Scientists have created the world's first method of creating high-quality perovskite materials that can utilize long-wavelength sunlight of 800 nanometers or longer, allowing for a wider absorption spectrum than what is normally possible.
Most current perovskite solar cells are geared to deal with shorter wavelengths, but the creation of perovskite materials with optical absorption spectra expanded to include longer wavelengths could greatly improve efficiency, the National Institute for Materials Science reported.
The new material, dubbed (MA)xFA1-xPbI3, is a mixture of the two cations MA and FA. These cations can absorb light at longer wavelengths, but come with "demerits" such as a mixing ratio and crystallization temperature that are difficult to control. Their tendency to form a mixed crystal phase has also made it difficult to create a method for fabricating high-purity, single-crystalline perovskite materials.
To solve these problems, a team of researchers developed a new method that allowed them to fabricate a new type of mixed cation-based perovskite material. They accomplished this by first fabricating a single-crystalline precursor material under alternating temperatures. They then performed a reaction between the precursor and methylammonium iodide. This process led to a perovskite material with a single crystalline phase and long fluorescence lifetime. The observations suggest electrons in the material rarely recombine and have long life spans. The optical absorption of the new material was 40 nm wider than that of current models and was significantly more efficient.
"In future studies, we intend to develop high-quality perovskite solar cells capable of utilizing a broader spectrum of sunlight by adjusting the ratio of the two cations," the researchers concluded.
The findings were published in a recent edition of the journal Advanced Materials.
