CIGS Light Absorption Layer Sulfurization via Slurry Coating
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Solution Overview
Problem
Conventional methods for forming CIGS light absorption layers in solar cells rely on hydrogen sulfide gas, which is toxic and expensive, leading to high fabrication costs and non-uniformity due to solid-gas reactions.
Innovation Solution
A method involving a substrate with a Group IB-IIIA-VIA compound light absorption layer, where a sulfur powder slurry is applied and subjected to a thermal process, replacing hydrogen sulfide gas and improving uniformity through a wet coating method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrogen sulfide gas is used in the sulfurization step, then the interface band gap can be increased, but the toxicity and cost increase significantly
Solution Approach 1:
The patent replaces expensive and toxic hydrogen sulfide gas with a cheaper alternative slurry containing sulfur powder dispersed in a solvent. This slurry can be applied as a coating and heated to release sulfur vapor in situ, achieving the desired sulfurization effect without the harmful properties of H2S gas
Solution Approach 2:
The patent introduces a slurry as an intermediary medium between the sulfur source and the CIGS light absorption layer. The slurry contains sulfur powder dispersed in a solvent, which serves as a carrier to deliver sulfur uniformly to the substrate and control the release rate during heating, avoiding direct use of toxic H2S gas
2Reliability
If hydrogen sulfide gas is used in the sulfurization step, then the interface band gap can be increased, but the fabrication cost becomes high
Solution Approach 1:
The patent replaces expensive hydrogen sulfide gas with a cheaper slurry formulation using sulfur powder and a solvent. The slurry can be prepared cost-effectively and applied using conventional coating techniques, significantly reducing material costs while maintaining the interface band gap improvement effect
3Reliability
If hydrogen sulfide gas is used in the sulfurization step, then the sulfurization reaction can proceed, but the uniformity of the light absorption layer deteriorates due to non-uniform gas distribution
Solution Approach 1:
The patent transitions from gas-phase sulfurization to liquid-phase slurry application. The slurry, being a liquid suspension, can be uniformly distributed across the substrate surface using coating techniques such as spin coating, dip coating, or spray coating, ensuring homogeneous sulfur distribution and subsequent uniform reaction during heating
Solution Approach 2:
The patent changes the physical state of the sulfur delivery medium from gas (H2S) to liquid slurry. This parameter change allows for better control of sulfur delivery through viscosity, concentration, and coating parameters, resulting in more uniform layer formation and improved manufacturing precision
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 reduces toxicity and cost, enhances the uniformity of the light absorption layer, and improves the interface band gap and open circuit voltage of solar cells.
Implementation Method 1
conducting a thermal process for the light absorption layer with the slurry
Data Source
AI summary
The disclosure discloses a method for modifying the light absorption layer, including: (a) providing a substrate; (b) forming a light absorption layer on the substrate, wherein the light absorption layer includes a Group IB element, Group IIIA element and Group VIA element; (c) forming a slurry on the light absorption layer, wherein the slurry includes a Group VIA element; and (d) conducting a thermal process for the light absorption layer with the slurry.