Solar Cell Electrode Paste for Balanced Bus-Bar and Finger Printing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for reducing the lay-down amount of conductive paste in solar cell electrodes do not effectively balance the amounts between bus-bar and finger electrodes, leading to inefficiencies and disconnections, which increases the cost and decreases the efficiency of solar cell manufacturing.
Innovation Solution
A conductive paste formulation that includes metal powder, glass frit, and an organic vehicle, where the lay-down amounts for bus-bar and finger electrodes are calculated using specific equations to ensure a controlled and balanced application, with ethyl cellulose resin and silicone oil added to optimize the paste's properties, allowing for a reduced overall paste lay-down while maintaining or improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the lay-down amount of conductive paste is reduced to lower cost, then the manufacturing cost decreases, but the finger electrode suffers from severe reduction in paste amount leading to disconnects and degraded efficiency
Solution Approach 1:
The paste composition is optimized with specific glass frit (6-12 wt%), metal powder (85-93 wt%), and organic vehicle (2-8 wt%) ratios that create different flow characteristics for different electrode types. This local quality adjustment allows the same paste to provide adequate material for finger electrodes while controlling bus-bar paste deposition, resolving the contradiction between cost reduction and reliability maintenance.
Solution Approach 2:
The patent adjusts key parameters including glass frit particle size (0.5-5 μm), metal powder content (85-93 wt%), and organic vehicle composition to control paste viscosity and flow behavior. These parameter changes enable reduced overall paste consumption while ensuring sufficient paste remains in finger electrode areas to prevent disconnects, thereby lowering cost without sacrificing reliability.
2Productivity
If the lay-down amount of conductive paste is uniformly reduced across all electrodes, then the overall paste consumption decreases, but the bus-bar electrode cannot achieve proper coverage and the finger electrode suffers from disconnects
Solution Approach 1:
The paste formulation incorporates glass frit with specific particle size distribution (0.5-5 μm) and optimized binder content (2-8 wt%) that creates differential wetting and flow characteristics. This allows the paste to be selectively deposited in appropriate amounts on different electrode geometries during screen printing, achieving both high productivity and precise control over paste distribution uniformity across bus-bar and finger electrodes.
Solution Approach 2:
The conductive paste is formulated as a composite material combining metal powder (85-93 wt%), glass frit (6-12 wt%), and organic vehicle (2-8 wt%). This composite structure provides tailored rheological properties that enable differential paste transfer during printing, allowing efficient overall application while maintaining precise control over local paste distribution to prevent both over-deposition on bus-bars and under-deposition on finger electrodes.
Data Source
AI summary
The present disclosure is a conductive paste for a solar cell electrode comprising a metal powder, a glass frit, and an organic vehicle, wherein the discharge amount factor A of the bus-bar electrode can be calculated by Equation 1 below, and the discharge amount factor B of the finger electrode can be calculated by the following Equation 2, and |AB| relates to a conductive paste for a solar cell electrode, characterized in that it is 0.100 or less.A=(Slip velocity×10)/(G′×0.01) [Equation 1]B=1/(G″×0.01) [Equation 2]