Buried Back Contact Solar Cell Structure for Leakage Control
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Solution Overview
Problem
Existing back contact structures for solar cells face challenges with high trench width control requirements and poor passivation effects, leading to electric leakage and reduced photovoltaic conversion efficiency.
Innovation Solution
A back contact structure featuring a silicon substrate with recesses, alternately disposed P-type and N-type doped regions, and multiple dielectric layers for improved passivation and carrier separation, allowing for easier width control and enhanced inner back reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single dielectric layer is used for passivation, then the structure is simple, but the passivation effect and inner back reflection effect are poor
Solution Approach 1:
The patent employs a composite dielectric layer structure consisting of multiple dielectric layers with different materials and properties. This composite structure provides superior passivation effect and inner back reflection effect compared to a single dielectric layer, while maintaining reasonable structural complexity.
2Reliability
If an ultra-condensed trench is formed to separate P-type and N-type doped regions, then electric leakage is prevented, but the trench width control requirement becomes very high and preparation becomes difficult
Solution Approach 1:
The patent introduces a dielectric layer as an intermediary substance to separate the P-type and N-type doped regions. This dielectric layer acts as a mediator that prevents direct contact between oppositely doped regions, thereby preventing electric leakage while allowing for more relaxed width control compared to ultra-condensed trenches.
3Loss of energy
If the doped polycrystalline silicon layer is made thin to reduce parasitic absorption, then light absorption is reduced, but if made thick then parasitic absorption increases
Solution Approach 1:
The patent optimizes the thickness parameter of the doped polycrystalline silicon layer to achieve a balance between reducing parasitic absorption and maintaining sufficient photo-generated current. By carefully controlling this parameter, the structure minimizes energy loss while preserving electrical performance.
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 reduces current leakage, facilitates multi-dimensional carrier collection, and increases photovoltaic conversion efficiency by improving passivation and inner back reflection, making it easier to prepare and align the doped regions.
Implementation Method 1
an ultrathin tunneling oxide layer
Implementation Method 2
surface passivation
Implementation Method 3
these electrons and holes are migrated to the doped polycrystalline silicon layer, to generate a voltage difference
Implementation Method 4
improving passivation and inner back reflection
Implementation Method 5
the existing trench is prepared through laser perforation
Data Source
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AI summary
A back contact structure includes: a silicon substrate including a back surface including a plurality of recesses disposed at intervals; a first dielectric layer disposed on the back surface of the silicon substrate, the first dielectric layer at least covering the plurality of recesses; a plurality of P-type doped regions and N-type doped regions disposed on the first dielectric layer and disposed alternately in the plurality of recesses; a second dielectric layer disposed between the plurality of P-type doped regions and the plurality of N-type doped regions; and a conductive layer disposed on the plurality of P-type doped regions and the plurality of N-type doped regions.