Transformation of Perovskite Nanoplatelets to Large Nanostructures Driven by Solvent Polarity

Perovskite nanoplatelets have potential use in optoelectronic and photocatalytic applications because of the enhanced quantum confinement they experience. However, often ignored is the effect of solvent polarity on the stability of these nanoplatelets. When perovskite nanoplatelets are exposed to small amounts (<1 vol %) of mildly polar solvents such as acetonitrile, the particles rapidly grow to larger nanostructures. Their quantum confinement is lost as they grow from uniform 2.6 nm thick particles to large nanostructures ∼85 nm in size. This ripening brings characteristic red-shifts in the absorption and photoluminescence of the particles as they transform. Using methyl acetate as a model polar solvent, we succeeded in establishing factors that control ligand desorption and lowering of the activation energy for ripening. These results highlight the challenges in using these quantum-confined nanoplatelets in applications such as photocatalysis, where polar solvents and/or intermediates may be unavoidable.