Self-Assembly of Heterogeneous Structured Rare-Earth Nanocrystals Controlled by Selective Crystal Etching and Growth for Optical Encoding

Programmatically assembling inorganic nanocrystals (NCs) into long-range-ordered superstructures has been well-documented as a theme to construct novel materials with unique properties. Herein, one-dimensional oriented self-assembly of core–shell structured rare-earth doped β-NaREF 4 NCs is reported. In the epitaxial growth process, β-NaREF 4 crystals featuring larger negative lattice mismatch usually exhibited longitudinal growth preference. In this case, the lateral crystal of the hexagonal prisms would be etched by OA – ions along the direction parallel to the (001) facets. This anisotropic morphology evolution can lead to the anisotropic noncovalent interactions between long-chain alkyls of oleic acid molecules and contribute to the oriented self-assembly in the ⟨001⟩ direction. On the basis of the studies on the heterogeneous NC self-assembly, a rare-earth nanohybrid assembly is further prepared by functionalizing the NC surface with a pH-responsive ligand N -(2-pyridinyl)benzoylacetamide (HPBA), and this nanohybrid self-assembly exhibits great potential in spatial–temporal dimensional optical encoding. This study provides a novel strategy based on selective crystal etching and epitaxial growth for oriented self-assembly of NCs and represents an important step toward the design of well-defined superstructures with unique properties.