Tunneling-Layer Solar Cell Structure for Lower Carrier Recombination
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Solution Overview
Problem
Conventional solar cells suffer from efficiency deterioration due to carrier recombination, long transfer distances, and surface defects on the semiconductor substrate.
Innovation Solution
A solar cell design that includes a monocrystalline silicon substrate with a doping area on the front surface and a polycrystalline silicon back surface field area, separated by tunneling layers, which effectively remove defects and facilitate carrier transfer, minimizing recombination sites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional solar cell structure is used, then the manufacturing process is simpler, but efficiency deteriorates due to carrier recombination and surface defects
Solution Approach 1:
The solar cell structure is segmented into multiple functional layers: a monocrystalline silicon substrate for photoelectric conversion, an amorphous silicon layer for passivation, and a polycrystalline silicon layer for carrier collection. This segmentation allows each layer to address specific problems (substrate defects, surface recombination, carrier transfer) thereby improving overall efficiency despite increased structural complexity
Solution Approach 2:
The invention uses composite material structure combining monocrystalline silicon, amorphous silicon, and polycrystalline silicon in specific layers. The monocrystalline substrate provides high quality photoelectric conversion, the amorphous silicon layer provides excellent passivation, and the polycrystalline silicon provides efficient carrier collection, together resolving the efficiency problem without requiring complete structural redesign
2Reliability
If the back surface of the semiconductor substrate is left untreated, then the manufacturing process is simpler, but recombination sites increase and efficiency decreases
Solution Approach 1:
The amorphous silicon layer is formed on the back surface of the monocrystalline silicon substrate before final device assembly. This preliminary passivation action prevents surface defect formation and carrier recombination at the back surface, addressing the efficiency problem before subsequent manufacturing steps
Solution Approach 2:
The amorphous silicon layer acts as an intermediary between the monocrystalline silicon substrate and the external environment. It mediates the interaction by providing a passivation interface that reduces surface recombination while allowing controlled carrier extraction, thus improving efficiency without requiring direct modification of the substrate itself
3Reliability
If carriers are transferred over long distances, then the device structure is simpler, but recombination increases and efficiency decreases
Solution Approach 1:
The invention introduces a vertical dimension to carrier collection by forming a polycrystalline silicon layer on the back surface, creating a three-dimensional carrier collection architecture. This allows carriers to be collected through both front and back surfaces, effectively reducing the lateral transfer distance and recombination probability while maintaining structural simplicity
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 design enhances the efficiency of the solar cell by improving open circuit voltage and short circuit current, while simplifying the manufacturing process and reducing costs.
Implementation Method 1
after forming a tunneling over an entire back surface of the monocrystalline silicon substrate
Implementation Method 2
carriers causing photoelectric conversion are efficiently transferred
Data Source
Figure 1
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Figure 3~4
AI summary
Discussed is a solar cell including a semiconductor substrate, a first tunneling layer entirely formed over a surface of the semiconductor substrate, a first conductive type area disposed on the surface of the semiconductor substrate, and an electrode including a first electrode connected to the first conductive type area.