Solar Cell Electroplating Support for Seed-Layer-Free Copper Deposition
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Solution Overview
Problem
Existing methods for depositing metallic materials on substrates, such as solar cells, face challenges including high costs, complexity, wafer breakage, and inefficiencies in both vertical and horizontal electroplating processes, particularly with larger and thinner wafers, and the need to replace silver with more abundant metals like copper.
Innovation Solution
A method involving a support structure with an electrode and counter electrode, allowing substrates to be oriented vertically or transversely in an electrolyte bath for electrodepositing metallic materials, using insoluble electrodes and sealing materials to prevent electrolyte penetration, enabling high-throughput deposition of copper or other metals on selected major surfaces without requiring a seed layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If copper is used to replace silver for forming metallic contacts on solar cells, then material cost is reduced, but copper oxidizes easily making it difficult to incorporate into screen printable paste
Solution Approach 1:
The invention extracts copper particles from the traditional screen printable paste formulation and applies them directly to the solar cell surface, eliminating the need for copper to be incorporated into paste binders and additives. This direct application approach avoids the oxidation problems that occur during paste fabrication while still achieving the cost reduction benefit of using copper instead of silver.
Solution Approach 2:
The invention introduces a conductive polymer coating as an intermediary layer between the copper particles and the environment. This coating protects the copper from oxidation while maintaining electrical conductivity, enabling copper to be used effectively without requiring complex paste formulations or capping layers.
2Reliability
If electroplating is used to form copper electrode pattern, then conductivity is improved, but additional masking step is required
Solution Approach 1:
The invention performs preliminary action by applying conductive polymer coating and copper particles to the entire solar cell surface before any patterning occurs. The masking step then selectively removes material from areas where metal contact is not desired, rather than requiring masking before deposition. This reverses the traditional sequence and eliminates the need for precise pre-masking alignment.
Solution Approach 2:
The invention inverts the traditional electroplating process by first depositing copper particles across the entire surface and then using masking to remove excess material, rather than masking first and then depositing. This inversion simplifies the process by eliminating the need for precise pre-masking and allows for easier pattern definition.
3Ease of manufacture
If vertical clip-based electroplating method is used, then industrial electroplating process is followed, but wafer breakage occurs with larger and thinner wafers
Solution Approach 1:
The invention replaces the mechanical vertical clip-based suspension system with a horizontal conveyor belt system. This substitution eliminates the mechanical stress and potential breakage points associated with vertical handling of large, thin wafers, while still enabling industrial-scale electroplating through the horizontal conveyor approach.
4Productivity
If both positive and negative polarities are formed on the same surface, then light absorption is maximized, but electroplating process becomes more complex
Solution Approach 1:
The invention applies a universal conductive polymer coating and copper particle deposition process to the entire solar cell surface, which then serves multiple functions: providing conductivity for both positive and negative polarities, enabling pattern definition through subsequent masking, and maintaining light absorption efficiency. This multi-functional approach simplifies the overall process while achieving bifacial contact formation.
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 method reduces material costs, minimizes wafer breakage, and enhances processing efficiency by allowing both major surfaces of solar cells to be plated simultaneously, suitable for bifacial modules, while avoiding the need for additional masking steps and seed layers.
Implementation Method 1
passing an electrical current through the electrolyte between the first major surface of the at least one substrate and the counter electrode such that the metallic material is deposited at least some areas of the first major surface of the at least one substrate
Implementation Method 2
passing an electrical current through the electrolyte between the first major surface of the at least one substrate and the counter electrode
Data Source
AI summary
A method for depositing a metallic material on a surface of a substrate comprising the steps of: providing the substrate having opposite first and second major surfaces; providing an arrangement for depositing a metallic material on a surface of the substrate, the arrangement comprising: a support structure having an electrode, a counter electrode, and an electrolyte for depositing metal ions onto one or more portions of the first major surface of the at least one substrate; attaching the substrate to the support structure wherein the electrode is in electrical contact with the substrate; contacting the substrate and the counter electrode with the electrolyte; and thereafter passing an electrical current through the electrolyte between the first major surface of the at least one substrate and the counter electrode such that the metallic material is deposited at at least some areas of the first major surface of the at least one substrate.