Photostability of luminescence of Ag-=SUB=-2-=/SUB=-S quantum dots and Ag-=SUB=-2-=/SUB=-S/SiO-=SUB=-2-=/SUB=- core/shell structures

Abstract

The paper presents regularities that demonstrate the effect of passivating ligands formation of thioglycolic acid and L-cysteine (TGA, L-Cys) and dielectric shells (SiO2) on Ag2S nanocrystals interface on the photostability of their IR luminescence. Using FTIR absorption spectroscopy, the interaction manifestations of passivating ligands molecules of TGA and L-Cys with Ag2S nanocrystals, as well as the formation of SiO2 shell due to the process of replacing organic ligands with a silica ligand (MPTMS) ("ligand exchange"), were found. In the case of replacing TGA with MPTMS, an increase in the luminescence quantum yield of Ag2S quantum dots (QDs) and its resistance to long-term exposure to exciting radiation was found. In the case of replacing L-Cys with MPTMS, the formation of a fragmentary SiO2/L-Cys shell on Ag2S nanocrystals was observed due to the partial replacement of L-Cys with MPTMS, which contributes to the reverse photodegradation of KT Ag2S luminescence of as a result of SiO2/L-Cys shell photodestruction. Keywords: photoluminescence, luminescence photostability, quantum yield, quantum dot, core/shell structures, FTIR spectroscopy.