Heterojunction Solar Cell Bandgap Segmentation
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Solution Overview
Problem
The design of multi-junction solar cells faces challenges in optimizing power conversion efficiency due to the need for current matching between subcells, which is typically achieved by altering the alloy composition of the base semiconductor layer, thereby compromising the output voltage.
Innovation Solution
A solar cell structure is proposed with a base semiconductor layer, an emitter semiconductor layer, and a depletion semiconductor layer positioned between them, where the depletion layer has a higher bandgap than both, effectively suppressing recombination and increasing output voltage while allowing independent optimization of current generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the alloy composition of the base semiconductor layer is altered to achieve current matching between subcells, then the current output is improved, but the output voltage deteriorates
Solution Approach 1:
The base semiconductor layer is segmented into two distinct layers: a first base semiconductor layer optimized for current generation and a second base semiconductor layer with higher bandgap optimized for voltage output. This segmentation allows each layer to independently optimize its function without compromising the other, resolving the contradiction between current output and voltage output.
Solution Approach 2:
Different regions of the base semiconductor layer are assigned different alloy compositions and bandgap energies. The first base semiconductor layer uses lower bandgap materials to maximize current generation, while the second base semiconductor layer uses higher bandgap materials to maintain voltage output. This local differentiation of material properties enables simultaneous optimization of both current and voltage.
2Productivity
If the alloy composition is engineered to yield higher current output, then the current generation is improved, but the power conversion efficiency deteriorates
Solution Approach 1:
The base semiconductor layer is divided into two functional segments: the first base semiconductor layer dedicated to current generation and the second base semiconductor layer dedicated to voltage maintenance. This segmentation ensures that energy is not wasted on generating current at the expense of voltage, thereby maintaining high power conversion efficiency while achieving high current output.
Solution Approach 2:
The base semiconductor layer is constructed as a composite structure with two different semiconductor materials having different bandgap energies. This composite approach allows the structure to simultaneously exploit the high current generation capability of lower bandgap materials and the voltage maintenance capability of higher bandgap materials, optimizing overall power conversion efficiency.
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 enhances power conversion efficiency by decoupling current and voltage performance, allowing for higher voltage output and improved blue response without degrading material properties.
Implementation Method 1
the depletion semiconductor layer having a third bandgap, wherein the third bandgap is greater than the first bandgap and the second bandgap
Data Source
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AI summary
A solar cell including a base semiconductor layer having a first bandgap, an emitter semiconductor layer having a second bandgap and a depletion semiconductor layer positioned between the base semiconductor layer and the emitter semiconductor layer, the depletion semiconductor layer having a third bandgap, wherein the third bandgap is greater than the first bandgap and the second bandgap.