Solar Cell Layer Structure for Low-Resistance Light Reception
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Solution Overview
Problem
Conventional solar cells with an intrinsic fine crystal silicon layer and an intrinsic amorphous silicon layer have a high internal resistance due to poor conductivity, leading to a decreased fill factor and efficiency.
Innovation Solution
A solar cell configuration that includes a first amorphous silicon layer, an amorphous silicon oxide layer, and a microcrystalline silicon layer on the light-receiving surface, with the oxygen atom concentration maximized in the amorphous silicon oxide layer, enhancing light transmission and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an intrinsic fine crystal silicon layer and an intrinsic amorphous silicon layer are added to achieve passivation and enhance fine crystallization, then light transmission to the photoelectric conversion layer is improved, but internal resistance increases and fill factor decreases
Solution Approach 1:
The patent changes the conductivity type parameter of the intrinsic layers from poor conductivity to high conductivity by introducing dopants. Specifically, the intrinsic amorphous silicon layer is changed to a conductive amorphous silicon layer with n-type or p-type conductivity, and the intrinsic fine crystal silicon layer is changed to a conductive fine crystal silicon layer with corresponding conductivity type, thereby reducing internal resistance while maintaining passivation quality.
Solution Approach 2:
The patent creates a composite structure where conductive amorphous silicon layers and conductive fine crystal silicon layers are combined with the crystalline silicon substrate. This composite approach allows the amorphous silicon layers to provide passivation while the fine crystal silicon layers provide light transmission, and the dopant introduction ensures all layers contribute to conductivity reduction of internal resistance.
2Reliability
If the thickness of intrinsic layers is increased to enhance passivation and fine crystallization, then light transmission is improved, but internal resistance increases and fill factor decreases
Solution Approach 1:
The patent changes the conductivity parameter of the amorphous silicon layers and fine crystal silicon layers by introducing dopants at specific concentrations. The conductive amorphous silicon layer has a dopant concentration of 1×10^19 to 1×10^21 atoms/cm³, and the conductive fine crystal silicon layer has a dopant concentration of 1×10^18 to 1×10^20 atoms/cm³, enabling these layers to maintain thin profiles while providing low resistance paths.
3Reliability
If amorphous silicon layer is used on light-receiving surface, then passivation is achieved, but parasitic absorption reduces light reaching photoelectric conversion layer
Solution Approach 1:
The patent changes the optical parameter of the amorphous silicon layer by controlling its thickness to 5 nm or less and introducing dopants to create a conductive amorphous silicon layer. This thin, doped structure reduces parasitic absorption while maintaining passivation quality, as the reduced thickness allows more light to reach the photoelectric conversion 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
This configuration increases the intensity of light reaching the photoelectric conversion layer and improves the fill factor and conversion efficiency of the solar cell.
Implementation Method 1
increasing transparency of the silicon layer to increase an intensity of the light reaching the photoelectric conversion layer
Implementation Method 2
a crystalline silicon substrate, which is a photoelectric conversion layer
Data Source
AI summary
A solar cell includes: an n-type first amorphous silicon layer provided on a first main surface of a crystalline silicon substrate; an amorphous silicon oxide layer provided on a first main surface of the first amorphous silicon layer; and an n-type fine crystal silicon layer provided on a first main surface of the amorphous silicon oxide layer. An oxygen atom concentration in the first amorphous silicon layer, the amorphous silicon oxide layer, and the fine crystal silicon layer has a maximum value in the amorphous silicon oxide layer with a thickness direction.