TOPCon Solar Cell Barrier Layer Against Electrode Burn-Through
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Solution Overview
Problem
Tunnel Oxide Passivating Contacts (TOPCon) solar cells face issues with electrode burn-through in the doped polysilicon layer, leading to increased recombination current density and reduced efficiency, and the reduction in doped polysilicon layer thickness to prevent this increases the risk of electrode penetration through the tunnel oxide layer.
Innovation Solution
A barrier layer made of silicon carbide and/or zinc oxide is formed in the electrode region, with a depth equal to or less than the thickness of the doped polysilicon layer, to prevent electrode burn-through and reduce recombination current density, while maintaining the lateral transport capability of carriers and field passivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the doped polysilicon layer thickness is reduced to prevent electrode burn-through, then electrode reliability is improved, but the risk of electrode penetration through the tunnel oxide layer increases
Solution Approach 1:
A barrier layer made of silicon carbide and/or zinc oxide is introduced between the electrode and the doped polysilicon layer. This intermediary layer prevents direct contact and potential burn-through while maintaining electrical connectivity, thus preventing electrode penetration through the tunnel oxide layer without requiring reduction of the polysilicon layer thickness.
Solution Approach 2:
The barrier layer uses composite material properties of silicon carbide and/or zinc oxide, which have high thermal stability and appropriate electrical characteristics. This composite approach provides both thermal barrier functionality to prevent burn-through and electrical conductivity to maintain device operation.
2Loss of energy
If the doped polysilicon layer thickness is reduced to prevent electrode burn-through, then recombination current density is reduced, but field passivation capability is weakened
Solution Approach 1:
The barrier layer serves as an intermediary that allows the doped polysilicon layer to maintain its original thickness for adequate field passivation, while the barrier layer itself provides a controlled interface that reduces recombination current density by preventing direct electrode contact with the 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 prevents electrode burn-through, reduces recombination current density, and improves the utilization of incident light by maintaining the thickness of the doped polysilicon layer, thereby enhancing the solar cell's efficiency.
Implementation Method 1
A barrier layer made of silicon carbide and/or zinc oxide is formed in the electrode region... to prevent electrode burn-through
Implementation Method 2
The tunnel oxide layer can selectively transport carriers
Implementation Method 3
the doped polysilicon layer acts as field passivation
Data Source
AI summary
A solar cell comprises a substrate having a first surface and a second surface opposite to each other in a first direction, wherein the first direction is a thickness direction of the substrate; a tunnel oxide layer located on the first surface and/or the second surface; a doped polysilicon layer located on a surface of the tunnel oxide layer away from the substrate; a barrier layer located in an electrode region of the solar cell and in contact with the doped polysilicon layer, wherein a doping type of the barrier layer is the same as the doped polysilicon layer; an electrode located in the electrode region and in contact with the barrier layer; characterized in that 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.