Localized Surface Plasmon Resonance in Ag-In-Te based Quantum Dots and Core/shell Nanocrystals

Localized surface plasmon resonance (LSPR) in plasmonic nanomaterials can concentrate light in the nano-dimension, leading to an enhancement of the light intensity by order of magnitude. While LSPR is a subject of extensive research in chalcogenide semiconductor nanocrystals (NCs), research on tellurium multinary chalcogenides (MnCs) remains elusive, possibly due to non-availability of the corresponding quantum dots (QDs). In this report, we show the sequential switching of plasmonic to non-plasmonic properties during the colloidal synthesis of AgInTe2 QDs. The reaction passes through several intermediates including AgInTe2/AgIn5Te8 core/shell NCs, AgInTe2 microrods (MRs), AgInTe2 QDs, and finally AgInTe2 quantum dot chain (QDC). Here, the AgInTe2/AgIn5Te8 core/shell NCs and AgInTe2 QDs depict strong LSPR absorption in the visible-NIR region until similar to 2000 nm. We propose that small-size quantum confined and cation deficient AgInTe2 particles are responsible for the observation of LSPR modes in both cases due to presence of the free carriers (holes). Our work on developing Te-based plasmonic MnC QDs may find significant advancement in the nanoscale light-matter interaction in semiconductor research.