Localized Surface Plasmon Resonance in Ag‐In‐Te Based Quantum Dots and Core/Shell Nanocrystals

Abstract 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 ~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.