Multi-Modal Silver Powder for Low Resistance Solar Electrodes
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Solution Overview
Problem
Conventional silver powders used in electrically conductive pastes for forming solar cell electrodes often result in high resistance values, which hinder efficient solar cell conversion efficiency.
Innovation Solution
A silver powder is produced by mixing a first silver powder with one peak in the dry particle size distribution and a second silver powder with two peaks in the dry distribution, resulting in a final powder with three peaks in the dry distribution and one peak in the wet distribution, optimizing particle size and agglomeration for lower resistance films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional silver powders are used as material for electrically conductive paste, then the paste can be easily manufactured, but the resulting electrode has high resistance value which reduces solar cell conversion efficiency
Solution Approach 1:
The invention segments the silver powder into multiple distinct particle size ranges (5-20 μm, 2-5 μm, and 0.5-2 μm), creating a multi-modal distribution rather than using a single size range. This segmentation allows different particle sizes to fulfill different functional roles: larger particles provide structural framework while smaller particles fill interstices and create conductive pathways, thereby reducing overall resistance while maintaining ease of manufacture.
Solution Approach 2:
The invention applies local quality by assigning different particle size characteristics to different regions of the electrode structure. The multi-modal particle distribution creates zones with varying particle densities and conductive properties throughout the electrode, optimizing local electrical pathways while maintaining overall manufacturing simplicity.
2Quantity of substance
If mixed metal particles with two size ranges are used, then particle packing density improves, but the electrode still exhibits relatively high resistance value
Solution Approach 1:
The invention further segments the particle size distribution into three distinct ranges rather than two, with specific attention to creating a fine particle fraction (0.5-2 μm) that is particularly effective at forming conductive networks. This triple segmentation enables both high packing density through interstitial filling and low resistance through enhanced conductive pathway formation.
Solution Approach 2:
The invention creates a composite particle size distribution system where three different particle size fractions work synergistically. Each fraction contributes differently: the coarse fraction (5-20 μm) provides structural stability, the intermediate fraction (2-5 μm) enhances packing, and the fine fraction (0.5-2 μm) creates efficient conductive pathways, collectively achieving both high density and low resistance.
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 resulting silver powder forms electrically conductive films with lower resistance values, enhancing solar cell conversion efficiency and reducing cavity area and size in fired films.
Implementation Method 1
a volume-based particle size distribution obtained by measuring the first silver powder in a dry process by means of a laser diffraction particle size distribution analyzer
Implementation Method 2
a volume-based particle size distribution obtained by measuring the silver powder in a wet process by means of a laser diffraction scattering particle size distribution analyzer
Data Source
AI summary
There are provided a silver powder, which is able to form an electrically conductive film having a lower resistance value than that of conventional electrically conductive films when the silver powder is used as the material of an electrically conductive paste which is fired to form the electrically conductive film, and a method for producing the same. A first silver powder having one peak or more, at each of which a frequency is a local maximum value in a volume-based particle size distribution obtained by measuring the first silver powder in a dry process by means of a laser diffraction particle size analyzer, is mixed with a second silver powder having two peaks or more, at each of which a frequency is a local maximum value in a volume-based particle size distribution obtained by measuring the second silver powder in a dry process by means of a laser diffraction particle size analyzer, to produce a silver powder having three peaks or more, at each of which a frequency is a local maximum value in a volume-based particle size distribution obtained by measuring the silver powder in a dry process by means of a laser diffraction particle size analyzer, the silver powder having one peak, at which a frequency is a local maximum value in a volume-based particle size distribution obtained by measuring the silver powder in a wet process by means of a laser diffraction scattering particle size analyzer.