Electrochromic Window Stack Insulation for Short-Circuit Defects
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Solution Overview
Problem
Conventional electrochromic windows suffer from high defectivity and low versatility due to short circuits caused by defects such as electrical shorts and pinholes, which affect their performance and visual quality, especially in larger substrates.
Innovation Solution
Incorporation of a defect-mitigating insulating layer between electronically conducting layers to prevent short circuits, using materials like metal oxides, nitrides, or oxynitrides with resistivity between 1 and 1010 Ohm-cm, and positioning it strategically within the electrochromic stack to encapsulate particles and prevent ejection during fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrochromic window structures are used, then the device can achieve basic electrochromic functionality, but high defectivity and short circuits occur due to particles and defects in the layers
Solution Approach 1:
An insulating layer is introduced as an intermediary between the first and second electrochromic layers. This layer prevents direct electrical contact between the layers, eliminating short circuits caused by particles or defects. The insulating layer acts as a mediator that blocks harmful electrical pathways while allowing the electrochromic functionality to remain intact.
Solution Approach 2:
The electrochromic device is segmented into distinct functional layers with the insulating layer positioned between the electrochromic layers. This segmentation separates the conductive pathways and prevents defect propagation across the entire device structure, allowing each layer to function independently without compromising overall reliability.
2Reliability
If the insulating layer is added to prevent short circuits, then reliability improves, but the device structure becomes more complex with additional layers
Solution Approach 1:
The insulating layer serves multiple functions simultaneously: it prevents short circuits between electrochromic layers, provides structural support, and maintains the integrity of the device stack. By combining multiple functions in a single layer, the overall complexity increase is minimized while achieving reliable short circuit prevention.
3Ease of manufacture
If particles are present in the electrochromic layers, then manufacturing is simplified, but particles can eject and cause short circuits during operation
Solution Approach 1:
The insulating layer is deposited beforehand to cushion or capture particles that may be present during manufacturing. This layer acts as a protective barrier that prevents particles from causing short circuits during subsequent operations or device operation, addressing the particle issue before it can cause harm.
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 short-related pinholes to less than 0.005 per square centimeter, enhancing the performance and visual quality of electrochromic devices by minimizing defects and maintaining optical state changes.
Implementation Method 1
a defect-mitigating insulating layer comprising a substantially transparent and electronically insulating material
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.