Transparent Metal Nanowire Networks With Halide Fusing
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Solution Overview
Problem
Current transparent conductive materials, such as indium tin oxide (ITO), face challenges including brittleness, high temperature deposition requirements, and cost inefficiencies, while alternative metal-grid solutions are costly and difficult to scale due to their reliance on patterning approaches like photolithography.
Innovation Solution
The development of a precursor ink containing metal nanowires, specifically silver nanowires, which are fused using halide anions to form sintered networks with low sheet resistance and high transparency, enabling the creation of transparent conductive films suitable for various applications without the need for high-temperature processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ITO is used as transparent conductor, then high transparency and conductivity are achieved, but brittleness and high temperature deposition requirements worsen
Solution Approach 1:
The patent changes the material parameters from ceramic ITO to metal nanowire networks, fundamentally altering the physical and chemical properties. This enables achieving similar electrical conductivity and transparency while eliminating brittleness and enabling flexibility on polymer substrates
Solution Approach 2:
The patent uses composite metal nanowire networks embedded in transparent polymer matrices, combining the electrical conductivity of metals with the flexibility and processability of polymers, thereby achieving both high transparency/conductivity and mechanical flexibility
2Reliability
If ITO is deposited using sputtering, then high transparency and conductivity are achieved, but high temperatures and vacuum requirements worsen manufacturing efficiency
Solution Approach 1:
The patent replaces the mechanical/physical sputtering process with a chemical solution-based approach. Metal nanowires are deposited from liquid precursors at room temperature, eliminating the need for vacuum equipment and high-temperature processing, thereby dramatically improving productivity and reducing costs
Solution Approach 2:
The patent changes the deposition parameters from high-temperature vacuum sputtering to room-temperature solution processing, fundamentally altering the manufacturing conditions to enable faster, cheaper, and more scalable production
3Reliability
If metal-grid solutions are used, then conductivity is improved, but cost and manufacturing complexity worsen due to photolithography requirements
Solution Approach 1:
The patent replaces the complex photolithography and patterning processes with direct solution-based deposition of nanowire networks. The nanowires self-assemble into conductive networks without requiring photoresists, etching, or cleanroom facilities, dramatically simplifying manufacturing
Solution Approach 2:
The patent changes the manufacturing parameters from multi-step photolithography processes to single-step solution deposition, eliminating the need for expensive equipment and complex process control, thereby reducing costs and improving scalability
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
The resulting sintered metal nanowire networks achieve simultaneously low sheet resistance and high optical transparency, making them suitable for a range of applications including touch sensors and displays, with improved conductivity and cost-effectiveness compared to traditional methods.
Implementation Method 1
chemical methods for fusing the nanowires to form networks
Implementation Method 2
silver nanowires can have an average diameter of no more than about 75 nm and a length of at least about 5 microns
Implementation Method 3
transparency to visible light of at least about 90%
Data Source
AI summary
Metal nanowires, such as silver nanowires coated on a substrate were sintered together to form fused metal nanowire networks that have greatly improved conductivity while maintaining good transparency and low haze. The method of forming such a fused metal nanowire networks are disclosed that involves exposure of metal nanowires to various fusing agents on a short timescale. The resulting sintered network can have a core-shell structure in which metal halide forms the shell. Additionally, effective methods are described for forming patterned structure with areas of sintered metal nanowire network with high conductivity and areas of un-sintered metal nanowires with low conductivity. The corresponding patterned films are also described. When formed into a film, materials comprising the metal nanowire network demonstrate low sheet resistance while maintaining desirably high levels of optical transparency with low haze, making them suitable for transparent electrode, touch sensors, and other electronic/optical device formation.