Electrochromic Devices with Planarizing Layer for Large-Area Applications
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Solution Overview
Problem
Electrochromic devices face challenges with high cost, low cycling durability, inadequate switching range and speed, and issues like light scattering, haze, and electrical shorts, particularly in large-area applications, due to existing deposition techniques and material limitations.
Innovation Solution
An electrochromic device with a planarizing layer structure, including a secondary electrochromic layer with a composition like LiaNiM1xM2yOz, where M1 and M2 are selected elements, and a method for fabricating such devices using techniques like dip coating, spin coating, or spray pyrolysis, to achieve improved surface roughness and optical properties, reducing manufacturing costs and increasing throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If vacuum deposition techniques (sputtering, thermal evaporation, electron beam evaporation, CVD) are used to fabricate EC thin films, then film quality and uniformity can be achieved, but the system becomes complex and expensive with slow deposition rates and high maintenance costs
Solution Approach 1:
The patent replaces complex vacuum-based mechanical deposition systems with a solution-based dip-coating process. The electrochromic layers are formed by dip-coating substrates in aqueous or alcoholic solutions containing metal salt precursors, followed by low-temperature heat treatment (200-400°C) to convert the salts to oxides. This substitution eliminates the need for expensive vacuum equipment while achieving uniform films with controlled thickness and composition.
Solution Approach 2:
The patent changes the deposition parameters from high-vacuum physical vapor deposition conditions to ambient or controlled-atmosphere solution processing. By controlling parameters such as dip-coating speed, solution concentration, pH, and heat treatment temperature, the method achieves precise control over film uniformity, composition, and morphology without requiring complex vacuum systems.
2Ease of manufacture
If sol-gel techniques are used to deposit EC layers, then manufacturing cost is reduced, but throughput becomes slow and significant chemical solution waste is generated
Solution Approach 1:
The patent employs periodic dip-coating cycles where the substrate is repeatedly dipped into and withdrawn from the electrochromic solution. Each dip-coating cycle deposits a controlled amount of material, and by adjusting the frequency and number of cycles, both cost-effective material deposition and improved throughput are achieved. The periodic nature allows for efficient batch processing while minimizing solution waste through controlled deposition rates.
3Ease of manufacture
If electrodeposition is used to deposit EC layers, then manufacturing cost is reduced, but it becomes difficult to deposit mixtures of metal oxides and maintain film uniformity across large-area devices
Solution Approach 1:
The patent uses composite aqueous or alcoholic solutions containing multiple metal salt precursors (e.g., tungsten, nickel, vanadium salts) that co-deposit to form mixed metal oxide electrochromic layers. The solution-based approach allows simultaneous deposition of multiple components with controlled ratios, achieving uniform composite films across large areas that are difficult to obtain by electrodeposition. The heat treatment step converts the mixed salt precursor into a uniform mixed oxide structure.
4Ease of manufacture
If spray pyrolysis is used to produce EC layers, then single layers can be formed, but additional heat treatment is required which increases time and cost
Solution Approach 1:
The patent merges the deposition and heat treatment steps into a single integrated process. By dip-coating the substrate in the electrochromic solution and then performing a single low-temperature heat treatment (200-400°C) to convert the metal salt precursors to oxides, the method eliminates the need for separate high-temperature spray pyrolysis and additional heat treatment steps. This integration reduces both time and cost while achieving uniform electrochromic layers.
5Ease of manufacture
If lamination is used to assemble EC devices, then single EC layers can be joined, but production complexity increases and additional weight is added
Solution Approach 1:
The patent merges multiple electrochromic layers and functional layers (ion conductor, transparent conductor, substrate) into a single integrated multilayer structure deposited directly on the substrate in sequence. This monolithic approach eliminates the need for separate lamination steps with polymer ion conductors or ormolytes, reducing production complexity and eliminating additional weight from lamination materials while maintaining device functionality.
6Ease of manufacture
If organic or ormolyte ion conductors are used in EC devices, then device assembly is simplified, but degradation risk increases when exposed to heat and ultraviolet radiation
Solution Approach 1:
The patent changes the ion conductor material from organic polymers or ormolytes to inorganic materials such as metal oxides (e.g., tungsten oxide, niobium oxide, tantalum oxide) or their composite forms. These inorganic ion conductors exhibit superior thermal and UV radiation stability while maintaining ionic conductivity. The inorganic materials are deposited using the same dip-coating and heat treatment process, simplifying assembly while dramatically improving durability for architectural applications.
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 enhances switching range and speed, reduces light scattering and electrical shorts, and lowers manufacturing costs, making electrochromic devices more viable for large-area applications.
Implementation Method 1
at least valleys of the underlying layer are filled by the lower surface of the at least one planarizing layer
Implementation Method 2
Electrochromic refers to the ability of certain materials to change color when an electrical charge is applied
Implementation Method 3
spray pyrolysis (SP) has been used to produce single EC layers at different substrate temperatures
Data Source
AI summary
An electrochromic device is disclosed which has a plurality of layers, including at least one planarizing layer having an upper surface roughness which is less than or equal to half of the upper surface roughness of an underlying layer in contact with a lower surface of the at least one planarizing layer, wherein at least valleys of the underlying layer are filled by the lower surface of the at least one planarizing layer. A method for fabricating the electrochromic device is also disclosed.