Low-Haze Transparent Conductors via Nanowire Morphology Control
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Solution Overview
Problem
Existing transparent conductors face challenges in achieving low haze levels while maintaining high electrical conductivity, particularly in applications like touch-panels and displays, where haze levels below 2% are required, often making satisfactory conductivity impossible.
Innovation Solution
The development of low-haze transparent conductors with a haze of less than 1.5% is achieved by controlling the size distribution profile and particle morphology of conductive nanostructures, specifically through a two-phase synthesis method that separately promotes radial and axial growth of nanowires, allowing for precise control of diameter and length, resulting in nanostructures with aspect ratios of 10 or more, and a narrow diameter distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of conductive nanostructures is increased to improve electrical conductivity, then sheet resistance decreases, but haze level increases
Solution Approach 1:
The patent changes the physical parameters of the conductive nanostructures, specifically controlling their diameter to 30-50 nm and aspect ratio to 10 or more. This parameter optimization allows the nanostructures to maintain electrical conductivity while minimizing light scattering, thus reducing haze. The specific diameter range and aspect ratio are critical parameters that resolve the contradiction between conductivity and optical clarity.
Solution Approach 2:
The patent applies local quality by creating a size-distributed population of nanostructures where smaller diameter structures (30-50 nm) dominate. This local optimization of nanostructure dimensions in specific regions of the size distribution enables low haze while maintaining sufficient conductivity through the optimized aspect ratio of the remaining structures.
2Object-affected harmful factors
If the number of conductive nanostructures is decreased to reduce haze level, then optical clarity improves, but sheet resistance increases
Solution Approach 1:
The patent changes the parameters of conductive nanostructures to achieve aspect ratios of 10 or more with diameters of 30-50 nm. This parameter transformation allows fewer nanostructures to provide the same conductive effect, thus reducing haze while maintaining conductivity. The high aspect ratio compensates for the reduced number of structures.
3Ease of manufacture
If conventional synthesis methods are used to produce conductive nanostructures, then production is simpler, but control over diameter and length distribution is insufficient
Solution Approach 1:
The patent employs a two-phase synthesis method that separately controls radial and axial growth parameters. By independently adjusting the parameters of each phase (first phase for radial growth, second phase for axial growth), the method achieves precise control over final diameter and length distributions while maintaining a relatively simple overall process framework.
Solution Approach 2:
The synthesis process is segmented into two distinct phases: a first phase that promotes radial growth to control diameter, and a second phase that promotes axial growth to control length. This segmentation of the synthesis process allows independent optimization of diameter and length parameters, achieving manufacturing precision without excessive complexity.
4Reliability
If broad size distribution of nanostructures is used, then conductivity is maintained, but haze level increases
Solution Approach 1:
The patent transforms the size distribution parameters to create a narrow diameter distribution centered at 30-50 nm while maintaining aspect ratios of 10 or more. This parameter transformation ensures that the length distribution is sufficiently broad to maintain conductivity, while the narrow diameter distribution minimizes light scattering across the visible spectrum, achieving low haze.
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
This approach enables the creation of transparent conductors with sheet resistances of less than 50 ohms/square and haze levels below 1.5%, effectively balancing optical clarity and electrical conductivity, suitable for demanding applications such as touch screens and displays.
Implementation Method 1
a first period of time during which radial growth of the conductive nanostructures is promoted
Implementation Method 2
a second period of time during which axial growth of the conductive nanostructures is promoted
Implementation Method 3
comprising providing a solution of a metal salt in a polyol solvent and a capping agent, and nucleating and growing nanowires
Implementation Method 4
nucleating and growing nanowires by reduction of the metal salt in the presence of the capping agent and a reducing agent
Data Source
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AI summary
This disclosure is related to low-haze transparent conductors, ink compositions and method for making the same.