Solar Cell Back Surface Cleaning for Carrier Recombination
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Solution Overview
Problem
Conventional methods for manufacturing back contact solar cells face challenges in preventing carrier recombination on the substrate surface due to contamination from ionized electrodes, making it difficult to effectively clean the surface without compromising the formation of semiconductor layers.
Innovation Solution
A method involving a cleaning process on specific regions of the substrate surface before forming semiconductor layers, including the use of a recombination layer with higher impurity content or microcrystalline structure to prevent carrier recombination, and forming semiconductor layers in a specific order to minimize contamination and improve productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cleaning process is performed on the back surface of the substrate before forming the i-type and p-type semiconductor layers, then carrier recombination can be prevented, but ionized p-side electrodes contaminate the back surface during subsequent processing
Solution Approach 1:
The invention divides the back surface into multiple regions: a first region where the i-type semiconductor layer is formed, a second region that is cleaned and where the n-type semiconductor layer is formed, and a third region where the p-type semiconductor layer is formed. This spatial segmentation allows the cleaning process to be applied selectively to the second region without affecting the other regions, thereby preventing contamination while maintaining carrier recombination prevention.
Solution Approach 2:
The invention applies different treatments to different regions of the back surface. The second region undergoes a cleaning process to remove contaminants and prevent carrier recombination, while the first and third regions are protected from this cleaning process to avoid removing the previously formed semiconductor layers. This local quality approach ensures that each region receives the appropriate treatment for its specific function.
2Reliability
If the cleaning process is performed before forming the p-side electrodes, then carrier recombination is prevented, but the component material of the p-side electrodes contaminates the back surface during electrode formation
Solution Approach 1:
The invention segments the back surface into distinct regions and sequences the formation of different semiconductor layers in specific regions at different times. The i-type layer is formed in the first region, then the second region is cleaned, and finally the n-type layer is formed in the second region. This segmentation allows cleaning to occur without interfering with electrode formation in other regions.
Solution Approach 2:
The invention performs the cleaning process of the second region before forming the n-type semiconductor layer in that region. This preliminary action ensures that the surface is clean and free from contaminants before the n-type layer is deposited, thereby preventing carrier recombination at the interface between the substrate and the n-type layer.
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 carrier recombination at the substrate surface, enhancing the solar cell's efficiency and productivity by allowing for the formation of semiconductor layers without contamination, thereby improving the solar cell's performance.
Implementation Method 1
a cleaning process such for example as a wet etching process is performed
Data Source
AI summary
A method for manufacturing a solar cell (100) includes the steps of: a step of cleaning an exposed region (R2) on a rear surface of an n-type crystalline silicon substrate (10n), wherein the step is carried out subsequent to a step of patterning an i-type amorphous semiconductor layer (11i) and a p-type amorphous semiconductor layer (11p) and prior to a step of forming an i-type amorphous semiconductor layer (12i).