Halogen-Enriched Buffer Layer for Thin-Film Solar Cells
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Solution Overview
Problem
Current thin-film solar cells based on Cu(In, Ga)(S, Se)2 require a cadmium sulfide buffer layer for high efficiency, but it is toxic, costly, and not environmentally friendly, and alternative buffer layers do not achieve the same efficiency or stability.
Innovation Solution
A layer system with a halogen-enriched buffer layer, specifically a first layer area adjacent to the absorber layer with a high halogen content and a second layer area with a lower halogen content, forming a halogen gradient to enhance efficiency and stability, using metal halide compounds like sodium chloride or indium chloride for enrichment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a cadmium sulfide buffer layer is used to achieve high efficiency, then the efficiency is improved, but the toxicity and environmental harm increase
Solution Approach 1:
The patent removes the toxic cadmium element from the buffer layer composition entirely, extracting the harmful component while retaining the essential buffering function through alternative materials that do not contain cadmium
Solution Approach 2:
The patent employs conventional, non-toxic materials that are easier and cheaper to handle and dispose of compared to cadmium-based materials, reducing the lifecycle costs associated with toxic waste management
2Productivity
If a cadmium sulfide buffer layer is used to achieve high efficiency, then the efficiency is improved, but the production costs increase
Solution Approach 1:
The patent substitutes expensive cadmium-based materials with conventional, cost-effective materials that eliminate the need for specialized safety equipment and expensive waste disposal procedures, thereby reducing overall production costs
3Object-affected harmful factors
If alternative buffer layers are used to eliminate cadmium, then the toxicity is reduced, but the efficiency and stability decrease
Solution Approach 1:
The patent applies different materials or compositions to different regions or interfaces within the buffer layer structure, optimizing local properties to achieve both stability and non-toxicity while maintaining overall device performance
Solution Approach 2:
The patent employs composite buffer layer structures combining multiple materials, where each component contributes specific properties that collectively achieve the desired stability and efficiency without relying on toxic cadmium
4Reliability
If the buffer layer thickness is increased to improve stability, then the stability is improved, but the light absorption losses increase
Solution Approach 1:
The patent optimizes the thickness parameter of the buffer layer to a specific range that balances the competing requirements of stability (requiring sufficient thickness) and light transmission (requiring minimal thickness), achieving the optimal compromise through precise parameter control
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 halogen-enriched buffer layer system achieves high efficiency and stability for thin-film solar cells, eliminating the need for toxic cadmium and reducing production costs while being environmentally friendly.
Implementation Method 1
the incident light is largely absorbed in a CU (in, GA) (S, SE) 2/CDs/Zno solar cell even with CDS layer thicknesses of a few 10 Nm. The light absorbed in the buffer layer is lost for the electrical yield
Implementation Method 2
this buffer layer enables electronic adjustment between absorber material and frontelectrode
Implementation Method 3
The light absorbed in the buffer layer is lost for the electrical yield, since the load carriers generated recombinate in this layer, since there are many crystal defects acting as recombination centers in this area of the hetero transition and in the buffer material
Implementation Method 4
It also offers protection against spotters in the subsequent process step in the deposition of the front electrode by DC magnetron spins
Data Source
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AI summary
The invention relates to a layer system (1) for thin-film solar cells (100) and solar panels, said system comprising an absorber layer (4) containing a chalcogenide semiconductor and a buffer layer (5) which is arranged on the absorber layer (4) and contains halogen-enriched InxSy, where 2/3 ≤ x/y ≤ 1. The buffer layer (5) consists of a first layer region (5.1) adjoining the absorber layer (4) and containing a halogen mole fraction A1 and a second layer region (5.1) adjoining the first layer region (5.2) and containing a halogen mole fraction A2. The ratio of A1/A2 is ≥2 and the layer thickness (d1) of the first layer region (5.1) ≤ 50% of the layer thickness (d) of the buffer layer (5).