Back Contact Solar Cell Laser Blocking Layer Process
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Solution Overview
Problem
The existing preparation process for back contact solar cells with passivated contact structures is complicated, difficult to control, and results in inconsistent photoelectric conversion efficiencies due to damage to passivation layers during film layer removal, leading to poor stability and efficiency.
Innovation Solution
A method involving double-sided polishing, laser blocking, and alkaline/acid cleaning to accurately control film layer removal, ensuring precise width and thickness, and forming isolated tunneling oxide and polysilicon layers, with texturing to enhance stability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography, laser or chemical corrosion is used to remove nanometer-thick film layers, then the film layers can be removed, but the passivation layer is damaged and process stability is poor
Solution Approach 1:
The patent introduces a laser blocking layer as an intermediary protective structure between the P+ doped polysilicon layer and the N+ doped polysilicon layer. This laser blocking layer absorbs laser energy during the texturing process, preventing direct laser damage to the passivation layer and enabling precise film layer removal while maintaining passivation layer integrity and process stability
Solution Approach 2:
The patent performs preliminary actions by first forming the P+ doped polysilicon layer and laser blocking layer, then selectively removing portions of these layers before forming the N+ doped polysilicon layer. This preliminary removal and protective layer formation enables subsequent precise processing without damaging the passivation layer
2Ease of manufacture
If direct laser ablation or photoresist introduction is used to form mask layers, then mask layers can be formed, but the process becomes complicated and difficult to control
Solution Approach 1:
The patent extracts and removes the complex photolithography and mask layer formation steps by using direct laser ablation to selectively remove portions of the P+ doped polysilicon layer and laser blocking layer. This simplifies the process by eliminating photoresist introduction, mask layer formation, and multiple photolithography steps while maintaining precise pattern control
Solution Approach 2:
The patent replaces the mechanical and chemical processes of photolithography (photoresist application, exposure, development, and mask removal) with a direct laser ablation process. This substitution simplifies the manufacturing process by using laser energy directly to define patterns without requiring complex photolithography equipment and chemical processing
3Manufacturing precision
If multiple sequential processing steps are used to form isolated P+ and N+ polysilicon layers, then the layers can be formed with proper isolation, but the process is time-consuming and inefficient
Solution Approach 1:
The patent merges multiple sequential processing steps into a more integrated process. By forming the P+ doped polysilicon layer and laser blocking layer together, then selectively removing portions of both layers in sequence, and forming the N+ doped polysilicon layer in the removed regions, the patent achieves precise layer isolation while reducing the total number of separate processing cycles and improving overall processing efficiency
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
Improves process stability, reduces carrier recombination, and enhances photoelectric conversion efficiency by ensuring consistent film layer removal and formation, simplifying the process while maintaining high efficiency.
Implementation Method 1
removing the laser blocking layer and the first silicon oxide layer in a first region on the back side of the silicon substrate by laser
Implementation Method 2
removing the first tunneling oxide layer and the P+ polysilicon layer in the first region by alkaline solution polishing
Implementation Method 3
removing the laser blocking layer and the first silicon oxide layer on the second region by acid cleaning
Data Source
Figure 1
Figure 2(A)~2(C)
Figure 3~4
AI summary
The present disclosure discloses a preparation method for a back contact solar cell and a back contact solar cell. The preparation method comprises: performing double-sided polishing treatment on a silicon substrate; stacking and forming a first tunneling oxide layer, a P+ polysilicon layer and a laser blocking layer on a back side of the silicon substrate from inside to outside, wherein a first silicon oxide layer is synchronously formed on the P+ polysilicon layer; removing the laser blocking layer and the first silicon oxide layer in a first region by laser, wherein the first region and a second region retaining the laser blocking layer are arranged alternately; removing the first tunneling oxide layer and the P+ polysilicon layer in the first region; controlling, in the first region, the formation of a second tunneling oxide layer and an N+ polysilicon layer stacked on the second tunneling oxide layer, which are isolated from and alternately arranged with the first tunneling oxide layer and the P+ polysilicon layer, and performing texturing treatment on a gap region in the first region adjacent to the second region and on a front side of the silicon substrate; removing the laser blocking layer and the first silicon oxide layer in the second region by acid cleaning, thereby improving the stability of the preparation process of a back contact solar cell.