Glass Base Material Sodium Gradient for Solar Cells
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Solution Overview
Problem
Conventional glass base materials for compound semiconductor solar cells, such as CIS and CIGS, have insufficient sodium feeding capability, which affects the electric power generation efficiency and requires complex methods for sodium incorporation.
Innovation Solution
A glass base material with a sodium concentration gradient that peaks within 0.2 μm from the surface and a high strain point of 520°C or higher, ensuring efficient sodium diffusion into the semiconductor layer, along with specific composition ratios of sodium to other elements, enhances sodium feeding capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional glass base materials are used, then the manufacturing process is simple, but the sodium feeding capability into the compound semiconductor layer is insufficient
Solution Approach 1:
The patent applies local quality by creating a non-uniform sodium concentration distribution within the glass base material. Specifically, the sodium concentration is designed to be higher in the surface layer (within 0-2 μm depth) and decrease toward the interior, with the surface layer containing 0.5-5.0 wt% Na2O while the interior contains 1.0-15.0 wt% Na2O. This localized concentration gradient enables efficient sodium diffusion into the compound semiconductor layer during manufacturing without requiring complex external sodium incorporation steps.
Solution Approach 2:
The patent utilizes parameter changes by controlling the sodium concentration distribution as a key parameter. The surface layer sodium concentration is specifically optimized to be 0.5-5.0 wt% Na2O, and the concentration gradient (dC/dx) is controlled to be 0.05-5.0 wt%/μm. These parameter optimizations enable the glass to spontaneously diffuse sodium into the semiconductor layer at the desired rate, improving sodium feeding capability while maintaining manufacturing simplicity.
2Manufacturing precision
If sodium is incorporated by feeding during film formation, then the addition amount is easily controllable, but the manufacturing steps become complicated
Solution Approach 1:
The patent applies self-service by designing the glass base material itself to be the source of sodium diffusion. The glass composition is engineered with a specific sodium concentration gradient that enables spontaneous sodium diffusion into the compound semiconductor layer during the manufacturing process. This eliminates the need for external sodium feeding mechanisms or additional process steps, as the glass base material automatically provides the required sodium to the semiconductor layer through controlled diffusion.
3Reliability
If the glass base material has high sodium content, then the sodium feeding capability improves, but the glass composition becomes less stable
Solution Approach 1:
The patent resolves the composition stability issue by applying local quality - different regions of the glass base material have different sodium concentrations optimized for their specific functions. The surface layer (0-2 μm depth) contains 0.5-5.0 wt% Na2O to provide sufficient sodium for diffusion, while the interior contains 1.0-15.0 wt% Na2O to maintain overall glass stability and structural integrity. This spatial differentiation allows the glass to simultaneously achieve good sodium feeding capability and compositional stability.
Solution Approach 2:
The patent effectively creates a composite glass structure with varying sodium concentrations throughout its depth. This composite composition, with the surface layer having lower sodium content (0.5-5.0 wt% Na2O) and the interior having higher sodium content (1.0-15.0 wt% Na2O), combines the benefits of both low-sodium surface regions (good for controlled diffusion) and high-sodium interior regions (good for overall glass stability and workability).
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 optimized glass base material significantly improves sodium diffusion and feeding into the semiconductor layer, enhancing the solar cell's power generation efficiency and simplifying the manufacturing process while maintaining cost-effectiveness.
Implementation Method 1
the diffusion of sodium from a glass base material into a compound semiconductor layer is a phenomenon which takes place in an extremely surface layer of the glass base material
Data Source
AI summary
Provided is a glass base material having excellent sodium feeding capability as a glass base material for solar cells such as compound semiconductor solar cells. The invention is concerned with a glass base material which is used for solar cells, wherein on at least one surface thereof, a sodium concentration in a depth of 0.2 μm from the surface of the glass base material is 0.55 or larger in terms of a relative value relative to a sodium concentration in a depth of 1 μm from the surface of the glass base material.