Ligand-induced surface reconstruction in Ag2S colloidal quantum dots for highly luminescent infrared fluorescence

Hae Mee Ju, Doheon Yoo, Min Jae Choi

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Silver sulfide (Ag2S) colloidal quantum dots (CQDs) have attracted attention as potential bio-imaging materials owing to their narrow bandgap and biocompatibility; however, their low photoluminescence quantum yield (PLQY) has limited their applications. Here we introduce ligand-induced surface reconstruction strategy to dramatically improve the PLQY of Ag2S CQDs. We found that the low PLQY of Ag2S CQDs is due to the undesirable formation of a metallic Ag core during the CQD synthesis. By introducing alkyl thiols as oxidizing agents, the metallic Ag core is reoxidized that Ag vacancies in CQDs are refilled. This induces a reduced metallic Ag core and Ag-rich stoichiometry in the CQDs. The CQDs after the surface reconstruction show a 150× enhancement of photoluminescence at 1230 nm, with an absolute PLQY of 9%. This research suggests that simple ligand treatments can help improve the surface and optical properties of silver chalcogenide CQDs, including Ag2S CQDs, which may allow development of advanced optoelectronic devices.

Original languageEnglish
Article number157706
JournalApplied Surface Science
Volume635
DOIs
StatePublished - 30 Oct 2023

Keywords

  • Colloidal quantum dots
  • Near-infrared
  • Photoluminescence
  • Silver sulfide
  • Surface reconstruction

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