Solar Cell Electrode Adhesive Layer Thermal Expansion
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Solution Overview
Problem
Existing solar cells have low efficiency due to suboptimal design of layers and electrodes, which hinders their widespread adoption as a next-generation alternative energy source.
Innovation Solution
A solar cell design featuring a photoelectric conversion unit with conductive type regions and an electrode structure that includes an adhesive layer with a specific coefficient of thermal expansion, providing conductivity and transparency, and an electrode layer with reflective properties, which enhances light reflection and contact characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional electrode structure is used, then the manufacturing process is simple, but the solar cell efficiency is low
Solution Approach 1:
The electrode is divided into multiple functional layers: adhesive layer (for bonding), reflective layer (for light reflection), and conductive layer (for electrical conduction). This segmentation allows each layer to perform its specific function optimally, thereby improving overall solar cell efficiency while maintaining manageable manufacturing complexity.
Solution Approach 2:
The electrode uses composite material structure combining different materials with complementary properties: adhesive materials for strong bonding, reflective materials (such as aluminum or silver) for light reflection, and conductive materials for electrical conduction. This composite approach enhances efficiency by maximizing the benefits of each material type.
2Illumination intensity
If the adhesive layer has high transparency, then light transmission is improved, but the contact characteristics between electrode and semiconductor substrate may deteriorate
Solution Approach 1:
The adhesive layer is designed with specific local properties: it is positioned between the reflective layer and semiconductor substrate, has controlled thickness (typically 50-200 nm), and uses materials with appropriate transparency and adhesion characteristics. This local optimization allows sufficient light transmission while maintaining reliable contact characteristics.
Solution Approach 2:
The transparency and contact characteristics are optimized by adjusting key parameters of the adhesive layer: thickness (thinner for better transparency, but sufficient for adhesion), material composition (selecting materials with appropriate optical and mechanical properties), and coefficient of thermal expansion (matching between layers). These parameter changes achieve the balance between light transmission and contact reliability.
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 enhanced electrode structure increases light reflection and improves contact between semiconductor substrates and electrodes, leading to improved solar cell efficiency and performance.
Implementation Method 1
an electrode layer formed on the adhesive layer... the electrode layer can include a plurality of layers, and the adhesive layer has a smaller thickness than each of the plurality of layers of the electrode layer... the first electrode layer can include at least one of Cu, Al, Ag, Au, and alloys thereof
Data Source
AI summary
A solar cell can include a photoelectric conversion unit including a semiconductor substrate, a tunneling layer disposed on the semiconductor substrate, a first conductive type region and a second conductive type region disposed on the tunneling layer at a same side of the semiconductor substrate, and a barrier region disposed between the first and second conductive type regions; and an electrode disposed on the photoelectric conversion unit and including an adhesive layer disposed on the first and second conductive type regions, and an electrode layer disposed on the adhesive layer, in which the adhesive layer has a coefficient of thermal expansion that is greater than a coefficient of thermal expansion of the photoelectric conversion unit and is less than a coefficient of thermal expansion of the electrode layer.