3 research outputs found
Solvent-Assisted Self-Assembly of CsPbBr<sub>3</sub> Perovskite Nanocrystals into One-Dimensional Superlattice
The
self-assembly of colloidal nanocrystals into ordered architectures
has attracted significant interest enabling innovative methods of
manipulating physicochemical properties for targeted applications.
This study reports the self-assembly of CsPbBr<sub>3</sub> perovskite
nanocrystals (NCs) in one-dimensional (1D) superlattice chains mediated
by ligand–solvent interactions. CsPbBr<sub>3</sub> NCs synthesized
at ≥170 °C and purified in a nonpolar solvent, hexane,
self-assembled into 1D chains, whereas those purified in polar solvents,
including toluene and ethyl acetate, were disordered or formed short-range
two-dimensional (2D) assemblies. The NCs assembled into 1D chains
showed red shifts in both the absorbance and photoluminescence spectra
relative to those of disordered NCs purified in a 50/50 hexane/ethyl
acetate mixture. Microscopy and X-ray diffraction results confirmed
the formation of polymeric nanostrands in hexane followed by organization
of the NCs into 1D chains along the nanostrands. Our results suggest
that excess aliphatic ligands remaining after purification of the
NCs complex with ionic Cs<sup>+</sup> and Br<sup>–</sup> species
through a hydrophobic effect; further, the alkyl chains of these ligands
interlace with each other through van der Waals forces. Collectively,
these interactions give rise to the nanostrands and subsequent self-assembly
of CsPbBr<sub>3</sub> into 1D chains. In polar solvents, the minimization
of repulsive forces between the solvent and the ligands drives proximal
CsPbBr<sub>3</sub> NCs together into short-range 2D assemblies or
disordered clusters. Our solvent-assisted self-assembly approach provides
a general strategy for designing 1D superlattice chains of nanocrystals
of any geometry, dimension, and composition by simply tuning the ligand–solvent
interactions