Heterojunction Solar Cell Contact Structure for Low-Diffusion Doping
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Solution Overview
Problem
Increasing the doping concentration of the doped amorphous silicon layer in heterojunction solar cells leads to impurity diffusion, reducing the passivation effect and decreasing open-circuit voltage and short-circuit current, which in turn affects the energy conversion efficiency.
Innovation Solution
Implementing an electrical contact reinforced structure with a second doped region having higher doping concentration and crystallization degree than the first doped region, shielded by an electrode layer, to enhance conductivity and minimize impurity diffusion into passivation layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the doping concentration of the doped amorphous silicon layer is increased to improve conductivity and fill factor, then the fill factor increases, but impurity diffusion into the passivation layer increases, reducing the passivation effect and decreasing open-circuit voltage
Solution Approach 1:
The doped amorphous silicon layer is segmented into two distinct regions: a first doped region with lower doping concentration that contacts the passivation layer, and a second doped region with higher doping concentration that contacts the electrode layer. This segmentation allows each region to perform its specific function - the first region maintains passivation quality while the second region provides high conductivity for charge collection.
Solution Approach 2:
Different doping concentrations are applied to different spatial locations within the doped amorphous silicon layer. The first doped region has a first doping concentration optimized for passivation interface quality, while the second doped region has a second doping concentration optimized for electrical conductivity. This local quality variation resolves the contradiction by providing high conductivity where needed without compromising passivation where required.
2Reliability
If the doping concentration of the doped amorphous silicon layer is increased to improve conductivity, then the fill factor increases, but the open-circuit voltage decreases due to reduced passivation effect
Solution Approach 1:
The doped amorphous silicon layer is divided into a first doped region adjacent to the passivation layer with lower doping concentration to maintain passivation quality, and a second doped region adjacent to the electrode layer with higher doping concentration to ensure conductivity. This segmentation allows simultaneous optimization of both passivation effect and fill factor.
Solution Approach 2:
The patent applies different doping concentrations at different locations within the doped amorphous silicon layer. The first doped region has optimized doping concentration for maintaining strong passivation effect at the interface with the passivation layer, while the second doped region has higher doping concentration for providing low-resistance electrical contact. This local quality differentiation resolves the contradiction between passivation quality and electrical conductivity.
3Reliability
If the doping concentration of the doped amorphous silicon layer is increased to improve conductivity, then the fill factor increases, but defects in the passivation layer increase causing carrier recombination and reducing short-circuit current
Solution Approach 1:
The doped amorphous silicon layer is segmented into a first doped region with lower doping concentration that interfaces with the passivation layer, minimizing impurity diffusion and preventing defect formation. The second doped region with higher doping concentration is separated from the passivation layer by this first region, allowing high conductivity without compromising passivation layer integrity. This segmentation prevents carrier recombination while maintaining high fill factor.
Solution Approach 2:
The patent implements local quality variation by using different doping concentrations in different regions. The first doped region has lower doping concentration specifically at the passivation layer interface to prevent impurity-induced defects, while the second doped region has higher doping concentration for conductivity. This localized approach eliminates defects in the passivation layer while maintaining high fill factor through the second doped region.
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 increases the fill factor, open-circuit voltage, and short-circuit current, thereby improving the energy conversion efficiency of the heterojunction solar cell.
Implementation Method 1
the doping concentration and the crystallization degree of the second doped region are both higher than those of the first doped region
Implementation Method 2
enhance conductivity and minimize impurity diffusion into passivation layers
Data Source
AI summary
The present disclosure relates to a heterojunction solar cell, including a substrate layer, a first passivation layer, a second passivation layer, an emission member, and a back surface field member. The emission member and the back field member each include a doped layer, a conducting layer, and an electrode layer sequentially disposed along the direction away from the substrate layer. One or both of the emission member and the back surface field member include an electrical contact reinforced structure. The electrical contact reinforced structure is a first doped region and a second doped region of the doped layer. The second doped region is disposed beside the first doped region and is shielded by the electrode layer. One or both of the doping concentration and the crystallization degree of the second doped regions are higher than those of the first doped region.