Spectrally tunable infrared plasmonic F,Sn:In₂O₃ nanocrystal cubes.

Area of Science:

• Materials Science
• Nanotechnology
• Optics

Background:

• Localized surface plasmon resonance (LSPR) in metal oxide nanocrystals (NCs) is challenging to tune for infrared (IR) applications.
• Noble metal nanoparticles typically offer LSPR tunability only in the visible spectrum.

Purpose of the Study:

• To develop tunable IR LSPR in faceted metal oxide NCs.
• To synthesize F,Sn:In2O3 NC cubes with controlled free carrier concentration and morphology.

Main Methods:

• Colloidal synthesis of fluorine, tin codoped indium oxide (F,Sn:In2O3) NC cubes.
• Controlled incorporation of Sn dopants to tune free carrier concentration.
• Liquid-air interface assembly for fabricating monolayer NC arrays.
• Coupling F,Sn:In2O3 NCs with PbS quantum dots to study Purcell effect.
• Infrared scanning transmission electron microscopy-electron energy loss spectroscopy (IR STEM-EELS) for near-field visualization.

Main Results:

• Achieved tunable IR LSPR in ~10 nm F,Sn:In2O3 NC cubes.
• Demonstrated shape-dependent multimodal LSPR modes (corner, edge, face-centered).
• Observed enhanced near-field enhancement (NFE) in NC film nanocavities.
• Showcased IR near-field dependent enhanced exciton lifetime decay via Purcell effect.
• Visualized tunable LSPR near-field confinement using IR STEM-EELS.

Conclusions:

• F,Sn:In2O3 NC cubes offer tunable IR LSPR for near-field applications.
• NC arrays enhance near-field effects, enabling control over exciton dynamics.
• IR STEM-EELS confirms spatial confinement and tunability of the near-field response.