Transparent Conductive Oxide Layer with Alternating Resistivity Bands
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Solution Overview
Problem
The challenge in photovoltaic cells is to enhance the conductivity of transparent conductive oxide layers without reducing their transparency, as existing solutions like metal grids cause shading losses and rely on expensive metals like Indium, which may become unsustainable.
Innovation Solution
A photovoltaic cell design featuring alternating bands of higher and lower resistivity in transparent conductive oxide layers, such as tin-doped indium oxide (ITO), zinc-doped indium oxide (IZO), or zinc-doped aluminum oxide (AZO), with localized overdoping to increase conductivity without increasing thickness, allowing for improved transparency and conductivity ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conductivity of transparent conductive oxide layers is increased by adding a metal grid, then the current extraction is improved, but the transparency is reduced due to shading effect
Solution Approach 1:
The invention extracts the metal grid component from the system entirely, replacing it with a transparent conductive oxide layer that provides both conductivity and transparency functions without the shading losses caused by metal grids
Solution Approach 2:
The invention changes the electrical parameters of the transparent conductive oxide layer by controlling doping concentrations and layer thickness to achieve the necessary conductivity without requiring a metal grid, thereby maintaining full transparency
2Reliability
If the thickness of transparent conductive oxide layers is increased to improve conductivity, then the electrical conduction is improved, but the transparency is reduced
Solution Approach 1:
The invention applies different doping concentrations at different depths within the transparent conductive oxide layer, with higher doping near the contact region for conductivity and lower doping toward the surface for transparency, optimizing both properties simultaneously
Solution Approach 2:
The invention creates a composite structure within the transparent conductive oxide layer by combining regions of different doping levels and potentially different material compositions to achieve both high conductivity and high transparency properties
3Reliability
If expensive metals like Indium are used to improve conductivity, then the electrical performance is improved, but the cost and sustainability are worsened
Solution Approach 1:
The invention replaces expensive, critical metals like Indium with abundant, inexpensive alternative materials such as zinc oxide and aluminum-doped zinc oxide, making the photovoltaic cells more sustainable and cost-effective
Solution Approach 2:
The invention optimizes the doping parameters and layer structure of alternative materials to achieve electrical performance comparable to or exceeding that of expensive metals, eliminating the need for rare and costly 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 increases the efficiency of photovoltaic cells by reducing resistivity and thickness, minimizing shading losses and the use of expensive metals, while maintaining transparency, leading to enhanced performance and sustainability.
Implementation Method 1
a layer of transparent electrically conductive material making it possible to transport the electrical charges coming from the junction out of this junction while allowing light to pass towards the junction
Implementation Method 2
photovoltaic cell provided with at least one photoelectric conversion semiconductor junction
Data Source
Figure 1~4
Figure 5~7A
Figure 7B~7E
AI summary
Photovoltaic cell (101, 102) comprising at least one photoelectric conversion semiconductor junction (4) covered on at least one of its faces by at least one conductive transparent layer (1, 5) for extracting electrical charges from the junction, wherein said conductive transparent layer comprises an alternation of bands of resistivity above a first threshold, called upper resistivity bands (11, 11, 53), and bands of resistivity below a second threshold, called lower resistivity bands (2, 3, 7) adapted to facilitate transport of said electrical charges.