Resistive Coating for Voltage Uniformity in Electrochromic Devices
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Solution Overview
Problem
Electrochromic devices face non-uniform appearance due to undesired voltage variations across the device, which increase with current load, cell spacing, and electrochromic dye concentration, despite efforts to enhance electrode conductivity.
Innovation Solution
Incorporating a resistive layer between the electrodes and the electrochromic material to increase the drive voltage supplied to the electrodes without increasing the voltage applied to the electrochromic material, thereby maintaining voltage uniformity and enhancing current delivery capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrode conductivity is increased to reduce voltage drop, then voltage uniformity is improved, but the current load capacity cannot be sufficiently increased to fully prevent undesired voltage variations
Solution Approach 1:
The patent applies local quality by creating a non-uniform resistive layer with varying thickness across the electrode surface. The resistive layer has greater thickness (and thus higher resistance) at regions farther from the voltage source and lesser thickness (lower resistance) at regions closer to the voltage source. This local variation in resistance compensates for the natural voltage drop, maintaining uniform voltage distribution across the electrochromic material while accommodating higher current loads.
Solution Approach 2:
The patent changes the resistance parameter of the electrode by introducing a resistive layer with controlled thickness variations. By adjusting the thickness of the resistive layer at different locations, the effective resistance is optimized to compensate for voltage drops. This parameter change allows the system to handle increased current loads while maintaining voltage uniformity across the device.
2Productivity
If device area is increased to enhance functionality, then productivity is improved, but current load increases causing undesired voltage drop and non-uniform appearance
Solution Approach 1:
The resistive layer implements local quality by having position-dependent thickness that specifically addresses voltage drops in larger area devices. Regions farther from the voltage source have increased resistive layer thickness to provide additional voltage compensation, enabling large-area devices to maintain uniform appearance and performance.
3Productivity
If cell spacing is decreased to improve device performance, then productivity is improved, but current load increases producing undesired voltage drop
Solution Approach 1:
The patent changes the resistance parameter through variable thickness resistive layer to compensate for increased current load resulting from decreased cell spacing. This allows the device to achieve improved performance with smaller cell spacing while maintaining voltage uniformity through the compensated resistance distribution.
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 effectively reduces voltage drops across the device, maintaining uniform coloration and appearance, allowing for larger device areas, decreased cell spacing, and increased dye concentrations while using existing low-voltage electrochromic materials.
Implementation Method 1
a resistive layer disposed between the conductive layer and the electrochromic material. The resistive layer may have a resistance of about 1,000 to about 10,000 Ω/square
Data Source
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AI summary
An electrode for an electrochromic device is provided that includes a resistive layer disposed over a conductive layer. The resistive layer is disposed between the conductive layer and an electrochromic material in the electrochromic device. The electrode reduces non-uniform response of the electrochromic material when the electrochromic device is in operation.