Physico-Chemical Nanomaterials Science

Glutathione-capped quaternary Ag–(In,Ga)–S quantum dots obtained by colloidal synthesis in aqueous solutions 
Lopushanska B.V.1, Azhniuk Y.M.1,2, Lopushansky V.V.2, Studenyak I.P.1, Zahn D.R.T.3 
1 Uzhhorod National University, 46 Pidhirna Str., 88000, Uzhhorod, Ukraine
E-mail: lopushanska5@gmail.com 
2 Institute of Electron Physics, Ukr. Nat. Acad. Sci., 21 Universytetska Str., 88017, Uzhhorod, Ukraine
3 Semiconductor Physics, Chemnitz University of Technology, Chemnitz, Germany
Research interest towards I–III–VI colloidal semiconductor quantum dots (QDs) is caused by their non-toxicity and the possibilities of size variation of their bandgap in a broad range, high luminescence efficiency, high photocatalytic activity, and possible applications in biology and medicine as well as in light sources and photovoltaic elements. Here we report on the synthesis and optical characterization of size-selected quaternary non-stoichiometric Ag–(In,Ga)–S QDs obtained at mild conditions in the presence of glutathione (GSH) from AgNO3, InCl3, GaCl3, and Na2S aqueous solutions with different [In]:[Ga] molar ratios in the reaction mixture. The QD size selection was carried out by repeated fractioning of the colloidal solutions by precipitation at 4000 rpm in the presence of a non-solvent (2-propanol) similarly to the Ag–In–S QDs obtained earlier [1].
The Ag–(In,Ga)–S QDs produced were characterized by optical absorption (Cary 50) and photoluminescence (PL) (Black Comet) as well as Raman spectroscopy (LabRAM, exc = 488 and 515 nm, and XPloRA Plus, exc = 532 nm). The measurements were performed at room temperature. The optical absorption edge and photoluminescence maxima exhibit a clear size-dependent shift. The effects of the [In]:[Ga] ratio in the reaction mixture on the optical absorption and PL parameters of the QDs formed are discussed.

1.	Raevskaya A., Lesnyak V., Haubold D., Dzhagan V., Stroyuk O., Gaponik N., Zahn D.R.T., Eychmüller A. A fine size selection of brightly luminescent water-soluble Ag−In−S and Ag−In−S/ZnS quantum dots // J. Phys. Chem. C – 2017. – 121. – P. 9032–9042.