Doped Tungsten Oxide Glazing for Solar Selectivity and RF Transparency
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Solution Overview
Problem
Existing solar control glazings for motor vehicles face challenges in achieving low solar factor, high light transmission, and transparency to radiofrequencies due to the use of metallic functional layers that block radio electromagnetic waves.
Innovation Solution
A transparent substrate with a stack of thin layers comprising a tungsten oxide layer doped with elements from group 1 of the IUPAC nomenclature, encapsulated between dielectric modules, which absorbs infrared radiation without blocking radiofrequency waves, enhancing selectivity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If metallic functional layers are used in solar control glazings, then solar selectivity is improved, but radiofrequency transparency deteriorates
Solution Approach 1:
The patent changes the material parameter from metallic to doped tungsten oxide, which fundamentally alters the electrical and optical properties. The doping with group 1 elements modifies the band structure and carrier concentration, enabling the material to achieve both high solar selectivity and radiofrequency transparency simultaneously
Solution Approach 2:
The patent creates a composite functional layer combining tungsten oxide with group 1 doping elements (such as lithium, sodium, or potassium). This composite material exhibits synergistic properties where the doped oxide maintains the solar control functionality while the doping elements adjust the electrical conductivity to allow radiofrequency transmission
2Reliability
If non-metallic absorbent layers are used instead of metallic layers, then radiofrequency transparency is improved, but solar selectivity deteriorates
Solution Approach 1:
The patent modifies the optical and electrical parameters of tungsten oxide through doping with group 1 elements. This changes the material's absorption characteristics in the solar spectrum while maintaining appropriate electrical conductivity for radiofrequency transmission, achieving both high solar selectivity and radiofrequency transparency
3Loss of energy
If doped tungsten oxide layers are used, then solar selectivity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent achieves enhanced solar selectivity by controlling the doping concentration and type of group 1 elements in tungsten oxide. The manufacturing process parameters (such as deposition conditions, doping ratios, and heat treatment) are optimized to produce the desired material properties while maintaining process feasibility
Solution Approach 2:
The doping elements are introduced at specific concentrations and distributions within the tungsten oxide layer to create local variations in electrical and optical properties. This allows optimization of solar selectivity in specific regions or layers while maintaining overall manufacturing simplicity
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 gain of up to 30% in solar selectivity and maintains a light transmission level of approximately 70%, ensuring effective radiofrequency transparency and long-term performance.
Implementation Method 1
an absorbent layer (1003) of tungsten oxide... which absorbs infrared radiation
Data Source
AI summary
A transparent substrate provided on one of its main surfaces with a stack of thin layers, the stack of layers including the following layers starting from the substrate a first dielectric module of one or more thin layers; an absorbent layer of tungsten oxide; a second dielectric module of one or more thin layers; wherein the tungsten oxide includes at least one doping element selected from the chemical elements of group 1 according to the IUPAC nomenclature, the absorbent layer of tungsten oxide includes cesium as a doping element, and the molar ratio of cesium to tungsten is between 0.01 and 1.