Nanowire Photovoltaic Devices with Tip-Side Electrodes and Air Gaps
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Solution Overview
Problem
Conventional photovoltaic solar cells face challenges such as high energy and cost intensiveness in manufacturing, limited power conversion efficiency, and issues with electrode design and material degradation, particularly in nanowire-based systems where charge recombination and photon absorption by insulators reduce efficiency.
Innovation Solution
The development of a photovoltaic energy conversion device using a canopy-style tip-side electrode and an air gap layer to minimize photon absorption and degradation, combined with a passivation layer to reduce charge recombination, and the use of optically transparent, electrically insulating solid filler materials to enhance electrical contact and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bulk monocrystalline or multicrystalline silicon wafers are used for photovoltaic solar panels, then structural strength and electrical conductivity are ensured, but manufacturing energy consumption and cost increase significantly
Solution Approach 1:
The patent uses nanowire arrays with localized p-n junctions formed through selective doping or material composition variations along the nanowire length, rather than requiring entire bulk wafers to be processed into p-n junctions. This localized approach reduces manufacturing energy while maintaining the essential photovoltaic function.
Solution Approach 2:
The patent transitions from bulk silicon (millimeter scale) to nanowire structures (nanometer to micrometer scale), fundamentally changing the dimensional parameters. This size reduction enables lower manufacturing temperatures and energy consumption while preserving electrical functionality through quantum confinement effects and enhanced surface-to-volume ratios.
2Reliability
If conventional bulk silicon wafers are used, then electrical conductivity is maintained, but power conversion efficiency is limited to 15%-20%
Solution Approach 1:
The patent implements localized doping regions at specific positions along the nanowire length to create p-n junctions, concentrating the electrical functionality in critical zones rather than requiring uniform conductivity throughout the entire structure. This enables more efficient charge separation and collection.
Solution Approach 2:
The patent transitions from two-dimensional planar junctions in bulk wafers to one-dimensional nanowire structures with axial p-n junctions. This dimensional change creates more favorable electric field distributions and charge carrier collection paths, improving power conversion efficiency.
3Use of energy by stationary object
If thin-film photovoltaic cells made from amorphous silicon or chalcogenide compounds are used, then material cost and manufacturing energy are reduced, but power conversion efficiency drops to 6%-10%
Solution Approach 1:
The patent uses nanoscale dimensional parameters (10-500 nm diameter, 1-100 μm length) to enhance the optical and electrical properties of thin-film materials. The reduced dimensions create quantum confinement effects and increased surface-to-volume ratios that improve carrier generation and collection, enabling thin-film structures to achieve efficiencies comparable to or exceeding bulk materials.
Solution Approach 2:
The patent employs composite nanowire structures with core-shell configurations or multi-material compositions (e.g., III-V semiconductor nanowires with oxide shells), combining the advantages of different materials to achieve both low manufacturing energy and high power conversion efficiency simultaneously.
4Stability of the object's composition
If insulating materials are used to fill spaces between nanowires in photovoltaic devices, then structural stability is improved, but photon absorption by insulators reduces power conversion efficiency
Solution Approach 1:
The patent removes insulating filler materials from the spaces between nanowires entirely, replacing them with transparent conductive oxides or air gaps. This extraction eliminates the harmful photon absorption by insulators while maintaining structural stability through alternative support mechanisms such as substrate integration or nanowire interlocking.
Solution Approach 2:
The patent introduces transparent conductive oxide materials as intermediary substances between nanowires, which serve dual functions: providing structural support and electrical connectivity while remaining optically transparent to allow photons to reach the active nanowire regions without absorption losses.
5Reliability
If conventional electrode designs are used in nanowire-based photovoltaic devices, then electrical contact is established, but charge recombination at electrode interfaces reduces power conversion efficiency
Solution Approach 1:
The patent uses transparent conductive oxides as intermediary layers between metal electrodes and semiconductor nanowires. These intermediary layers provide ohmic electrical contact while their wide bandgap prevents charge recombination at the interface, simultaneously achieving good electrical contact and high power conversion efficiency.
Solution Approach 2:
The patent employs composite electrode structures combining metal layers with transparent conductive oxides, creating multi-functional interfaces that provide both excellent electrical conductivity and reduced charge recombination through the synergistic properties of the composite materials.
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 enhances power conversion efficiency, reduces material costs, and improves long-term stability by minimizing charge recombination and photon absorption, while maintaining effective electrical contact and conductivity.
Implementation Method 1
each spot, a nanowire epitaxially grows outwardly from the substrate... each nanowire exhibits a photovoltaic property, i.e., is capable of absorbing incident photons and providing an associated photocurrent to an external load
Implementation Method 2
A catalyst material such as gold or titanium is deposited on a substrate... Under the influence of the catalyst, the precursor gases at least partially decompose into their respective elements
Implementation Method 3
The spaces between the array of PV nanowires are filled with an optically transparent, electrically insulating solid filler material
Implementation Method 4
an air gap layer remains that laterally surrounds the PV nanowires between the substrate surface layer and the layer of electrically conductive material
Data Source
AI summary
Nanowire-based photovoltaic energy conversion devices and related fabrication methods therefor are described. A plurality of photovoltaic (PV) nanowires extend outwardly from a surface layer of a substrate, each PV nanowire having a root end near the substrate surface layer and a tip end opposite the root end. For one preferred embodiment, a canopy-style tip-side electrode layer contacts the tip ends of the PV nanowires and is separated from the substrate surface layer by an air gap layer, the PV nanowires being disposed within the air gap layer. For another preferred embodiment, a tip-side electrode layer is disposed upon a layer of optically transparent, electrically insulating solid filler material that laterally surrounds the PV nanowires along a portion of their lengths, wherein an air gap is disposed between the solid filler layer and the substrate surface layer. Methods for fabricating the nanowire-based photovoltaic energy conversion devices are also described.