Researchers produce highest efficiency 1-sun solar cell

• Scientists at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) produced a solar cell with a record 39.5% performance under 1-sun global illumination. This is the highest possible effectiveness solar cell of any type, measured using typical 1-sun conditions.

" The new cell is extra effective and has a simpler design that may be useful for a variety of new applications, such as highly area-constrained applications or low-radiation room applications," claimed Myles Steiner, a senior scientist in NREL's High-Efficiency Crystalline Photovoltaics (PV) Group as well as principal investigator on the project. He worked alongside NREL colleagues Ryan France, John Geisz, Tao Song, Waldo Olavarria, Michelle Young, and also Alan Kibbler.

Details of the development are described in the paper "Triple-junction solar cells with 39.5% terrestrial and also 34.2% room effectiveness enabled by thick quantum well superlattices," which shows up in the May issue of the journal Joule.

NREL scientists previously set a record in 2020 with a 39.2% effective six-junction solar cell using III-V materials.

Several of the most effective recent solar cells have been based upon the inverted metamorphic multijunction (IMM) architecture that was created at NREL. This freshly enhanced triple-junction IMM solar cell has now been contributed to the most effective Research-Cell Performance Chart. The chart, which shows the success of speculative solar cells, consists of the previous three-junction IMM record of 37.9% developed in 2013 by Sharp Corporation of Japan.

The improvement in effectiveness adhered to research into "quantum well" solar cells, which use lots of really thin layers to change solar cell buildings. The researchers developed a quantum well solar cell with unprecedented performance and executed it right into a gadget with 3 junctions with different bandgaps, where each junction is tuned to capture and utilize a various slice of the solar spectrum.

The III-V products, so called as a result of where they fall on the periodic table, span a wide variety of energy bandgaps that permit them to target various parts of the solar range. The leading junction is made from gallium indium phosphide (GaInP), the center of gallium arsenide (GaAs) with quantum wells, and the bottom of lattice-mismatched gallium indium arsenide (GaInAs). Each material has actually been very optimized over decades of research study.

" A key element is that while GaAs is an outstanding material and also normally used in III-V multijunction cells, it does not have rather the right bandgap for a three-junction cell, suggesting that the equilibrium of photocurrents in between the three cells is not optimum," said France, elderly scientist and also cell developer. "Below, we have customized the bandgap while maintaining exceptional material quality by using quantum wells, which allows this gadget and potentially various other applications."

The scientists used quantum wells in the middle layer to extend the bandgap of the GaAs cell and also boost the quantity of light that the cell can take in. Importantly, they developed optically thick quantum well gadgets without major voltage loss. They additionally discovered just how to anneal the GaInP leading cell during the development procedure in order to improve its performance and also exactly how to minimize the threading dislocation density in lattice-mismatched GaInAs, talked about in different publications. Altogether, these three materials inform the novel cell design.

III-V cells are recognized for their high efficiency, but the manufacturing procedure has generally been pricey. So far, III-V cells have actually been used to power applications such as space satellites, unmanned aerial vehicles, as well as other specific niche applications. Researchers at NREL have been pursuing considerably decreasing the manufacturing price of III-V cells and also providing alternate cell designs, which will certainly make these cells economic for a variety of new applications.

The new III-V cell was also evaluated for how efficient it would be in space applications, specifically for communications satellites, which are powered by solar cells and also for which high cell performance is crucial, and came in at 34.2% for a beginning-of-life measurement. Today design of the cell appropriates for low-radiation environments, and higher-radiation applications may be allowed by further growth of the cell framework.