Silver Conductive Laminate for High-Transmittance Low-Resistance Optics
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Solution Overview
Problem
Existing transparent conductive films face challenges in achieving both high transmittance and low electric resistance, as increasing film thickness to reduce resistance decreases transmittance, and silver thickness adjustments do not effectively alter light absorption, making it difficult to achieve 90% transmittance and 20 Ω/square or less surface resistance.
Innovation Solution
A conductive laminate is formed by laminating a zinc-free metal oxide first transparent material layer, a silver metal layer, and a zinc-containing metal oxide second transparent material layer on a transparent substrate, with the silver layer thickness being 7 nm or more, to suppress light absorption and achieve high transmittance and low electric resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of metal oxide film is increased to decrease resistance value, then electric conductivity is improved, but transmittance decreases
Solution Approach 1:
The patent uses a composite structure consisting of a metal oxide film (first transparent material layer), a silver film (metal layer), and another metal oxide film (second transparent material layer). This composite laminate achieves low resistance and high transmittance simultaneously by combining the electrical conductivity of silver with the transparency of metal oxide films, resolving the contradiction between conductivity and transmittance that plagues single-material solutions.
Solution Approach 2:
The patent applies different materials with different properties at different locations in the laminate structure. The silver layer provides high conductivity where needed, while the metal oxide layers provide transparency at the interfaces with the substrate and environment. This local differentiation of material properties allows the system to achieve both high transmittance and low resistance without compromise.
2Illumination intensity
If the thickness of silver film is reduced to increase transmittance, then light absorption is decreased, but electric conductivity increases
Solution Approach 1:
The patent combines silver film with metal oxide films to create a composite structure where the metal oxide layers compensate for the reduced conductivity of thinner silver layers. The interfaces between metal oxide and silver reduce light absorption while the overall laminate maintains low resistance through the synergistic combination of materials.
Solution Approach 2:
The metal oxide films act as intermediary layers between the silver film and the surrounding environment (substrate and air). These intermediary layers reduce the harmful light absorption effect of silver while maintaining electrical conductivity, effectively mediating between the conflicting requirements of transmittance and conductivity.
3Reliability
If heat treatment is applied to enhance transparency and reduce resistance of ITO, then electric conductivity and transmittance are improved, but substrates weak to heat are damaged
Solution Approach 1:
The patent employs materials and processes that do not require high-temperature heat treatment, making the process compatible with heat-sensitive substrates. The silver-based composite structure achieves the desired electrical and optical properties through its inherent material properties and interface effects rather than through thermal processing, avoiding damage to delicate substrates.
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 configuration results in a conductive laminate with low electric resistance and high transmittance, suitable for applications in optical devices like touch panels and light emitting elements, with reduced power consumption and improved performance.
Implementation Method 1
a laminate made by sandwiching a very thin silver thin film with transparent materials having a high refractive index was very effective, and research and development for these materials were widely carried out. This laminate achieves high transmittance and low resistance by having electrical conductivity with silver and by suppressing the surface reflection to increase the transmittance by the optical interference effect between the high refractive index material and the silver.
Data Source
AI summary
Provided are a conductive laminate capable of achieving both high transmittance and low electric resistance, and various optical devices equipped with the same. A conductive laminate (1) includes a first transparent material layer (3), a metal layer (4) mainly composed of silver, and a second transparent material layer (5) laminated on at least one surface of a transparent substrate (2) in this order from the side of the transparent substrate (2), wherein the first transparent material layer (3) is composed of a zinc-free metal oxide, the second transparent material layer (5) is composed of a zinc-containing metal oxide, and the metal layer (4) has a thickness of 7 nm or more.