NiWTaO Counter Electrode for Fast, Clear Electrochromic Switching
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Solution Overview
Problem
Existing electrochromic devices face issues with material stability over time, switching speed, and optical properties, such as tinted states being too blue and transparent states too yellow, limiting their commercial potential.
Innovation Solution
The development of a novel electrochromic stack using a cathodically coloring layer of tungsten oxide (WOx) and an anodically coloring layer of nickel tungsten tantalum oxide (NiWTaO) with specific atomic ratios, deposited directly in contact without an ion conductor layer, and an integrated deposition system for precise layer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrochromic materials (tungsten oxide and nickel oxide) are used, then the device can achieve basic electrochromic functionality, but material stability over time deteriorates
Solution Approach 1:
The patent applies composite materials by combining nickel oxide, tungsten oxide, and tantalum oxide in specific ratios to create a counter electrode material that achieves both electrochromic functionality and long-term stability. The composite Ni-W-Ta-Ox material provides synergistic effects where each component contributes to overall performance, resolving the contradiction between basic functionality and material stability over time.
2Speed
If conventional electrochromic materials are used, then the device can achieve coloration transition, but switching speed deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the atomic ratios of nickel, tungsten, and tantalum in the counter electrode material, as well as controlling deposition parameters during fabrication. By adjusting these parameters within specific ranges, the material achieves both fast switching speed and long-term stability, resolving the contradiction between speed and reliability.
3Illumination intensity
If conventional electrochromic materials are used, then the device can achieve tinted state, but optical properties deteriorate (tinted states too blue, transparent states too yellow)
Solution Approach 1:
The patent applies local quality by creating an anodically coloring layer with specific spatial distribution of nickel, tungsten, and tantalum atoms. The controlled atomic ratios and layer structure provide localized optical properties that achieve neutral transparent states and accurate tinted states, resolving the contradiction between optical clarity and color control.
4Ease of operation
If a separately deposited ion conductor layer is used between cathodically coloring layer and anodically coloring layer, then ion transport is facilitated, but device complexity increases
Solution Approach 1:
The patent applies merging by integrating the ion conductor functionality directly into the anodically coloring counter electrode layer through the nickel tungsten tantalum oxide composite material. This eliminates the need for a separate ion conductor layer while maintaining efficient ion transport, resolving the contradiction between operational ease and device complexity.
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 provides improved material stability, faster switching speeds, and clearer optical transitions, enhancing the commercial viability of electrochromic devices.
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
The anodically coloring layer may be formed by sputtering one or more sputter targets to form the NiWTaO.
Implementation Method 3
Anodic electrochromic materials are also known, e.g., nickel oxide (e.g. NiO).
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 nickel tungsten tantalum oxide (NiWTaO). This material is particularly beneficial in that it is very transparent in its clear state.