The solar scene is being illuminated. And it’s blinding.
A team of researchers at the US Department of Energy’s National Renewable Energy Laboratory (NREL) has created a solar cell with a record efficiency of 39.5 percent under 1-sun global illumination, breaking the world record for solar cell efficiency, according to a recent study published in the journal Joule.
Amazingly, it has the highest efficiency recorded for any type of cell ever measured in real-world conditions.
A record-setting solar cell
The record was accomplished under lighting conditions equivalent to that of the sun, according to a press release. While earlier experimental solar cells have attained efficiencies of up to 47.1 percent, it is crucial to emphasize that they did so under extremely concentrated light. In fact, the world record for solar cell efficiency at 47.1 percent was achieved in 2019, with researchers using multi-junction concentrator solar cells developed at National Renewable Energy Laboratory.
The solar cell was also tested for its potential in space, especially for powering communications satellites, which are powered by solar cells and require high cell efficiency. Under such conditions, it was seen that it has 34.2 percent efficiency.
“The new cell is more efficient and has a simpler design that may be useful for a variety of new applications, such as highly area-constrained applications or low-radiation space applications,” said principal investigator Myles Steiner, a senior scientist in NREL’s High-Efficiency Crystalline Photovoltaics Group in an initial TechXplore report.
The secret ingredient
The novel solar cell is built on an architecture known as inverted metamorphic multijunction (IMM) cells. The cell has three components that generate electric current in response to light.
Importantly, each of those junctions is built of a different material: gallium indium phosphide on top, gallium arsenide in the center, and gallium indium arsenide on the bottom. As these materials specialize in various light wavelengths, this allows the cell to capture more energy from the whole light spectrum.
Moreover, the researchers used “quantum wells” in the middle layer, which enabled them to achieve the new record efficiency. When the researchers sandwiched a conductive layer between two other materials with a wider band gap, they were able to get the electrons confined to two dimensions, which allowed the material to capture more light in return.
This solar cell’s middle layer comprised up to 300 quantum wells, which greatly increased the total efficiency, according to a report from New Atlas. However, it should be noted that producing this type of cell is expensive, which is something that plagues the renewables industry already. Before the novel cell can become widespread, the researchers will need to reduce the expenses and find potential new uses.