Solar Cell With Segmented Emitter Sheet Resistance
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Solution Overview
Problem
Conventional solar cells face inefficiencies in light absorption and carrier collection due to the uniformity of emitter regions and surface field regions, leading to reduced power output and increased recombination of electron-hole pairs.
Innovation Solution
A solar cell design featuring a substrate with n-type single crystal silicon, a p-type emitter region with varying sheet resistances, and surface field regions with specific doping concentrations and shapes, along with anti-reflection and passivation layers to enhance light absorption and carrier collection, including a reflection layer to increase incident light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform emitter regions are used in conventional solar cells, then manufacturing is simplified, but light absorption efficiency and carrier collection are reduced
Solution Approach 1:
The emitter region is divided into multiple regions with different sheet resistances (first emitter region with higher sheet resistance, second emitter region with lower sheet resistance) positioned at different locations. This local differentiation allows optimization of both light absorption and carrier collection in different areas, resolving the contradiction between manufacturing simplicity and power output.
Solution Approach 2:
The solar cell structure is segmented into distinct functional regions including first and second emitter regions, surface field regions, and anti-reflection layers with different properties. This segmentation enables each region to be optimized for its specific function while maintaining overall manufacturing feasibility.
2Device complexity
If uniform emitter regions are used in conventional solar cells, then device structure is simplified, but carrier recombination increases
Solution Approach 1:
Different emitter regions are assigned different sheet resistances tailored to their specific functional requirements. The first emitter region has higher sheet resistance to reduce recombination, while the second emitter region has lower sheet resistance for efficient carrier collection. This local quality differentiation resolves the contradiction between structural simplicity and carrier collection efficiency.
3Ease of manufacture
If conventional anti-reflection layers are used, then manufacturing is straightforward, but light absorption efficiency is limited
Solution Approach 1:
The anti-reflection structure uses composite layers including aluminum oxide and silicon nitride with different optical and electrical properties. This composite structure enhances light absorption efficiency through improved anti-reflection properties while maintaining manufacturing feasibility through established deposition techniques.
Solution Approach 2:
The solution extends the anti-reflection function to multiple dimensions by creating both front surface anti-reflection layers and back surface passivation layers. This multi-dimensional approach to light management improves overall light absorption efficiency without significantly complicating the manufacturing process.
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 improves light absorption and carrier collection efficiency, reducing recombination and increasing the open-circuit voltage and short-circuit current, thereby enhancing the overall solar cell performance.
Implementation Method 1
a first anti-reflection layer which is positioned on the emitter region, on which the plurality of first electrodes are not positioned, and is formed of aluminum oxide
Implementation Method 2
a second anti-reflection layer which is positioned on the first anti-reflection layer and is formed of silicon nitride
Implementation Method 3
A solar cell generally includes semiconductor parts, which respectively have different conductive types, for example, a p-type and an n-type and thus form a p-n junction
Data Source
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AI summary
A solar cell includes a substrate formed of n-type single crystal silicon, an emitter region of a p-type which is positioned at a first surface of the substrate and includes a first emitter region having a first sheet resistance and a second emitter region having a second sheet resistance less than the first sheet resistance, a plurality of surface field regions of the n-type locally positioned at a second surface opposite the first surface of the substrate, a plurality of first electrodes which are positioned only on the second emitter region to be separated from one another and are connected to the second emitter region, and a plurality of second electrodes which are positioned on the plurality of surface field regions to be separated from one another and are connected to the plurality of surface field regions.