Selective Emitter Spot Rows for Metal Printing Alignment Tolerance
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Solution Overview
Problem
The manufacturing process of high-efficiency selective emitter (SE) solar cells faces challenges in achieving precise alignment between laser spots and metal electrodes, with larger laser spots affecting open-circuit voltage and power generation efficiency, while smaller spots require higher precision alignment.
Innovation Solution
A method involving a silicon wafer with a first edge and midline, where laser spots are arranged in spot rows parallel to the edge, with intersecting rows and sub-spot regions, gradually increasing in area from the midline to the edge, to improve alignment and contact precision between metal electrodes and the SE.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser spots are made larger, then alignment between metal electrodes and laser spots becomes easier, but open-circuit voltage and power generation efficiency are reduced
Solution Approach 1:
The patent applies local quality by varying the laser spot area across different regions of the solar cell. Specifically, laser spots near the edges of the silicon wafer have larger areas to accommodate electrode positioning deviations, while laser spots in the center region have smaller areas to maintain high open-circuit voltage. This spatial variation in spot size allows each region to be optimized for its specific requirements, resolving the contradiction between alignment ease and efficiency.
2Loss of energy
If laser spots are made smaller, then open-circuit voltage and power generation efficiency are improved, but alignment precision between metal electrodes and laser spots becomes more difficult to achieve
Solution Approach 1:
The patent implements local quality by creating a non-uniform laser spot size distribution across the wafer surface. Edge regions utilize larger laser spots with lower power density to tolerate alignment variations, while central regions employ smaller laser spots with higher power density to maximize voltage output. This localized differentiation allows the system to achieve both high efficiency in critical areas and robust alignment tolerance in peripheral areas.
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 method enhances alignment accuracy, reduces contact resistance, increases fill factor, and improves solar cell efficiency by adapting to deviations in metal electrode positions, particularly at the edges, while maintaining low contact resistance at the middle position.
Implementation Method 1
illuminating the surface of the silicon wafer by laser spots to form the SE
Data Source
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AI summary
A method for improving alignment between a selective emitters and metal printing, including: providing silicon wafer including first edge and midline parallel to the first edge; texturing and diffusing surface of the silicon wafer; and illuminating the surface of the silicon wafer by laser spots to form the SE. Multiple laser spots are arranged between the first edge and the midline to form spot rows, extension directions of the spot rows are parallel to the first edge, M spot rows are arranged and M is a positive integer and M>1. The M spot rows include N sub-spot regions, N is a positive integer and 1<N≤M, the sub-spot regions include at least one spot row, and areas of the laser spots in each sub-spot region are equal. The areas of the laser spots in different sub-spot regions from the midline pointing to the first edge gradually increases.