Non-Fullerene Active Layers for Transparent Solar Cells
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Solution Overview
Problem
Conventional organic photovoltaic (OPV) devices face challenges in achieving high transparency and power conversion efficiency (PCE) due to limitations in absorption window and material properties, particularly in using fullerene derivatives, which restrict the absorption to UV or near-UV radiation, and result in low average visible transmission (AVT) and PCE.
Innovation Solution
The development of active layers comprising non-fullerene components and hole-scavenging components, which absorb near-infrared radiation and form diluted systems, allowing for enhanced transparency and stability, and the use of tandem solar cell structures with amorphous silicon subcells to improve light harvesting and conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fullerene derivatives (PCBM, PC70BM) are used as acceptor materials in bulk heterojunction solar cells, then the device can be fabricated with conventional materials, but the absorption window is limited to UV or near-UV radiation resulting in low average visible transmission (AVT) and power conversion efficiency (PCE)
Solution Approach 1:
The patent changes the optical absorption parameters by replacing fullerene derivatives with non-fullerene acceptors that have different absorption spectra. The non-fullerene acceptors are designed to absorb in the visible to near-infrared region (700-1000 nm) rather than UV region, fundamentally altering the absorption window and enabling high AVT while maintaining PCE.
Solution Approach 2:
The patent employs composite active layer formulations combining non-fullerene acceptors with specific donor materials (e.g., PTB7-Th, REG-105) and hole scavenging components. These composite materials leverage synergistic effects to achieve both high transparency and efficient charge generation, overcoming the limitations of single-component systems.
2Illumination intensity
If the photoactive layer thickness is decreased to increase average visible transmission, then transparency is improved, but power conversion efficiency deteriorates
Solution Approach 1:
The patent optimizes the thickness parameter of the photoactive layer to a specific range (50-200 nm) that balances optical transmission and charge generation efficiency. This optimized thickness allows sufficient light transmission while maintaining adequate path length for photon absorption and charge carrier generation.
Solution Approach 2:
The use of composite materials with high absorption coefficients in the visible-NIR region enables thinner film design. The non-fullerene acceptors and donor materials are engineered to have strong absorption in the target wavelength range, allowing efficient charge generation even in thin films with high transparency.
3Illumination intensity
If non-fullerene acceptors are used to absorb near-infrared radiation and achieve high transparency, then average visible transmission is improved, but device stability and charge recombination behavior may be compromised
Solution Approach 1:
The patent stabilizes the device by formulating composite active layers with carefully selected donor materials and hole scavenging components that work synergistically with non-fullerene acceptors. The hole scavenging components specifically address charge recombination issues by efficiently removing holes, preventing detrimental recombination processes and enhancing device stability.
Solution Approach 2:
The hole scavenging component acts as an intermediary that mediates between the photo-generated electrons in the non-fullerene acceptor and the holes, preventing direct recombination. This intermediary role of the hole scavenger protects the charge carriers and maintains device stability while preserving the high transparency benefits of non-fullerene acceptors.
4Reliability
If conventional donor/acceptor ratios (1:1 to 1:4 w/w) are used in bulk heterojunction solar cells, then charge generation is optimized, but average visible transmission remains low and cannot exceed 50% while maintaining PCE >5%
Solution Approach 1:
The patent fundamentally changes the compositional parameter by using non-fullerene acceptors with superior optical properties. These acceptors enable the system to achieve high AVT (>70%) while maintaining PCE >5%, breaking the conventional trade-off relationship that limited AVT to 50% maximum for efficient devices.
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 enables the creation of highly transparent and efficient OPV devices with AVT > 70% and PCE > 5%, and when combined with ternary blends, achieves PCE of 6%, while maintaining high thermal stability and visual transparency.
Implementation Method 1
organic photovoltaics (OPV)... harvesting the infrared part of the spectrum for the light-to-current conversion
Implementation Method 2
shift the absorption window of the active layer material from the visible (400-700 nm) to the near-infrared (NIR) part of the spectrum
Data Source
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AI summary
Embodiments of the present disclosure describe an active layer of an optoelectronic device comprising a non-fullerene component and optionally one or more hole-scavenging components. Embodiments of the present disclosure describe an optoelectronic device comprising a first electrode material, an active layer, and a second electrode material, wherein the first electrode material and the second electrode material are on opposing sides of the active layer, wherein the active layer comprises a non-fullerene component and optionally one or more hole-scavenging components.