Solar Cell Residual Damage Layer Gettering
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Solution Overview
Problem
Current solar cell manufacturing methods face challenges in increasing photoelectric conversion efficiency and bulk lifetime while maintaining a simplified process, as contaminants and damaged layers from slicing steps can reduce solar cell performance and are difficult to completely remove.
Innovation Solution
Leaving a residual damaged layer of 0.2 to 5 µm on the monocrystalline silicon substrate after texture formation enhances the getter effect, improving bulk lifetime and solar cell performance without increasing the number of manufacturing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the damaged layer is completely removed by deep chemical etching, then the surface recombination rate is reduced, but the getter effect is weakened and bulk lifetime is reduced
Solution Approach 1:
Instead of completely removing the damaged layer (excessive action), the patent applies partial etching that leaves a residual damaged layer of 0.2 to 5 µm thickness. This partial action optimizes the balance between reducing surface recombination and maintaining the getter effect for trapping impurities, thereby preserving bulk lifetime.
Solution Approach 2:
The patent changes the parameter of damaged layer thickness from complete removal (0 µm) to a controlled residual thickness (0.2 to 5 µm). This parameter optimization allows the damaged layer to serve dual functions: reducing surface recombination while maintaining gettering capability for impurity atoms.
2Object-affected harmful factors
If multiple cleaning steps are added to remove contaminants, then contamination is reduced, but the manufacturing process complexity increases
Solution Approach 1:
The patent converts the harmful damaged layer from slicing into a beneficial gettering site. Instead of adding cleaning steps to remove contaminants, the residual damaged layer actively traps impurity atoms, transforming a potential harm into a useful function that reduces contamination effects without increasing process complexity.
Solution Approach 2:
The residual damaged layer provides self-service by automatically trapping impurity atoms through its gettering effect. This eliminates the need for additional active cleaning steps, as the damaged layer itself performs the contamination control function.
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
The residual damaged layer acts as getter sites for impurity atoms, prolonging minority carrier lifetime and enhancing conversion efficiency, while maintaining a simplified process by utilizing existing slicing damage, thus improving solar cell performance and reducing contamination issues.
Implementation Method 1
the damaged layer which originates from the slicing step and is left near the surface functions as getter site
Implementation Method 2
Anisotropic etching makes use of a difference in etch rate dependent on silicon plane orientation
Data Source
Figure 1~2
Figure 3A~3D
AI summary
Disclosed is a solar cell having a silicon monocrystal substrate surface with a textured structure and, near the surface of said substrate, a damage layer reflecting the slice processing history from the time of manufacture of the silicon monocrystal substrate. The damage layer near the surface of the silicon monocrystal substrate is derived from the slice processing history at the time of manufacture of the substrate and functions as a gettering site, contributing to a longer lifetime of the substrate minority carriers. Thanks to this effect, the solar cell characteristics are dramatically increased. Further, new damage need be inflicted, and no additional work is required because damage from the slicing is used.