TOPCON Solar Cell Texturing and Localized Emitter for Bifaciality
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Solution Overview
Problem
Existing TOPCON cells face challenges in improving their bifaciality factor and efficiency while also requiring complex and costly manufacturing processes.
Innovation Solution
A method involving double-sided texturing, boron and phosphorus diffusion, laser grooving, and selective emitter formation to enhance the bifaciality factor and reduce costs, including the use of borosilicate and phosphorosilicate glasses to protect and simplify the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional TOPCON cell manufacturing is used, then cell efficiency exceeds 25%, but the bifaciality factor remains low and difficult to improve
Solution Approach 1:
The manufacturing process is divided into three distinct texturing stages with specific temperature and time parameters for each stage. The first texturing forms initial surface structure, the second texturing enhances light trapping, and the third texturing optimizes the final surface morphology. Each stage segments the overall texturing function to achieve progressive improvement in bifaciality factor while controlling process complexity through standardized parameters.
Solution Approach 2:
The patent systematically varies key process parameters including temperature (65-75°C for texturing, 950-1000°C for boron diffusion, 900-950°C for phosphorus diffusion) and time (350-450 seconds for texturing, 4000-5000 seconds for boron diffusion, 3000-4000 seconds for phosphorus diffusion). By optimizing these parameters at each stage, the method improves bifaciality factor while maintaining manageable manufacturing complexity through parameter standardization.
2Productivity
If multiple texturing and diffusion steps are performed, then light absorption and carrier generation are enhanced, but manufacturing costs and process complexity increase
Solution Approach 1:
The patent combines multiple functions into integrated process steps. For example, the texturing process simultaneously creates surface structure for light trapping and prepares the surface for subsequent diffusion by removing oxidation layers. The diffusion process combines dopant introduction with glass formation in a single step. This merging reduces the number of separate process steps while maintaining high cell efficiency through cumulative effects of each combined operation.
Solution Approach 2:
The method performs preliminary texturing and surface preparation before diffusion processes. The first and second texturing stages pre-form the surface morphology and remove oxidation layers in advance, creating optimal conditions for subsequent boron and phosphorus diffusion. This preliminary action ensures that the diffusion processes proceed more efficiently with better dopant incorporation, reducing the need for additional corrective steps and overall simplifying the manufacturing process.
3Manufacturing precision
If standard texturing and diffusion processes are used, then cell structure is formed, but mechanical damage and ion damage occur during processing
Solution Approach 1:
The patent applies a protective glass layer formation as a cushioning measure before the laser grooving and emitter formation steps. The phosphorosilicate glass formed during phosphorus diffusion acts as a protective layer that cushions the silicon surface against mechanical damage during subsequent processing. This beforehand cushioning protects the freshly formed diffusion layers and surface structures from damage while allowing precise emitter formation through laser grooving without causing excessive mechanical or ion damage.
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 significantly improves the bifaciality factor and efficiency of TOPCON cells by reducing process complexity and costs, enhancing light absorption and carrier generation, and minimizing mechanical and ion damage.
Implementation Method 1
first double-sided texturing the silicon wafer to form first textured surfaces on the front side and the back side
Implementation Method 2
performing boron diffusion on the back side to form a boron diffused layer and a borosilicate glass
Implementation Method 3
performing phosphorus diffusion to form a phosphorus diffused layer and the phosphorosilicate glass
Implementation Method 4
laser grooving to form a localized emitter
Data Source
AI summary
The present application provides a method for preparing a TOPCON cell and a TOPCON cell. The preparation method includes steps of: double-sided texturing the silicon wafer multiple times. Polysilicon is deposited on the front side, and then phosphorus diffusion is performed to form a doped polysilicon layer and a phosphorosilicate glass; alternatively, the phosphorus diffusion is performed to form the phosphorus diffused layer and the phosphorosilicate glass. Laser grooving is performed to form localized emitters. After third double-sided texturing on the silicon wafer, the double-sided rounding is performed.