Segmented Electrodeposition for Uniform Solar Cell Deposition
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Solution Overview
Problem
Conventional electrodeposition methods face challenges in achieving uniform deposition on large area resistive substrates, such as glass coated with transparent conductive oxide, due to high sheet resistance, which limits current density and increases production time and cost.
Innovation Solution
The use of a plurality of ohmic contact pins that are electrically isolated from the counter electrode, allowing for direct contact with the substrate to supply plating potential, thereby overcoming the resistance and enabling higher deposition currents while maintaining film uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electrodeposition methods are used on large area resistive substrates, then the substrate can be coated with a thin layer of material, but the deposition is non-uniform due to high sheet resistance causing voltage non-uniformities
Solution Approach 1:
The invention divides the single counter electrode into multiple segmented counter electrodes arranged in an array. Each counter electrode segment is independently controlled and positioned to correspond with contact pins on the substrate. This segmentation allows independent potential control of each region, compensating for voltage non-uniformities caused by substrate resistance and achieving uniform deposition across large areas.
Solution Approach 2:
The invention applies different potentials to different regions of the counter electrode array based on local requirements. Each counter electrode segment can be independently biased to compensate for local variations in substrate resistance, contact resistance, and deposition rate. This local quality control ensures uniform deposition by tailoring the electrical characteristics to each specific region of the substrate.
2Productivity
If higher plating currents are used to increase deposition rate, then productivity improves, but film uniformity deteriorates due to voltage non-uniformities across the substrate
Solution Approach 1:
By segmenting the counter electrode into multiple independently controllable units, the system can handle higher total currents while maintaining uniformity. Each segment distributes a portion of the total current locally, preventing the voltage non-uniformities that would occur with a single high-current counter electrode. This enables high-speed deposition across the entire substrate area.
Solution Approach 2:
The invention dynamically adjusts the potential parameters of individual counter electrode segments to maintain uniform deposition even at high plating currents. By independently controlling the potential of each segment, the system compensates for current distribution variations and maintains film uniformity while achieving high productivity through increased overall current density.
3Manufacturing precision
If a single counter electrode is used, then the apparatus is simple, but uniform deposition over large areas cannot be achieved due to inherent substrate resistance
Solution Approach 1:
The counter electrode is divided into multiple segments arranged in an array, with each segment corresponding to a region of the substrate. This segmentation enables uniform deposition control across large areas while keeping each individual segment relatively simple in structure. The modular nature of the segmentation allows for scalable design that adapts to different substrate sizes.
Solution Approach 2:
The segmented counter electrode array serves multiple functions simultaneously: it acts as the cathode for electrodeposition, provides independent potential control for each substrate region, and enables both uniform deposition and high-current operation. This multi-functionality achieves improved deposition uniformity without proportionally increasing device complexity.
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 allows for faster and more uniform electrodeposition on large area substrates, improving throughput and reducing production costs by enabling higher plating currents without compromising film thickness or chemical stoichiometry.
Implementation Method 1
establishing a plurality of ohmic contacts to a resistive substrate film
Implementation Method 2
supply plating potential to the substrate (working electrode)
Implementation Method 3
electrodeposition is generally a plating process that uses electrical current to reduce or oxidize chemical species of a desired material from a solution and coat a conductive substrate with a thin layer of that material
Implementation Method 4
uses electrical current to reduce or oxidize chemical species of a desired material from a solution
Implementation Method 5
Solar or photovoltaic cells are devices that convert photons into electricity by the photovoltaic effect
Data Source
AI summary
The invention relates generally to electrodeposition apparatus and methods. When depositing films via electrodeposition, where the substrate has an inherent resistivity, for example, sheet resistance in a thin film, methods and apparatus of the invention are used to electrodeposit materials onto the substrate by forming a plurality of ohmic contacts to the substrate surface and thereby overcome the inherent resistance and electrodeposit uniform films. Methods and apparatus of the invention find particular use in solar cell fabrication.