Scrolled Graphene Solar Cell for Broadband Absorption
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Solution Overview
Problem
Current solar cells face challenges in achieving high efficiency due to high fabrication complexity and costs, limited broadband absorption, and inefficient conversion of solar energy into electrical current, particularly with multi-junction cells and carbon nanotube-based technologies.
Innovation Solution
A scrolled graphene structure is used to capture a broader range of photon energies, maintaining monolayer properties and allowing access to both positive and negative curvature, which enhances solar absorption and conversion efficiency by decoupling layers and enabling a curvature gradient for efficient light absorption and thermoelectric effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If multi-junction solar cells are used to achieve high efficiency, then energy conversion efficiency is improved, but fabrication complexity and production costs increase
Solution Approach 1:
The patent combines multiple junction functions into a single carbon-based material structure. Instead of stacking multiple semiconductor layers with different bandgaps, the invention uses a single carbon nanotube or graphene-based structure that can absorb multiple wavelengths simultaneously, merging the functionality of multiple subcells into one integrated component.
Solution Approach 2:
The patent changes the material parameter from conventional semiconductors to carbon-based materials (carbon nanotubes, graphene). This parameter change enables broadband absorption in a single material, eliminating the need for multiple junctions with different bandgaps while maintaining high energy conversion efficiency.
2Use of energy by moving object
If vertically aligned carbon nanotube forests are used to achieve broadband absorption, then solar energy absorption is improved, but conversion to electrical current becomes impractical
Solution Approach 1:
The patent transitions from the vertically aligned one-dimensional nanotube forest structure to a two-dimensional graphene-based structure or horizontally oriented carbon nanotubes. This dimensional change enables practical electrical contact and current extraction while preserving broadband absorption capabilities.
Solution Approach 2:
The patent introduces graphene as an intermediary material that facilitates both broadband light absorption and efficient charge carrier extraction. Graphene's unique properties serve as a bridge between light absorption and electrical current generation, solving the conversion problem in nanotube-based devices.
3Loss of energy
If conventional multi-junction solar cell design is used, then wavelength-specific absorption is improved, but sunlight must fall perpendicularly or reflectors are required
Solution Approach 1:
The patent creates a universal carbon-based solar cell structure that can absorb sunlight from various angles simultaneously. The material's inherent broadband absorption properties eliminate the need for precise perpendicular alignment or reflector systems, making the device operationally versatile under different lighting conditions.
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 scrolled graphene structure increases solar absorption across a wider spectrum, potentially achieving efficiencies comparable to silicon solar cells, with improved flexibility and reduced manufacturing complexities, while enabling the conversion of absorbed energy into electrical current through hot carrier generation and thermoelectric effects.
Implementation Method 1
vertically aligned carbon nanotubes, although the challenge with using the carbon nanotube 'forests' as a solar cell is that there is no practical way to convert the absorbed solar energy into a usuable electrical current
Implementation Method 2
The subcells are also positioned in optical series such that the subcell with the largest bandgap is on top (facing the sun) and the other subcells are positioned in order of descending width of the bandgap. Hence, in the top subcell only the photons with the highest energy are absorbed
Implementation Method 3
enabling the conversion of absorbed energy into electrical current through hot carrier generation and thermoelectric effects
Implementation Method 4
enabling the conversion of absorbed energy into electrical current through hot carrier generation and thermoelectric effects
Data Source
AI summary
This relates to a device for detecting or converting light or heat energy, the device comprising: a Graphene sheet formed into a scroll such as to provide a monolayer structure in which the radius of curvature of the graphene sheet increases on increasing distance from the longitudinal axis of the scroll.