Characterization of $ZnS-AgInS_2$ quantum dot synthesized via light-material interaction

Abstract

Colloidal semiconductor nanocrystals, also called quantum dots, have attracted great attention over the last few decades, for their excellent optoelectronic properties and promising technological applications in various fields. However, the most studied II-VI semiconductor nanocrystals contain toxic heavy metals such as Cd, Pb, Hg, and so on, which limited practical applications. For this reason, metal chalcogenide nanocrystals offer opportunities as alternatives with high absorption coefficient, low toxicity and biocompatibility. Recently, light-material interactions became a special tool for nanomaterial research due to the ability to stimulate physical and/or chemical reactions with extremely high spatial and temporal controllability. Several groups reported laser-induced synthesis method of metal oxides, and novel metal nanostructures including triangular plates, decahedrons, and tetrahedrons. In this work, ultrafast synthesis method of $ZnS-AgInS_2$ nanoparticles are developed through xenon flash lamp irradiation in the millisecond range. The as-synthesized quantum dots exhibited average size around 4 nm, photoluminescence (PL) quantum yield over 40 % with intensive emission around 1.9 eV. The correlation between the crystal structure and defect-related emission characteristics were investigated by TEM, EDS, XRD, XPS analysis and PL lifetime study. Finally, flash-induced multi-step nucleation and growth mechanism was thoroughly demonstrated.