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

• Published in: Journal of alloys and compounds 2022-08, Vol.911, p.164977, Article 164977
• Main Authors: Kosman, Rafał, Olejniczak, Adam, Pawlyta, Mirosława, Bezkrovnyi, Oleksii, Cichy, Bartłomiej
• Format: Article
• Language: English
• Subjects: Adatoms; AgInS2; AgInS2/CdS; AgInS2/HgS; AgInS2/ZnS; Cadmium; Defects; Density functional theory; Doping; Homology; Mercury (metal); Photoluminescence; Quantum dots; Silver; Spectral sensitivity
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2022.164977

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 discussed in terms of comprehensive spectroscopic measurements as well as theoretical predictions performed 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 relaxation 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. [Display omitted] •Alloying AgInS2 QDs with Cd and Hg is of different nature to that observed for Zn.•Spectral changes induced by Zn, Cd and Hg alloying are caused by native defects.•Doping with Zn, Cd and Hg ions may either partially passivate or induce defects formation.•Both Cd and Hg ions have much stronger impact on the defects structure than Zn ions.•Mercury dopants form metallic Hg-Ag complexes in AgInS2 resulting in spectral redshift.