Textured Silicon Solar Cell Electrodes for Low Reflectance Adhesion
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Solution Overview
Problem
Existing solar cell technologies face challenges in reducing light reflectance and improving electrode adhesion to the substrate, which affects electrical properties such as contact resistance, serial resistance, and conversion efficiency.
Innovation Solution
A silicon substrate with at least 5 raised portions having a cross-sectional height of 50 nm or more per 5 µm length, combined with a composition for solar cell electrodes that includes a conductive powder, glass frit, organic binder, surface tension modifier, and solvent, applied to form electrodes with a water contact angle of 15° to 60° for improved adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a surface of a substrate is textured and/or is formed with an anti-reflection film, then reflectance of light incident on a solar cell is reduced, but adhesion of an electrode to the substrate deteriorates
Solution Approach 1:
The invention applies different surface treatments to different regions of the substrate. Specifically, it forms a plurality of protrusions on the substrate surface, creating local variations in surface topology. This allows certain regions to have enhanced light trapping properties while other regions provide good mechanical adhesion for electrodes, thus resolving the contradiction between reducing reflectance and maintaining adhesion.
Solution Approach 2:
The invention utilizes curved surface features (protrusions with specific radius of curvature) to achieve both optical and mechanical functions. The curved surfaces of the protrusions effectively reduce light reflectance through multiple internal reflections, while the three-dimensional curved structure provides increased surface area and mechanical interlocking for electrode adhesion, simultaneously addressing both requirements.
2Object-affected harmful factors
If a surface of a substrate is textured, then reflectance of light incident on a solar cell is reduced, but electrical properties such as contact resistance and serial resistance deteriorate
Solution Approach 1:
The invention creates regions with different surface characteristics through the protrusion structure. The protrusions provide excellent light trapping, while the valleys or flat regions between them ensure good electrical contact. This spatial differentiation allows the surface to simultaneously achieve low reflectance and good electrical properties.
Solution Approach 2:
The invention effectively creates a composite surface structure combining different topographical features (protrusions and intervening regions) that serve different functions. This composite structure enables the surface to exhibit both optical benefits (reduced reflectance) and electrical benefits (good contact resistance), resolving the contradiction between these two performance aspects.
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 solution effectively reduces light reflectance, enhances electrode adhesion to the substrate, and improves electrical properties such as contact resistance, serial resistance, and short-circuit current, leading to higher conversion efficiency of the solar cell.
Implementation Method 1
the silicon substrate is formed with at least 5 raised portions having a cross-sectional height (h) of 50 nm or more per 5 μm length
Implementation Method 2
the composition is applied on the silicon substrate to form the electrode and is deposited on the silicon substrate area formed with the raised portions
Implementation Method 3
the composition has a water contact angle of 15° to 60°, and wherein the water contact angle of the composition is measured by dropping distilled water on the surface of a film of the composition
Implementation Method 4
the composition has a water contact angle of 15° to 60°
Implementation Method 5
Solar cells generate electricity using the photovoltaic effect of a PN junction which converts photons of sunlight into electricity
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The solar cell (100) includes: a silicon substrate (10); and an electrode (23) formed on the silicon substrate, wherein the silicon substrate is formed with at least 5 raised portions having a cross-sectional height of 50 nm or more per 5 µm length, and the electrode is formed of a composition for solar cell electrodes having a water contact angle of 15° to 60°.