Cadmium Telluride Film Deposition via Aqueous Precursors
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Solution Overview
Problem
Current manufacturing techniques for cadmium telluride (CdTe) films in photovoltaic technology face high fabrication costs and poor film quality, necessitating a method to reduce costs and improve efficiency.
Innovation Solution
A method involving sequential deposition of aqueous precursor solutions containing cadmium and tellurium ions directly on a substrate, with optional high shear wash steps and post-deposition treatments like annealing in a reducing environment, to form high-quality CdTe films without hazardous intermediates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If close-spaced sublimation is used to deposit CdTe films, then film quality can be improved, but manufacturing costs and energy consumption increase due to high vacuum requirements and high processing temperatures
Solution Approach 1:
The invention changes the deposition parameters from high vacuum and high temperature conditions to atmospheric pressure and lower temperature conditions by using solution-based chemical deposition, thereby reducing energy consumption while maintaining film quality
Solution Approach 2:
The invention replaces the mechanical vacuum-based deposition system with a chemical solution-based deposition system, eliminating the need for high vacuum equipment and high temperature processing while achieving comparable or superior film quality
2Reliability
If traditional vapor deposition methods are used, then film adherency can be achieved, but hazardous cadmium intermediates are formed during the process
Solution Approach 1:
The invention converts the harmful intermediate step involving hazardous cadmium compounds into a beneficial direct deposition process where cadmium ions are deposited directly as CdTe film without forming hazardous intermediates, eliminating the harm while maintaining film adherency
Solution Approach 2:
The invention uses aqueous precursor solutions containing cadmium ions as a safe intermediary medium that delivers cadmium directly to the substrate without forming hazardous cadmium intermediates, replacing the harmful vapor-phase cadmium compounds
3Ease of manufacture
If sequential deposition of aqueous precursor solutions is used, then manufacturing costs can be reduced and hazardous intermediates avoided, but film crystallinity and quality must be maintained comparable to vapor-deposited layers
Solution Approach 1:
The invention performs preliminary actions including substrate preparation, controlled sequential deposition of cadmium and tellurium precursor solutions, and post-deposition treatment to ensure proper crystallization, thereby achieving high film quality through careful process design before final film formation
Solution Approach 2:
The invention optimizes deposition parameters such as precursor solution concentration, deposition temperature, drying conditions, and post-deposition treatment parameters to achieve high crystallinity and film quality comparable to vapor deposition while using low-cost solution-based processing
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 reduces manufacturing costs and improves film quality, achieving high crystallinity and efficiency comparable to vapor-deposited layers, while avoiding the formation of hazardous cadmium intermediates.
Implementation Method 1
The telluride precursor solution can include Te2− ions in solution such that the Te2− ions binds with the Cd2+ ions forming a CdTe film adherently formed directly on the substrate
Implementation Method 2
The method can optionally include a high shear wash step following each tellurium deposition. Such a high shear wash step can remove unreacted materials, remove non-adhered materials
Implementation Method 3
In yet another optional example, the method can include drip coating a cadmium chloride, a magnesium chloride treatment, and/or a post-deposition annealing step in a reducing environment such as forming gas
Data Source
AI summary
A method of creating cadmium telluride films is presented. The method demonstrates heterogeneous nucleation of CdTe directly on a substrate through sequential deposition of aqueous precursor solutions containing cadmium and telluride ions, respectively. The method can include (i) applying a cadmium precursor solution to the substrate to form a cadmium precursor film on the substrate, (ii) applying a telluride precursor solution to the cadmium precursor film. The telluride precursor solution includes Te2− in solution such that a CdTe film is adherently formed directly on the substrate.