Multilayer Quantum Dot Solar Concentrators for Reabsorption Loss Reduction
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Solution Overview
Problem
Current luminescent solar concentrators (LSCs) based on quantum dots (QDs) face efficiency limitations, with single-layer devices achieving external optical efficiencies below the commercial viability threshold of approximately 6%, necessitating an improved design to enhance energy harvesting and reduce costs.
Innovation Solution
The implementation of multi-layer LSC devices utilizing engineered QDs with varying band gaps, where each layer absorbs different parts of the solar spectrum, including tandem configurations with a higher band-gap top layer and a lower band-gap bottom layer, and optionally an intermediate layer, to achieve spectral splitting and reduce reabsorption losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-layer LSC devices are used, then device structure is simple, but external optical efficiency is below 6% commercial viability threshold
Solution Approach 1:
The LSC device is divided into multiple layers, each containing quantum dots with specific band gaps optimized for different portions of the solar spectrum. This segmentation allows each layer to specialize in absorbing particular wavelengths, thereby increasing overall external optical efficiency while maintaining manageable structural complexity through modular design.
Solution Approach 2:
The invention transitions from a single-layer two-dimensional structure to a multi-layer three-dimensional configuration. By stacking layers with different band gap energies, the device captures photons across a broader spectral range in the vertical dimension, significantly improving external optical efficiency without proportionally increasing horizontal footprint.
2Loss of energy
If quantum dots with varying band gaps are used in multi-layer configuration, then spectral coverage is improved and reabsorption losses are reduced, but device complexity increases
Solution Approach 1:
Each layer in the multi-layer LSC device is assigned specific local qualities through the selection of quantum dots with particular band gap energies. The top layer uses wider band gap QDs for high-energy photon absorption, while bottom layers use narrower band gap QDs for lower-energy photons. This local optimization minimizes reabsorption losses by ensuring that emitted photons from one layer do not overlap with absorption bands of other layers, while the overall device complexity remains controlled through systematic material selection.
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 approach achieves external quantum efficiencies of at least 6% and up to 10% in some embodiments, significantly improving device efficiency and potentially reducing the cost of solar electricity by 13% to 34% compared to standalone silicon PV modules, with enhanced photostability and reabsorption-free light propagation.
Implementation Method 1
Solar photons incident onto a larger-area device face (area A1) are absorbed by the fluorophores, reemitted at a longer wavelength
Implementation Method 2
guided by total internal reflection to the device edges (area A2), where they are collected by PV cells
Data Source
AI summary
Luminescent solar concentrators (LSCs) based on engineered quantum dots (QDs) are disclosed that include at least one lower band-gap energy LSC layer and at least one higher band-gap energy LSC layer. The higher band-gap energy LSC layer has a higher internal quantum efficiency (IQE) than the lower band-gap energy LSC layer. The lower band-gap energy LSC layer may broadly absorb the remainder of the solar spectrum that is not absorbed by previous layers. An external optical efficiency (EQE) of at least 6%, and in some cases, more than 10%, may be achieved by such LSCs.