Radially Stacked Solar Cells Using Spiral Strain Gradient
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Solution Overview
Problem
Current solar cells based on transition metal dichalcogenides (TMDCs) suffer from low absorption and conversion efficiencies due to limited solar radiation absorption in active layers with atomic scale thickness, which restricts their potential in photovoltaic applications.
Innovation Solution
A solar cell architecture featuring a spiral structure formed by a barrier layer with gradient strain, where a heterostructure of TMDC layers is attached, creating multiple heterojunctions and an optical cavity to enhance light absorption and energy collection, including a reflective core to maximize light interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If atomic scale thickness TMDC layers are used, then material cost is reduced and flexibility is improved, but absorption efficiency deteriorates to 5-10%
Solution Approach 1:
The patent transforms the planar 2D TMDC structure into a 3D spiral configuration by wrapping the thin film around a sacrificial core. This dimensional change allows the light to interact with the absorber material multiple times along the spiral path, effectively increasing the absorption path length from nanometer scale to micrometer scale without increasing material thickness, thereby resolving the contradiction between thin material usage and sufficient light absorption.
Solution Approach 2:
The patent introduces a curved spiral geometry instead of a flat planar structure. The curved path of the spiral wrap creates an extended optical path length within a compact footprint, allowing photons to traverse through the thin TMDC layers multiple times. This curvature-based design enables efficient light absorption despite the limited thickness of the atomic-scale material.
2Adaptability or versatility
If multiple TMDC layers are stacked radially, then broadband absorption is improved, but device complexity increases
Solution Approach 1:
The patent divides the light absorption function across multiple radially stacked TMDC layers, each potentially tuned to absorb different portions of the solar spectrum. By segmenting the absorber into discrete layers with different bandgaps, the system achieves broadband coverage while maintaining the simplicity of a modular stacked architecture rather than requiring a single complex material.
Solution Approach 2:
The patent employs composite heterostructures combining different TMDC materials (e.g., MoS2, MoSe2, WSe2) with complementary bandgap energies. This composite approach enables each layer to contribute to specific wavelength ranges, collectively achieving broad spectral absorption. The use of van der Waals heterostructures simplifies the integration process compared to traditional epitaxial growth of complex alloys.
3Loss of energy
If spiral structure with reflective core is implemented, then light absorption efficiency is enhanced to 85%, but manufacturing complexity increases
Solution Approach 1:
The patent uses a sacrificial core (such as a metal rod or nanoparticle array) as a preliminary structure around which the TMDC thin film is wrapped. This core serves as a temporary mold that defines the spiral geometry during fabrication. After the heterostructure is assembled around the core, the sacrificial material is removed, leaving the desired spiral configuration. This preliminary action simplifies the manufacturing process by avoiding direct fabrication of the complex spiral shape.
Solution Approach 2:
The sacrificial core acts as an intermediary element during the fabrication process. It provides a physical template that enables the thin film to self-organize into the desired spiral configuration without requiring complex lithography or patterning steps. The core mediates between the simple planar thin film deposition process and the complex spiral final structure, making the manufacturing process more feasible.
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
This design achieves an absorption efficiency of at least 85% and a conversion efficiency of at least 20%, significantly improving upon the low efficiencies of previous TMDC-based solar cells by effectively harnessing solar radiation across a broader spectrum.
Implementation Method 1
forming a barrier layer having a gradient strain on the sacrificial layer... The barrier layer, the first light absorbing layer, and the second light absorbing layer form a spiral structure having a spiral shape resulting from the gradient strain of the barrier layer
Implementation Method 2
Few to single atomic layers of TMDC are direct semiconductors with band-gap between 1 and 3 electron volts (eV). A large absorption per thickness has been reported for several TMDCs... absorption and conversion efficiencies are low, in the order of 5-10% and a few percent, respectively
Implementation Method 3
The method can further include attaching a reflective core to the second light absorbing layer, wherein the reflective core is positioned at a center of the spiral structure subsequent to the removing of the sacrificial layer
Data Source
AI summary
A solar cell for collecting solar radiation can include a barrier layer such as a dielectric barrier layer and a heterostructure including a first light absorbing layer and at least a second light absorbing layer. A method for forming the solar cell can include forming a sacrificial layer on a support substrate and forming the barrier layer on the sacrificial layer. The barrier layer is formed to have a strain gradient through its thickness. The heterostructure is attached to the barrier layer and the sacrificial layer is removed, thereby separating the barrier layer and the heterostructure from the support substrate. During the removal of the sacrificial layer, the strain gradient causes the barrier layer and heterostructure, to roll, curl, or spiral, thereby resulting in a radially stacked heterostructure that provides a light concentrating optical cavity having multiple light absorbing layers with different band gaps.