Interband Cascade Photovoltaic Architecture for High Efficiency
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Solution Overview
Problem
Conventional photovoltaic devices face limitations in achieving high conversion efficiency due to the availability of semiconductor materials with a range of bandgaps that span the solar or heat spectrum and matching between multiple junctions, leading to suboptimal performance in absorbing and converting solar or thermal energy into electricity.
Innovation Solution
The interband cascade photovoltaic architecture, comprising absorption, intraband transport, and interband tunneling regions, allows for the absorption of photons and efficient electron flow, eliminating the need for heavily-doped p-n junctions and enabling higher open-circuit voltage and conversion efficiency by using type-II quantum well or superlattice structures with tailored bandgaps and transport mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple junction cells with different band-gap materials are used to achieve high conversion efficiency, then conversion efficiency is improved, but material availability and integration complexity worsen
Solution Approach 1:
The device is segmented into multiple functional regions (absorption region, intraband transport region, interband tunneling region) within a single junction structure. Each region performs a specific function: the absorption region captures photons across a broad spectrum, the intraband transport region separates carriers, and the interband tunneling region enables efficient charge collection. This segmentation allows high conversion efficiency without requiring integration of multiple different band-gap materials.
Solution Approach 2:
The intraband transport region acts as an intermediary between the absorption region and the interband tunneling region. It facilitates carrier separation and transport by creating appropriate potential gradients, enabling efficient energy conversion without direct contact between dissimilar materials. This intermediary structure simplifies the overall device architecture while maintaining high efficiency.
2Device complexity
If conventional p-n junctions are used, then device simplicity is maintained, but open-circuit voltage and conversion efficiency are limited
Solution Approach 1:
The invention changes key parameters of the p-n junction by introducing graded bandgap structures and multiple functional regions with tailored doping profiles. The absorption region uses a gradient bandgap to maximize photon absorption, while the interband tunneling region employs heavy doping to create quantum tunneling effects. These parameter changes enable open-circuit voltages exceeding 1.2V, significantly higher than conventional single-junction cells, while maintaining a relatively simple single-junction architecture.
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 architecture achieves significantly higher open-circuit voltages and conversion efficiencies compared to conventional PV devices, with potential for over 50% efficiency in thermophotovoltaic systems and improved performance under high-intensity illumination, minimizing losses associated with high-current operation.
Implementation Method 1
Photovoltaic (PV) devices, such as solar cells, are important for the conversion of solar and thermal energy into electricity
Implementation Method 2
an interband tunneling region configured to act as an electron barrier
Implementation Method 3
an intraband transport region configured to act as a hole barrier
Data Source
AI summary
A photovoltaic (PV) device, comprising a PV interband cascade (IC) stage, wherein the IC PV stage comprises an absorption region with a band gap, the absorption region configured to absorb photons, an intraband transport region configured to act as a hole barrier, and an interband tunneling region configured to act as an electron barrier. An IC PV architecture for a photovoltaic device, the IC PV architecture comprising an absorption region, an intraband transport region coupled to the absorption region, and an interband tunneling region coupled to the intraband transport region and to the adjacent absorption region, wherein the absorption region, the intraband transport region, and the interband tunneling region are positioned such that electrons will flow from the absorption region to the intraband transport region to the interband tunneling region.