Trench Design for High-Efficiency Backside Solar Cells
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Summary
Problems
Polysilicon doped regions in solar cells experience high recombination in the space charge region where they touch, leading to reduced efficiency due to the low lifetime of charge carriers.
Innovation solutions
A trench structure separates the P-type and N-type doped regions, formed over a thin dielectric layer, with a textured surface to enhance solar radiation collection and prevent recombination, using polysilicon doped with boron and phosphorus, and a silicon nitride layer with positive fixed charge density for passivation.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If a trench structure is introduced to separate doped regions, then recombination is prevented and efficiency is improved, but device complexity increases
Why choose this principle:
The patent divides the contact structure by introducing a trench between the P-type and N-type doped polysilicon regions. This segmentation physically separates regions that would otherwise be in direct contact, preventing carrier recombination at the interface while maintaining electrical functionality through separate contact points on the substrate.
Principle concept:
If a trench structure is introduced to separate doped regions, then recombination is prevented and efficiency is improved, but device complexity increases
Why choose this principle:
The trench acts as an intermediary barrier between the P-type and N-type doped regions. By introducing this intermediate structure filled with dielectric material or void space, the patent prevents direct interaction between oppositely doped regions, thereby eliminating the recombination pathway while allowing each region to function independently.
Application Domain
Data Source
AI summary:
A trench structure separates the P-type and N-type doped regions, formed over a thin dielectric layer, with a textured surface to enhance solar radiation collection and prevent recombination, using polysilicon doped with boron and phosphorus, and a silicon nitride layer with positive fixed charge density for passivation.
Abstract
A solar cell includes polysilicon P-type and N-type doped regions on a backside of a substrate, such as a silicon wafer. A trench structure separates the P-type doped region from the N-type doped region. Each of the P-type and N-type doped regions may be formed over a thin dielectric layer. The trench structure may include a textured surface for increased solar radiation collection. Among other advantages, the resulting structure increases efficiency by providing isolation between adjacent P-type and N-type doped regions, thereby preventing recombination in a space charge region where the doped regions would have touched.