Triple-Layer Solar Cell Passivation for Lower 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 through plasma-enhanced chemical vapor deposition and atomic layer deposition processes, to enhance light absorption and reduce reflectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high refractive index passivation layer (silicon nitride) is used on the solar cell surface, then the passivation effect is improved, but the reflectivity increases and light absorption decreases
Solution Approach 1:
The patent divides the single passivation layer into three distinct layers with different refractive indices: a first passivation layer (refractive index 1.6-1.8), a second passivation layer with SiuNv material (refractive index 1.8-2.0), and a third passivation layer with SirOs material (refractive index 1.4-1.6). This segmentation creates a gradient structure that progressively reduces reflectivity while maintaining passivation effectiveness.
Solution Approach 2:
The patent changes the refractive index parameter across the passivation layers by selecting materials with specific refractive indices. The third passivation layer uses SirOs material with a lower refractive index (1.4-1.6) compared to the second layer (1.8-2.0), creating an optical gradient that reduces reflection. The atomic ratios (v/u for SiuNv and s/r for SirOs) are also optimized to control refractive indices and achieve the desired optical properties.
2Device complexity
If a single passivation layer is used, then the structure is simple, but the photoelectric conversion rate is low due to high reflectivity
Solution Approach 1:
The patent employs a composite passivation structure consisting of three layers made from different materials: a dielectric material for the first layer, SiuNv material for the second layer, and SirOs material for the third layer. Each material is selected for its specific optical and electrical properties, creating a composite structure that simultaneously achieves low reflectivity and high passivation performance, thereby improving photoelectric conversion rate.
3Reliability
If the refractive index of the passivation layer is high, then the passivation effect is good, but the open circuit voltage and short circuit current are low
Solution Approach 1:
The patent transitions from a single-dimensional (single-layer) passivation approach to a multi-dimensional (three-layer) structure. By adding the vertical dimension of layering with progressively optimized refractive indices, the patent achieves both good passivation and high power output. The third passivation layer with SirOs material specifically addresses the power limitation by reducing reflectivity in the wavelength range that contributes to open circuit voltage and short circuit 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 carrier concentration, and improves open-circuit voltage, short-circuit current, and filling factor, resulting in enhanced photoelectric conversion efficiency.
Implementation Method 1
the second passivation layer includes a first Si u N v material... the third passivation layer includes a Si r O s material... optimized through plasma-enhanced chemical vapor deposition and atomic layer deposition processes
Implementation Method 2
optimized through plasma-enhanced chemical vapor deposition and atomic layer deposition processes
Implementation Method 3
The first passivation layer includes a dielectric material; the second passivation layer includes a first Si u N v material... the third passivation layer includes a Si r O s material... to enhance light absorption and reduce reflectivity
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.