AZO/ITO Layer Stacks for Solar Cell Transparency and Conductivity
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Solution Overview
Problem
Existing TCO layers in solar cells face challenges in achieving high transparency, low resistance, and low contact resistance, with indium-based TCO being expensive and scarce, and existing deposition methods are costly and limited by process chamber constraints.
Innovation Solution
Employing a layer stack of thinly covered aluminum-doped zinc oxide (AZO) with indium tin oxide (ITO) to form a TCO layer, optimizing the layer structure through in-line coating with interpenetrating material flows to enhance conductivity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If indium-based TCO layer is used to achieve high transparency and low resistance, then electrical conductivity is improved, but manufacturing cost increases and material availability decreases
Solution Approach 1:
The patent changes the material composition parameters by replacing indium-based TCO with aluminum-doped zinc oxide (AZO), altering the chemical composition to achieve similar electrical conductivity properties while reducing dependence on expensive and scarce indium materials
Solution Approach 2:
The patent employs AZO which is a cheaper and more abundant alternative to indium-based TCO materials, reducing manufacturing costs while maintaining the functional requirements for electrical conductivity in solar cell applications
2Illumination intensity
If TCO layer properties are optimized for high transparency, then light absorption is improved, but electrical conductivity decreases
Solution Approach 1:
The patent optimizes the doping concentration and layer thickness parameters of AZO to achieve a balance between transparency and electrical conductivity, adjusting these parameters to simultaneously satisfy optical and electrical performance requirements
Solution Approach 2:
The patent uses aluminum-doped zinc oxide as a composite material that combines the transparency characteristics of zinc oxide with the conductivity enhancement provided by aluminum doping, achieving both high transparency and adequate electrical conductivity
3Reliability
If TCO layer contact resistance is reduced, then charge carrier transport is improved, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes the local properties of the AZO layer at the interface with the metallic grid and underlying a-Si layer, adjusting doping concentration and thickness in these specific regions to achieve low contact resistance while keeping the rest of the layer structure relatively simple
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
The AZO/ITO layer stack achieves comparable efficiency to pure ITO while reducing costs and overcoming aging issues, offering a more cost-effective and efficient TCO layer solution.
Implementation Method 1
forming a transparent, electrically conductive first layer including oxygen and indium on the solar cell precursor; forming one or more than one transparent, electrically conductive second layer including oxygen and having a greater proportion of indium
Data Source
AI summary
Disclosed herein are devices, systems, and methods for processing a solar cell precursor. The processing may include forming a transparent, electrically conductive first layer over the solar cell precursor. The processing may also include forming a transparent, electrically conductive second layer over the solar cell precursor, preferably in physical contact with the first layer. The first layer may comprise at least indium, zinc, and oxygen and the second layer may comprise oxygen and a greater proportion of indium than the first layer.