TOPCon Passivating Contact Structure with Graded Polysilicon Doping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The growth uniformity of the tunnel oxide layer and the heavily doped polysilicon layer in tunnel oxide passivated contact (TOPCon) solar cells is difficult to control, leading to imbalanced process effects that reduce conversion efficiency.
Innovation Solution
A method involving the formation of an initial stack structure with alternately stacked polysilicon and doped layers, where the innermost and outermost layers are polysilicon layers, and the dopant concentration is asymmetrically distributed to prevent tunnel layer penetration and ensure uniform dopant distribution after activation, reducing contact resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tunnel oxide layer and a heavily doped polysilicon layer are formed on the back of the cell to form a passivating contact structure, then good surface passivation is provided, but the growth uniformity of the tunnel oxide layer and the heavily doped polysilicon layer is difficult to control, making it difficult to balance the process effects
Solution Approach 1:
The patent divides the doped polysilicon layer into multiple segments (first doped polysilicon layer, second doped polysilicon layer, third doped polysilicon layer) with different dopant concentrations. This segmentation allows each layer to contribute differently to the overall passivation effect, improving growth uniformity while maintaining reliable surface passivation.
Solution Approach 2:
The patent applies local quality by creating a dopant concentration gradient where different regions of the polysilicon structure have different dopant concentrations. The first doped polysilicon layer has a first dopant concentration, the second has a second dopant concentration, and the third has a third dopant concentration, allowing optimal local conditions for both passivation and uniform growth.
2Reliability
If the dopant concentration in the doped layer is increased to improve passivation effect, then the passivation quality improves, but the dopant may penetrate into the tunnel layer, damaging its passivation effect
Solution Approach 1:
The patent changes the dopant concentration parameter across different polysilicon layers to resolve the contradiction. By using a gradient structure where dopant concentration varies from the first doped polysilicon layer through the second to the third doped polysilicon layer, the system achieves strong passivation at the interface while preventing excessive dopant diffusion into the tunnel layer.
Solution Approach 2:
The patent creates a composite structure combining multiple polysilicon layers with different doping characteristics. This composite doped polysilicon layer structure provides both the necessary passivation effect and controls dopant diffusion, as each layer contributes different properties to the overall system.
3Object-affected harmful factors
If a heavily doped polysilicon layer is formed to reduce contact resistivity, then contact resistivity decreases, but the process balance between tunnel oxide layer and polysilicon layer becomes difficult to control
Solution Approach 1:
The patent segments the heavily doped polysilicon layer into three distinct doped layers with different dopant concentrations. This segmentation allows the system to achieve low contact resistivity through the third doped polysilicon layer while the first and second layers provide gradient transition that maintains process balance and prevents defects.
Solution Approach 2:
The patent systematically changes the dopant concentration parameter across the three polysilicon layers. The first doped polysilicon layer has a first dopant concentration, the second has a second dopant concentration, and the third has a third dopant concentration, creating an optimized gradient that reduces contact resistivity while maintaining manufacturability and process balance.
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 improves the passivation effect of the tunnel layer and enhances the conversion efficiency of the solar cell by balancing process effects on the tunnel oxide layer and the doped stack structure.
Implementation Method 1
activating the dopant in the doped layer, such that the dopant diffuses into the polysilicon layers
Data Source
Figure 1~2
Figure 3~5
Figure 6~9
AI summary
The present application relates to a passivating contact structure and a preparation method thereof, and a solar cell and a preparation method thereof. In the method for preparing the passivating contact structure, a tunnel layer is formed on a side of a substrate, and an initial stack structure is formed on a side of the tunnel layer away from the substrate. The initial stack structure includes polysilicon layers and a doped layer alternately stacked with each other. In the initial stack structure, an innermost layer is a layer most adjacent to the tunnel layer, an outermost layer is a layer most away from the tunnel layer, and the innermost layer and the outermost layer are both polysilicon layers. The doped layer is a polysilicon material layer doped with a dopant. The dopant in the doped layer is activated, such that the dopant diffuses into the polysilicon layers, thereby transforming the initial stack structure into a doped stack structure with uniform distribution of dopant.