Solar Cell Barrier-Layered Polysilicon Contacts for TOPCon Current Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing tunnel oxide passivated contact (TOPCon) solar cells face challenges in balancing light absorption and metallization due to the use of thicker doped polycrystalline silicon layers, which increase production costs and reduce short-circuit current, while also risking silver particle burn-through of the tunneling oxide layer.
Innovation Solution
A solar cell design incorporating multiple doped polysilicon layers with barrier layers and varying doping concentrations, along with a tunneling oxide layer, to reduce the overall thickness of the polycrystalline silicon layer, minimize parasitic absorption, and prevent silver particle burn-through, thereby enhancing electron transmission and reducing metal recombination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thicker doped polycrystalline silicon layer is used to prevent silver particle burn-through, then the reliability of the tunneling oxide layer is improved, but the short-circuit current decreases due to increased parasitic absorption
Solution Approach 1:
The doped polycrystalline silicon layer is divided into multiple sub-layers with different thicknesses and doping concentrations. The first doped polycrystalline silicon layer has a thickness of 5-20nm and high doping concentration for effective passivation, while the second doped polycrystalline silicon layer has a thickness of 20-50nm and lower doping concentration to reduce parasitic absorption. This segmentation allows the structure to simultaneously protect the tunneling oxide layer and minimize light absorption losses.
Solution Approach 2:
Different regions of the doped polycrystalline silicon structure have different properties optimized for their specific functions. The first layer near the tunneling oxide layer has high doping concentration for effective passivation and protection, while the second layer has lower doping concentration to reduce parasitic absorption. This local quality variation allows each layer to perform its specific function optimally.
2Loss of energy
If a thinner doped polycrystalline silicon layer is used to reduce parasitic absorption, then the short-circuit current is improved, but the risk of silver particle burn-through increases
Solution Approach 1:
The protective function is segmented between two layers: the first layer provides the primary protection with high doping concentration, while the second layer adds additional protection against silver particle burn-through with lower doping concentration. This segmentation allows thinner overall structure while maintaining reliability.
Solution Approach 2:
The structure uses a composite of two doped polycrystalline silicon layers with different properties. The combination of high-doping first layer and low-doping second layer creates a composite structure that provides both protection and reduced parasitic absorption, achieving properties that neither layer could provide alone.
3Reliability
If the doped polycrystalline silicon layer thickness is increased to ensure effective passivation, then the open circuit voltage is improved, but the production cost increases
Solution Approach 1:
The passivation function is achieved through segmented layers with optimized thicknesses. The first layer (5-20nm) provides the critical passivation effect with high doping concentration, while the second layer (20-50nm) provides additional protection. This segmentation achieves effective passivation with a thinner overall structure (50-70nm) compared to conventional single layers, reducing material costs and production complexity.
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 solution improves open circuit voltage, short-circuit current, and photoelectric conversion efficiency by reducing the thickness of the polycrystalline silicon layer, while maintaining effective passivation and minimizing production costs.
Implementation Method 1
a tunneling oxide layer and a doped polysilicon layer together form a passivation contact structure, which allows majority carriers to pass through the tunneling oxide layer while blocking minority carriers
Implementation Method 2
due to the strong close to-infrared light absorption of the doped polycrystalline silicon layer itself
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The solar cell, the method for preparing the solar cell, and the photovoltaic module are provided according to the embodiments of the present application. The solar cell includes a silicon substrate, multiple first electrodes, and a second electrode. The solar cell further includes a tunneling oxide layer arranged on a surface of the silicon substrate away from the silicon substrate, multiple doped polysilicon layers arranged on a surface of the tunneling oxide layer away from the silicon substrate, and at least one barrier layer. The at least one barrier layer is arranged between every adjacent two doped polysilicon layers of the multiple doped polysilicon layers, and the multiple first electrodes are electrically connected to different doped polysilicon layers. The solar cell provided according to the present application can reduce the total thickness of the polycrystalline silicon layer, so that a thinner polycrystalline silicon layer can reduce parasitic absorption, thereby increasing short-circuit current. Moreover, the risk of slurry burning through the tunneling oxide layer is reduced by the barrier layer, while reducing metal recombination, which increases the open circuit voltage of the solar cell, thereby improving the photoelectric conversion efficiency of the solar cell.