Hybrid Stacked Photovoltaic Device with Conductive Adhesive
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Solution Overview
Problem
Existing stacked-junction photovoltaic devices are expensive to produce and not easily integrated into modular arrays, with high-temperature processing steps causing contamination issues between different semiconductor materials, limiting their efficiency and flexibility.
Innovation Solution
A hybrid stacked-junction photovoltaic device is formed by separately fabricating a lower I-III-VI junction and an upper III-V junction, bonding them together on a flexible substrate using a transparent conductive adhesive with conductive nanostructures, and interconnecting multiple stacks to optimize energy capture from a wide range of photon energies without the need for a separate substrate for the upper cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If stacked-junction photovoltaic devices are made by attaching separate cells with metal interconnects and bonding agents, then the device can capture a broader spectrum of sunlight energy, but the device becomes expensive to produce and complex to manufacture
Solution Approach 1:
The patent merges the upper and lower photovoltaic cells into a single monolithic structure grown on one continuous substrate, eliminating the need for separate cells, metal interconnects, and bonding agents. This integration maintains the stacked-junction functionality for broad spectrum capture while dramatically simplifying the manufacturing process and reducing production costs.
Solution Approach 2:
The patent segments the photovoltaic device into distinct functional regions (upper and lower cells with different bandgaps) that are grown separately on the same substrate and then electrically connected through conductive pathways, allowing each region to optimize for specific wavelength ranges while maintaining manufacturing simplicity.
2Manufacturing precision
If high-temperature processing steps are used to fabricate stacked-junction devices, then the semiconductor layers can be properly formed, but material contamination occurs between different semiconductor materials
Solution Approach 1:
The patent applies different bandgap materials in specific local regions of the device - higher bandgap materials in the upper cell region and lower bandgap materials in the lower cell region - allowing each region to be optimized for its function while growing on the same substrate at controlled temperatures that prevent contamination.
Solution Approach 2:
The patent changes the growth temperature parameters during fabrication to prevent material contamination while still forming proper semiconductor layers, using lower temperatures that avoid the contamination issues associated with high-temperature processing of multiple semiconductor materials.
3Stability of the object's composition
If traditional rigid substrates are used for photovoltaic cells, then the cells have structural stability, but the device weight increases and flexibility is reduced
Solution Approach 1:
The patent replaces traditional rigid substrates with flexible substrates that allow the photovoltaic device to be lightweight and adaptable to various surfaces, while the monolithic growth structure provides sufficient structural stability for practical applications.
4Ease of manufacture
If separate substrates are used for upper and lower photovoltaic cells, then each cell can be independently fabricated, but the overall device complexity and production cost increase
Solution Approach 1:
The patent combines the fabrication process for upper and lower cells into a single monolithic growth process on one substrate, eliminating the need for separate fabrication and subsequent assembly, thereby reducing integration complexity and production cost while maintaining the functional benefits of stacked junctions.
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 lightweight, flexible, and efficient multiple-junction photovoltaic devices that can capture a broader spectrum of sunlight energy, reducing production costs and avoiding material contamination, while maintaining high performance through careful bandgap selection and layer design.
Implementation Method 1
Photovoltaic junctions are photon-energy dependent. Typically, photons are absorbed, and electron-hole pairs created, only when an arriving photon is at least of a particular minimum energy, roughly corresponding to an energy bandgap of the photon-absorbing layer of the photovoltaic device.
Implementation Method 2
bonding them together on a flexible substrate using a transparent conductive adhesive with conductive nanostructures
Data Source
AI summary
A photovoltaic (PV) device has at least one lower PV cell on a substrate, the cell having a metallic back contact, and a I-III-VI absorber, and a transparent conductor layer. An upper PV cell is adhered to the lower PV cell, electrically in series to form a stack. The upper PV cell has III-V absorber and junction layers, the cells are adhered by transparent conductive adhesive having filler of conductive nanostructures or low temperature solder. The upper PV cell has no substrate. An embodiment has at least one shape of patterned conductor making contact to both a top of the upper and a back contact of the lower cells to couple them together in series. In an embodiment, a shape of patterned conductor draws current from excess area of the lower cell to the upper cell, in an alternative embodiment shapes of patterned conductor couples I-III-VI cells not underlying upper cells in series strings, a string being in parallel with at least one stack. In an embodiment, the bonding agent is a polymeric adhesive containing conductive nanostructures. In an embodiment the III-V absorber is grown on single crystal, substrate. A method for forming the device is described.