Cylindrical Solar Cell System with Exposed P-N Junction
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Solution Overview
Problem
Traditional silicon-based solar cells have low light absorbing efficiency due to partial photons being absorbed by the front electrode and N-type silicon layer, resulting in sparse carrier generation and low photoelectric conversion efficiency.
Innovation Solution
The method involves creating a round P-N junction preform with stacked silicon layers, cutting it into rectangular and arc-shaped solar cells, where the P-N junction is exposed directly to incident light, reducing obstruction by electrodes and increasing the light absorbing surface area, thereby enhancing photoelectric conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a traditional silicon-based solar cell structure with front electrode and N-type silicon layer is used, then the solar cell can be manufactured with standard processes, but the light absorbing efficiency is low due to photon absorption by the front electrode and N-type silicon layer
Solution Approach 1:
The solar cell structure is segmented into distinct functional regions: a P-type silicon layer with exposed P-N junction surface for light absorption, an N-type silicon layer for carrier separation, and a rear electrode. By segmenting the light absorption function from the electrode function, the P-N junction is directly exposed to incident light without being obscured by a front electrode, thereby improving light absorbing efficiency while maintaining manufacturability through standard layer deposition processes.
Solution Approach 2:
The invention transitions from a traditional planar top-illuminated structure to a structure where the P-N junction is exposed on the surface, creating a new dimensional arrangement for light interaction. This dimensional reconfiguration allows light to directly reach the active P-N junction region without passing through absorbing layers, effectively increasing the light absorbing efficiency while preserving ease of manufacture through conventional semiconductor fabrication techniques.
2Reliability
If the front electrode and N-type silicon layer are present in the light path, then the solar cell structure is complete for carrier collection, but the photoelectric conversion efficiency is reduced due to sparse carrier generation
Solution Approach 1:
Instead of placing the electrode first and then the active layer (traditional approach), the invention inverts the structure by exposing the P-N junction surface directly to light, with the N-type layer positioned to collect carriers generated at the junction. This inverted arrangement ensures that light first interacts with the carrier-generating P-N junction before reaching the carrier-collecting N-type layer, maximizing photoelectric conversion efficiency while maintaining reliable carrier collection.
Solution Approach 2:
The front electrode is extracted from the light path by positioning it only at the rear of the solar cell structure. The P-N junction is taken out from being buried under the N-type layer and electrode, and is instead exposed on the surface to directly receive incident light. This extraction eliminates the harmful effect of front electrode absorption on photoelectric conversion efficiency while preserving the N-type layer's essential carrier collection function.
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 approach increases the light absorbing efficiency of the P-N junction, leading to higher electron-hole pair generation and improved photoelectric conversion efficiency in solar cells.
Implementation Method 1
a plurality of electron-hole pairs (carriers) can be generated in the P-N junction due to photon excitation
Implementation Method 2
The N-type silicon layer serves as a photoelectric conversion element
Data Source
AI summary
A solar cell system making method includes steps of making a round P-N junction preform by (a) stacking a P-type silicon layer and a N-type silicon layer on top of each other, and (b) forming a P-N junction near an interface between the P-type silicon layer and the N-type silicon layer; stacking the plurality of P-N junction preforms along a first direction and forming an electrode layer between each adjacent two of the plurality of P-N junction preforms; and forming a first collection electrode on a first of the plurality of P-N junction preforms and forming a second collection electrode on a last of the plurality of P-N junction preforms to form a cylindrical solar cell system. Further, a step of cutting the cylindrical solar cell system can be performed.