Semi-Transparent Organic Photovoltaic Devices for Building Integration
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Solution Overview
Problem
Current semi-transparent organic photovoltaic (OPV) cells face a trade-off between power conversion efficiency (PCE) and average photopic transmittance, limiting their light utilization efficiency (LUE), which is essential for building-integrated photovoltaic applications.
Innovation Solution
The development of OPV cells with an outcoupling layer configured to enhance visible light transmission and near-infrared light reflection, combined with an anti-reflective coating, to improve LUE by optimizing the thickness and composition of sublayers within these layers, and using specific materials like magnesium fluoride and carbazole derivatives in the outcoupling layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If semi-transparent organic photovoltaic cells use narrow band excitonic absorption spectra to allow visible light transmission, then visible transmittance is improved, but power conversion efficiency deteriorates due to limited spectral absorption
Solution Approach 1:
The patent divides the solar spectrum into distinct segments: visible light (400-700nm) is transmitted through the device, while near-infrared light (700-1200nm) is absorbed by the organic active layer. This spectral segmentation allows the device to simultaneously maintain high visible transmittance and achieve power conversion efficiency through targeted NIR absorption, resolving the trade-off between transparency and energy generation
Solution Approach 2:
The patent applies local quality by designing the organic active layer with specific molecular structures (such as low-bandgap polymers and non-fullerene acceptors) that exhibit selective absorption characteristics. The active layer is engineered to have high absorption coefficient specifically in the near-infrared region while remaining transparent in the visible region, allowing different parts of the spectrum to serve different functions (transmission vs. energy conversion)
2Illumination intensity
If semi-transparent photovoltaics are designed to balance energy generation with visual comfort, then average photopic transmittance is improved, but light utilization efficiency deteriorates due to reduced light absorption
Solution Approach 1:
The patent transitions from conventional broad-spectrum absorption to a dimensionally selective approach by exploiting the wavelength dimension. The organic active layer is designed to absorb photons in the near-infrared dimension (700-1200nm) while allowing visible photons (400-700nm) to pass through. This dimensional separation in the electromagnetic spectrum allows the device to maintain high visible transmittance for visual comfort while capturing NIR energy for power generation, thereby improving light utilization efficiency without compromising photopic transmittance
3Power
If broad optical absorption spectra are used in inorganic solar cells such as silicon, then power conversion efficiency is improved, but visible light transmission deteriorates limiting utility in building-integrated applications
Solution Approach 1:
The patent fundamentally changes the material parameter from inorganic silicon to organic semiconductors, which exhibit different optical properties. Organic materials have tunable absorption spectra determined by their molecular structure, allowing the absorption edge to be positioned in the near-infrared region. This parameter change enables the active layer to absorb NIR light for power generation while remaining transparent in the visible range, achieving both high PCE and visible transmittance for building-integrated applications
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 configuration enhances LUE by up to 3.56% and maintains or improves PCE, allowing for higher energy harvesting while maintaining visual comfort through improved transparency and reduced visible reflection.
Implementation Method 1
an outcoupling (OC) layer that coats a surface of the first electrode such that the first electrode is positioned between the outcoupling layer and the active layer. The outcoupling layer is configured to enhance visible light transmission and/or near infrared light reflection through the OPV cell.
Implementation Method 2
The outcoupling layer is configured to enhance visible light transmission and/or near infrared light reflection through the OPV cell.
Implementation Method 3
an anti-reflective coating positioned over a surface of the second electrode such that the second electrode is positioned between the anti-reflective coating and the active layer
Implementation Method 4
an active layer comprising at least one donor material and at least one acceptor material, positioned between the first electrode and the second electrode
Data Source
AI summary
An organic photovoltaic cell comprises a first electrode, a second electrode, an active layer comprising at least one donor material and at least one acceptor material, positioned between the first electrode and the second electrode, an outcoupling layer positioned on a surface of the first electrode such that the first electrode is positioned between the outcoupling layer and the active layer, and an anti-reflective coating positioned over a surface of the second electrode such that the second electrode is positioned between the anti-reflective coating and the active layer, wherein the organic photovoltaic cell is at least semi-transparent to at least one wavelength range. A method of fabricating an organic device is also described.