Laser Ablation of PV Front Contact Layer Using Auxiliary Trench
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Solution Overview
Problem
Existing methods for removing layer material in photovoltaic multilayer structures using laser radiation often result in short-circuit paths due to increased electrical conductivity along processing edges, particularly in the absorber layer, which is problematic during both separating trench structuring and edge decoating of photovoltaic modules.
Innovation Solution
A method involving the introduction of an auxiliary trench adjacent to the target removal area using laser radiation, which serves as a controlled breaking line to isolate the front contact layer from the absorber layer, preventing short-circuit paths and facilitating efficient material removal without severing the carrier substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser radiation is used to remove layer material in photovoltaic multilayer structures, then material removal efficiency is improved, but short-circuit paths are formed due to increased electrical conductivity along processing edges
Solution Approach 1:
The patent applies preliminary action by introducing an auxiliary trench before the main material removal step. This auxiliary trench is created adjacent to the target removal area to serve as a pre-established breaking line. The auxiliary trench prevents the formation of short-circuit paths by providing a predetermined separation zone before the laser removes the layer material, thus ensuring electrical isolation is maintained while enabling efficient material removal.
2Reliability
If mechanical scratching or cutting techniques are used to introduce separating trenches, then electrical isolation is achieved, but production time and cost increase
Solution Approach 1:
The patent replaces mechanical scratching or cutting techniques with laser radiation for introducing the auxiliary trench. This substitution eliminates wear of mechanical tools and reduces production time while maintaining the electrical isolation function. The laser-based approach creates the auxiliary trench without the drawbacks of mechanical methods, achieving both reliability and productivity improvements.
3Productivity
If laser radiation parameters are increased to improve material removal speed, then productivity increases, but thermal damage to the absorber layer increases causing more short-circuits
Solution Approach 1:
The patent segments the material removal process into two distinct steps: first creating an auxiliary trench adjacent to the target area, then removing the layer material in the target area. This segmentation allows the laser parameters to be optimized for each step independently, enabling faster removal in the second step without causing excessive thermal damage to the absorber layer, thus improving productivity while minimizing harmful thermal effects.
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 effectively prevents short-circuit issues while enabling efficient and reliable removal of layer material, reducing production effort and ensuring electrical isolation of the front contact layer from the absorber layer, thus improving the process for both separating trench structuring and edge decoating of photovoltaic modules.
Implementation Method 1
layer material in a predeterminable target removal line area is removed by means of laser radiation
Implementation Method 2
along which the layer material to be removed can be blasted off in a controlled manner
Data Source
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AI summary
The method for removing a layer material of a layer structure on a carrier substrate (1) in an actual removal line area, where the layer structure has lower and upper electrically conductive layers (2, 8) and a single- or multi-layered intermediate layer material, comprises introducing an auxiliary trench in the layer material along two opposing sides of the actual removal line area using a laser beam in an auxiliary step, and irradiating the laser beam on the layer material in the actual removal line area laterally next to the auxiliary trench in a removal step. The method for removing a layer material of a layer structure on a carrier substrate (1) in an actual removal line area, where the layer structure has lower and upper electrically conductive layers (2, 8) and a single- or multi-layered intermediate layer material, comprises introducing an auxiliary trench in the layer material along two opposing sides of the actual removal line area using a laser beam in an auxiliary step, and irradiating the laser beam on the layer material in the actual removal line area laterally next to the auxiliary trench in a removal step, so that the layer material present in the actual removal line area is removed in the thickness of the upper electrically conductive layer, where the layer material is removed up to the carrier substrate through the removal step and/or the auxiliary trench is introduced with a predetermined lateral distance (A) from the actual removal line area and acts as a breaking line in the removal step for electrically insulatingly breaking-off the layer material of the upper electrically conductive layer in the area laterally between the auxiliary trench and the actual removal line area using the laser beam. The auxiliary trench is introduced up to a depth, which is smaller than a removal depth of the layer material in the actual removal line area during the removal step. The laser beam differs itself with respect to the wavelength, power density and/or pulse duration of the laser beam during the removal step. The upper electrically conductive layer is a front contact layer of a photovoltaic-multilayer structure on the carrier substrate and the actual removal line area is an isolation trench, which is introduced through the front contact layer. The actual removal line area is an area of the photovoltaic-multilayer structure from which the layer is to be removed, on the carrier substrate, where the single- or multi-layered intermediate layer material contains an absorber layer (6) of the photovoltaic-multilayer structure. The laser beam is irradiated from the back side of the carrier substrate in the removal step, and is irradiated with a wavelength, which is selectively chosen for absorption through the absorber layer. The laser beam in the auxiliary step is selectively chosen for absorption through the front contact layer.