Heterogeneous Counter Electrode Layers for Electrochromic Switching
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Solution Overview
Problem
Electrochromic devices have historically suffered from various problems that have prevented the technology from realizing its full commercial potential, including limitations in coloration transition, transmittance, absorbance, and reflectance.
Innovation Solution
The development of electrochromic devices with a counter electrode layer comprising multiple sublayers with different compositions and morphologies, including a gradient in composition, to enhance optical properties and switching behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-layer counter electrode is used, then the device structure is simple, but the optical properties and switching performance are insufficient
Solution Approach 1:
The counter electrode is divided into multiple sublayers (first sublayer, second sublayer, third sublayer) with different compositions and functions. The first sublayer contains nickel oxide and tungsten oxide, the second sublayer contains nickel oxide, tungsten oxide, and aluminum oxide, and the third sublayer contains nickel oxide and tungsten oxide. This segmentation allows each sublayer to contribute differently to the overall performance, improving switching kinetics and optical properties while maintaining structural organization.
Solution Approach 2:
The patent employs composite material structures where different metal oxides are combined in specific ratios and sequences. The counter electrode comprises composite layers with nickel oxide, tungsten oxide, and aluminum oxide in varying concentrations across sublayers. These composite structures enable synergistic effects that enhance both the electrochromic response and structural stability.
2Illumination intensity
If the counter electrode composition is homogeneous, then the manufacturing process is simple, but the coloration transition and transmittance control are limited
Solution Approach 1:
Different sublayers are designed with specific local compositions optimized for their positions. The first sublayer near the electrochromic layer has a composition optimized for ion exchange, the second sublayer contains aluminum oxide for structural stability and optical control, and the third sublayer is optimized for electrochemical activity. This local quality variation enables precise control over transmittance and coloration transition at different depths of the electrode.
Solution Approach 2:
The patent systematically varies compositional parameters (metal oxide ratios, concentrations of nickel, tungsten, and aluminum oxides) across different sublayers. By changing these parameters in a controlled manner from one sublayer to the next, the device achieves enhanced transmittance control and coloration transition characteristics that cannot be obtained with uniform composition.
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 proposed solution improves the visual properties and switching performance of electrochromic devices, achieving a transmitted b* value of 14 or lower and visible transmittance of at least 55% in the clearest state.
Implementation Method 1
Electrochromism is a phenomenon in which a material exhibits a reversible electrochemically-mediated change in an optical property when placed in a different electronic state, typically by being subjected to a voltage change. The optical property is typically one or more of color, transmittance, absorbance, and reflectance.
Implementation Method 2
a first sublayer including a first anodically tinting material, and (b) a second sublayer including a second anodically tinting material
Data Source
AI summary
The embodiments herein relate to electrochromic stacks, electrochromic devices, and methods and apparatus for making such stacks and devices. In various embodiments, an anodically coloring layer in an electrochromic stack or device is fabricated to include a heterogeneous structure, for example a heterogeneous composition and/or morphology. Such heterogeneous anodically coloring layers can be used to better tune the properties of a device.