Tandem Solar Cell Substrate Etching for Flat Surface
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Solution Overview
Problem
Crystalline silicon substrates used in solar cells have pyramid-shaped defects from saw marks, which hinder uniform deposition of perovskite unit layers and lead to shunts, degrading fill factor characteristics in tandem solar cells.
Innovation Solution
A method involving isotropic and anisotropic etching using acid and alkali solutions, respectively, to remove saw damage and defects, resulting in a flat substrate with improved surface roughness, allowing for uniform unit layer formation and suppressing shunts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional saw wire cutting is used to process crystalline silicon substrates, then manufacturing cost is reduced and productivity is improved, but pyramid-shaped defects and surface damage are generated that hinder uniform perovskite layer deposition
Solution Approach 1:
The patent applies preliminary chemical etching treatment to the silicon substrate surface before perovskite deposition. By performing this etching step in advance, the saw-induced pyramid defects are removed or modified, creating a flat surface that enables uniform perovskite layer formation. This preliminary action resolves the surface quality issue without affecting the saw cutting productivity.
2Use of energy by moving object
If texture is formed on the substrate surface to increase sunlight path, then light absorption is improved, but the pyramid-shaped defects are not removed and cause non-uniform perovskite layer formation
Solution Approach 1:
Instead of forming texture on the substrate and accepting the pyramid defects, the patent inverts the approach by chemically etching the substrate surface first to remove the pyramid defects, then forming a controlled texture or keeping the surface flat. This reversal ensures that the perovskite layer deposits uniformly on a defect-free surface while still maintaining good light absorption through alternative mechanisms.
Solution Approach 2:
The patent changes the chemical parameters of the substrate surface through controlled etching processes. By adjusting etching time, temperature, and chemical composition, the pyramid-shaped defects are selectively removed while creating a surface morphology that is optimal for both light absorption and uniform perovskite deposition, thus resolving the contradiction between light trapping and layer uniformity.
3Manufacturing precision
If repeated SDE etching is performed to remove pyramid defects, then surface roughness is reduced, but the defects persist and productivity decreases due to multiple processing steps
Solution Approach 1:
The patent extracts or removes the problematic pyramid-shaped defects through a single, optimized chemical etching step that specifically targets these defects. By designing an etching process that selectively removes the saw-induced damage in one step rather than requiring repeated treatments, the method achieves both high surface flatness and maintained productivity.
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 method achieves a substrate with no pyramid-shaped defects, enabling uniform perovskite unit layer deposition and enhancing fill factor characteristics and efficiency of tandem solar cells.
Implementation Method 1
isotropic etching the substrate
Implementation Method 2
removing saw damage on a surface of the substrate by anisotropic etching the isotropically etched substrate
Implementation Method 3
a method involving isotropic and anisotropic etching using acid and alkali solutions, respectively, to remove saw damage and defects
Data Source
AI summary
Discussed is a tandem solar cell manufacturing method including etching a crystalline silicon substrate, whereby a solar cell can be obtained which does not have a pyramid-shaped defect on a surface of the substrate, inhibits the generation of a shunt through the substrate having excellent surface roughness properties, and can secure fill factor properties, the solar cell being capable of being obtained through the tandem solar cell manufacturing method. The method includes preparing a crystalline silicon substrate; performing an isotropic etching process of the substrate; and removing a saw damage on a surface of the substrate by performing an anisotropic etching process of the isotropically etched substrate.