Full-Back TOPCon Solar Cell with Merged Deposition for Lower Cost
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Solution Overview
Problem
The preparation of full-back electrode solar cells with TOPCon technology is complex and costly, requiring significant upgrades to the PERC production line, which hinders cost reduction and efficiency improvement in the photovoltaic industry.
Innovation Solution
A low-cost preparation method for a passivated contact full-back electrode solar cell using a P-type monocrystalline Si wafer, involving a three-in-one multi-layer film deposition in a single process step, including a tunnel silicon oxide, in-situ doped amorphous silicon film, and texturing mask layer, followed by laser ablation and electrode printing, utilizing PECVD and ALD devices for efficient film deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If TOPCon technology is used for full-back electrode solar cell preparation, then conversion efficiency is improved (above 25% in large area), but manufacturing cost and process complexity increase significantly
Solution Approach 1:
The patent combines multiple film deposition steps (tunnel oxide layer, intrinsic polysilicon layer, and texturing mask layer) into a single PECVD process step, reducing the number of separate deposition devices and process steps. This merging approach maintains the high efficiency benefits of TOPCon technology while significantly simplifying the manufacturing process and reducing equipment complexity.
Solution Approach 2:
The patent uses a single PECVD device to perform multiple functions: depositing the tunnel oxide layer, forming the intrinsic polysilicon layer, and creating the texturing mask layer. This multi-functionality approach eliminates the need for separate ALD, PECVD, and texturing equipment, thereby reducing overall device complexity while achieving TOPCon-level efficiency.
2Manufacturing precision
If TOPCon technology is implemented on prior PERC production line, then cell efficiency is improved, but upgrading cost increases
Solution Approach 1:
The patent merges multiple specialized deposition steps into a single PECVD process, allowing the production line to upgrade to TOPCon technology using existing or minimally modified PECVD equipment. This approach achieves high cell efficiency while minimizing upgrading costs by avoiding the need for multiple specialized deposition devices.
Solution Approach 2:
The PECVD device performs self-service by sequentially depositing multiple layers (tunnel oxide, intrinsic polysilicon, and mask layer) in one continuous process without requiring intervention from separate specialized devices. This self-service capability reduces equipment investment and upgrading costs while maintaining high efficiency production.
3Manufacturing precision
If multiple separate deposition steps are used for tunnel oxide and polysilicon layers, then film quality is improved, but process time and manufacturing cost increase
Solution Approach 1:
The patent combines the deposition of tunnel oxide layer, intrinsic polysilicon layer, and texturing mask layer into a single PECVD process step. This merging maintains the required film quality through precise process control while significantly reducing process time and increasing productivity by eliminating multiple separate deposition cycles.
Solution Approach 2:
The PECVD process operates continuously to deposit all necessary layers in sequence without interruption or intermediate steps. This continuous action maintains film quality through consistent process parameters while maximizing productivity by eliminating the time losses associated with multiple separate deposition steps and device transitions.
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 reduces process steps, silver paste consumption, and manufacturing costs while maintaining high efficiency, enabling better cost performance and large-scale production of high-performance solar cells.
Implementation Method 1
growing a tunnel silicon oxide (SiO x) film layer, an in-situ doped amorphous Si film layer, and a texturing mask layer on the back of the Si wafer
Implementation Method 2
etching a part of the texturing mask layer at a certain area on the back of the Si wafer by a laser
Implementation Method 3
depositing an aluminum oxide (AlO x) film on the front and back of the Si wafer
Implementation Method 4
ablating, by the laser, a part of the AlO x film, and a part of the SiN x passivation film or the SiN x /SiON x laminated passivation film at the certain area on the back of the Si wafer
Implementation Method 5
an aluminum paste is used in the backfield area to form a second electrode, wherein an Al-back surface field (Al-BSF) layer is formed in a region where the aluminum paste and the Si wafer are in direct contact during the sintering process
Data Source
Figure 1
AI summary
The present invention discloses a low-cost passivated contact full-back electrode solar cell and a preparation method thereof. The preparation method includes: S1, configuring a P-type monocrystalline silicon (Si) wafer as a Si substrate and performing an alkali polishing; S2, performing an RCA cleaning and a hydrogen fluoride (HF) cleaning; S3, growing a tunnel silicon oxide (SiOx) film layer, an in-situ doped amorphous Si film layer, and a texturing mask layer on the back of the Si wafer; S4, performing an annealing activation on the amorphous Si film layer to form a polycrystalline Si film layer; S5, etching the texturing mask layer by a laser; S6, performing a double-sided texturing on the Si wafer; S7, performing the HF cleaning to completely remove the texturing mask layer; S8, depositing an aluminum oxide (AlOx) film on the front and back of the Si wafer; S9, depositing a silicon nitride (SiNx) passivation film or a silicon nitride/silicon oxynitride (SiNx/SiONx) laminated passivation film on the front and back of the Si wafer; S10, ablating, by the laser, a part of the AlOx film and a part of the SiNx passivation film or the SiNx/SiONxlaminated passivation film on the back of the Si wafer; and S11, performing a screen-printing and a sintering on the back of the Si wafer, where a silver paste is used in a passivated contact area, and an aluminum paste is used in a backfield area.