Electrochromic Devices with Patterned Current Modulating Structure
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Solution Overview
Problem
Large area electrochromic devices experience slow and spatially non-uniform switching due to voltage drop issues across transparent conductive coatings, leading to the 'iris effect' where transmissivity varies significantly across the device.
Innovation Solution
A multi-layer electrochromic device with a patterned current modulating structure having non-uniform cross-layer resistance, comprising a combination of resistive and insulating materials, is used to ensure uniform potential drop across the device, facilitating rapid and coordinated switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large area electrochromic devices use transparent conductive coatings for electrical contact, then electrical conductivity is improved, but voltage drop increases causing non-uniform switching
Solution Approach 1:
The patent applies local quality by creating a patterned current modulating structure with spatially varying resistance properties. The structure includes regions with different resistance values arranged in a specific pattern to compensate for the voltage drop that occurs across large area devices. This local variation in resistance ensures that the potential distribution remains relatively uniform across the entire device area, thereby achieving uniform switching throughout the large area electrochromic device.
2Ease of operation
If voltage is applied at the edge of the device, then electrical contact is established, but transmissivity becomes non-uniform across the device area
Solution Approach 1:
The patterned current modulating structure implements local quality by having different resistance characteristics in different spatial regions. The structure is designed with lower resistance near the voltage application edge and higher resistance toward the center, which compensates for the natural voltage drop gradient. This creates a more uniform potential distribution across the device, ensuring uniform transmissivity changes throughout the entire area while maintaining ease of electrical contact at the edge.
3Area of stationary object
If device area is increased for architectural applications, then coverage area is improved, but switching speed decreases and becomes non-uniform
Solution Approach 1:
The patent applies local quality through a patterned current modulating structure with spatially varying resistance that is specifically designed for large area devices. The structure creates localized current modulation that compensates for the increased voltage drop path length in large area configurations. This enables large area devices to achieve uniform and relatively fast switching by optimizing the resistance distribution pattern across the extended device area.
Solution Approach 2:
The current modulating structure employs composite materials with different resistance properties arranged in a patterned configuration. This composite structure allows for tailored electrical characteristics in different regions of the large area device, enabling optimized current distribution that maintains fast and uniform switching across the entire extended area.
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 enables uniform and rapid switching across the entire area of large electrochromic devices, reducing the 'iris effect' and improving switching performance by maintaining consistent transmissivity.
Implementation Method 1
the first current modulating structure being a patterned structure having a non-uniform cross-layer resistance
Implementation Method 2
capable of coordinated switching over substantially their entire area... from a first optical state, e.g., a transparent state, to a second optical state, e.g., a reflective or colored state
Data Source
AI summary
A multi-layer device comprising a first substrate, a first electrically conductive layer and a first current modulating structure on a surface thereof, the first current modulating structure comprising a composite of a resistive material and a patterned insulating material, the first current modulating structure having a cross-layer resistance to the flow of electrical current through the first current modulating structure that varies as a function of position.