Researchers from the Huazhong University of Science and Technology in China have developed an all-perovskite tandem solar cell with a record power conversion efficiency of 28.49%.

The research paper, ‘Surface chemical polishing and passivation minimize non-radiative recombination for all-perovskite tandem solar cells,’ was published in Nature Communications.

The all-perovskite tandem solar cells combine two materials to capture a broader range of sunlight, making it more efficient.

Besides increased efficiency, the researchers also note that the cell demonstrated durability, performing optimally after 550 hours of continuous operation.

Solar cell manufacturers and researchers have been trying to use perovskite to replace silicon as it is less expensive and allows for solar cells in uneven or even bendable configurations.

While the material’s commercial use is limited, the university’s researchers created cells using it with far fewer defects, resulting in record efficiency.

They were able to establish a Sn–Pb mixed perovskite film, which resulted in increased efficiency.

“Sn–Pb mixed perovskite solar cells with bandgaps of 1.32 and 1.25 eV realize power conversion efficiencies of 22.65% and 23.32%, respectively. We also obtain a certified power conversion efficiency of 28.49% of two-junction all-perovskite tandem solar cells,” the report said.

The efficiency improvement of all-perovskite tandem solar cells is largely hindered by the surface defects induced non-radiative recombination loss in Sn–Pb mixed narrow bandgap perovskite films.

The researchers used a surface reconstruction strategy utilizing a surface polishing agent, 1,4-butane diamine, together with a surface passivator, ethylenediammonium diiodide, to eliminate Sn-related defects and passivate organic cation and halide vacancy defects on the surface of Sn–Pb mixed perovskite films, the report said.

In March, the National University of Singapore announced a record 27.1% energy conversion efficiency from a novel triple-junction solar cell they developed. The researchers had engineered a new type of perovskite solar cell by incorporating cyanate, a unique molecule, into its structure.

Meanwhile, the Massachusetts Institute of Technology and other institutions suggest that Perovskite solar panels could become more efficient and sturdier over longer periods by engineering the nanoscale structure of perovskite devices.