Transparent Heat Shielding Material via Alkali Metal and Halogen Co-Doping
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Solution Overview
Problem
Conventional heat shielding films face challenges with instability, high fabrication costs, insufficient infrared light shielding, and the inability to achieve high visible light transmission and heat shielding simultaneously due to limitations in materials like silver films, transparent conductive oxides, and tungsten oxide with alkali metal doping.
Innovation Solution
A transparent heat shielding material comprising tungsten oxide with alkali metal and halogen co-doping, represented by MxWO3-yAy, is developed, which is synthesized through a reduction reaction in a hydrogen environment, allowing for high visible light transmission and effective infrared light shielding without absorbing visible light, and can be formed using a low-cost, simple coating process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional heat shielding films are made of multi-layered silver film, then heat shielding function is provided, but stability in air deteriorates and fabrication cost increases
Solution Approach 1:
The patent replaces expensive and unstable silver film with a cheaper, stable alternative: tungsten oxide thin film doped with alkali metal elements. This doping approach provides sufficient heat shielding function without requiring the multi-layered silver structure, thereby reducing fabrication cost while improving air stability.
Solution Approach 2:
The patent modifies the optical and electrical properties of tungsten oxide by doping with alkali metal elements (such as lithium, sodium, potassium, rubidium, or cesium). This parameter change enables the material to achieve appropriate conductivity and heat shielding performance without requiring complex multi-layered silver structures.
2Illumination intensity
If heat shielding films are made of transparent conductive oxides like ATO or ITO, then transparency is maintained, but infrared light shielding capability deteriorates due to low conductivity and plasma wavelength greater than 1000 nm
Solution Approach 1:
The patent changes the plasma wavelength parameter of tungsten oxide by doping with alkali metal elements, shifting it into the infrared region (below 1000 nm). This parameter modification enables the material to shield infrared light effectively while maintaining high visible light transmission, resolving the contradiction between transparency and infrared shielding capability.
3Object-affected harmful factors
If heat shielding films are made of lanthanum hexaboride (LaB6) material, then infrared light shielding capability is improved with plasma wavelength of 700 nm to 1100 nm, but visible light transmission deteriorates due to light absorption in visible range
Solution Approach 1:
The patent adjusts the plasma wavelength of tungsten oxide through alkali metal doping to fall within the infrared region while maintaining transparency in the visible range. Unlike LaB6 which absorbs visible light, the doped tungsten oxide achieves infrared shielding with plasma wavelength control, preserving high visible light transmission.
4Object-affected harmful factors
If tungsten oxide with alkali metal element doping is used to shield against infrared light, then infrared light shielding ability improves to greater than 90%, but visible light transmission deteriorates below 70%
Solution Approach 1:
The patent optimizes the doping concentration and type of alkali metal elements in tungsten oxide to achieve a balance where infrared light shielding exceeds 90% while visible light transmission remains above 70%. This precise parameter control resolves the trade-off between infrared shielding and visible transparency.
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 material achieves high transparency and heat shielding ability with improved infrared light shielding ratios, enhancing the heat shielding capability while maintaining visible light transmission, and can be fabricated using a low-cost, low-temperature coating process.
Implementation Method 1
the plasma wavelength thereof is greater than 1000 nm. Accordingly, a partial infrared light with a wavelength between 800 nm and 1000 nm passes through the conventional heat shielding film
Implementation Method 2
a reduction reaction is applied to the mixture in a hydrogen environment to form a material of MxWO3-yAy
Data Source
AI summary
A transparent heat shielding material, a fabrication method thereof and a transparent heat shielding structure are provided. The transparent heat shielding material is represented by MxWO3-yAy, wherein M is at least one element of alkali metal, W is tungsten, O is oxygen, A is halogen, 0<x≦1, and 0<y≦0.5. The transparent heat shielding material MxWO3-yAy is formed from tungsten oxide with at least one alkali metal cation and halogen anion co-doping into. The transparent heat shielding structure includes one or more layers of a transparent heat shielding film, wherein the transparent heat shielding film includes the material MxWO3-yAy.