Solar Cell Passivation Stack for Low-Reflectivity Light Absorption
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Solution Overview
Problem
Existing solar cells face challenges in improving light absorption efficiency, particularly for both long and short wavelengths, leading to issues with color appearance and internal reflection.
Innovation Solution
A solar cell design featuring a passivation stack with specific thicknesses and compositions of oxygen-containing dielectric, silicon nitride, and silicon oxynitride layers, optimized to reduce internal reflection and enhance absorption efficiency by adjusting nitrogen, silicon, and oxygen content gradients, enabling better absorption of short and long wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional passivation structure is used, then the manufacturing process is simple, but the light absorption efficiency is insufficient
Solution Approach 1:
The passivation structure is divided into multiple functional layers including an oxygen-containing dielectric layer (1 nm-15 nm thick), a first passivation layer (30 nm-60 nm thick), and a second passivation layer (20 nm-40 nm thick). Each layer serves specific functions for light management and surface passivation, enabling improved light absorption efficiency while maintaining manufacturing feasibility through sequential deposition processes.
Solution Approach 2:
The patent employs composite material composition in the passivation stack, combining oxygen-containing dielectric materials (such as aluminum oxide, gallium oxide, titanium oxide, or hafnium oxide) with silicon-based passivation materials. This composite structure optimizes both optical properties for light absorption and electrical properties for surface passivation, resolving the contradiction between manufacturing simplicity and performance enhancement.
2Productivity
If the passivation layer thickness is increased to improve absorption, then light absorption efficiency improves, but internal reflection increases
Solution Approach 1:
Different regions of the passivation structure have optimized local properties: the oxygen-containing dielectric layer (1 nm-15 nm) provides field passivation and controls refractive index at the interface, the first passivation layer (30 nm-60 nm) provides primary surface passivation, and the second passivation layer (20 nm-40 nm) enhances optical absorption. This local optimization of thickness and material composition at each interface minimizes internal reflection while maximizing absorption efficiency.
Solution Approach 2:
The patent optimizes the thickness parameters of each layer within specific ranges to control optical interference and refractive index matching. By precisely controlling the thickness of the oxygen-containing dielectric layer (1 nm-15 nm), first passivation layer (30 nm-60 nm), and second passivation layer (20 nm-40 nm), the structure achieves reduced internal reflection across different wavelength bands while maintaining high light absorption efficiency.
3Ease of manufacture
If element content is uniformly distributed, then the manufacturing process is simple, but absorption efficiency for different wavelengths is suboptimal
Solution Approach 1:
The patent implements non-uniform element distribution within the passivation layers to optimize optical performance. The oxygen-containing dielectric layer contains metal oxide materials with specific oxygen content gradients, while the silicon-based passivation layers have controlled compositions. This local variation in element content (oxygen, silicon, nitrogen) at different positions within the stack enables enhanced absorption efficiency across different wavelength bands while maintaining compatibility with standard deposition processes.
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 achieves improved light absorption efficiency, reducing internal reflection and emission, resulting in a darker appearance and increased short-circuit current, with the solar cell and photovoltaic module exhibiting lower reflectivity across various wavelength bands.
Implementation Method 1
The passivation stack includes an oxygen-containing dielectric layer, a first passivation layer, and a second passivation layer that are sequentially disposed in a direction away from the front surface... optimized to reduce internal reflection and enhance absorption efficiency by adjusting nitrogen, silicon, and oxygen content gradients
Implementation Method 2
The tunneling oxide layer and the doped conductive layer that are sequentially disposed on the rear surface
Data Source
AI summary
A solar cell and a photovoltaic module are provided. The solar cell includes an N-type substrate having a front surface and a rear surface, a passivation stack disposed on the front surface, and a tunneling oxide layer and a doped conductive layer disposed on the rear surface. The passivation stack includes an oxygen-containing dielectric layer including a metal oxide material, a first passivation layer including an oxygen-containing silicon nitride material, and a second passivation layer including a silicon oxynitride material. A thickness of the oxygen-containing dielectric layer is in a range of 1 nm to 15 nm in a direction perpendicular to the front surface, a thickness of the first passivation layer is in a range of 30 nm to 60 nm in the direction perpendicular to the front surface, and a thickness of the second passivation layer is in a range of 20 nm to 40 nm in the direction perpendicular to the front surface.