Laser Detachment of Thin-Film Solar Cell Functional Layers
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Solution Overview
Problem
Existing recycling methods for thin-film solar cell modules face challenges in efficiently detaching the functional layers from the substrate without damaging the substrate or causing excessive thermal stress, which can lead to the plastic layer melting and adhering back to the substrate, making it difficult to separate the layers intact.
Innovation Solution
A laser-based method where the substrate is scanned with a laser beam to detach the functional layers, with controlled scanning patterns and cooling techniques to minimize thermal load, allowing the plastic layer to be peeled off from the substrate and subsequently from the cover layer, while maintaining the integrity of the remaining layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a laser beam is used to detach functional layers from the substrate, then the separation efficiency is improved, but the thermal load may cause the plastic layer to melt and adhere back to the substrate
Solution Approach 1:
The patent applies local quality by selectively targeting the laser beam at the first electrode layer while avoiding the plastic layer. The laser parameters (wavelength, power, scanning speed) are optimized to ensure absorption by the electrode layer without transmitting excessive heat to the plastic encapsulation, thus achieving localised heating only where needed for detachment.
Solution Approach 2:
The patent employs periodic action through pulsed laser irradiation or controlled scanning patterns. By using intermittent laser exposure rather than continuous heating, the system allows heat dissipation between pulses, preventing cumulative thermal buildup that would melt the plastic layer while still achieving effective detachment of the electrode layer.
2Speed
If the laser beam power is increased to improve detachment, then the separation speed increases, but the plastic layer may melt and lose its integrity
Solution Approach 1:
The patent applies parameter changes by optimizing the laser beam characteristics (wavelength, power density, scanning speed, pulse duration) to match the absorption properties of the first electrode layer. By tuning these parameters, the system achieves rapid heating of the electrode layer for fast detachment while keeping the peak temperature below the melting point of the plastic encapsulation.
Solution Approach 2:
The patent replaces mechanical separation methods with a controlled thermal field approach. Instead of applying physical force to separate layers, the system uses selective laser heating to create thermal gradients that cause differential expansion and adhesion failure at the electrode-substrate interface, achieving separation without mechanical stress on the plastic layer.
3Manufacturing precision
If the laser scans the entire surface to ensure complete detachment, then the separation completeness is improved, but the processing time increases
Solution Approach 1:
The patent applies preliminary action by first performing a survey scan or using optical sensors to identify the precise boundaries and characteristics of the functional layers before the main detachment process. This preliminary information allows the system to optimize the scanning pattern and focus the laser only on critical areas, ensuring complete detachment while minimizing unnecessary scanning and reducing overall processing time.
Solution Approach 2:
The patent segments the detachment process into multiple passes or zones. The laser scanning is divided into different regions with optimized parameters for each zone, allowing parallel processing or prioritized treatment of critical areas. This segmentation enables complete separation while reducing total processing time by avoiding uniform scanning of the entire module surface.
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 effectively separates the substrate from the functional layers with reduced thermal stress, ensuring the plastic and cover layers remain intact, enabling efficient recycling of solar cell components without damage to the substrate.
Implementation Method 1
the first electrode layer is able to absorb the laser beam used
Implementation Method 2
the local thermal load from the energy input must be kept as low as possible
Implementation Method 3
with only the first electrode layer being at least partly evaporated
Data Source
AI summary
A method for recycling thin-film solar cell modules which are which are composed of a substrate layer with a superimposed structure of functional layers, a plastic layer that encapsulates the functional layers, and a cover layer. The substrate layer is transparent to a working laser beam, and the first functional layer, an electrode layer, is able to absorb this working laser beam. The free surface of the substrate layer is scanned with the working laser beam so that the first electrode layer, due to having absorbed the working laser beam, is at least partially vaporized and the superimposed structure of the functional layers is thus detached from the substrate layer. The substrate layer, separately from the functional layers that are attached to the plastic layer and the cover layer, is subsequently available for separate further processing.