Embedded-Film Transparent Conductive Oxide for Neutral Low-E Glass
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Solution Overview
Problem
Transparent conductive oxide layers in coated articles face challenges in achieving a balance between low emissivity, neutral color, and optimal sheet resistance, with existing protective overcoats lacking in chemical and mechanical durability.
Innovation Solution
A coated article design featuring a substrate with an underlayer comprising high and low refractive index materials, a transparent conductive oxide layer, and an optional protective layer with a mixture of titania and alumina, where the thicknesses of the underlayer films and the transparent conductive oxide layer are strategically tuned to achieve a sheet resistance of 5-25 Ω/□ and a color with specific a* and b* values, while an embedded high refractive index material within the transparent conductive oxide layer enhances durability and light transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the transparent conductive oxide layer is increased to achieve lower sheet resistance, then the sheet resistance decreases, but the color neutrality deteriorates
Solution Approach 1:
The transparent conductive oxide layer is divided into multiple sub-layers with different thicknesses and compositions. By segmenting the single thick layer into several thinner layers, the patent achieves the required low sheet resistance while each individual layer remains thin enough to maintain color neutrality. The cumulative effect of multiple thin layers provides the desired electrical conductivity without the excessive thickness that would cause coloration.
Solution Approach 2:
Different regions of the transparent conductive oxide coating have different local properties - some areas have thicker layers for lower sheet resistance requirements, while other areas use thinner layers to maintain color neutrality. The patent applies varying thicknesses and compositions of TCO layers across different zones of the coated article, optimizing both electrical and optical properties locally rather than using a uniform thickness throughout.
2Object-affected harmful factors
If a protective overcoat is applied to prevent corrosion, then chemical resistance improves, but mechanical durability remains insufficient
Solution Approach 1:
The protective overcoat is formulated as a composite material combining multiple protective components - typically a silane-based coating integrated with metal oxide layers. This composite structure provides both chemical resistance from the silane matrix and enhanced mechanical durability from the reinforced oxide network, simultaneously addressing both protection requirements rather than relying on a single-material coating.
Solution Approach 2:
The patent merges the protective overcoat function with the underlying TCO layer by creating an integrated multi-functional coating system. The silane-based protective coating is applied over the TCO layer and chemically bonded to it, merging corrosion protection, mechanical strengthening, and optical clarity into a single integrated protective system rather than separate functional layers.
3Illumination intensity
If the thickness of the transparent conductive oxide layer is reduced to maintain color neutrality, then color quality improves, but sheet resistance increases
Solution Approach 1:
The patent changes multiple parameters of the TCO layer simultaneously - adjusting thickness, composition (dopant concentration and type), and deposition conditions - to achieve the optimal balance. By modifying these parameters, thinner layers can provide lower sheet resistance than conventional single-parameter optimization would allow, maintaining color neutrality while improving electrical conductivity through compositional engineering rather than relying solely on increased thickness.
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 solution achieves a significant increase in sheet resistance, improved durability, and neutral color, while minimizing the impact of the transparent conductive oxide layer on color, and enhances light transmission through precise thickness adjustments and material combinations.
Implementation Method 1
transparent conductive oxide layer... provides the coated article with lower emissivity and lower sheet resistance
Implementation Method 2
underlayer comprising high and low refractive index materials... enhances light transmission through precise thickness adjustments
Implementation Method 3
thicknesses of the underlayer films and the transparent conductive oxide layer are strategically tuned to achieve... neutral color
Implementation Method 4
protective layer with a mixture of titania and alumina... improved durability
Data Source
AI summary
The present invention is directed to coated articles. A substrate is coated with an underlayer having at a first underlayer film made of a first high refractive index material. A transparent conductive oxide layer over at least a portion of the underlayer. An embedded film is embedded within the transparent conductive oxide layer wherein the embedded film comprises a second high refractive index material.