Quantum Structure Emitter for High-Efficiency Solar Cells
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Solution Overview
Problem
Current silicon-based solar cells face limitations in efficiency and temperature coefficient, with commercial technologies struggling to exceed 23% efficiency and experiencing significant power efficiency drops at elevated temperatures, particularly in desert regions.
Innovation Solution
A semiconductor component with a highly doped silicon-germanium quantum structure emitter is introduced, featuring a triple-layer quantum structure with tunnel barriers and a quantum well, which enhances light absorption and reduces temperature coefficient by minimizing bandgap reduction due to temperature increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional silicon solar cell structures are used, then manufacturing simplicity is maintained, but efficiency is limited to below 23%
Solution Approach 1:
The emitter is segmented into multiple quantum wells separated by barrier layers, creating a multi-layered structure. Each quantum well is further divided into regions with different doping concentrations (highly doped regions and intrinsic regions), allowing independent optimization of different functional zones within the emitter to achieve both high efficiency and manufacturability
Solution Approach 2:
The solar cell employs a composite emitter structure combining silicon-based quantum wells with semiconductor barrier layers having different band gaps. This composite approach allows the quantum wells to absorb a broader spectrum of light while the barrier layers provide selective carrier transport, achieving over 23% efficiency through material composition rather than simple structural complexity
2Productivity
If conventional solar cell designs are used, then cost-effectiveness is maintained, but efficiency cannot exceed 23% in production
Solution Approach 1:
The invention changes key parameters of the emitter by introducing quantum confinement effects through nanoscale layer thicknesses (quantum well widths on the order of nanometers). This parameter change at the quantum level fundamentally alters the optical and electrical properties, enabling production efficiencies above 23% while using standard semiconductor fabrication techniques that maintain cost-effectiveness
Solution Approach 2:
Different regions of the emitter are assigned different local qualities: quantum wells with specific width and doping for light absorption, barrier layers with higher band gaps for carrier selection, and varying doping concentrations in different zones. This local optimization allows the overall device to exceed 23% efficiency while each component can be manufactured using established processes
3Reliability
If standard silicon solar cells are used, then simplicity of operation is maintained, but power efficiency drops to approximately half at temperatures of around 85°C
Solution Approach 1:
The composite emitter structure with quantum wells and barrier layers creates a more temperature-stable system. The quantum confinement effects and selective carrier transport through the barrier layers reduce the sensitivity to thermal effects, maintaining over half the power efficiency even at 85°C compared to conventional cells, while requiring no change in operational procedure
Solution Approach 2:
By changing the emitter structure to include quantum-confined states with discrete energy levels, the temperature coefficient of the open-circuit voltage is reduced. The quantum well structure maintains more stable electrical characteristics over temperature ranges, improving reliability in hot environments without complicating operation
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 design significantly increases the short-circuit current and maintains voltage stability, achieving efficiencies greater than 30% and reducing the temperature coefficient by more than half, while being producible using existing techniques at low costs.
Implementation Method 1
The layer sequence itself, acting as an active absorber, consists of a triple heterostructure embedded in the space charge region of a pn junction and exploiting quantum mechanical effects
Implementation Method 2
EP 2 469 608 A1, a silicon-based, single-stage solar cell is known which, instead of light conversion inside a melt-pulled semiconductor material, utilizes current generation within a very thin, deposited quantum structure. The layer sequence itself, acting as an active absorber, consists of a triple heterostructure embedded in the space charge region of a pn junction and exploiting quantum mechanical effects
Data Source
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Figure 3~4
AI summary
In one embodiment, the semiconductor device, which is preferably a solar cell, comprises a quantum structure emitter (23). The quantum structure emitter (23) consists of a first layer (2) of an undoped semiconductor material with a large band gap, a second, middle, highly doped layer (3) of a semiconductor material with a low band gap, and a third, undoped layer (2) of a semiconductor material with a large band gap.