Facile anion-exchange reaction in mixed-cation lead bromide perovskite nanocrystals.

The present paper reports a facile and fast anion exchange reaction approach for perovskite nanocrystals (NCs). The reaction has been applied to a mixed-cation sample, namely FA 0.8 Cs 0.2 PbBr 3, and just employs lead halide precursors to achieve a significant shift in the nanocrystals emission. Within 30 minutes reaction time and a molar ratio between the NCs and the halide precursors of 1 : 1, it was possible to cover more than 120 nm in the visible region. The exchanged NCs maintain their cubic-shaped morphology and narrow emission peak width for the whole compositional range explored. The present approach also allows a reduction in solvent use since it does not require any halide precursor synthesis nor complex post-synthesis treatments.