ITO Coating Sputtering for Electrochromic Mirror Conductivity
Solution Overview
Problem
Existing electrochromic mirrors and windows face challenges in achieving uniform darkening and low sheet resistance while maintaining optical and physical properties, particularly with ITO coatings, which often result in increased absorption, bending of substrates, and high costs due to the use of expensive metals.
Innovation Solution
The use of a sputtering process at higher pressures and oxygen flow rates to produce ITO coatings with reduced bulk resistivity, stress, and absorption, optimizing the microstructure and morphology to achieve lower sheet resistance and uniform darkness or brightness without substrate bending and cost constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ITO coatings are used to achieve low sheet resistance, then conductivity is improved, but absorption increases and substrate bending occurs
Solution Approach 1:
The patent applies parameter changes by modifying the sputtering process conditions, specifically using higher pressures (3-10 mTorr) and oxygen flow rates (10-50 sccm) during ITO coating deposition. These parameter changes result in ITO coatings with reduced bulk resistivity (0.5-2.0 ohm-cm) and lower stress, achieving sheet resistance below 10 ohms/sq while maintaining reduced absorption and minimizing substrate bending.
Solution Approach 2:
The patent employs composite materials by creating ITO coatings with optimized microstructure and morphology through controlled sputtering parameters. The resulting composite structure achieves a balance between electrical conductivity and optical properties, producing coatings that simultaneously provide low sheet resistance and reduced absorption characteristics.
2Ease of manufacture
If conventional sputtering processes are used, then manufacturing is simple, but ITO coatings exhibit high bulk resistivity and stress
Solution Approach 1:
The patent modifies conventional sputtering parameters by operating at higher pressures (3-10 mTorr compared to typical 0.5-2 mTorr) and increased oxygen flow rates (10-50 sccm). These parameter changes transform the coating deposition process to produce ITO films with reduced bulk resistivity (0.5-2.0 ohm-cm) and lower intrinsic stress, while maintaining manufacturing feasibility.
3Reliability
If ITO coating thickness is increased to reduce sheet resistance, then conductivity improves, but absorption increases
Solution Approach 1:
The patent changes the sputtering parameters to achieve better coating quality per unit thickness. By using higher pressures and oxygen flow rates, the process produces denser, more uniform ITO coatings with lower bulk resistivity. This allows achieving target sheet resistance values with optimized thickness while minimizing absorption through improved coating microstructure.
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
This approach results in electrochromic elements with improved conductivity, reduced absorption, and lower substrate stress, enabling faster and more uniform darkening while reducing the weight and cost of the assembly.
Implementation Method 1
The use of a sputtering process at higher pressures and oxygen flow rates to produce ITO coatings with reduced bulk resistivity, stress, and absorption
Data Source
Figure 1~2b
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AI summary
Electro-optic elements are becoming commonplace in a number of vehicular and architectural applications. Various electro-optic element configurations provide variable transmittance and or variable reflectance for windows and mirrors. The present invention relates to various thin-film coatings, electro-optic elements and assemblies incorporating these elements.