Lateral Multi-Junction Solar Cell With Spectral Splitting Micro-Optics
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Solution Overview
Problem
Conventional solar cells face efficiency limitations due to single energy band-gap constraints, and existing multi-junction solar cell architectures are either complex, bulky, or require precise alignment, making them unsuitable for compact and high-efficiency applications.
Innovation Solution
A high-efficiency lateral multi-junction tandem solar cell design incorporating a micro-lens layer with low refractive index material and integrated micro-optics, featuring alternating N+ semiconductor segments and Indium Gallium Nitride members with a short-pass filter, and reflective mirrors to concentrate and spectrally split incident light, reducing thickness and manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single energy band-gap solar cell is used, then the device complexity is low, but the efficiency is limited due to inability to absorb full solar spectrum
Solution Approach 1:
The solar cell is divided into multiple photovoltaic cells with different band-gaps arranged in a lateral array. Each cell is optimized to absorb specific wavelength ranges of sunlight, with wider band-gap cells capturing high-energy photons and narrower band-gap cells capturing lower-energy photons, thereby segmenting the solar spectrum absorption across multiple specialized components
Solution Approach 2:
The patent transitions from vertical stacking (tandem configuration) to lateral arrangement of photovoltaic cells with different band-gaps. This dimensional change allows for simpler optical coupling and reduced manufacturing complexity while maintaining the multi-bandgap advantage for enhanced spectral coverage and efficiency
2Productivity
If vertical tandem solar cells are used to increase efficiency, then the power conversion efficiency improves, but the device complexity and manufacturing difficulty increase significantly
Solution Approach 1:
Instead of stacking cells vertically with complex tunnel junctions and current matching requirements, the patent inverts the approach by arranging cells with different band-gaps laterally in an array. This inversion simplifies the optical and electrical design, allowing each cell to be independently optimized and connected without the stringent requirements of vertical tandem structures
Solution Approach 2:
The lateral array configuration allows a single substrate to support multiple photovoltaic cells with different band-gaps, each functioning independently to capture different portions of the solar spectrum. This multi-functional approach eliminates the need for complex current matching and tunnel junctions required in vertical tandems
3Productivity
If vertical tandem solar cells are used to achieve high efficiency, then the power conversion efficiency improves, but the thickness and weight increase
Solution Approach 1:
The patent arranges multiple photovoltaic cells laterally rather than stacking them vertically, which reduces the overall thickness of the solar cell structure. This dimensional reconfiguration maintains the multi-bandgap efficiency advantage while significantly reducing the structural thickness and associated weight compared to vertical tandem configurations
4Productivity
If vertical tandem solar cells are used to increase efficiency, then the power conversion efficiency improves, but the manufacturing precision requirements become extremely high
Solution Approach 1:
The patent inverts the conventional vertical stacking approach by using lateral arrangement of photovoltaic cells. This inversion dramatically reduces the alignment precision requirements during manufacturing, as lateral positioning is less critical than the precise vertical alignment and current matching required in tandem structures
Solution Approach 2:
By dividing the solar cell into laterally arranged segments with different band-gaps, the patent allows each segment to be manufactured and optimized independently. This segmentation reduces the cumulative precision requirements compared to vertical tandems, where multiple layers must be precisely aligned and current-matched
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 a compact, high-efficiency solar cell with reduced thickness and weight, simplified alignment, and lower manufacturing costs, comparable to vertical tandem cells, while maintaining high efficiency and spectral optimization.
Implementation Method 1
a micro-lens layer that has an upper surface formed to concentrate incident light impinging on the solar cell
Implementation Method 2
A second photovoltaic cell element having a short-pass filter element formed with an upper surface of the second photovoltaic cell element
Implementation Method 3
a pattern of reflective mirrors formed on a upper surface of the refractive surface member to reflect light between the reflective mirrors and the first and second photovoltaic cell elements
Implementation Method 4
Solar cells are solid-state devices that directly convert sunlight into electricity. This conversion is typically called the photovoltaic effect, which is the physical process through which the solar cell converts photons from incident sunlight directly into electricity
Data Source
AI summary
A high-efficiency lateral multi-junction solar cell (C) includes ultra-low profile planar spectral band splitting micro-optics having a shortpass filter (48) reflecting desired frequencies of light (24) to a reflective mirror (58) combined with spectrally optimized photovoltaic (solar) cells.