Electrochromic Element Electrode Thickness Gradient
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Solution Overview
Problem
Existing electrochromic elements suffer from transmittance non-uniformity due to voltage drop gradients across large surfaces, which is not effectively addressed by previous solutions that focus on electrode conductivity or resistance ratios, limiting their reliability and configurational freedom.
Innovation Solution
The electrochromic element features transparent electrodes with varying resistivity based on distance from the electric supply, ensuring a potential difference of 20 mV or less across the surface, achieved by proportional thickness reduction of the electrodes, which reduces transmittance non-uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the electrode area is increased to cover a larger field of view, then the light regulation coverage is improved, but the voltage drop gradient across the electrode surface increases causing transmittance non-uniformity
Solution Approach 1:
The electrode thickness is varied locally across the electrode surface, being thinner at regions farther from the electric supply portion and thicker near the supply portion. This local variation in thickness compensates for the voltage drop gradient by reducing the resistance in high-voltage-drop regions, thereby achieving uniform potential distribution and transmittance across the entire electrode area.
Solution Approach 2:
The physical parameter of electrode thickness is changed across different regions of the electrode. By making the thickness a function of the distance from the electric supply portion, the resistance distribution is optimized to compensate for voltage drops, ensuring that the potential difference across any two points on the electrode surface remains within an acceptable range (e.g., 20 mV or less).
2Reliability
If the electrode resistance is reduced to minimize voltage drop, then the potential uniformity is improved, but the configurational freedom and design flexibility are reduced
Solution Approach 1:
Instead of using a uniform thickness electrode, the invention employs local quality variation by making the electrode thickness dependent on the distance from the electric supply portion. This allows the resistance to be optimized locally to compensate for voltage drops while maintaining design flexibility in other aspects of the electrochromic element.
Solution Approach 2:
The electrode structure is made dynamic in terms of its thickness profile, adapting the thickness according to the position relative to the electric supply portion. This dynamic design enables the electrode to automatically compensate for voltage drop variations without requiring complex external control mechanisms, thereby maintaining potential uniformity while preserving configurational freedom.
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 configuration significantly reduces transmittance non-uniformity to 5% or less, enhancing the light regulation capabilities and reliability of the electrochromic elements, particularly in applications like variable neutral density filters for imaging devices.
Implementation Method 1
The amount of light passing through the electrodes can be regulated in such a manner that the transmittance of a compound in the electrochromic layer is varied by applying a voltage to the electrochromic layer from the electrodes.
Implementation Method 2
At least one of the electrochemically active anodic and cathodic materials is an electrochromic material, that is, a material that exhibits an absorption band in the visible light region by electrochemical oxidation or reduction.
Implementation Method 3
When the electrochromic element has a large area, the influence of a voltage drop in a surface of each electrode is particularly large. This is because the resistivity of a material contained in the electrode is two orders of magnitude greater than that of metal.
Data Source
AI summary
Potential non-uniformity in a surface of an electrode in an electrochromic element is improved during coloring and color erasing. The electrochromic element includes a pair of transparent electrodes and an electrochromic layer placed between the transparent electrodes. Each of the transparent electrodes includes an end portion having an electric supply portion. The electric supply portions face each other. The surface resistivity of each of the transparent electrodes increases with the increase of the distance from a corresponding one of the electric supply portions. The potential of the transparent electrodes is such that the difference between the maximum and minimum potentials in a surface of each transparent electrode is less than or equal to a predetermined value.