Understanding the growth mechanisms of ultrasmall silver selenide quantum dots for short-wave infrared detectors

Håvard Mølnås, Shlok Joseph Paul, Michael R. Scimeca, Navkawal Mattu, Ingrid J. Paredes, Jason A. Röhr, Vikash Kumar Ravi, Letian Li, André D. Taylor, Ayaskanta Sahu

Research output: Contribution to journalArticlepeer-review


Colloidal quantum dots (CQDs) allow for wavelength-tunable, economic, and elegant access to the infrared (IR) spectrum by utilizing inter- and intraband excitonic transitions in narrow bandgap semiconductors. With the emergence of new applications for IR detection, developing competitive non-toxic and environmentally benign alternatives to heavy metal-containing semiconductors is of increasing importance. Over the last decade, silver selenide (Ag2Se) has emerged as an alternative to lead- and mercury-based QDs, especially with large, intraband Ag2Se CQDs showing promising performance in the mid-wave IR. Herein we explored the critical nucleation and growth mechanisms of ultrasmall (2.5–3.5 nm) interband absorbing Ag2Se CQDs operating in the near to short-wave IR. Classical nucleation and growth was observed at most reaction conditions, with a growth temperature of 140 °C and a Ag:Se precursor molar ratio of 1:2 providing the most robust control over the IR absorption spectrum. We proceeded to perform an in-depth study of the impact of surface ligand chemistry of CQD thin-films on resulting optoelectronic properties. By tuning the functional groups and optimizing ligand exchange parameters, we obtained IR responsivity values of ∼25 mA/W in photoconductor devices and ∼1.8 mA/W in photodiode devices in the range 800 – 1250 nm.

Original languageEnglish (US)
Article number131946
JournalColloids and Surfaces A: Physicochemical and Engineering Aspects
StatePublished - Oct 5 2023


  • Colloidal quantum dot (CQD)
  • Growth mechanism
  • Ligand engineering
  • Near-infrared (NIR)
  • Photoconductor
  • Photodiode
  • Short-wave-infrared (SWIR)
  • Silver chalcogenide

ASJC Scopus subject areas

  • Surfaces and Interfaces
  • Physical and Theoretical Chemistry
  • Colloid and Surface Chemistry


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