Rear-Contact Solar Cell Layout for Low Contact Resistance
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Solution Overview
Problem
The existing solar cell technologies face challenges with high contact resistance due to difficulties in forming a good ohmic contact between the doped conductive layer and the rear metal electrode after the rear surface is polished, which affects the photoelectric conversion efficiency.
Innovation Solution
A solar cell design featuring a substrate with a textured region and a flat region on the rear surface, where a doped surface field with doping elements is formed on the textured region, and a tunneling dielectric layer and doped conductive layer are created on the flat region, allowing the rear electrode to be in direct contact with the doped surface field, thereby reducing contact resistivity and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the rear surface is polished to improve light reflection and reduce surface recombination, then optical loss is reduced, but contact resistance between the doped conductive layer and rear metal electrode increases
Solution Approach 1:
The patent divides the rear surface into two distinct regions: a textured region for optical reflection and a flat region for electrical contact. The flat region is specifically created to provide a smooth surface that enables good ohmic contact between the doped conductive layer and the rear metal electrode, while the textured region maintains light reflection properties. This local differentiation resolves the contradiction by assigning different surface qualities to different functional areas.
Solution Approach 2:
The rear surface is segmented into functionally distinct zones: a textured region occupying a first area for optical management and a flat region occupying a second area for electrical contact. This segmentation allows the solar cell to simultaneously achieve low optical loss through the textured region and low contact resistance through the flat region, resolving the trade-off between these two performance parameters.
2Productivity
If the rear surface is polished to improve photoelectric conversion efficiency, then optical performance is improved, but the formation of good ohmic contact becomes more difficult
Solution Approach 1:
The patent creates a localized flat region on the rear surface specifically designed to facilitate the formation of good ohmic contact. This flat region provides a smooth, uniform surface that enables reliable electrical contact between the doped conductive layer and the metal electrode, while the surrounding textured region maintains high photoelectric conversion efficiency through enhanced light reflection. This local quality differentiation makes the manufacturing process easier by providing a dedicated contact area.
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 design enhances the mobility of carriers, reduces contact resistivity, and improves the photoelectric conversion efficiency by forming a good ohmic contact and reducing carrier recombination rates, leading to increased utilization of light and improved solar cell performance.
Implementation Method 1
a doped surface field is formed in the textured region of the substrate, there are doping elements in the doped surface field
Implementation Method 2
a tunneling dielectric layer, where the tunneling dielectric layer is located on the flat region of the rear surface of the substrate
Implementation Method 3
polish a pyramid textured structure boron-doped on the rear surface, which increases the internal reflection of light
Implementation Method 4
The factors that affect the performance (e.g., photoelectric conversion efficiency) of a solar cell
Data Source
AI summary
The present disclosure provides a solar cell. The solar cell includes a substrate, where the substrate has a front surface and a rear surface, the rear surface includes a textured region and a flat region, a doped surface field is formed in the textured region of the substrate; a tunneling dielectric layer, where the tunneling dielectric layer is located on the flat region; a doped conductive layer, where the doped conductive layer is located on the tunnelling dielectric layer, the doped conductive layer has doping elements, and the doped conductive layer has the same type of the doping elements with the doped surface field; a rear electrode, where a part of a bottom portion of the rear electrode is located in the doped conductive layer and the part of the bottom portion of the rear electrode is in contact with the doped surface field.