Syntheses of Colloidal F:In2O3 Cubes: Fluorine-Induced Faceting and Infrared Plasmonic Response

Abstract

Cube-shaped nanocrystals (NCs) of conventional metals like gold and silver generally exhibit localized surface plasmon resonance (LSPR) in the visible region with spectral modes determined by their faceted shapes. However, faceted NCs exhibiting LSPR response in the infrared (IR) region are relatively rare. Here, we describe the colloidal synthesis of nanoscale fluorine-doped indium oxide (F:In2O3) cubes with LSPR response in the IR region, wherein fluorine was found to both direct the cubic morphology and act as an aliovalent dopant. Single-crystalline 160 nm F:In2O3 cubes terminated by (100) facets and concave cubes were synthesized using a colloidal heat-up method. The presence of fluorine was found to impart higher stabilization to the (100) facets through density functional theory calculations that evaluated the energetics of F-substitution at surface oxygen sites. These calculations suggest that the cubic morphology results from surface binding of F atoms. In addition, fluorine acts as an anionic al...