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September 25, 2009ACS NanoOpen Access

Size-Dependent Optical Properties of Colloidal PbS Quantum Dots

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Authors

IMIwan MoreelsGhent UniversityKLKarel LambertUniversity College GhentDSD. SmeetsASML (Netherlands)

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Implication

Spectroscopic analysis demonstrates size-dependent absorption and microsecond exciton lifetimes in colloidal lead sulfide quantum dots, highlighting the significance of local field effects.

Key Points

  • To quantitatively evaluate the size-dependent optical properties and molar extinction coefficients of colloidal lead sulfide quantum dots across different energy ranges.
  • Combined optical absorbance spectroscopy with elemental analysis of colloidal PbS quantum dot suspensions across multiple particle sizes.
  • Modeled high-energy absorption via Maxwell-Garnett effective medium theory using bulk dielectric functions and applied tight-binding calculations to evaluate band gap oscillator strength.
  • At high energies, the molar extinction coefficient (ε) scales directly with quantum dot volume (d^3), confirming that quantum confinement has no effect in this regime and providing a metric for dot concentration.
  • Near the band gap, ε scales with d^1.3 and oscillator strength increases linearly with diameter (d), matching tight-binding model predictions.
  • Calculated exciton lifetimes for PbS and PbSe quantum dots span 1 to 3 μs, showing consistency with experimental time-resolved luminescence spectroscopy literature.

Cite This Study

Moreels et al. (2009) studied this question.

synapsesocial.com/papers/69dbdb0850e1971baba3d13fhttps://doi.org/10.1021/nn900863a
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