Spectroscopic and structural implications of hosting Zn2+, Cd2+ and Hg2+ ions in the AgInS2 quantum dots

This work address the issue of spectral implications provided by doping AgInS2 QDs with Zn2+ and its higher homologues including Cd2+ and Hg2+. The impact of alloying AgInS2 QD with IIB group atoms is here dis-cussed in terms of comprehensive spectroscopic measurements as well as theoretical predictions per -formed within the Density Functional Theory. It is shown that each of the admixtures used induces a completely different spectral response including complete reversal character for Cd2+ and Hg2+ ions. Observed differences were here associated with changes in the native defects structure and possible re-laxation pathways due to doping. It is shown that Zn2+ ions results in quite weak impact on the emission properties of the AgInS2 QDs. Highest impact was found for Cd2+ and Hg2+ ions. Doping AgInS2 QDs with Cd2+ results in successive deactivation of the relaxation pathways which were typical for pristine AgInS2 QDs leading to significant shortening of the photoluminescence lifetime and partial band symmetrisation. Doping with Hg2+ ions was found to be of completely opposite character. It was found that mercury adatom has the lowest affinity to the AgInS2 surface giving rise to formation of metallic Hg-Ag complexes on a surface which may be responsible for anomalous behaviour of Hg-doped AgInS2 QDs.(C) 2022 The Author(s). Published by Elsevier B.V. CC_BY_4.0

Automated summary

This work investigates the spectral implications of doping AgInS2 quantum dots with Zn2+ and its higher homologues Cd2+ and Hg2+. The study utilizes comprehensive spectroscopic measurements and theoretical predictions to analyze the effects of alloying AgInS2 quantum dots with IIB group atoms. It is observed that each admixture induces a distinct spectral response, with Cd2+ and Hg2+ ions showing a complete reversal of character. The differences in spectra are associated with changes in defect structures and relaxation pathways. The study finds that Zn2+ ions have a weak impact on the emission properties, while Cd2+ and Hg2+ ions have the highest impact. Doping with Cd2+ deactivates relaxation pathways, resulting in shortened photoluminescence lifetime and partial band symmetrization. Conversely, doping with Hg2+ ions leads to the formation of metallic Hg-Ag complexes on the surface, displaying anomalous behavior in Hg-doped AgInS2 quantum dots.