Fluorine-Doped Tin Oxide Film via Spray Coating for Defogging
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Solution Overview
Problem
Existing methods for producing fluorine-doped tin oxide (FTO) transparent conductive films for defogging applications face challenges such as high material costs, complex equipment requirements, and reduced heat, chemical, and abrasion resistance, as well as difficulties in achieving low resistance and high transmittance.
Innovation Solution
A method involving a spray coating process to form an FTO transparent conductive film with a specific molar ratio of fluorine to tin and a controlled crystal plane ratio, using a precursor solution of tin oxide and fluorine dissolved in deionized water, applied between 400 to 550°C, to create a film with improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If ITO transparent conductive film is formed and heated at about 500°C, then transmittance is improved, but heat resistance, chemical resistance and abrasion resistance are reduced
Solution Approach 1:
The patent changes the material composition parameter by replacing ITO with FTO (fluorine-doped tin oxide). FTO maintains high transmittance while providing superior heat resistance, chemical resistance, and abrasion resistance due to its different chemical composition and stability characteristics under high-temperature conditions
Solution Approach 2:
The patent uses a composite structure consisting of multiple layers including the FTO transparent conductive film layer, dielectric barrier layer, organic intermediate layer, and glass layers. This composite structure achieves both high transmittance and improved durability through the synergistic properties of each layer
2Illumination intensity
If organic tin compound is used as main material for FTO film, then transmittance is improved, but material cost increases and heat resistance decreases
Solution Approach 1:
The patent changes the chemical composition parameter by using inorganic tin oxide instead of organic tin compound as the main material. This substitution maintains the transparent conductive properties and transmittance while significantly improving heat resistance and reducing material cost
3Manufacturing precision
If sputtering or CVD method is used to fabricate tin oxide film, then film quality is improved, but equipment complexity and cost increase
Solution Approach 1:
The patent replaces the complex mechanical vacuum systems of sputtering and CVD methods with a chemical solution-based spray coating method. This substitution achieves comparable film quality through chemical deposition from aqueous precursor solutions, eliminating the need for expensive vacuum equipment and gas delivery systems
Solution Approach 2:
The patent changes the fabrication method parameter from physical vapor deposition (sputtering/CVD) to chemical solution deposition (spray coating). This parameter change simplifies the equipment requirements while maintaining control over film composition and properties through solution chemistry parameters
4Illumination intensity
If dielectric barrier layer is disposed between FTO film and glass substrate, then transmittance is improved, but processing speed decreases
Solution Approach 1:
The patent merges the dielectric barrier layer formation with the FTO film formation processes. By using a spray coating method that deposits both the dielectric layer and FTO layer in sequence without requiring vacuum environment changes or complex equipment transitions, the processing speed is maintained while achieving the transmittance benefits of the dielectric barrier 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
The solution results in an FTO transparent conductive film with excellent heat resistance, chemical resistance, and abrasion resistance, low electrical resistance, and high transmittance, suitable for defogging applications, with a simpler and cost-effective manufacturing process.
Implementation Method 1
spray coating process to form an FTO transparent conductive film... using a precursor solution of tin oxide and fluorine dissolved in deionized water, applied between 400 to 550°C
Implementation Method 2
U.S. Pat. No. 3,677,814 discloses a method in which an organic tin compound having a tin-fluorine bond is formed by pyrolysis
Implementation Method 3
fluorine-doped tin oxide (FTO) transparent conductive film glass having low resistance and high transmittance
Implementation Method 4
The dielectric barrier layer is introduced to prevent a decrease in transmittance due to change of the color of the windshield which is caused by diffusion of Na ions of the glass layer into the FTO transparent conductive film
Data Source
AI summary
Disclosed herein are a fluorine-doped tin oxide (FTO) transparent conductive film glass used for defogging purposes comprising a glass layer, a dielectric barrier layer, a functional layer, a metal electrode layer, a plastic intermediate layer, and a glass layer, stacked in this sequential order, in which the functional layer comprises an FTO transparent conductive film having a molar ratio of F to Sn in the range of 0.5 to 2, mainly including a (301) crystal plane and being formed by a spray coating method, and a method of fabricating the same.