Low-E Coating Antiscattering Layer for Thermal Toughening
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Solution Overview
Problem
Existing heat-resistant low-emissivity multilayer systems for transparent substrates, such as windows, suffer from high light scattering and inadequate infrared radiation emission after thermal toughening due to diffusion processes between TiO2 and ZnO layers, which degrade the refractive index and increase emissivity.
Innovation Solution
Incorporating a mixed oxide antiscattering layer with a thickness of at least 0.5 nm, made of NiCrOx or InSnOx (ITO), between the high-refractive index layer and the ZnO wetting layer, along with a specific layer structure including a barrier layer and cover coatings, to prevent diffusion and enhance thermal stability and optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a TiO2 layer is placed adjacent to a ZnO layer in the lower antireflection coating, then the refractive index is optimized for antireflection, but diffusion processes occur during thermal toughening that destroy the TiO2 layer and form Zn2TiO4, causing high light scattering
Solution Approach 1:
An intermediate antiscattering layer made of metal oxides (such as SiO2, TiO2, Nb2O5, or their combinations) is inserted between the high-refringence layer and the ZnO wetting layer. This intermediary layer prevents direct contact and diffusion between TiO2 and ZnO during thermal toughening, eliminating the formation of light-scattering Zn2TiO4 while maintaining the optical performance of the high-refringence layer.
Solution Approach 2:
The lower antireflection coating is segmented into distinct functional layers: a high-refringence layer for optical performance, an intermediate antiscattering layer for protection, and a ZnO wetting layer for adhesion. This segmentation allows each layer to perform its specific function without interfering with others, preventing diffusion-related degradation.
2Object-affected harmful factors
If an SnO2 antiscattering layer is placed between the high-refringence layer and ZnO layer to protect during toughening, then light scattering is reduced, but the emissivity does not reach the desired low values and transmission in the visible range is insufficient
Solution Approach 1:
The invention changes the material parameters of the antiscattering layer by selecting metal oxides with specific optical properties (such as SiO2, TiO2, Nb2O5) that have different refractive indices and optical characteristics compared to SnO2. This allows optimization of both the antiscattering function and the optical transmission/emissivity properties by adjusting the composition and thickness of the intermediate layer.
3Device complexity
If the TiO2 layer is directly adjacent to the ZnO layer without an intermediate antiscattering layer, then the structure is simple, but diffusion processes during thermal toughening destroy the TiO2 layer and form Zn2TiO4, resulting in high emissivity and poor thermal insulation
Solution Approach 1:
An intermediate antiscattering layer made of metal oxides (such as SiO2, TiO2, Nb2O5, or their combinations) is inserted between the high-refringence layer and the ZnO wetting layer. This intermediary layer prevents direct contact and diffusion between TiO2 and ZnO during thermal toughening, eliminating the formation of light-scattering Zn2TiO4 while maintaining the optical performance of the high-refringence layer.
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
Significantly reduces light scattering, increases visible transmission, lowers surface resistance, and improves infrared radiation emission, resulting in enhanced thermal insulation and optical clarity without compromising scratch sensitivity or stability during extended thermal treatments.
Implementation Method 1
diffusion processes via which the TiO2 layer is destroyed take place on the boundary surface between TiO2 and ZnO
Implementation Method 2
the proportion of light scattered by these multilayer systems is relatively high
Implementation Method 3
reduce the surface resistance, and therefore the emission values, and to achieve values that are as high as possible within the infrared radiation range
Data Source
AI summary
In a heat-resistant low-emissivity (low-E) multilayer system that includes a silver layer as functional layer, for transparent substrates, in particular for window panes, which has, between the surface of the substrate and the silver layer, a high-refringence layer, in particular made of TiO2, Nb2O5 or TiNbOx, and, immediately below the silver layer, a layer essentially consisting of ZnO, a mixed oxide layer with a thickness of at least 0.5 nm, made of NiCrOx or InSnOx (ITO) that serves as antiscattering layer is placed between the high-refringence layer and the ZnO layer.