Solar Cell with 3D Nano-Structures for Light Trapping
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Solution Overview
Problem
Conventional silicon solar cells have a limited light extraction surface area, leading to low utilization efficiency as some sunlight is absorbed or reflected without being converted into electrical energy.
Innovation Solution
The method involves creating a solar cell with a silicon substrate featuring three-dimensional nano-structures on its surface, which increases the light absorption area and enhances the photoelectric conversion efficiency by allowing multiple reflections and absorptions of sunlight, thereby improving the overall light utilization efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a smooth surface is used for light extraction, then the manufacturing process is simple, but the light absorption area is small and utilization efficiency is low
Solution Approach 1:
The patent transforms the flat two-dimensional surface into a three-dimensional nanostructured surface with cones, pillars, or wires. This dimensional transformation increases the effective surface area for light absorption while maintaining manufacturability through established semiconductor fabrication techniques such as photolithography and chemical vapor deposition.
Solution Approach 2:
The patent employs curved nanostructures such as conical shapes with varying radii and cylindrical pillars instead of flat surfaces. These curved geometries increase the light absorption area and enhance light trapping through multiple internal reflections, directly addressing the limitation of small absorption area on smooth surfaces.
2Device complexity
If a smooth surface is used for light extraction, then the device structure is simple, but the photon residence time is short and conversion efficiency is low
Solution Approach 1:
By transitioning from a 2D smooth surface to 3D nanostructures, the patent creates multiple light reflection paths and extends the optical path length within the semiconductor material. This increases photon residence time without significantly complicating the fabrication process, as the nanostructures are formed using standard semiconductor manufacturing techniques.
Solution Approach 2:
The curved surfaces of conical and cylindrical nanostructures facilitate multiple internal reflections of incident light, prolonging the time photons spend in the active region. This curvature-based light trapping mechanism effectively increases photon residence time while maintaining a relatively simple device architecture.
3Ease of manufacture
If a smooth surface is used for light extraction, then the fabrication process is straightforward, but the frequency range of absorbed light is limited
Solution Approach 1:
The patent implements nanostructures with varying local geometries, including different cone angles, pillar diameters, and wire spacings. These local variations in structure create different resonant frequencies and absorption characteristics, enabling the solar cell to absorb a broader spectrum of light while using standard fabrication processes to create the diverse structures.
Solution Approach 2:
The patent varies key geometric parameters of the nanostructures, such as height, radius, spacing, and shape, to optimize absorption across different light frequencies. By adjusting these parameters during fabrication, the solar cell can be tuned to absorb a wider frequency range while maintaining manufacturing simplicity through conventional semiconductor processing techniques.
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 use of three-dimensional nano-structures on the silicon substrate increases the light absorption area, prolongs photon residence time, and broadens the frequency range of light absorbed, resulting in improved light absorbing and photoelectric conversion efficiencies.
Implementation Method 1
The use of three-dimensional nano-structures on the silicon substrate increases the light absorption area, prolongs photon residence time, and broadens the frequency range of light absorbed
Implementation Method 2
enhances the photoelectric conversion efficiency by allowing multiple reflections and absorptions of sunlight
Implementation Method 3
Solar cells work via photovoltaic effects of the semiconductor materials. The silicon substrate and the doped silicon layer can form a number of P-N junctions, the P-N junctions can produce a number of electron-hole pairs under excitation of the sunlight
Data Source
AI summary
A solar cell is provided. The solar cell includes a silicon substrate, a back electrode, a doped silicon layer, and an upper electrode. The silicon substrate includes a first surface, a second surface, and a number of three-dimensional nano-structures located on the first surface. The three-dimensional nano-structures are located on the second surface. The three-dimensional nano-structures are linear protruding structures that are spaced from each other, and a cross section of each linear protruding structure is an arc. The doped silicon layer is attached to the three-dimensional nano-structures and the second surface between the three-dimensional nano-structures.