Solar Cell Electrode Composition for Fine-Line Screen Printing
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Solution Overview
Problem
Current methods for printing solar cell electrodes struggle to achieve fine linewidth and high aspect ratio patterns with high conversion efficiency, as they are influenced by viscosity, dryness, and adhesion, and lack effective rheological control.
Innovation Solution
A composition for solar cell electrodes comprising 50-90 wt% conductive powder, 1-15 wt% glass frit, 3-40 wt% organic vehicle, and 0.01-2 wt% thixotropic agent, specifically formulated to satisfy certain viscosity ratios and include leaded or lead-free glass frits, binder resins, and thixotropic agents like amine or fumed silica compounds, enabling screen-printing of fine patterns with high aspect ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional printing methods (gravure offset or screen-printing) are used with traditional paste compositions, then the printing process can be performed, but it is difficult to achieve fine linewidth and high aspect ratio patterns
Solution Approach 1:
The invention changes the rheological parameters of the paste composition by introducing a thixotropic agent and controlling the viscosity ratio between static and dynamic states. This allows the paste to maintain shape during printing (high static viscosity) while flowing through the screen mesh (low dynamic viscosity), enabling fine linewidth and high aspect ratio patterns to be achieved
Solution Approach 2:
The invention uses a composite paste composition containing conductive powder, glass frit, organic vehicle, and thixotropic agent. This composite formulation combines materials with different properties to achieve both the required printability and the desired fine pattern geometry, resolving the contradiction between manufacturing precision and ease of manufacture
2Manufacturing precision
If the paste composition has high viscosity to maintain pattern shape, then aspect ratio is improved, but the composition becomes difficult to print and fill fine linewidth features
Solution Approach 1:
The invention introduces thixotropy to make the paste composition dynamic in its viscosity characteristics. The paste transitions from a high-viscosity state (when stationary, maintaining pattern shape) to a low-viscosity state (when sheared during printing, enabling screen filling). This dynamic behavior resolves the contradiction between maintaining aspect ratio and achieving printability
Solution Approach 2:
The invention controls the viscosity ratio parameter between static and dynamic states to be within a specific range. This parameter control allows the paste to exhibit high viscosity for pattern formation while maintaining low enough viscosity for screen printing, simultaneously achieving high aspect ratio and good printability
3Manufacturing precision
If the linewidth is reduced to achieve fine patterns, then manufacturing precision is improved, but the amount of conductive material decreases affecting electrical performance
Solution Approach 1:
The invention changes the aspect ratio parameter of the printed pattern, enabling vertical lines to be formed with high aspect ratios. This allows the conductive material to be concentrated in the vertical direction (improving electrical connection) while maintaining fine horizontal linewidth (improving manufacturing precision), thus resolving the contradiction between linewidth reduction and electrical performance
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 composition allows for the realization of printed patterns with fine linewidth and high aspect ratio, achieving high conversion efficiency and excellent printability, as demonstrated by the calculated thixotropic indices and performance metrics such as low serial resistance and high short circuit current.
Implementation Method 1
screen-printing is significantly influenced by rheology or thixotrophy
Implementation Method 2
The silver paste composition is applied on an anti-reflection film, and includes silver powder, glass frit powder, an organic binder and a plasticizer
Implementation Method 3
The electrodes of the solar cell are formed on the wafer by applying, patterning, and baking an electrode composition
Data Source
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AI summary
The embodiments of present invention relate to a composition for solar cell and electrodes fabricated using the same. More specifically, it is related to the composition can be printed in fine-line width on a substrate by screen-printing and provides excellent conversion efficiency, and electrodes fabricated using the same.