Hybrid Passivation Back-Contact Cell for Stable Laser Processing
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Solution Overview
Problem
Traditional heterojunction back contact cells face challenges with low actual filling factor, photoelectric conversion efficiency, and yield due to sensitivity to thermal effects and mechanical damage, limiting mass production and commercialization.
Innovation Solution
A hybrid passivation back contact cell is developed, combining the tunneling oxide layer and N-type doped silicon crystal layer from TOPCON technology with the traditional heterojunction passivation film layer, using a high-temperature manufacturing process to create a hybrid passivation structure that improves stability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional heterojunction back contact cell technology is used, then the manufacturing process is simple with low surface recombination rate, but the filling factor and photoelectric conversion efficiency are low due to sensitivity to thermal effects and mechanical damage
Solution Approach 1:
The patent applies composite materials by combining TOPCON technology (tunneling oxide layer and N-type doped silicon crystal layer) with traditional heterojunction passivation film layer to form a hybrid passivation structure. This composite structure integrates the advantages of both technologies: the tunneling oxide layer provides thermal stability and mechanical strength, while the amorphous silicon thin film maintains low surface recombination rate. The hybrid structure resolves the contradiction by creating a multi-layer composite that simultaneously improves filling factor and maintains passivation stability.
2Reliability
If traditional heterojunction back contact cell technology is used, then the open circuit voltage is high, but the yield is low due to sensitivity to chemical contamination and mechanical scratch
Solution Approach 1:
The patent applies beforehand cushioning by introducing a tunneling oxide layer beneath the amorphous silicon thin film. This oxide layer serves as a protective cushion that prevents direct contact between the fragile amorphous silicon and the substrate, thereby reducing sensitivity to mechanical scratch and chemical contamination during manufacturing. The tunneling oxide layer absorbs mechanical stress and chemical attacks, protecting the passivation structure and improving yield while maintaining high open circuit voltage.
3Productivity
If laser processing is introduced to improve mass production efficiency, then the processing speed increases, but the amorphous silicon thin film is damaged due to thermal effect
Solution Approach 1:
The patent applies intermediary by introducing a tunneling oxide layer as a mediator between the laser processing system and the amorphous silicon thin film. This oxide layer has higher thermal resistance and can withstand higher temperatures, serving as a thermal buffer that protects the heat-sensitive amorphous silicon from laser-induced thermal damage. The intermediary layer allows laser processing to proceed at higher speeds while preventing thermal degradation of the passivation film, thereby improving mass production efficiency without causing damage.
4Ease of manufacture
If more printing processes are added to achieve back contact electrode opening, then the electrode transfer is complete, but the efficiency is reduced by mechanical contact
Solution Approach 1:
The patent applies mechanics substitution by replacing traditional mechanical printing processes with laser processing for back contact electrode opening. The hybrid passivation structure, particularly the tunneling oxide layer, enables direct laser ablation through the passivation layers to create electrode openings without requiring multiple mechanical printing steps. This substitution eliminates mechanical contact with the cell surface, preventing damage to the passivation while achieving complete electrode transfer, thereby improving efficiency and maintaining ease of manufacture.
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 hybrid passivation structure enhances the filling factor, photoelectric conversion efficiency, and yield, allowing for simpler fabrication and lower material costs, while maintaining high process stability and efficiency.
Implementation Method 1
a tunneling oxide layer and an N-type doped silicon crystal layer sequentially arranged in an outward direction perpendicular to the back surface
Implementation Method 2
Laser processing for a cell surface belongs to a non-contact mode, and can reduce an efficiency reduction of the cell caused by a processing technology
Data Source
AI summary
The present disclosure pertains to the field of back contact cell technologies, and particularly relates to a hybrid passivation back contact cell and a fabrication method thereof, the hybrid passivation back contact cell including: an N-type doped silicon substrate having a light receiving surface and a back surface, and a first semiconductor layer and a second semiconductor layer which are arranged on the back surface, wherein the second semiconductor layer includes an intrinsic silicon layer and a P-type doped silicon layer sequentially arranged in an outward direction perpendicular to the back surface, and the first semiconductor layer includes a tunneling oxide layer and an N-type doped silicon crystal layer sequentially arranged in the outward direction perpendicular to the back surface.