Alkali Metal-Doped Polyimide Laminate for High-Temp Solar Cells
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Solution Overview
Problem
Thin film solar cells using polyimide substrates face challenges with high temperature processing due to warpage and poor mechanical properties, leading to lower energy conversion efficiency and defects in light-absorbing layers, while existing solutions like metal base layers compromise efficiency and require additional barrier film formation.
Innovation Solution
A laminate structure incorporating a polyimide layer doped with alkali metals, such as lithium or sodium, and a metal base layer, allowing for high-temperature processing without warpage and eliminating the need for a barrier film, with the alkali metal doping enhancing crystal growth and energy conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If polyimide substrates are used for thin film solar cells, then flexibility and light weight are improved, but high temperature processing capability deteriorates
Solution Approach 1:
The invention uses a composite substrate structure comprising a polyimide film layer and a glass fiber reinforcement layer. The glass fiber mesh embedded in the polyimide matrix provides high temperature stability and dimensional stability, while the polyimide matrix maintains flexibility and light weight. This composite structure enables the substrate to withstand high temperature processing (500-600°C) required for defect-free light-absorbing layer formation while retaining the advantages of flexible substrates.
2Reliability
If polyimide substrates are baked at high temperatures of 500°C or above, then defect formation in light-absorbing layer is reduced, but warpage and mechanical property deterioration occur
Solution Approach 1:
The glass fiber reinforcement layer embedded in the polyimide film provides exceptional dimensional stability and rigidity. The glass fiber mesh structure resists thermal expansion and prevents warpage during high temperature baking processes (500-600°C), while the polyimide matrix maintains flexibility. This composite structure enables high temperature processing without substrate deformation.
Solution Approach 2:
The invention modifies the thermal and mechanical parameters of the polyimide substrate by incorporating glass fiber reinforcement. The glass fiber content and distribution are optimized to achieve the desired balance between flexibility, dimensional stability, and high temperature resistance. The glass fiber mesh structure specifically targets improving dimensional stability during thermal processing.
3Temperature
If metal base layers are used as substrates, then high temperature processing capability is improved, but energy conversion efficiency deteriorates and additional barrier film formation is required
Solution Approach 1:
The invention replaces expensive metal base layers with a cost-effective polyimide-glass fiber composite substrate that achieves comparable high temperature performance. The polyimide-glass fiber substrate eliminates the need for additional barrier films, reducing process complexity and cost while maintaining the ability to withstand high temperature processing required for defect-free light-absorbing layer formation.
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 laminate enables thin film solar cells to be processed at temperatures of at least 550°C, improving flexibility, energy conversion efficiency, and eliminating the need for a barrier film, while maintaining structural integrity and enhancing crystal structure of the light-absorbing layer.
Implementation Method 1
an alkali metal-doped layer disposed on one surface of the polyimide layer
Data Source
AI summary
The present invention relates to a laminate including an alkali metal-doped layer. The laminate is processable at high temperatures of at least 550° C. and has excellent durability and barrier properties. Due to these advantages, the laminate can be used to fabricate a thin film solar cell with high flexibility and improved energy conversion efficiency. The present invention also relates to a thin film solar cell including the laminate.