III-V Single-Junction and Multijunction Solar Cells
We develop advanced III-V solar cell technology and share our results by publishing in high-impact journals and transferring the resulting intellectual property to industry.
We have a distinguished record of accomplishment in the field, including the invention of the original gallium indium phosphide/gallium arsenide (GaInP/GaAs) multijunction cell, its transfer to the high-efficiency cell industry, and the invention and development of inverted metamorphic multijunction (IMM) cell technology.
We have expertise in:
- Developing advanced III-V solar cell architectures for terrestrial and space applications
- Epitaxial growth and processing of ultrahigh-efficiency III-V multijunction solar cells
- Metamorphic materials science and engineering
- Growth of challenging new III-V alloys
- Characterizing and analyzing multijunction photovoltaics
- Developing and applying experimentally grounded device physics models of multijunction cell performance
- Numerical modeling of cell performance, including effects of luminescent coupling, inhomogeneous illumination, cell heating, and three-dimensional flow of electrical current
- Developing III-V photovoltaics for high-temperature operation, photoelectrochemical hydrogen production, and thermophotovoltaic structures for energy storage applications.
Excess electricity can be stored in the form of very high-temperature heat and recovered by means of thermophotovoltaic cells. With external partners, we are developing GaAs, GaInAs, and tandem IMM cells for energy storage applications, funded by ARPA-E and Shell/GCxN. In addition to high photovoltaic efficiency, the cells are designed to have very high sub-bandgap reflectance to boost the thermophotovoltaic system efficiency to >50%. We also develop cells for other thermophotovoltaic applications, including as the heat-to-electricity converter in power generation systems and for the conversion of waste process heat to electricity.
To learn more about thermophotovoltaic cells, read The Right Resources To Develop Thermophotovoltaic Technologies.
NREL has extensive expertise and capabilities for the development, fabrication, characterization, and analysis of photovoltaic cells with optimal bandgaps for power-beaming receivers. We develop PV receiver cell architectures with extremely high performance over a range of bandgaps from 0.6–2.1 eV (wavelengths from 600 to 2000 nm) and beyond, and irradiances as high as 100 W/cm2. We also have extensive capabilities for optoelectronic characterization and analysis of these PV cells, including testing under high-irradiance illumination.
To learn more about optical power beaming, read Reliable Power for Remote Applications.
Tools and Capabilities
We use the following as we develop and transfer multijunction cell technology:
- Cluster tool, which comprises a metal-organic vapor-phase epitaxy growth system connected via load locks to a molecular-beam epitaxy growth system and an analytical chamber
- Two stand-alone metal-organic vapor-phase epitaxy growth systems
- Stand-alone molecular-beam epitaxy growth system
- Cleanroom in which epitaxial wafers can be processed into full devices
- Suite of cell testing techniques, including current-voltage and quantum efficiency testing of full multijunction cells
- Numerical modeling of cell performance issues relevant for incorporation into real-world systems, including inhomogeneous illumination, cell heating, and three-dimensional flow of electrical current.