered N-heteroaromatic compound, which can be photochemically converted to electrically-conductive silver metal at room temperature using a photosensitizer and electromagnetic radiation, allowing for rapid and flexible deposition on various substrates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If nanoparticle-based inks are used for fabricating electrically-conductive silver patterns, then electrical conductivity is improved, but manufacturing cost and process time increase

Engineering Contradiction:
Improveelectrical conductivityVSAvoidmanufacturing cost and process time
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent changes the chemical parameters of the silver source from pre-formed nanoparticles to molecular silver complexes. This allows the silver to be deposited and reduced in-situ during printing, eliminating the need for separate sintering processes and reducing manufacturing steps while maintaining electrical conductivity.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent extracts the sintering step from the manufacturing process by using molecular silver complexes that can be directly reduced to conductive silver metal upon printing and exposure, eliminating the need for high-temperature sintering that is required for nanoparticle-based inks.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If high-temperature sintering is used to process nanoparticle inks, then electrical conductivity is improved, but substrate compatibility deteriorates

Engineering Contradiction:
Improveelectrical conductivityVSAvoidsubstrate compatibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes the processing temperature parameter from high-temperature sintering to room temperature or low-temperature processing by using photosensitive molecular silver complexes. This allows the use of temperature-sensitive polymeric substrates while still achieving electrically conductive silver patterns.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the thermal sintering mechanism with a photochemical reduction mechanism. Instead of using heat to fuse nanoparticles, the invention uses light exposure to reduce molecular silver complexes directly to conductive silver metal, enabling processing on heat-sensitive substrates.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Stability of the object's composition

If thiolate encapsulating surfactants are used to prevent aggregation in silver nanoparticle inks, then particle stability is improved, but sintering temperature requirement increases

Engineering Contradiction:
Improveparticle stabilityVSAvoidsintering temperature
Core Design Contradiction:
Stability of the object's compositionVSTemperature

Solution Approach 1:

The patent extracts the surfactant encapsulation step by using molecular silver complexes that do not require stabilizing agents. The silver complexes are inherently stable in solution and can be directly reduced to metal without needing surfactants, thereby eliminating the need for high-temperature sintering to remove surfactants.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the chemical form of silver from encapsulated nanoparticles to molecular complexes, fundamentally altering the stability mechanism. The molecular complexes achieve stability through coordination chemistry rather than surfactant encapsulation, allowing direct reduction at low temperatures.

Inventive Principle:
Principle #35Parameter changes

4Reliability

If silver halide emulsions are used for photolithographic fabrication, then electrical conductivity is improved, but manufacturing complexity and cost increase

Engineering Contradiction:
Improveelectrical conductivityVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the complex multi-step photolithographic processing by using directly printable molecular silver complexes. The invention combines the silver source, binder, and curing mechanism into a single printable composition that forms conductive patterns in one step upon printing and exposure, eliminating the need for separate emulsion coating, exposure, development, and rinsing steps.

Inventive Principle:
Principle #2Taking out (Extraction)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables the rapid generation of electrically-conductive silver metal at room temperature, reducing manufacturing costs and expanding substrate compatibility, including polymers, metals, and glass, with improved stability and controllable chemical activity, suitable for various printing techniques.

Implementation Method 1

photochemically converted to electrically-conductive silver metal at room temperature using a photosensitizer and electromagnetic radiation

Methodology Applied
Scientific EffectPhotochemical conversion: Photopolymerisation

Data Source

PatentEP3496951B1Silver ion carboxylate n-heteroaromatic complexes and uses
Publication Date: 2021.06.23 EASTMAN KODAK CO
  • EP3496951B1 patent drawingFigure 1
  • EP3496951B1 patent drawingFigure 2
  • EP3496951B1 patent drawingFigure 3

AI summary

A non-hydroxylic-solvent soluble silver complex comprises a reducible silver ion complexed with an α-oxy carboxylate and a 5- or 6-membered N- heteroaromatic compound. The non-hydroxylic-solvent soluble silver complex can be represented by the following formula (I): (Ag+) a (L) b (P) c (I) wherein L represents the a-oxy carboxylate; P represents the 5- or 6-membered N- heteroaromatic compound; a is 1 or 2; b is 1 or 2; and c is 1, 2, 3, or 4, provided that when a is 1, b is 1, and when a is 2, b is 2. Such complexes can be incorporated into photosensitive compositions that are then used to provide photosensitive thin films or photosensitive thin film patterns in various precursor and product articles. The reducible silver ions can be quickly and efficiently reduced to electrically-conductive silver metal upon exposure to UV-visible radiation in various methods.