Electrochromic Layer Stack Insulation for Particle-Induced Shorts
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Solution Overview
Problem
Conventional electrochromic windows suffer from high defectivity and low versatility due to issues like short circuits caused by particle ejections and poor layer adhesion, leading to visible defects and reduced performance.
Innovation Solution
Incorporation of a defect-mitigating insulating layer with specific electronic resistivity and materials like cerium oxide, titanium oxide, or nickel tungsten oxide between conductive layers to prevent short circuits and encapsulate particles, ensuring proper layer adhesion and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrochromic window structures are used without additional insulating layers, then the device complexity is low, but the reliability deteriorates due to short circuits and high defectivity
Solution Approach 1:
An insulating layer is introduced as an intermediary between the counter electrode layer and the second transparent conductive layer. This intermediate layer prevents direct contact between conductive layers, eliminating short circuit pathways while maintaining device functionality. The insulating layer acts as a mediator that resolves the electrical conflict between adjacent conductive layers.
Solution Approach 2:
The device structure is segmented into distinct functional layers with the insulating layer positioned between conductive layers. This segmentation creates electrical isolation zones that prevent defect propagation and short circuits, dividing the potential failure pathways into separate, isolated regions.
2Reliability
If particles are allowed to remain during fabrication without encapsulation, then the manufacturing process is simpler, but the reliability worsens due to particle ejections causing short circuits
Solution Approach 1:
The insulating layer is deposited before subsequent conductive layers are formed, creating a protective barrier in advance. This preliminary action encapsulates any particles present during fabrication, preventing them from causing short circuits when subsequent layers are deposited or when the device is assembled.
Solution Approach 2:
The insulating layer serves as a cushioning barrier that absorbs or isolates the harmful effect of particle ejections. By placing this protective layer beforehand, the device is cushioned against potential short circuits from particles, converting a potentially catastrophic defect into a contained, non-functional issue.
3Reliability
If electrochromic layers are made with high conductivity for better performance, then the electrochromic effect is enhanced, but the reliability deteriorates due to increased susceptibility to short circuits
Solution Approach 1:
Different regions of the device are assigned different electrical properties: the electrochromic layers maintain high conductivity for performance, while the insulating layer provides low conductivity for isolation. This local differentiation of electrical quality allows each layer to optimize its function without compromising the other.
Solution Approach 2:
The insulating layer mediates between the high-conductivity electrochromic layers, allowing them to maintain their performance-optimizing conductivity while the intermediary prevents direct electrical contact that would cause short circuits. The mediator enables high performance in active layers without sacrificing reliability.
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
Significantly reduces the number of visible pinhole and short-related defects, enhancing the electrochromic device's performance and visual quality by minimizing electrical shorts and particle ejections during fabrication.
Implementation Method 1
a defect-mitigating insulating layer which prevents electronically conducting layers and/or electrochromically active layers from contacting layers of the opposite polarity and creating a short circuit
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, typically by being subjected to a voltage change
Data Source
AI summary
Electrochromic devices and methods may employ the addition of a defect-mitigating insulating layer which prevents electronically conducting layers and/or electrochromically active layers from contacting layers of the opposite polarity and creating a short circuit in regions where defects form. In some embodiments, an encapsulating layer is provided to encapsulate particles and prevent them from ejecting from the device stack and risking a short circuit when subsequent layers are deposited. The insulating layer may have an electronic resistivity of between about 1 and 108 Ohm-cm. In some embodiments, the insulating layer contains one or more of the following metal oxides: aluminum oxide, zinc oxide, tin oxide, silicon aluminum oxide, cerium oxide, tungsten oxide, nickel tungsten oxide, and oxidized indium tin oxide. Carbides, nitrides, oxynitrides, and oxycarbides may also be used.