CdSSe Window Layer for Activated CdSeTe Photovoltaic Junctions
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Solution Overview
Problem
Existing photovoltaic devices face efficiency losses due to the scattering of charge carriers at grain boundaries and recombination of electrons and holes, which are exacerbated by aggressive activation processes that can degrade the thin window layer, leading to reduced performance.
Innovation Solution
Incorporating a CdSSe layer as an n-type window layer or interfacial layer in the p-n junction, which protects the CdS window layer during aggressive activation processes, allowing for more potent activation of the absorber layer without compromising the integrity of the thin window layer, thereby enhancing charge carrier mobility and junction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a thin window layer is used to allow maximum light transmission, then light absorption efficiency is improved, but the window layer becomes vulnerable to degradation during activation processes
Solution Approach 1:
The patent employs a composite window layer structure consisting of CdS and CdSSe materials. The CdSSe component serves as a protective layer that is more resistant to degradation during activation processes, while the CdS component maintains optimal optical properties for light transmission. This composite approach allows the window layer to be sufficiently thin for high light transmission while the CdSSe portion provides enhanced structural integrity and resistance to activation-induced damage.
2Productivity
If aggressive activation processes are applied to improve absorber layer performance, then charge carrier generation is enhanced, but the window layer suffers degradation
Solution Approach 1:
The CdSSe layer acts as an intermediary protective barrier between the activation process and the CdS window layer. During aggressive activation treatments, the CdSSe layer absorbs much of the chemical and thermal stress, preventing direct interaction with the more sensitive CdS window layer. This mediator layer enables the application of potent activation conditions that enhance charge carrier generation in the absorber layer while preserving window layer integrity.
3Reliability
If the window layer is made thicker to maintain robust p-n junction, then junction stability is improved, but light transmission efficiency decreases
Solution Approach 1:
The patent applies local quality by creating a non-uniform window layer structure where different regions have different compositions and thicknesses. The CdSSe portion is strategically positioned to provide localized protection and structural support, while other regions maintain optimal thickness for light transmission. This spatial variation in material properties allows the window layer to simultaneously achieve sufficient robustness for stable p-n junction formation and adequate thinness for high light transmission efficiency.
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 CdSSe layer maintains the thin window layer's integrity, enabling more aggressive activation conditions that improve the absorber layer, resulting in higher charge carrier generation and improved photovoltaic device efficiency.
Implementation Method 1
A photovoltaic structure generates electrical power by converting light into direct current electricity using semiconductor materials that exhibit the photovoltaic effect
Implementation Method 2
photons, packets of energy, are absorbed within the semiconductor to excite electrons to a higher energy state
Data Source
AI summary
A photovoltaic device includes a substrate structure and a p-type semiconductor absorber layer. A photovoltaic device may include a CdSeTe layer. A process for manufacturing a photovoltaic device includes forming a CdSeTe layer over a substrate. The process includes forming a p-type cadmium selenide telluride absorber layer.