Triple Passivation Solar Cell Structure for Low Reflectivity
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Solution Overview
Problem
Existing solar cells have high reflectivity due to the use of silicon nitride passivation layers with high refractive indices, leading to low open-circuit voltage, short-circuit current, and photoelectric conversion rates.
Innovation Solution
A solar cell design featuring a sequence of passivation layers with specific refractive index ranges, including a dielectric first passivation layer, a high refractive index second Si u N v layer, and a low refractive index third Si r O s layer, optimized for light absorption across different wave lengths, reducing reflectivity and enhancing carrier concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high refractive index passivation layer (silicon nitride) is used to achieve good passivation effect, then carrier concentration increases, but reflectivity becomes too high reducing light absorption
Solution Approach 1:
The single passivation layer is segmented into three distinct layers with different refractive indices. The first layer (SiNx) has high refractive index for passivation, the second layer (SiO2) has medium refractive index for transition, and the third layer (SiO2 with specific stoichiometry) has low refractive index for anti-reflection. This segmentation allows each layer to perform its specific function optimally.
Solution Approach 2:
The patent uses a composite structure combining three different materials (SiNx, SiO2, and SiO2 with varying stoichiometry) in a layered configuration. This composite approach leverages the complementary properties of each material: SiNx for passivation and medium-wave light management, SiO2 for optical transition, and the third layer for broadband anti-reflection across UV and visible spectra.
2Ease of manufacture
If a single passivation layer is used to simplify structure, then manufacturing is easier, but photoelectric conversion rate remains low
Solution Approach 1:
The passivation function is segmented across three layers, each with specific thickness and material composition. The first layer (3-8nm SiNx) provides interface passivation, the second layer (50-100nm SiO2) provides optical transition, and the third layer (80-150nm SiO2) provides anti-reflection. This segmentation enables high photoelectric conversion while maintaining manufacturability through standardized deposition processes.
Solution Approach 2:
The patent optimizes multiple parameters including layer thicknesses, refractive indices, and material stoichiometry ratios. By precisely controlling these parameters, the structure achieves both manufacturing feasibility and superior photoelectric performance with conversion rates exceeding 22%.
3Reliability
If high refractive index material is used to increase carrier concentration, then open circuit voltage improves, but short-circuit current decreases due to light reflection
Solution Approach 1:
The optical management is segmented across three layers: the first SiNx layer manages medium and long-wave light while providing passivation, the second SiO2 layer manages transition wavelengths, and the third SiO2 layer manages short-wave and UV light. This segmentation ensures broadband light absorption and maximizes short-circuit current while maintaining high open circuit voltage.
Solution Approach 2:
Each layer is designed with local quality optimized for its specific function: the first layer has high nitrogen content for passivation and medium-wave light management, the second layer has intermediate properties for optical transition, and the third layer has specific oxygen-to-silicon ratio for UV and short-wave light anti-reflection. This local optimization resolves the contradiction between voltage and current.
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 reduces reflectivity, increases open-circuit voltage, short-circuit current, and filling factor, and improves photoelectric conversion efficiency, allowing for the production of dark-colored solar cell modules.
Implementation Method 1
the refractive index of the third passivation layer is smaller than a refractive index of the second passivation layer
Implementation Method 2
the existing solar cell with the passivation layer still has relatively high reflectivity for the incident light
Implementation Method 3
The passivation structure on the surface of the solar cell has a relatively high refractive index and relatively good passivation effect, so that as much incident light as possible can be absorbed by the solar cell, and a carrier concentration of the solar cell can be increased
Implementation Method 4
A solar cell can be used widely due to a good photoelectric conversion capacity
Data Source
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AI summary
A solar cell includes a substrate having a front surface and a back surface opposite to the front surface; a first passivation layer, a second passivation layer and a third passivation layer sequentially formed on the front surface of the substrate and in a direction away from the substrate; where the first passivation layer includes a dielectric material; the second passivation layer includes a first SiuNv material, and a value of v/u is 1.3≤v/u≤1.7; and the third passivation layer includes a SirOs material, and a value of s/r is 1.9≤s/r≤3.2; and a tunneling oxide layer and a doped conductive layer sequentially formed on the back surface of the substrate and in a direction away from the back surface; the doped conductive layer and the substrate are doped to have a same conductivity type.