TOPCon Electrode Barrier Layer for Thinner Polysilicon Contacts
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Solution Overview
Problem
The reduction in thickness of the doped polysilicon layer in Tunnel Oxide Passivating Contacts solar cells to improve light utilization is hindered by the increased risk of electrode burning through the polysilicon layer, leading to higher recombination current density and efficiency losses.
Innovation Solution
A barrier layer made of silicon carbide and/or zinc oxide is introduced in the electrode region, etched to a predetermined depth within the doped polysilicon layer to prevent electrode penetration and maintain the layer's integrity, reducing the risk of electrode burn-through and enhancing light utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the thickness of the doped polysilicon layer is reduced to improve light utilization, then the absorption of incident light by the doped polysilicon layer is reduced and light utilization is improved, but the risk of the electrode burning through the polysilicon layer increases and recombination current density increases
Solution Approach 1:
A barrier layer is introduced as an intermediary between the electrode and the doped polysilicon layer. This barrier layer prevents direct contact between the electrode and the polysilicon layer, thereby eliminating the harmful effect of electrode burn-through while allowing the polysilicon layer to be made thinner for improved light utilization. The barrier layer acts as a protective mediator that resolves the contradiction between reducing polysilicon thickness and preventing electrode burn-through.
Solution Approach 2:
The original single-layer structure of electrode直接接触doped polysilicon is segmented into multiple layers by inserting a barrier layer. This segmentation creates distinct functional zones: the barrier layer handles electrode protection while the thinned doped polysilicon layer focuses on light utilization. This structural segmentation allows each layer to be optimized independently, resolving the technical contradiction.
2Loss of energy
If the thickness of the doped polysilicon layer is reduced to improve light utilization, then the absorption of incident light is reduced, but the recombination current density increases due to electrode-substrate contact
Solution Approach 1:
The barrier layer serves as an intermediary that prevents the harmful effect of recombination current density by blocking direct contact between the electrode and substrate. This allows the doped polysilicon layer to be thinned for improved light utilization without generating the harmful recombination currents that would otherwise occur.
Solution Approach 2:
The harmful function of direct electrode-substrate contact that generates recombination current density is extracted and eliminated by inserting the barrier layer. This separation removes the source of harmful recombination currents while preserving the beneficial light utilization properties of the thinned polysilicon layer.
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 barrier layer effectively reduces recombination current density to ≤100 fA/cm² and allows for further reduction in doped polysilicon thickness, improving solar cell efficiency by minimizing light absorption and preventing electrode penetration.
Implementation Method 1
The tunnel oxide layer can selectively transport carriers
Implementation Method 2
the doped polysilicon layer acts as field passivation
Implementation Method 3
a barrier layer located in an electrode region of the solar cell and in contact with the doped polysilicon layer
Implementation Method 4
Tunnel Oxide Passivating Contacts solar cell (TOPCon)
Data Source
Figure 1~2A
Figure 2B~3
Figure 4A~4B
AI summary
A solar cell and method for producing the solar cell are disclosed. The solar cell comprises a substrate, a tunnel oxide layer, a doped polysilicon layer, a barrier layer, an electrode, wherein a method of forming the barrier layer includes etching the doped polysilicon layer in the electrode region in the first direction to form a groove with a predetermined depth and forming the barrier layer in the groove, wherein the predetermined depth is equal to or less than a thickness of the doped polysilicon layer, a material of the barrier layer includes silicon carbide and/or zinc oxide. Since forming the barrier layer that is in contact with the doped polysilicon layer in the electrode region, when firing the electrode, the doped polysilicon layer will be ablated only after the electrode burns through the barrier layer. Therefore, the barrier layer reduces the risk of the electrode burning through the doped polysilicon layer.