Three-dimensional controlled growth of monodisperse sub-50 nm heterogeneous nanocrystals

The ultimate frontier in nanomaterials engineering is to realize their composition control with atomic scale precision to enable fabrication of nanoparticles with desirable size, shape

and surface properties. Such control becomes even more useful when growing hybrid

nanocrystals designed to integrate multiple functionalities. Here we report achieving such

degree of control in a family of rare-earth-doped nanomaterials. We experimentally verify the

co-existence and different roles of oleate anions (OA-) and molecules (OAH) in the crystal

formation. We identify that the control over the ratio of OA- to OAH can be used to

directionally inhibit, promote or etch the crystallographic facets of the nanoparticles.

This control enables selective grafting of shells with complex morphologies grown over

nanocrystal cores, thus allowing the fabrication of a diverse library of monodisperse

sub-50 nm nanoparticles. With such programmable additive and subtractive engineering a

variety of three-dimensional shapes can be implemented using a bottom–up scalable

approach.