Bifacial Solar Cell Layers for Higher Conversion Efficiency
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Solution Overview
Problem
Conventional solar cells have low current conversion efficiency due to light being incident on only one surface of the substrate, limiting the photoelectric conversion efficiency.
Innovation Solution
A solar cell design with a substrate of a first conductive type, an emitter layer of a second conductive type, and protective and anti-reflection layers formed of specific materials with fixed charges, along with a back surface field layer, allowing light to be incident on both surfaces of the substrate, reducing reflectance, and enhancing light absorption and carrier separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If light is incident on only one surface of the substrate, then the structure is simple, but the current conversion efficiency is low
Solution Approach 1:
The patent transitions from single-sided light reception to double-sided light reception by adding functional layers on both surfaces of the substrate. This dimensional expansion allows light to enter from two directions simultaneously, effectively doubling the light utilization area and improving current conversion efficiency without significantly increasing structural complexity
2Use of energy by moving object
If an anti-reflection layer is formed on the light receiving surface, then light transmittance increases, but the device complexity increases
Solution Approach 1:
The protective layers formed on both surfaces of the substrate serve multiple functions simultaneously: they provide mechanical protection to the substrate, reduce light reflectance through their optical properties, and passivate surface defects. This multi-functionality reduces the need for separate dedicated anti-reflection layers, thereby limiting the increase in device complexity while still improving light transmittance
3Productivity
If a double-sided light receiving solar cell is developed, then photoelectric conversion efficiency increases, but the device complexity increases
Solution Approach 1:
The patent applies different conductive types to different surfaces: the front surface has a p-type emitter layer while the back surface has an n-type emitter layer, with the substrate being n-type. This local differentiation optimizes carrier collection at each surface while maintaining overall structural simplicity. The selective application of doping types locally enhances photoelectric conversion efficiency without requiring complex overall restructuring
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 increases the efficiency of the solar cell by improving light utilization and reducing recombination of carriers, resulting in enhanced photoelectric conversion efficiency.
Implementation Method 1
Each of the first protective layer and the second protective layer is formed of a material having fixed charges of the same conductive type as the first conductive type
Implementation Method 2
an anti-reflection layer is formed on a light receiving surface of the substrate, so as to reduce a reflectance of light incident on the substrate and increase a light transmittance of a predetermined wavelength band
Implementation Method 3
Solar power generation to convert light energy into electric energy using a photoelectric conversion effect
Data Source
AI summary
A bifacial solar cell includes a silicon substrate; an emitter layer; a plurality of first electrodes locally on the emitter layer; a first aluminum oxide layer on the emitter layer; a first silicon oxide layer between the first aluminum oxide layer and the emitter layer; a first anti-reflection layer on the first aluminum oxide layer; a back surface field layer on the silicon substrate; a second aluminum oxide layer on the silicon substrate; a second silicon oxide layer between the second aluminum oxide layer and the silicon substrate; a second anti-reflection layer on the second aluminum oxide layer; and a plurality of second electrodes respectively on the back surface field layers through the second anti-reflection layer, the second aluminum oxide layer and the second silicon oxide layer.