Graphene Multijunction Solar Cell for High Efficiency
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Solution Overview
Problem
Current photovoltaic technology faces limitations in efficiency and cost, with maximum energy conversion at about 25% due to high semiconductor material costs and handling difficulties, and is not competitive with fossil-fuel technologies.
Innovation Solution
A multijunction solar cell design using graphene-based sub-cells with varying band gaps, stacked with n-type and p-type semiconductive graphene to form a graphene p-n junction, allowing for increased photon absorption and reduced material usage, with a thin-film approach on flexible substrates to decrease production costs and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional semiconductor materials are used in photovoltaic cells, then the device can convert light to electricity, but the production cost is high and handling is difficult
Solution Approach 1:
The patent changes the fundamental material parameter from traditional semiconductors to graphene, which has unique electronic and optical properties. Graphene's zero-bandgap structure and high carrier mobility enable new photovoltaic mechanisms that reduce production costs while maintaining or improving efficiency
Solution Approach 2:
The invention uses composite structures combining graphene with other materials to create multijunction solar cells. The combination of different graphene-based junctions (p-n, p-i-n) with varying bandgaps creates a composite system that optimizes both cost and efficiency
2Reliability
If traditional photovoltaic technology is used, then the device can generate electricity from solar energy, but the maximum energy conversion efficiency is limited to about 25%
Solution Approach 1:
The patent divides the solar cell into multiple junctions (multijunction structure) with different bandgap energies. Each junction segment captures a specific portion of the solar spectrum, and the segments are stacked in series to achieve overall efficiency exceeding 25% while managing structural complexity through modular design
Solution Approach 2:
The invention transitions from traditional planar photovoltaic structures to vertically stacked multijunction configurations. This dimensional arrangement allows multiple bandgap transitions to occur in series along the vertical dimension, capturing broader solar spectrum without requiring lateral expansion
3Reliability
If multiple sub-cells with different band gaps are stacked, then energy conversion efficiency increases, but the device complexity increases
Solution Approach 1:
The patent systematically varies the bandgap parameter across different graphene-based junctions in the stack. By controlling doping levels and material composition to achieve specific bandgap values (e.g., 0.3 eV, 0.5 eV, 1.1 eV), the design optimizes photon capture across the solar spectrum while maintaining manufacturability
Solution Approach 2:
Each sub-cell in the multijunction stack is designed with locally optimized properties - different bandgaps, doping concentrations, and thicknesses - tailored to capture specific wavelength ranges. This local quality differentiation maximizes overall efficiency while the modular nature of each sub-cell keeps individual components relatively simple
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 graphene-based multijunction solar cell achieves higher energy conversion efficiency, potentially reaching 85% with multiple junctions, while reducing production costs and improving handling and installation ease, offering advantages over traditional III-V semiconductor materials.
Implementation Method 1
devices for conversion of light to electricity using graphene-based solar cells
Implementation Method 2
Apparatus and method for converting electromagnetic radiation into an electrical current, applying the combination of a photovoltaic and a thermovoltaic element are known
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
This disclosure relates to structures for the conversion of light into energy. More specifically, the disclosure describes devices for conversion of light to electricity using photovoltaic cells comprising graphene.