Solar Cell Poly-Silicon Protrusions for Light Trapping and Passivation
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Solution Overview
Problem
The photoelectric conversion efficiency of existing solar cells needs to be improved due to optical losses and recombination of photo-generated carriers at the surface and in the interior of the silicon substrate.
Innovation Solution
A solar cell design featuring a first doped polycrystalline silicon layer with larger protrusion structures on the front surface and a second doped polycrystalline silicon layer with smaller protrusion structures on the rear surface, where the first layer is thinner than the second layer, enhancing internal reflection and passivation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If film layers are formed to reduce optical losses and carrier recombination, then photoelectric conversion efficiency is improved, but device complexity increases
Solution Approach 1:
The patent employs porous silicon layers with controlled porosity (30-70%) to reduce optical losses. The porous structure increases light scattering and absorption path length while maintaining material simplicity, avoiding the need for multiple complex film layers
Solution Approach 2:
The patent modifies the refractive index and porosity parameters of the silicon layers to optimize optical performance. By controlling the porosity gradient and refractive index distribution, the device achieves reduced optical losses without adding structural complexity
2Loss of energy
If the thickness of the first doped polycrystalline silicon layer is reduced, then carrier recombination is reduced, but light trapping capability deteriorates
Solution Approach 1:
The patent applies different porosity characteristics to different regions of the silicon layer. The first porous silicon layer has higher porosity (40-60%) for reduced recombination, while the second porous silicon layer has lower porosity (20-40%) for enhanced light trapping, creating local quality optimization
Solution Approach 2:
The patent creates a composite structure with two porous silicon layers having different porosity characteristics and doping types. This composite approach allows simultaneous optimization of carrier recombination reduction in the first layer and light trapping enhancement in the second layer
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 improves photoelectric conversion efficiency by reducing optical losses and recombination rates, increasing fill factor, short-circuit current, and open-circuit voltage.
Implementation Method 1
A surface of the first doped polycrystalline silicon layer away from the substrate has a plurality of first protrusion structures. The second doped polycrystalline silicon layer is insulated from the first doped polycrystalline silicon layer, and a surface of the second doped polycrystalline silicon layer away from the substrate has a plurality of second protrusion structures
Implementation Method 2
An average thickness of the plurality of first protrusion structures is greater than an average thickness of the plurality of second protrusion structures
Implementation Method 3
A solar cell is a device that converts solar energy into electrical energy. Solar cells generate carriers based on the photovoltaic principle
Implementation Method 4
a first doped polycrystalline silicon layer doped with N-type dopant ions and disposed over the front surface or over the rear surface, a second doped polycrystalline silicon layer doped with P-type dopant ions and disposed over the rear surface
Data Source
AI summary
Embodiments of the present disclosure provide a solar cell and a photovoltaic module. The solar cell includes: a substrate having a front surface and a rear surface, a first doped polycrystalline silicon layer doped with N-type dopant ions and disposed over the front surface or over the rear surface, and a second doped polycrystalline silicon layer doped with P-type dopant ions and disposed over the rear surface. A surface of the first doped polycrystalline silicon layer away from the substrate has a plurality of first protrusion structures. A surface of the second doped polycrystalline silicon layer away from the substrate has a plurality of second protrusion structures. An average thickness of the first protrusion structures is greater than an average thickness of the second protrusion structures, and a thickness of the first doped polycrystalline silicon layer is not greater than a thickness of the second doped polycrystalline silicon layer.