NiWTaO Counter Electrode Stack for Stable Neutral Electrochromics
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Solution Overview
Problem
Electrochromic devices, particularly electrochromic windows, face challenges with material stability over time, switching speed, and optical properties, such as tinted states being too blue and transparent states being too yellow, limiting their commercial potential.
Innovation Solution
The development of an electrochromic stack using a novel composition of nickel tungsten tantalum oxide (NiWTaO) with specific atomic ratios, formed through sputtering targets, and an integrated deposition system that deposits cathodically and anodically coloring layers in direct physical contact without a separate ion conductor layer, enhancing material stability and optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrochromic materials (tungsten oxide and nickel oxide) are used, then the basic electrochromic function is achieved, but material stability over time deteriorates and optical properties worsen (tinted states too blue, transparent states too yellow)
Solution Approach 1:
The patent applies composite materials by combining nickel oxide, tungsten oxide, and tantalum oxide in specific ratios to create a multi-component electrochromic material. This composite approach allows the material to achieve both improved stability over time and neutral optical properties, resolving the contradiction between reliability and composition stability. The synergistic effect of multiple oxides compensates for the individual limitations of each material.
Solution Approach 2:
The patent employs parameter changes by precisely controlling the atomic ratios of nickel, tungsten, and tantalum in the electrochromic material, as well as controlling deposition parameters such as sputtering power and oxygen partial pressure. These parameter optimizations enable the material to achieve both long-term stability and neutral optical appearance, simultaneously improving reliability and composition stability.
2Speed
If conventional electrochromic materials are used, then the device structure is simpler, but switching speed deteriorates
Solution Approach 1:
The patent uses composite materials consisting of nickel oxide, tungsten oxide, and tantalum oxide to achieve fast switching speed. The multi-component composition provides multiple charge transfer pathways and improved ion transport kinetics, enabling rapid electrochromic switching while accepting increased material complexity.
Solution Approach 2:
The patent applies local quality by creating regions with different oxide compositions and stoichiometries within the electrochromic layer. This spatial variation in material properties optimizes local charge transfer and ion transport, contributing to enhanced switching speed while managing overall material complexity.
3Ease of manufacture
If conventional materials are used, then manufacturing is easier, but optical properties worsen (color neutrality)
Solution Approach 1:
The patent employs parameter changes by optimizing deposition conditions including sputtering power, oxygen partial pressure, and substrate temperature to achieve neutral optical properties. These controlled parameter variations enable precise tuning of the electrochromic material's optical characteristics while maintaining manufacturability through standard deposition techniques.
Solution Approach 2:
The patent applies local quality by controlling the spatial distribution and stoichiometry of different oxide components during deposition. This localized control of material composition enables achievement of neutral optical appearance in the final product while using conventional manufacturing processes.
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 improves material stability and switching speed, providing more neutral and clear tinted states, thus enhancing the commercial viability of electrochromic devices by optimizing the composition and deposition process of NiWTaO in electrochromic stacks.
Implementation Method 1
The anodically coloring layer may be formed by sputtering one or more sputter targets to form the NiWTaO
Implementation Method 2
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
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.