Solar Cell Graded Impurity Field Regions
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Solution Overview
Problem
Conventional solar cells face inefficiencies due to carrier recombination and loss at the surface defects, leading to reduced energy conversion efficiency.
Innovation Solution
A solar cell design incorporating a crystalline semiconductor substrate with a front surface field region and passivation layers made of amorphous silicon, along with an anti-reflection layer, to enhance carrier collection and reduce surface defects, featuring a graded impurity concentration in the field regions to optimize field strength and passivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional solar cell structure is used, then the manufacturing process is simple, but carrier recombination and loss at surface defects reduce energy conversion efficiency
Solution Approach 1:
The solar cell structure is segmented into multiple functional regions: a crystalline semiconductor substrate, a first field region with first impurities, a second field region with second impurities, and a third field region with third impurities. Each region has specific impurity concentrations and thicknesses designed to address particular issues. This segmentation allows optimization of carrier collection and surface defect management in different zones, thereby improving energy conversion efficiency while maintaining manageable manufacturing complexity through modular design
Solution Approach 2:
Different field regions are created with locally optimized properties: the first field region has higher impurity concentration near the surface to passivate defects, while deeper regions have lower concentrations to maintain carrier collection. The second and third field regions have graded impurity concentrations tailored to their specific depths and functions. This local quality approach ensures that each region performs its specific function optimally, improving overall energy conversion efficiency
2Productivity
If surface passivation is enhanced to reduce carrier loss, then energy conversion efficiency improves, but the device structure and manufacturing process become more complex
Solution Approach 1:
The patent merges multiple functions into the field regions: they simultaneously provide surface passivation to reduce carrier recombination at defects and create internal electric fields for carrier separation and collection. The graded impurity concentration profiles in the first, second, and third field regions accomplish both passivation and field formation in a single integrated structure, improving energy conversion efficiency without proportionally increasing manufacturing complexity
Solution Approach 2:
The impurity concentration parameters are changed in a graded manner across the field regions. The first field region has impurity concentrations ranging from 1×10^16 to 1×10^21 atoms/cm³, the second field region has concentrations from 1×10^15 to 1×10^20 atoms/cm³, and the third field region has concentrations from 1×10^14 to 1×10^19 atoms/cm³. These parameter changes optimize the balance between passivation effectiveness and manufacturing feasibility
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 design significantly increases the short-circuit current by reducing carrier loss and enhancing light absorption, resulting in improved energy conversion efficiency.
Implementation Method 1
When light is incident on the solar cell, a plurality of electron-hole pairs are generated in the semiconductor parts. The electron-hole pairs are separated into electrons and holes by the photovoltaic effect.
Data Source
AI summary
A solar cell is discussed, and includes a substrate; a first field region; a first electrode directly formed on an emitter region; and a second electrode directly formed on a second field region, wherein a second passivation layer comprises a first back passivation portion and a second back passivation portion. Furthermore, the first back passivation portion is merely positioned between the emitter region and the substrate and the second field region and the substrate, and the second back passivation portion is positioned between the emitter region and the second field region, and wherein the first back passivation portion positioned between the emitter region and the substrate is physically separated from first back passivation portion positioned between the second field region and the substrate.