Photovoltaic Cell Doping Profile for Lower Contact Recombination
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Solution Overview
Problem
Conventional passivated contact photovoltaic cells, such as HIT and TOPCon cells, face limitations in improving conversion efficiency due to recombination losses in the metal contact region, with existing phosphorus doping distribution studies failing to effectively enhance field effect and passivated contact.
Innovation Solution
A photovoltaic cell design featuring a substrate with a tunneling layer, field passivation layer, and electrodes, where the doping concentration of the first doping element in the field passivation layer is higher than in the tunneling layer and substrate, and a high activation rate is achieved, improving passivation and conversion efficiency by optimizing phosphorus doping distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional passivated contact cells (HIT or TOPCon) are used, then the cell structure is simple and manufacturing is easier, but recombination loss in the metal contact region increases and conversion efficiency cannot be improved further
Solution Approach 1:
The patent segments the contact region into multiple functional layers: a first contact layer with high doping concentration for carrier collection, a second contact layer with low doping concentration for reduced recombination, and a third contact layer with intermediate doping concentration as a transition zone. This segmentation allows each layer to perform its specific function optimally, reducing overall recombination loss while maintaining manufacturability through systematic layer-by-layer fabrication.
Solution Approach 2:
The patent applies local quality by creating spatially varying doping concentrations within the contact structure. The doping concentration is locally optimized: highest at the metal interface for efficient carrier collection, gradually decreasing through the contact layers to minimize recombination at the surface. This local optimization of doping profiles enables reduced recombination loss while maintaining ease of manufacture through controlled doping processes.
2Power
If the doping concentration in the contact region is increased to improve carrier collection, then electrical conductivity improves, but recombination loss increases due to higher doping concentration at the metal contact interface
Solution Approach 1:
The patent applies parameter changes by systematically varying the doping concentration parameter across different contact layers. The first contact layer has high doping concentration (1E19-1E20 atoms/cm³) for high electrical conductivity and carrier collection. The second contact layer has low doping concentration (1E16-1E17 atoms/cm³) for reduced recombination. The third contact layer has intermediate doping concentration (1E18-1E19 atoms/cm³) as a transition. This parameter optimization resolves the contradiction between conductivity and recombination loss.
Solution Approach 2:
The patent resolves the contradiction by adding a vertical dimension to the doping concentration profile. Instead of uniform doping, the doping concentration varies through the thickness of the contact structure, creating a graded profile. This dimensional approach allows high conductivity near the metal interface while maintaining low recombination at the semiconductor surface, effectively decoupling the two competing requirements.
3Device complexity
If a uniform doping concentration is used throughout the contact structure, then the manufacturing process is simpler, but the field effect and passivation effect cannot be effectively enhanced
Solution Approach 1:
The patent segments the contact structure into three distinct layers with different doping concentrations, each serving specific functions. The first layer (high doping) provides carrier collection, the second layer (low doping) provides passivation, and the third layer (intermediate doping) provides transition and field effect. This segmentation enhances passivation effect while maintaining manageable device complexity through systematic layer fabrication.
Solution Approach 2:
The patent applies local quality by optimizing doping concentration at different locations within the contact structure. Each layer has locally optimized doping levels tailored to its specific function: high doping near the metal for conductivity, low doping at the semiconductor interface for passivation, and intermediate doping in between for transition. This local optimization enhances passivation effect while the modular structure keeps device complexity manageable.
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 optimized doping configuration enhances the passivation effect and conversion efficiency of the photovoltaic cell by reducing recombination losses and improving the field effect, leading to increased open-circuit voltage and short-circuit current.
Implementation Method 1
a tunneling layer, a field passivation layer, a first passivation film, and a first electrode that are sequentially disposed on a rear surface of the substrate, where the first electrode penetrates the first passivation film and is in contact with the field passivation layer
Implementation Method 2
the substrate, the tunneling layer and the field passivation layer all include a same first doping element, a doping concentration of the first doping element in the tunneling layer is less than a doping concentration of the first doping element in the field passivation layer
Implementation Method 3
the first doping element is annealed and activated to obtain an activated first doping element
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Embodiments of the present disclosure relate in general to photovoltaic technology, and more specifically to a photovoltaic cell and a photovoltaic module. The photovoltaic cell includes: a substrate; a tunneling layer, a field passivation layer, a first passivation film, and a first electrode that are sequentially disposed on a rear surface of the substrate. The first electrode penetrates the first passivation film and is in contact with the field passivation layer. A doping concentration of the first doping element in the tunneling layer is less than a doping concentration of the first doping element in the field passivation layer, and the doping concentration of the first doping element in the tunneling layer is greater than a doping concentration of the first doping element in the substrate. The field passivation layer includes a first doping region and a second doping region, and a doping curve slope of the first doping region is greater than a doping curve slope of the second doping region. In the embodiments of the present disclosure, the doping concentration of the first doping element in the field passivation layer is greater than the doping concentration of the first doping element in the tunneling layer and the substrate, and the first doping element achieves a high activation rate in the field passivation layer, which is conducive to improving the passivation effect and the conversion efficiency of the photovoltaic cell.