Laser Stop Layer for Foil Metallization in Solar Cells
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Solution Overview
Problem
Current solar cell metallization techniques face challenges in achieving high-throughput, damage-free metal patterning on the backside of solar cells, particularly with thick or highly reflective metals like aluminum, due to the need for high laser energy that can cause damage to underlying structures and lack of a suitable laser-energy window for complete metal isolation without over-etching.
Innovation Solution
A foil-based metallization process using a paste with opacifying pigments, an inorganic binder, and an organic medium is applied to form non-conductive material regions that act as a laser stop during metal patterning, preventing damage to underlying layers while allowing complete metal isolation, and a sticky damage buffer layer ensures proper adhesion and alignment of metal foils during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high laser energy is used to pattern thick or highly reflective metals like aluminum, then complete metal isolation is achieved, but damage to underlying structures occurs
Solution Approach 1:
A laser stop layer comprising a inorganic binder and opacifying pigment is introduced as an intermediary between the metal foil and the underlying semiconductor structure. This layer absorbs and scatters laser energy, preventing excessive penetration and damage to the underlying structures while enabling complete metal isolation through laser ablation
Solution Approach 2:
The laser stop layer is formed as a composite material combining an inorganic binder with opacifying pigments. This composite structure provides both adhesion to the underlying layers and high laser energy absorption capability, resolving the contradiction between achieving complete metal isolation and preventing damage to underlying structures
2Manufacturing precision
If high laser energy is used to pattern metal, then complete metal isolation is achieved, but the process becomes less suitable for high-throughput manufacturing
Solution Approach 1:
The laser stop layer acts as a mediator that modifies the laser-matter interaction, creating a more efficient ablation process. The layer absorbs laser energy and converts it to thermal energy, which rapidly vaporizes the metal foil, enabling faster and more complete isolation without requiring excessively high laser energies that would reduce manufacturing throughput
3Object-affected harmful factors
If a laser stop layer is introduced to prevent damage, then damage-free metal patterning is achieved, but the process complexity increases
Solution Approach 1:
The laser stop layer is applied in advance to the substrate before metal foil deposition. This preliminary action prepares the surface to receive and process the laser energy appropriately, simplifying the overall process by pre-configuring the damage prevention mechanism rather than requiring complex real-time control during laser patterning
Solution Approach 2:
The use of a composite material comprising inorganic binder and opacifying pigment provides a straightforward, well-defined process step that is easy to control and reproduce, reducing process complexity despite the addition of the laser stop layer
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 approach enables efficient, damage-free metal patterning with improved throughput and reduced operational costs by using a paste with high ablation resistance and low firing temperatures, maintaining cell performance and efficiency.
Implementation Method 1
laser ablating through the metal foil in alignment with the locations between the alternating N-type and P-type semiconductor regions
Implementation Method 2
the non-conductive material regions act as a laser stop during the laser ablating
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 1E~1F
AI summary
Approaches for the foil-based metallization of solar cells and the resulting solar cells are described. For example, a method of fabricating a solar cell involves forming a plurality of alternating N-type and P-type semiconductor regions in or above a substrate. The method also involves forming a paste between adjacent ones of the alternating N-type and P-type semiconductor regions. The method also involves curing the paste to form non-conductive material regions in alignment with locations between the alternating N-type and P-type semiconductor regions. The method also involves adhering a metal foil to the alternating N-type and P-type semiconductor regions. The method also involves laser ablating through the metal foil in alignment with the locations between the alternating N-type and P-type semiconductor regions to isolate regions of remaining metal foil in alignment with the alternating N-type and P-type semiconductor regions. The non-conductive material regions act as a laser stop during the laser ablating.