Solar Cell Multi-Layer Passivation Light Reflectance
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Solution Overview
Problem
Conventional solar cells face inefficiencies in light absorption and carrier recombination due to reflectance losses at the back surface, particularly with thin substrates, leading to reduced absorptance and short-circuit current characteristics.
Innovation Solution
A solar cell design incorporating a multi-layered passivation layer structure on the back surface, comprising a high refractive index amorphous silicon layer and a low refractive index amorphous silicon nitride layer, with an optional silicon oxide layer, to enhance light reflectance and reabsorption, thereby reducing carrier recombination and improving absorptance and short-circuit current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If a thin substrate is used to reduce material cost and weight, then manufacturing cost and weight are reduced, but light absorption efficiency and carrier collection are worsened due to increased reflectance losses at the back surface
Solution Approach 1:
The patent converts the harmful reflectance loss at the back surface into a beneficial effect by introducing a multi-layered passivation structure that reflects long-wavelength light back into the thin substrate, enabling reabsorption and turning the previously wasted light into useful energy for carrier generation
Solution Approach 2:
The patent employs a composite multi-layered passivation structure consisting of different materials (amorphous silicon, amorphous silicon nitride, silicon oxide) with varying refractive indices, where each layer serves a specific function in managing light reflection and absorption to compensate for the thin substrate's limitations
2Device complexity
If a simple single-layer passivation structure is used to reduce device complexity, then manufacturing process is simplified, but light reflectance and reabsorption efficiency are insufficient leading to poor short-circuit current characteristics
Solution Approach 1:
The patent segments the passivation function into multiple distinct layers, each with specific thickness and material properties, where the first layer (amorphous silicon) provides one function and the second layer (amorphous silicon nitride) provides another, collectively achieving superior light management compared to a single layer
Solution Approach 2:
The patent optimizes specific parameters including the thickness of each passivation layer (first layer: 50-100 nm, second layer: 10-50 nm), the refractive index ratio between layers (1.57-2.11), and material composition to maximize light reflectance and reabsorption efficiency in the long-wavelength band
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 multi-layered passivation layer structure increases light reflectance and absorptance in the long wavelength band, enhancing the efficiency of the solar cell by improving short-circuit current characteristics and reducing carrier recombination.
Implementation Method 1
the multi-layered passivation layer structure increases light reflectance and absorptance in the long wavelength band
Implementation Method 2
The electron-hole pairs are separated into electrons and holes by the photovoltaic effect
Data Source
AI summary
A solar cell and a method for manufacturing the same are discussed. The solar cell includes a substrate of a first conductive type, an emitter region of a second conductive type opposite the first conductive type, the emitter region forming a p-n junction along with the substrate, a passivation layer which is positioned on a back surface of the substrate and has a plurality of via holes exposing portions of the back surface of the substrate, a first electrode connected to the emitter region, and a second electrode which is positioned on a back surface of the passivation layer and is connected to the substrate through the plurality of via holes.