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How structural and vibrational features affect optoelectronic properties of non-stoichiometric quantum dots: computational insights.

Manav BhatiSergei A IvanovThomas P SenftleSergei TretiakDibyajyoti Ghosh
Published in: Nanoscale (2023)
While stoichiometric quantum dots (QDs) have been well studied, a significant knowledge gap remains in the atomistic understanding of the non-stoichiometric ones, which are predominantly present during the experimental synthesis. Here, we investigate the effect of thermal fluctuations on structural and vibrational properties of non-stoichiometric cadmium selenide (CdSe) nanoclusters: anion-rich (Se-rich) and cation-rich (Cd-rich) using ab initio molecular dynamics (AIMD) simulations. While the excess atoms on the surface fluctuate more for a given QD type, the optical phonon modes are mostly composed of Se atoms dynamics, irrespective of the composition. Moreover, Se-rich QDs have higher bandgap fluctuations compared to Cd-rich QDs, suggesting poor optical properties of Se-rich QDs. Additionally, non-adiabatic molecular dynamics (NAMD) suggests faster non-radiative recombination for Cd-rich QDs. Altogether, this work provides insights into the dynamic electronic properties of non-stoichiometric QDs and proposes a rationale for the observed optical stability and superiority of cation-rich candidates for light emission applications.
Keyphrases
  • molecular dynamics
  • quantum dots
  • density functional theory
  • high resolution
  • clinical trial
  • ionic liquid
  • molecular dynamics simulations
  • sensitive detection
  • mass spectrometry
  • risk assessment
  • heavy metals