In the realm of energy materials, a team of researchers from the Italian Institute of Technology (IIT) in Genoa has made a notable discovery that could potentially impact the development of perovskite solar cells. The team, led by Dr. Liberato Manna, has successfully synthesized a new type of perovskite nanocrystal, ethylammonium lead iodide (EAPbI3), which challenges the conventional understanding of perovskite structures.
The researchers have pushed the boundaries of the Goldschmidt tolerance factor, a criterion used to predict the stability of perovskite structures. By inserting an unusually large ethylammonium cation into the perovskite structure, they have created a new member of the lead halide perovskites family. This insertion results in a significantly larger lattice parameter compared to other lead halide perovskites, such as those based on cesium, methylammonium, or formamidinium.
However, the EAPbI3 nanocrystals are highly unstable. They quickly evolve into a non-perovskite delta-EAPbI3 polymorph within a day. Moreover, they are very sensitive to electron irradiation, degrading to lead iodide (PbI2) upon exposure to an electron beam. This degradation process is similar to that of other hybrid lead iodide perovskites, but the researchers found that it can be slowed down by partially replacing the ethylammonium ions with cesium ions.
Despite their instability, the EAPbI3 nanocrystals exhibit photoluminescence emission that can be tuned in the range of 664-690 nm by regulating their size during synthesis. The emission efficiency can be improved by partially alloying the ethylammonium site with cesium or formamidinium cations. Additionally, the morphology of the nanocrystals can be controlled to be either nanocubes or nanoplatelets, depending on the synthesis conditions.
The practical applications of this research for the energy sector are still under exploration. However, the ability to tune the optical properties of perovskite nanocrystals and control their morphology could potentially lead to improvements in the efficiency and stability of perovskite solar cells. The research was published in the journal Nature Communications, providing a platform for further discussion and development in the field of perovskite materials.
This article is based on research available at arXiv.