Double-Sided TOPCon Cell With Co-Doped Polysilicon Contacts
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Solution Overview
Problem
Current solar cells with tunnel oxide passivated contacts (TOPCon) face limitations in efficiency due to recombination losses at the metal semiconductor contact, particularly at the front side, which also requires excellent passivation and optical transmittance.
Innovation Solution
A double-sided passivated contact cell is developed, where both the front and rear sides feature a tunnel layer, a doped polysilicon layer, and a passivation layer. The doped polysilicon layers are co-doped with boron and carbon or phosphorus and carbon, respectively, to enhance passivation and light transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal semiconductor contact is used at the front side to achieve good electrical contact, then electrical conductivity is improved, but recombination loss increases and efficiency deteriorates
Solution Approach 1:
The patent changes the material parameters by replacing the metal contact with a polysilicon-based passivated contact structure. The polysilicon layer is heavily doped to achieve good electrical conductivity while the tunnel oxide layer provides excellent surface passivation, eliminating the recombination loss problem associated with metal contacts.
Solution Approach 2:
The patent employs a composite structure consisting of multiple layers: tunnel oxide layer, polysilicon layer, and dielectric layer. This composite material system combines the advantages of different materials to achieve both low contact resistance and high surface passivation quality, resolving the contradiction between electrical conductivity and recombination loss.
2Loss of energy
If a passivated contact structure is used at the front side to reduce recombination loss, then recombination loss is reduced, but optical transmittance may deteriorate and parasitic absorption increases
Solution Approach 1:
The patent applies local quality by making the polysilicon layer heavily doped only in the contact region where electrical conductivity is needed, while maintaining a thin tunnel oxide layer to minimize optical absorption. The dielectric layer is positioned to provide passivation without significantly blocking light transmission to the active regions.
Solution Approach 2:
The patent optimizes the thickness and doping concentration parameters of the polysilicon layer to achieve a balance between electrical performance and optical properties. By carefully controlling these parameters, the structure achieves low recombination loss while maintaining adequate optical transmittance.
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 approach significantly reduces carrier recombination, increases the open-circuit voltage, and enhances solar cell efficiency by improving light transmittance and reducing parasitic absorption losses.
Implementation Method 1
The tunnel oxide passivated contact (TOPCon) is a passivated structure for crystalline silicon solar cells, and consists of an ultra-thin silicon oxide layer
Implementation Method 2
one of the doped polysilicon layer at the front side and the doped polysilicon layer at the rear side is a boron and carbon co-doped polysilicon layer, and the other of the doped polysilicon layer at the front side and the doped polysilicon layer at the rear side is a phosphorus and carbon co-doped polysilicon layer
Data Source
AI summary
The present disclosure provides a double-sided passivated contact cell, where a front side and a rear side of the double-sided passivated contact cell each are provided with a tunnel layer, a doped polysilicon layer, and a passivation layer sequentially from an inside to an outside; and for the doped polysilicon layer at the front side and the doped polysilicon layer at the rear side, one of the doped polysilicon layer at the front side and the doped polysilicon layer at the rear side is a boron and carbon co-doped polysilicon layer, and the other of the doped polysilicon layer at the front side and the doped polysilicon layer at the rear side is a phosphorus and carbon co-doped polysilicon layer. The present disclosure further provides a preparation method of the double-sided passivated contact cell.