Ligand-Mediated Release of Halides for Color Tuning of Perovskite Nanocrystals with Enhanced Stability

The
rich chemistry of metal halide perovskites has enabled various
methods of band structure control and surface passivation. Here we
report a highly facile and efficient post-treatment approach for precise
color tuning of cesium lead halide perovskite nanocrystals (NCs) with
enhanced stability. By utilizing a special multifunctional organic
ligand, triphenyl­(9-phenyl-9H-carbazol-3-yl)­phosphonium bromide (TPP-Carz),
carbon–halide bond cleavage can be achieved to release halide
ions from halogenated solvents in a controlled manner for color tuning
of perovskite NCs via ion exchange. Besides controlled release of
halide ions for anion exchange, TPP-Carz can effectively passivate
the surfaces of perovskite NCs simultaneously. As a result, perovskite
NCs prepared by this post-treatment method with tunable colors over
the entire visible spectrum have shown significantly improved luminescence
and stability in comparison to the ones prepared using reactive anion
precursors without surface passivation by TPP-Carz.