IMI Electrochromic Transparent Electrodes for Uniform Darkening
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Solution Overview
Problem
Existing electrochromic elements face challenges in achieving high reflectivity, cost-effectiveness, and uniform darkening due to issues with sheet resistance and material stability, particularly with indium-tin oxide layers.
Innovation Solution
The development of an electrochromic element with a transparent electrode layer comprising an insulator/metal/insulator stack, using materials like indium tin oxide, indium zinc oxide, and silver, which reduces sheet resistance and enhances reflectivity while maintaining optical and physical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If indium-tin oxide layers are used as transparent electrodes, then electrical conductivity is improved, but sheet resistance increases and uniformity deteriorates
Solution Approach 1:
The transparent electrode is divided into multiple discrete conductive traces rather than using a continuous uniform layer. This segmentation allows each trace to be independently optimized for conductivity while the overall pattern can be designed to ensure uniform potential distribution across the electrochromic element, resolving the contradiction between high conductivity and uniform sheet resistance.
2Ease of manufacture
If transparent electrode layers are made thinner to reduce cost, then material cost decreases, but reflectivity and electrical performance deteriorate
Solution Approach 1:
The patent employs a composite electrode structure combining multiple materials (indium-tin-oxide, indium-zinc-oxide, and silver) in a layered configuration. This composite approach allows thin layers of expensive materials to be combined with thinner or alternative layers, achieving cost reduction while maintaining or enhancing reflectivity and electrical performance through synergistic material properties.
3Speed
If electrochromic elements are designed for faster darkening response, then switching speed improves, but uniformity of darkening deteriorates
Solution Approach 1:
The segmented conductive trace design creates dynamically optimized electrical fields that can be tailored to achieve uniform potential distribution across the electrochromic element during switching. The geometry, spacing, and connectivity of the traces are designed to ensure simultaneous charging of all electrochromic regions, enabling fast response while maintaining uniform darkening across the entire element.
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 achieves a high color rendering index, faster and more uniform darkening, and reduced production costs, addressing the limitations of previous electrochromic systems.
Implementation Method 1
an electrochromic medium located between the first and second substrates, wherein the electrochromic medium has a light transmittance that is variable upon the application of an electric field thereto
Implementation Method 2
the transparent electrode layer comprises a first insulator layer, at least one metal layer, and a second insulator layer
Data Source
AI summary
An electrochromic element comprises a first substrate having a first surface and a second surface opposite the first surface, a second substrate in spaced-apart relationship to the first substrate and having a third surface facing the second surface and a fourth surface opposite the third surface, and an electrochromic medium located between the first and second substrates, wherein the electrochromic medium has a light transmittance that is variable upon application of an electric field thereto. The electrochromic element further comprises a transparent electrode layer covering at least a portion of at least a select one of the first surface, the second surface, the third surface, and the fourth surface, wherein the transparent electrode layer comprises an insulator/metal/insulator stack. The materials utilized to construct the insulator/metal/insulator stack are selected to optimize optical and physical properties of the electrochromic element such as reflectivity, color, electrical switch stability, and environmental durability.