Glutathione-Capped Quaternary Ag–(In,Ga)–S Quantum Dots Obtained by Colloidal Synthesis in Aqueous Solutions

Abstract

Ag–(In,Ga)–S quantum dots (QDs) were obtained by colloidal synthesis from aqueous solutions with different [In]/[Ga] precursor ratios in the presence of glutathione ligands under mild conditions. Size-selected fractions of the colloidal solutions were separated by the repeated centrifuging with addition of 2-propanol. The QD chemical composition determined by X-ray photoelectron spectroscopy is noticeably In-enriched with respect to the precursor ratio. The QD size estimated from the halfwidth of X-ray diffraction peaks for the non-fractioned colloidal solutions is about 2 nm. The synthesized QDs reveal a shift of the absorption edge and the photoluminescence (PL) peak maximum toward higher energies with decreasing the QD size. Experimentally measured Raman spectra of the Ag–(In,Ga)–S QDs are noticeably affected by size-related factors.