Immersion Coating for Solar Absorber Film Quality
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Solution Overview
Problem
Existing deposition techniques for Co3O4 solar absorbers face challenges such as high reflectance, inadequate adherence and quality of films, and limited scalability, which hinder their efficiency and practicality for large-scale solar energy applications.
Innovation Solution
A modified immersion coating technique is employed, involving submersion, draining, discharging, drying, and decomposition of precursor films on substrates, allowing for the deposition of thin films with a thickness of less than 10 μm. This method can be cyclically repeated to achieve the desired film thickness and optical properties, using Co3O4/CuO layers to enhance absorptivity and reduce reflectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional deposition techniques (sputtering, traditional coating) are used to deposit Co3O4 coatings, then film quality and adherence can be improved to some degree, but the scalability for wide-area coating applications is limited and operational temperatures must be high
Solution Approach 1:
The patent replaces conventional mechanical/physical deposition techniques (sputtering, traditional coating) with a chemical solution-based immersion method. The substrate is immersed in a precursor solution containing cobalt salts, allowing chemical deposition of Co3O4 films at lower temperatures with better scalability. This substitution enables wide-area coating while maintaining film quality through chemical reactions rather than mechanical processes.
Solution Approach 2:
The patent changes the operational parameters by using lower deposition temperatures compared to conventional techniques. The immersion method allows deposition at temperatures suitable for various substrates including plastics, while maintaining film quality through controlled chemical reactions. The precursor solution concentration, immersion time, and drying conditions are optimized to achieve desired film properties without high-temperature processing.
2Use of energy by moving object
If Co3O4 coatings are deposited to achieve high solar absorption, then absorptivity is improved, but reflectance remains high at 20-30% which undermines effectiveness
Solution Approach 1:
The patent applies local quality by creating a textured or non-uniform surface morphology on the Co3O4 coating through the immersion deposition process. The precursor solution penetration and drying create variations in film thickness and surface structure at different locations, which effectively reduces reflectance. This local variation in film properties allows the coating to trap light more effectively while maintaining high absorptivity.
Solution Approach 2:
The patent creates a composite structure by combining Co3O4 with other materials or creating a multi-layered coating system. The immersion method allows for deposition of composite coatings that incorporate multiple functional components, where the combination of materials works synergistically to reduce reflectance while enhancing solar absorption. The precursor solution can contain multiple metal salts that form composite oxide structures.
3Manufacturing precision
If advanced deposition techniques like sputtering are used, then film quality can be maintained, but the operation must be small-scale which restricts broader application
Solution Approach 1:
The patent replaces complex mechanical sputtering equipment with a simple immersion tank system. The deposition process uses basic laboratory equipment (beaker, substrate holder, drying oven) rather than sophisticated vacuum sputtering apparatus. This substitution dramatically simplifies the device complexity while maintaining film quality through controlled chemical deposition, enabling the process to be easily scaled from laboratory to industrial production.
Solution Approach 2:
The patent uses inexpensive precursor solutions that can be easily prepared and discarded after use. The immersion method consumes relatively small amounts of precursor material, and the solutions can be refreshed easily without requiring complex system maintenance. This approach replaces expensive, maintenance-intensive sputtering equipment with simple, low-cost consumable precursors, making the process economically viable for large-scale production.
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 method achieves efficient and cost-effective deposition of solar absorber coatings with improved optical absorption and reduced reflectance, demonstrating enhanced performance and scalability for solar energy applications.
Implementation Method 1
draining the precursor liquid by gravity at a controlled flow rate to a collection vessel
Implementation Method 2
drying the homogenous precursor deposition layer in a drying chamber to form a precursor film
Implementation Method 3
decomposing the single film on the substrate at a decomposition temperature to form the thin film
Data Source
AI summary
A method and a system for depositing a thin film with a thickness under 10 μm. The method includes submerging a substrate in a precursor liquid in a deposition vessel having an inlet pipe and outlet pipe and a substrate holder that suspends the substrate inside the deposition vessel at an immersion depth. The outlet pipe is situated at a first height lower than the immersion depth, while the inlet pipe is connected above it, allowing for controlled filling and draining, managed by a drain valve. The excess precursor liquid is discharged from the substrate by gravity to a collection vessel, creating a uniform layer. This layer is then dried in a drying chamber, after which one side of the substrate is cleared to leave a single film which is then heated providing thin film formation.