Multijunction Dye Solar Cells for High Photovoltage
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Solution Overview
Problem
Current dye-sensitized solar cells (DSCs) face limitations in achieving high photovoltage and efficiency due to energetic waste from high-energy solar spectrum photons and stability issues, particularly with perovskite solar cells, which also raise environmental and health concerns.
Innovation Solution
The development of sequential series multijunction dye-sensitized solar cells (SSM-DSCs) using dyes with an electron deficient acceptor moiety, medium electron density π-bridge moiety, and electron rich donor moiety, along with a cobalt redox shuttle, to enhance voltage output and efficiency by optimizing dye structure and layer thicknesses, and incorporating antireflective coatings and immersion oils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If perovskite solar cells are used to achieve high efficiency, then power conversion efficiency is improved, but stability and environmental safety deteriorate
Solution Approach 1:
The solar spectrum is segmented into multiple wavelength ranges by dividing the single junction cell into multiple subcells, each optimized for specific wavelength ranges. This segmentation allows each subcell to operate at optimal efficiency for its designated spectrum portion while maintaining overall system stability through modular architecture.
Solution Approach 2:
Different dyes with specific molecular structures are assigned to different subcells based on their absorption characteristics. Each subcell employs locally optimized dye structures (donor-π-bridge-acceptor type with specific electron-rich donors, electron-deficient acceptors, and medium electron density π-bridges) matched to their spectral requirements, achieving high efficiency without compromising stability.
2Device complexity
If single junction DSCs are used to simplify device structure, then device complexity is reduced, but photovoltage and efficiency deteriorate due to energetic waste
Solution Approach 1:
The device is segmented into multiple subcells connected in series, where each subcell handles a specific portion of the solar spectrum. This segmentation enables additive photovoltage generation while maintaining manageable device complexity through modular design and systematic optical management.
Solution Approach 2:
The patent transitions from a single-dimensional (single junction) approach to a multi-dimensional (multijunction stacked) architecture. By stacking subcells vertically with optimized thicknesses and incorporating immersion oils for enhanced light trapping, the system captures photons across multiple energy dimensions, achieving high photovoltage without excessive complexity.
3Productivity
If thicker active layers are used to increase light absorption, then photocurrent is improved, but voltage and fill factor deteriorate
Solution Approach 1:
The total active layer thickness is segmented across multiple subcells, with each subcell having an optimized thickness range (0.5-5.0 μm) that balances light absorption with voltage maintenance. This segmentation allows the system to achieve high total photocurrent while each individual layer maintains optimal voltage characteristics.
Solution Approach 2:
Each subcell's active layer thickness is locally optimized based on its specific dye absorption characteristics and spectral role. Front subcells have thinner layers to maintain high voltage, while rear subcells have thicker layers to maximize current generation from transmitted light, achieving global optimization through local customization.
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
SSM-DSCs achieve record high photovoltages of up to 4.7 V and power conversion efficiencies of over 7%, enabling efficient solar energy capture and storage without external bias, while maintaining photocurrent and fill factor, and are more environmentally friendly compared to perovskite systems.
Implementation Method 1
sensitizer dyes... DSCs are an exceptionally attractive solar cell technology for efficiently converting high potential energy photons
Implementation Method 2
one highly studied type of solar cell includes perovskite solar cells (PSCs), which have been reported with record efficiencies for powering water splitting and CO2 reduction catalysts
Implementation Method 3
Co(bpy-pz)23+/2+ was first reported in 2011 by Gratzel et al. as a legitimate alternative to I−/I− and Co(bpy)33+/2+ for DSCs with Y123 sensitizer
Implementation Method 4
incorporating antireflective coatings and immersion oils
Implementation Method 5
incorporating antireflective coatings and immersion oils
Data Source
AI summary
Provided herein are dyes, dye-sensitized solar cells, and sequential series multijunction dye-sensitized solar cell devices. The dyes include an electron deficient acceptor moiety, a medium electron density ?-bridge moiety, and an electron rich donor moiety comprising a biaryl, a substituted biaryl, or an R1, R2, R3 substituted phenyl where each of R1, R2, and R3 independently comprises H, aryl, multiaryl, alkyl substituted aryl, alkoxy substituted aryl, alkyl substituted multiaryl, alkoxy substituted multiaryl, OR4, N(R5)2, or a combination thereof; each R4 independently comprises H, alkyl, aryl, alkyl substituted aryl, alkoxy substituted aryl, or a combination thereof; and each R5 independently comprises aryl, multiaryl, alkyl substituted aryl, alkoxy substituted aryl, alkyl substituted multiaryl, alkoxy substituted multiaryl, or a combination thereof. The solar cells include a glass substrate, a dye-sensitized active layer, and a redox shuttle. The devices include at least two dye-sensitized solar cells connected in series.