Solar Cell Electrode Lines with Mixed Particle Shapes
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Solution Overview
Problem
Existing solar cells face issues with solder material penetration into bus bar electrodes, leading to reduced adhesion and reliability, due to the porous structure of silver particles in conventional inks which facilitates tin diffusion.
Innovation Solution
A solar cell design featuring first and second electrode lines with different particle shapes and sizes, where the first electrode line includes spherical particles for improved electrical properties and the second electrode line includes a combination of spherical and non-spherical particles to complicate solder material penetration, thereby enhancing durability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spherical silver particles are used in the electrode line, then electrical conductivity is improved, but solder material penetration increases due to porous structure
Solution Approach 1:
The patent uses a composite particle system combining spherical silver particles (for conductivity) with non-spherical conductive particles (for penetration resistance). This composite structure allows the electrode line to simultaneously achieve excellent electrical properties and resistance to solder material infiltration, resolving the contradiction between conductivity and penetration resistance.
Solution Approach 2:
The patent applies different particle characteristics to different functional requirements within the same electrode line. Spherical particles provide the necessary electrical conductivity, while non-spherical particles provide physical barriers against solder penetration. This local differentiation of particle properties allows simultaneous optimization of both electrical performance and penetration resistance.
2Object-affected harmful factors
If non-spherical particles are used in the electrode line, then solder material penetration is reduced, but electrical conductivity deteriorates
Solution Approach 1:
The patent combines non-spherical conductive particles with spherical silver particles to create a composite electrode line that achieves both penetration resistance and electrical conductivity. The non-spherical particles provide physical barriers while the spherical silver particles maintain electrical pathways, resolving the contradiction between penetration resistance and conductivity.
Solution Approach 2:
The patent assigns different particle shapes to different functional roles: non-spherical particles are positioned to provide penetration resistance, while spherical particles are positioned to provide conductivity. This functional differentiation within the composite structure allows simultaneous achievement of both properties.
3Ease of manufacture
If uniform particle structure is used in the electrode line, then manufacturing is simplified, but adhesion deteriorates due to solder penetration
Solution Approach 1:
The patent uses a composite particle structure combining spherical and non-spherical particles to prevent solder penetration and improve adhesion. While the particle composition is heterogeneous, the manufacturing process remains relatively simple by controlling the overall particle size distribution and composition ratios, balancing manufacturing ease with adhesion improvement.
Solution Approach 2:
The patent introduces particle heterogeneity at the micro-scale level while maintaining uniformity at the macro-scale level. The different particle shapes are distributed throughout the electrode line to provide localized penetration resistance, while the overall structure maintains manufacturing simplicity through controlled composition ratios and size distributions.
Data Source
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AI summary
Provided is a solar cell including: a semiconductor substrate; a conductive area disposed on one surface of the semiconductor substrate; a first electrode line (41) disposed on the conductive area and extending in a first direction; and a second electrode line (42) disposed on the conductive area and extending in a second direction different from the first direction, wherein the first electrode line includes first particles (411) having a spherical shape and a first average diameter, and the second electrode line includes the first particles (411) and second particles (422), the second particles having a non-spherical shape and a second average diameter.