Tempering Electrochromic Devices on Glass Substrates
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Solution Overview
Problem
Conventional methods for tempering glass with electrochromic devices fabricated on it result in damage, such as lithium loss, redistribution, morphology modification, and interfacial layer thickness changes, which degrade the device's performance.
Innovation Solution
Fabricating electrochromic devices on glass substrates before tempering, using techniques like lithium ion management, diffusion barriers, and graded layer compositions to mitigate these issues, and employing chemical strengthening methods like ion exchange with potassium nitrate to enhance glass strength without damaging the devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If glass is tempered after electrochromic device fabrication, then glass strength is improved, but device functionality is destroyed
Solution Approach 1:
The patent applies preliminary action by fabricating the electrochromic device on the glass substrate before tempering. The device is constructed with all its functional layers (electrochromic layer, ion conductor, electrodes, encapsulation) intact on the glass, and then the entire assembly is tempered together. This preliminary fabrication ensures the device structure is established before the high-stress tempering process begins.
Solution Approach 2:
The patent uses an intermediary approach by incorporating a diffusion barrier layer between the glass substrate and the electrochromic device layers. This barrier prevents harmful interactions (such as alkali metal diffusion) between the glass and device materials during tempering, allowing the glass to be strengthened while protecting the device functionality. The barrier acts as a mediator that enables both glass tempering and device survival.
2Shape
If glass is cut or ground before tempering, then desired geometry is achieved, but catastrophic breakage occurs after tempering
Solution Approach 1:
The patent applies preliminary action by achieving the desired glass geometry through cutting and grinding operations before the tempering process. The glass substrate is shaped to its final dimensions and configuration while in its annealed state, before any tempering occurs. This ensures all geometric modifications are completed when the glass is more tolerant of mechanical processing.
Solution Approach 2:
The patent inverts the conventional sequence by tempering the glass substrate first (to achieve strength), then fabricating the electrochromic device on the tempered glass. This reversal allows the glass to be strengthened before any device fabrication steps, eliminating the risk of post-tempering breakage during device manufacturing. The sequence is inverted from the traditional approach to preserve glass integrity.
3Strength
If electrochromic device is exposed to tempering process, then glass strength increases, but device performance degrades due to lithium loss and redistribution
Solution Approach 1:
The patent uses an intermediary diffusion barrier layer that selectively prevents lithium ion migration between the electrochromic device and the glass substrate during tempering. This barrier allows the glass to be strengthened through the tempering process while blocking the pathway that would otherwise cause lithium loss and redistribution in the device layers.
Solution Approach 2:
The patent applies parameter changes by carefully controlling the tempering process parameters (temperature, time, atmosphere) to minimize lithium migration while achieving adequate glass strengthening. The tempering is conducted at temperatures and durations that optimize both glass strength improvement and lithium stability in the device.
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
This approach allows for the production of high-quality electrochromic devices that maintain functionality and performance after tempering or chemical strengthening, reducing defects and enhancing energy efficiency by only processing high-quality glass substrates.
Implementation Method 1
Glass tempering is a process by which glass is thermally treated to increase its strength. During tempering the glass is subjected to high heat until its softening point is reached and then the glass is rapidly cooled.
Implementation Method 2
strengthening the glass substrate with a chemical process... coating the annealed glass pane with potassium nitrate... The EC device and the annealed glass pane are then heated to between about 300°C and about 400°C.
Implementation Method 3
Lithium ions in the electrochromic device are driven into the electrochromic layer, the counter electrode layer, and/or a region between the electrochromic layer and the counter electrode layer.
Data Source
Figure 1A~1B
Figure 1C
Figure 2A
AI summary
This disclosure provides systems, methods, and apparatus for tempering or chemically strengthening glass substrates having electrochromic devices fabricated thereon. In one aspect, an electrochromic device is fabricated on a glass substrate. The glass substrate is then tempered or chemically strengthened. The disclosed methods may reduce or prevent potential issues that the electrochromic device may experience during the tempering or the chemical strengthening processes, including the loss of charge carrying ions from the device, redistribution of charge carrying ions in the device, modification of the morphology of materials included in the device, modification of the oxidation state of materials included in the device, and the formation of an interfacial region between the electrochromic layer and the counter electrode layer of the device that impacts the performance of the device.