Textured Semiconductor Surface Etching for Tandem Solar Cell Deposition
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Solution Overview
Problem
Existing methods for generating textured surfaces on semiconductor layers for tandem solar cells face challenges in achieving a suitable surface morphology for subsequent layer deposition, particularly with solution-based methods, which can lead to short circuits due to protruding pyramid tips.
Innovation Solution
A method involving anisotropic etching with a first alkaline etching solution to create pyramid-shaped textures, followed by anisotropic etching with a second alkaline etching solution to reduce the height difference between peaks and valleys, thereby modifying the texture to be suitable for solution-based deposition of subsequent layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anisotropic etching with alkaline etching solution is used to create pyramid-shaped textures on semiconductor surface, then light reflectance is reduced and light absorption is improved, but the pyramid tips protrude through subsequently deposited layers causing short circuits
Solution Approach 1:
The etching process is divided into two distinct stages: first, strong anisotropic etching creates the pyramid structure for light trapping; second, weak isotropic etching removes the problematic pyramid tips. This segmentation allows each etching step to optimize for its specific function without compromising the other.
Solution Approach 2:
The patent applies different etching characteristics (strong anisotropic vs. weak isotropic) to different stages of the same surface treatment process. The first etching solution (e.g., KOH with additives) creates pyramids with specific local geometry, while the second etching solution (e.g., diluted KOH or TMAH) selectively removes only the tip regions, creating a locally modified surface morphology that eliminates short circuits while preserving light-trapping functionality.
2Use of energy by moving object
If strong anisotropic etching is used to create deep pyramid textures for light trapping, then light absorption increases, but the height difference between peaks and valleys becomes too large for uniform layer deposition
Solution Approach 1:
The weak isotropic etching step is performed as a preliminary action before layer deposition. This pre-treatment reduces the height difference between pyramid peaks and valleys, creating a more uniform surface that allows subsequent perovskite layers to be deposited evenly without bridging across large height differences, while the pyramid structure remains intact for light trapping.
3Shape
If isopropanol or isopropanol-free additives are used during etching to form pyramids, then pyramid-shaped textures are successfully created, but the pyramid tips remain too sharp and protrude through deposited layers
Solution Approach 1:
The patent extracts and removes only the problematic pyramid tip regions through the second weak isotropic etching step. The bulk pyramid structure formed by the first etching (with isopropanol or isopropanol-free additives) is preserved for light trapping, while the extracted tip portions—which cause short circuits—are selectively removed to create rounded or truncated surfaces that prevent electrical breakdown.
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 modified textured surface allows for effective solution-based deposition of perovskite layers in tandem solar cells, preventing short circuits and maintaining low reflectance, thus enhancing the efficiency and yield of the solar cells.
Implementation Method 1
anisotropic etching of a surface of a semiconductor layer with a first alkaline etching solution to generate a surface of the semiconductor layer comprising pyramid-shaped textures
Implementation Method 2
anisotropic etching of the surface comprising the pyramid-shaped textures with a second alkaline etching solution, which differs from the first alkaline etching solution, to cause material removal of the pyramid-shaped textures
Data Source
AI summary
In a method for generating a textured surface of a semiconductor layer, a surface of the semiconductor layer is etched anisotropically with a first alkaline etching solution to generate a surface of the semiconductor layer including pyramid-shape textures. Subsequently, the surface including the pyramid-shaped textures is etched anisotropically with a second alkaline etching solution, which differs from the first alkaline etching solution, to cause material removal of the pyramid-shaped textures, thereby reducing a height difference between peaks and neighboring valleys of the pyramid-shaped textures. A method for manufacturing a tandem solar cell further includes generating a first solar cell structure of the tandem solar cell including the textured surface, and generating a second solar cell structure of the tandem solar cell on the side of the first solar cell structure on which the textured surface is arranged.