Structural and Optical Characterisation of Size-Selected Glutathione-Capped Colloidal Cu–In–S Quantum Dots

Size-selected series of copper-deficient colloidal Cu–In–S quantum dots (QDs) stabilized with glutathione are obtained by the exchange reaction in aqueous solutions under mild synthesis conditions. The optical bandgap and photoluminescence maximum position shift toward higher energies with decreasing QD size. Based on X-ray diffraction data, the QDs are assigned to a tetragonal chalcopyrite-type structure. The average size of QDs, estimated from the Scherrer formula and from the comparison with the absorption edge-based sizing curves, exhibits a fair agreement, being in the interval of 1.2–2.9 nm. The Raman spectra of Cu–In–S QDs are analyzed with the account for the QD structure, confinement-related effects, non-stoichiometry, and possible existence of secondary phases.