Solar Cell Efficiency Sets a New Peak

Researchers at the US Department of National Renewable Energy Laboratory (NREL) constructed a solar cell with a record 39.5 percent efficiency in 1-sun global irradiation. This is the most efficient solar cell of any sort when measured in the same conditions. 

The record was set under sunlight-like lighting conditions. While previous experimental solar cells achieved an efficiency of up to 47.1 percent, it is important to note that they did so in highly concentrated illumination.

In fact, researchers used multi-junction parabolic reflector solar cells produced at NREL to set a worldwide record for solar cell productivity of 47.1 percent in 2019.

The solar cell was also assessed for its possibilities in space, particularly for powering satellite systems, which use solar cells and require great cell performance. It was discovered that it had a 34.2 percent efficiency under these settings.

According to Myles Steiner, an NREL senior scientist, the new cell is more powerful and has a simplified design that could be beneficial for a range of new technologies, such as very area-constrained uses or low-radiation space implementations. The report, which publishes in the May edition of the periodical Joule, goes into further detail about the development.

The innovative solar cell is based on the IMM cell design. The cell has 3 parts that produce an electric current in response to light exposure.

Notably, each of the interconnections is constructed of three different materials that work in various light wavelengths, allowing the cell to gather more electricity from the entire light spectrum.

Furthermore, the researchers used “quantum wells” in the inner part. This enabled them to set a new benchmark for efficiency.

The electrons were restricted to two dimensions after the researchers placed a conductive surface between two different materials with a greater band gap. As a result, the material was able to capture more sunlight.

They also created optically dense quantum well devices that have very little voltage loss. Besides, they also learned how to polymerize the GaInP top cell during the formation process to increase its efficiency and how to limit threading wear rate in lattice-mismatched GaInAs, both of which are covered in separate papers. These various components work together to form a unique cell design.

NREL researchers have also worked on dramatically lowering the cost of producing III-V cells and building other cell designs. Their aim is to make these cells an economically solution to use in different applications.

The III-V materials, named after their position on the periodic table, have a wide range of energy bandgaps, allowing them to target different sections of solar energy.

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