Solar Cell Double-Layer Anti-Reflection Structure
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Solution Overview
Problem
Conventional solar cells face inefficiencies due to reflection and absorption losses, particularly with single-layer anti-reflection structures, which limit light incidence and carrier collection efficiency.
Innovation Solution
A solar cell design featuring a double-layer anti-reflection structure with a silicon nitride first anti-reflection layer and a silicon oxide second anti-reflection layer, optimized in refractive index and thickness to minimize reflection and absorption, combined with a selective emitter structure and textured surface to enhance light trapping and carrier collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer anti-reflection structure is used, then the device complexity is reduced, but light incidence efficiency and carrier collection efficiency deteriorate
Solution Approach 1:
The anti-reflection layer is segmented into two distinct layers: a first anti-reflection layer (silicon nitride, 65-95 nm thick with refractive index 2.05-2.15) and a second anti-reflection layer (silicon oxide, 80-110 nm thick with refractive index 1.50-1.70). This segmentation allows each layer to contribute differently to light management, with the higher refractive index layer addressing shorter wavelengths and the lower refractive index layer addressing longer wavelengths, thereby improving overall light incidence efficiency across the solar spectrum
Solution Approach 2:
The patent employs a composite anti-reflection structure combining two different materials (silicon nitride and silicon oxide) with complementary optical properties. This composite approach creates a gradient refractive index profile that more effectively reduces reflection across a broader wavelength range compared to a single-material layer, enhancing light trapping without proportionally increasing structural complexity
2Ease of manufacture
If a single-layer anti-reflection structure is used, then the manufacturing process is simplified, but absorption losses increase
Solution Approach 1:
The anti-reflection function is segmented between two layers with different optical characteristics. The first layer (silicon nitride) primarily addresses reflection in the blue-green spectrum, while the second layer (silicon oxide) addresses reflection in the red-infrared spectrum. This segmentation reduces total absorption losses by ensuring more complete light absorption across all wavelengths, with each layer optimized for its specific wavelength range
Solution Approach 2:
The patent systematically varies critical parameters including refractive index (2.05-2.15 for first layer, 1.50-1.70 for second layer), thickness (65-95 nm and 80-110 nm respectively), and material composition to optimize the anti-reflection performance. These parameter changes create a more effective optical gradient that minimizes both reflection and absorption losses across the solar spectrum
3Ease of manufacture
If uniform emitter layer is used, then the manufacturing process is simpler, but carrier collection efficiency deteriorates
Solution Approach 1:
The emitter layer is designed with spatially varying properties: the first emitter region has higher impurity doping concentration (lower sheet resistance) optimized for electrical contact and carrier collection, while the second emitter region has lower impurity doping concentration (higher sheet resistance) optimized for optical absorption and light trapping. This local differentiation allows each region to perform its specific function more effectively, improving overall carrier collection efficiency without requiring completely new manufacturing 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 proposed design significantly improves light incidence and carrier collection efficiency, leading to enhanced solar cell performance with increased short-circuit current, open-circuit voltage, and fill factor, achieving efficiencies greater than 17.7%.
Implementation Method 1
a first anti-reflection layer positioned on the emitter layer, the first anti-reflection layer having a refractive index of about 2.05 to 2.15... a second anti-reflection layer positioned on the first anti-reflection layer, the second anti-reflection layer having a refractive index of about 1.5 to 1.7
Implementation Method 2
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.
Implementation Method 3
The semiconductor substrate may have a textured surface
Data Source
AI summary
A solar cell is discussed. The solar cell according to an embodiment includes a substrate of a first conductive type, an emitter layer of a second conductive type opposite the first conductive type, which forms a p-n junction along with the substrate, a first anti-reflection layer on the emitter layer, a second anti-reflection layer on the first anti-reflection layer, a first electrode part connected to the emitter layer, and a second electrode part connected to the substrate. The first anti-reflection layer is formed of silicon nitride, and the second anti-reflection layer is formed of silicon oxide.