Nanosecond Laser Structuring of Thin-Film Solar Cells
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Solution Overview
Problem
Existing methods for structuring thin-film solar cells, such as using mechanical gravers or picosecond lasers, are inefficient and prone to creating wide tracks and short circuits due to thermal effects, and are costly.
Innovation Solution
Heating an optically dense metallization layer with a nanosecond laser through a transparent substrate to evaporate components of the semiconductor layer, preventing short circuits and allowing for precise layer removal and edge deletion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a mechanical graver is used to structure thin-film solar cells, then structuring can be performed, but the tracks become wide and the method is slow
Solution Approach 1:
The patent replaces the mechanical graver system with a laser-based system. The laser beam focuses energy to create narrow tracks through ablation of the semiconductor layer, eliminating mechanical contact. This substitution achieves both narrow track widths (improved precision) and high processing speeds (improved productivity) by using optical energy instead of mechanical cutting.
2Manufacturing precision
If a picosecond laser is used to structure thin-film solar cells, then narrow tracks can be achieved, but the equipment cost becomes very high
Solution Approach 1:
The patent changes the laser pulse duration parameter from picoseconds to nanoseconds. This parameter change maintains the ability to create narrow tracks through precise energy deposition while significantly reducing equipment cost. Nanosecond lasers are commercially available and much more affordable than picosecond lasers, thus resolving the contradiction between precision and cost.
3Ease of operation
If structuring is performed from the front side, then the process is simple, but the electrically conductive layer melts and flows down causing short circuits
Solution Approach 1:
The patent inverts the structuring direction by performing laser processing from the rear side of the solar cell instead of the front side. The laser beam passes through the transparent substrate and ablates the semiconductor layer from below, creating tracks that do not cause the front electrically conductive layer to melt or flow down. This inversion maintains process simplicity while preventing short circuits and improving reliability.
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 enables efficient, cost-effective, and precise removal of layers in thin-film solar cells, reducing the risk of short circuits and improving the structuring process.
Implementation Method 1
Heating an optically dense metallization layer with a nanosecond laser through a transparent substrate to evaporate components of the semiconductor layer
Implementation Method 2
Heating an optically dense metallization layer with a nanosecond laser through a transparent substrate
Data Source
Figure 1~2
Figure 3
AI summary
In a method for removing at least sections of at least one semiconductor layer (4) of a layer stack (1), an optically dense metallisation layer (3) is heated such that the semiconductor layer located on top is detached.