Micro-Optical Tandem LSC with Embedded Quantum Dots
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Luminescent solar concentrators face low power conversion efficiencies and scalability issues due to parasitic absorption by luminophores and incomplete light trapping, limiting their commercialization and widespread adoption in photovoltaic power generation.
Innovation Solution
The development of a micro-optical tandem luminescent solar concentrator (MOTLSC) with embedded luminophores, planar solar cells, selectively-reflective metasurface mirrors, and novel waveguide materials to minimize photon thermalization losses and enhance light trapping, incorporating CdSe/CdS quantum dots and bifacial cells for improved energy conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional LSCs with suspended luminophores in polymer matrix are used, then diffuse sunlight can be captured, but power conversion efficiency remains low due to parasitic absorption and incomplete light trapping
Solution Approach 1:
The device is segmented into distinct functional layers: a waveguide layer with embedded luminophores, separate PV cells positioned at edges, and selective mirrors. This segmentation allows optimization of each component's function while reducing parasitic absorption by ensuring luminophores are properly contained and positioned within the waveguide structure.
Solution Approach 2:
Luminophores are embedded within the waveguide material itself, creating a nested structure where the luminophores are contained inside the waveguide matrix. This nesting ensures close coupling between the luminophores and waveguide, improving light trapping while maintaining structural integrity and reducing parasitic losses.
2Area of stationary object
If LSCs are designed for architectural applications with large area, then diffuse light utilization is improved, but scalability and commercialization are limited by low efficiency
Solution Approach 1:
The waveguide structure implements local quality optimization by embedding luminophores specifically within the waveguide material at locations optimized for light trapping. The PV cells are positioned at specific edge locations where light concentration is maximized, and selective mirrors are placed to redirect specific wavelength ranges, creating locally optimized regions that collectively enhance overall power generation from large areas.
Solution Approach 2:
The invention changes key parameters including the refractive index matching between waveguide and surrounding materials to enhance light trapping, optimizes the spectral response by selecting luminophores with specific emission characteristics, and adjusts the geometric configuration to maximize the ratio of illuminated area to PV cell area while maintaining high power conversion efficiency.
3Power
If geometric gain is increased to concentrate light, then light concentration improves, but losses from absorption and escaped light increase
Solution Approach 1:
Selective mirrors act as intermediaries between the waveguide and the environment, redirecting escaped light back into the waveguide structure. These mirrors are positioned to intercept light that would otherwise be lost and reflect it back at angles that facilitate re-trapping, thereby reducing energy losses while maintaining high light concentration through geometric gain.
Solution Approach 2:
The system maintains continuous useful action by implementing multiple reflection paths and using selective mirrors to redirect escaped light back into the conversion process. This creates a continuous cycle where light that initially escapes can be recaptured and converted, ensuring that the useful action of light-to-electricity conversion continues rather than terminating at the first loss point.
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 MOTLSC design achieves enhanced spectral efficiency across the solar spectrum, increasing power conversion efficiency by up to 31.1% even under low direct normal incidence conditions, with a balanced output power generation from both the luminescent solar concentrator and silicon subcell.
Implementation Method 1
a waveguide configured to trap light incident on a first surface via total internal reflection
Implementation Method 2
the waveguide including embedded luminophores configured to absorb at least a portion of the trapped light and emit photoluminesced light
Implementation Method 3
the at least one embedded planar cell configured to absorb and convert at least a portion of the photoluminesced light to an electric signal
Data Source
AI summary
Luminescent solar concentrators in accordance with various embodiments of the invention can be designed to minimize photon thermalization losses and incomplete light trapping using various components and techniques. Cadmium selenide core, cadmium sulfide shell (CdSe/CdS) quantum dot (“QD”) technology can be implemented in such devices to allow for near-unity QDs and sufficiently large Stokes shifts. Many embodiments of the invention include a luminescent solar concentrator that incorporates CdSe/CdS quantum dot luminophores. In further embodiments, anisotropic luminophore emission can be implemented through metasurface/plasmonic antenna coupling. In several embodiments, red-shifted luminophores are implemented. Additionally, top and bottom spectrally-selective filters, such as but not limited to selectively-reflective metasurface mirrors and polymeric stack filters, can be implemented to enhance the photon collection efficiency. In some embodiments, luminescent solar concentrator component is optically connected in tandem with a planar Si subcell, forming a micro-optical tandem luminescent solar concentrator.