Full-Back Electrode TOPCon Solar Cell for Lower-Cost PERC Upgrades
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Solution Overview
Problem
The preparation of full-back electrode solar cells is complex and costly, making it challenging to upgrade existing PERC production lines for efficiency improvements and cost reduction, while the minority carrier lifetime of P-type Si wafers needs to meet the technical requirements of the full-back cell structure.
Innovation Solution
A low-cost preparation method for passivated contact full-back electrode solar cells involving sequential steps such as alkali polishing, RCA and HF cleaning, growth of tunnel silicon oxide and amorphous Si film layers, annealing activation, double-sided texturing, and deposition of aluminum oxide and silicon nitride films, followed by laser ablation and screen-printing, utilizing PECVD and ALD for efficient film deposition and reducing process steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If full-back electrode cell technology is implemented to improve efficiency and eliminate front grid line shading loss, then photoelectric conversion efficiency is improved, but production cost and process complexity increase significantly
Solution Approach 1:
The patent combines multiple functions into a single integrated back electrode structure that incorporates both the positive and negative electrodes on the back surface, eliminating the need for separate front grid lines and reducing overall structural complexity while maintaining high efficiency
Solution Approach 2:
The back electrode structure serves multiple functions simultaneously: it acts as both the positive and negative electrode carrier, provides passivation through the tunnel oxide layer, enables texturing for light trapping, and facilitates simplified manufacturing processes compatible with existing PERC production lines
2Productivity
If TOPCon technology with tunnel oxide layer and polycrystalline Si film layer is used to reduce recombination under metal grid lines, then cell efficiency is improved, but manufacturing cost increases
Solution Approach 1:
The patent optimizes the thickness and doping concentration parameters of the tunnel oxide layer and polycrystalline Si film layer to achieve the minimum required passivation effect, reducing material usage and manufacturing cost while maintaining high cell efficiency
Solution Approach 2:
The patent uses a thin tunnel oxide layer that provides effective passivation at minimal thickness, reducing material costs while maintaining the necessary electrical isolation and passivation function
3Duration of action of stationary object
If PERC production line is upgraded to full-back electrode cell production to extend service cycle, then equipment utilization is improved, but process complexity and cost increase
Solution Approach 1:
The patent incorporates texturing mask layer deposition and annealing activation steps that prepare the structure in advance for the final electrode formation, allowing existing PERC production equipment to be utilized with minimal modification while achieving full-back electrode functionality
Solution Approach 2:
The patent divides the back electrode structure into distinct functional layers (tunnel oxide layer, polycrystalline Si film layer, texturing mask layer) that can be deposited and processed separately using existing PERC production line equipment, facilitating incremental upgrades
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 method results in solar cells with improved cost performance and efficiency, reducing the manufacturing cost per watt and extending the service life of the PERC device, while promoting large-scale production of low-cost, high-performance solar cells with good process compatibility.
Implementation Method 1
tunnel oxide passivated contact (TOPCon) technology is considered to be the next generation of passivation technology
Implementation Method 2
performing an annealing activation on the amorphous Si film layer so that the amorphous Si film layer is transformed into a polycrystalline Si film layer
Implementation Method 3
ablating, by the laser, a part of the AlOx film, and a part of the SiNx passivation film or the SiNx/SiONx laminated passivation film on the back of the Si wafer
Implementation Method 4
utilizing PECVD and ALD for efficient film deposition
Implementation Method 5
simultaneously depositing an aluminum oxide (AlOx) film on the front and back of the Si wafer
Implementation Method 6
performing a screen-printing and a sintering on the back of the Si wafer
Implementation Method 7
performing a screen-printing and a sintering on the back of the Si wafer
Data Source
AI summary
A preparation method of a low-cost passivated contact full-back electrode solar cell includes: performing alkali polishing on a Si wafer; performing RCA cleaning and HF cleaning; growing a tunnel SiOx film layer, an in-situ doped amorphous Si film layer, and a texturing mask layer on the back of the Si wafer; performing annealing activation on the amorphous Si film layer to form a polycrystalline Si film layer; etching the texturing mask layer; performing double-sided texturing on the Si wafer; performing HF cleaning to remove the texturing mask layer; depositing an AlOx film on the front and back of the Si wafer; depositing a SiNx passivation film on the front and back of the Si wafer; ablating a part of the AlOx film and a part of the SiNx passivation film on the back of the Si wafer; and performing screen-printing and sintering on the back of the Si wafer.