Thin Glass Substrate Warp Control for Solar Cells
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Solution Overview
Problem
Conventional glass substrates with conductive films for solar cells face issues with power generation variation and poor sealability, particularly when thinned, leading to warp deformation and leakage of iodine electrolyte solutions in dye-sensitized solar cells.
Innovation Solution
A glass substrate with a conductive film is developed, where the warp deformation is limited to 0.5 µm/cm² or less, and the glass substrate has a strain point of 525°C or more, with a thermal expansion coefficient between 60 to 85×10^-7 /°C, and a film formation temperature between 420 to 600°C, to minimize warp deformation and ensure excellent sealability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the thickness of the glass substrate is reduced to thin the solar cell, then the weight and thickness of the solar cell are reduced, but warp deformation occurs leading to power generation variation and poor sealability
Solution Approach 1:
The patent applies parameter changes by optimizing the thermal expansion coefficient of the glass substrate to a specific range (60-85×10^-7/°C) and controlling the film formation temperature (420-600°C) to minimize warp deformation. This allows the use of thin glass substrates (1.1-2.0 mm) while maintaining sufficient flatness (warp deformation ≤5 µm/cm²) for uniform power generation and effective sealing.
2Weight of moving object
If the thickness of the glass substrate is reduced to thin the solar cell, then the weight and thickness of the solar cell are reduced, but sealability deteriorates leading to leakage of iodine electrolyte solution
Solution Approach 1:
The patent controls the thermal expansion coefficient of the glass substrate within a specific range (60-85×10^-7/°C) and optimizes the film formation temperature (420-600°C) to minimize warp deformation. This ensures that even thin glass substrates maintain sufficient flatness for effective sealing, preventing leakage of the iodine electrolyte solution while achieving weight reduction.
3Ease of manufacture
If FTO is used as the conductive film to reduce cost and improve chemical stability, then the production cost is reduced and chemical stability is improved, but the resistivity is higher compared to ITO
Solution Approach 1:
The patent optimizes the film formation temperature of the FTO conductive film within the range of 420-600°C to achieve the desired balance between electrical conductivity and chemical stability. This temperature control ensures that the FTO film forms with appropriate crystalline structure and grain size, minimizing resistivity while maintaining the cost advantages and chemical stability of FTO compared to ITO.
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 solution reduces power generation variation and enhances sealability, allowing for uniform power generation and effective sealing in thin solar cell applications, particularly in dye-sensitized solar cells.
Implementation Method 1
the film is formed by causing a mixed gas of compounds containing tin and fluorine to undertake a thermal decomposition reaction on a glass substrate heated at about 400°C or more
Implementation Method 2
the warp deformation amount W of the glass substrate is 0.5 µm/cm² or less, and the glass substrate has a strain point of 525°C or more, with a thermal expansion coefficient between 60 to 85×10^-7 /°C
Data Source
Figure 1~2
Figure 3
AI summary
A glass substrate with a conductive film, which ensures that variation of power generation is less likely to occur when used in a thin solar cell, and is excellent in the sealability with a sealant, is provided. A glass substrate with a conductive film for a solar cell which comprises a glass substrate having a thickness of 2 mm or less and a conductive film formed on the glass substrate, wherein the warp deformation amount W of the glass substrate represented by the following formula is 0.5 µm/cm2 or less. W = D/L2 (D: the maximum warpage (µm) of the glass substrate, and L: the diagonal length (cm) of the glass substrate)