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Dual-Junction GaAs Photovoltaics for Low Irradiance Wireless Power Transfer in Submillimeter-Scale Sensor Nodes.
Eunseong Moon1, Michael Barrow1, Jongyup Lim1
1Department of Electrical and Computer Engineering, University of Michigan, Ann Arbor, MI 48109 USA.
IEEE Journal of Photovoltaics
|November 23, 2020
Summary
Dual-junction gallium arsenide photovoltaic cells offer efficient wireless power for Internet of Things and bio-implantable devices. These sub-millimeter cells achieve high efficiency and voltage under low light, enabling batteryless operation.
Area of Science:
- Materials Science
- Electrical Engineering
- Renewable Energy
Background:
- Miniaturized electronic devices like Internet of Things (IoT) and bio-implantable systems require efficient, low-power energy sources.
- Traditional photovoltaic (PV) solutions often struggle with low-flux illumination and space constraints inherent in these applications.
Purpose of the Study:
- To demonstrate sub-millimeter scale dual-junction gallium arsenide (GaAs) photovoltaic cells and modules for efficient wireless power transfer.
- To meet the demanding voltage and efficiency requirements for IoT and bio-implantable applications under low-flux illumination.
Main Methods:
- Fabrication of dual-junction GaAs PV cells at sub-millimeter scale.
- Characterization of single-cell and module performance under low-flux 850 nm near-infrared LED illumination.
- Evaluation of power conversion efficiency and output voltage.
Main Results:
- A single dual-junction PV cell (150 μm × 150 μm) achieved over 22% power conversion efficiency and >1.2 V output voltage.
- Dual-junction PV modules with 4 series-connected cells produced >5 V output voltage.
- Module power conversion efficiency exceeded 23%.
Conclusions:
- The dual-junction approach effectively increases output voltage per cell, reducing area losses for miniaturized applications.
- These sub-millimeter GaAs PV cells are suitable for batteryless operation of miniaturized CMOS IC chips and direct battery charging.
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