Plasmonic Coupling between Metallic and Degenerately-doped Semiconductor Nanocrystals

As the size of the material reaches the nanoscale, how light interacts with matter changes significantly. This gives nanostructures unique optical properties. One of them is the surface plasmon resonance absorption. Surface plasmon resonance derives from the collective oscillations of electrons on the surface of a conductive nanocrystal when interacting with light of a specific wavelength. Interesting coupling effects have been revealed when two metallic nanocrystals of the same or different materials are put in close proximity. This phenomenon has been observed and deeply studied in metallic nanocrystals, such as gold or silver. Recently, plasmon absorption has been demonstrated also for doped semiconductors nanocrystals, such as tin doped indium oxide (ITO). A new challenge in the field is therefore to study coupling effects between metallic and doped semiconductor nanocrystals, if any exists.

As such, we investigated the interactions between gold and ITO nanocrystals. Specifically, we measured their optical activity as a function of composition and interparticle spacing. These nanocrystals were synthesized by wet chemistry approaches that generate nanocrystals perfectly dispersible in different solvents thanks to the presence of organic ligands on their surface. Additionally, by exchanging these ligands, the effect of changing the distance between the particles was studied. The optical properties of these gold and ITO nanocrystals were then measured both in solution and in films obtained by depositing these solutions onto glass film via spin coating and drop casting. In this presentation, we report our findings on plasmonic coupling effects between metallic and doped semiconductor nanocrystals.