Surface ligands increase photoexcitation relaxation rates in Cdse quantum dots

Svetlana Kilina, Kirill A. Velizhanin, Sergei Ivanov, Oleg V. Prezhdo, Sergei Tretiak

Research output: Contribution to journalArticlepeer-review

111 Citations (Scopus)

Abstract

Understanding the pathways of hot exciton relaxation in photoexcited semiconductor nanocrystals, also called quantum dots (QDs), is of paramount importance in multiple energy, electronics and biological applications. An important nonradiative relaxation channel originates from the nonadiabatic (NA) coupling of electronic degrees of freedom to nuclear vibrations, which in QDs depend on the confinement effects and complicated surface chemistry. To elucidate the role of surface ligands in relaxation processes of nanocrystals, we study the dynamics of the NA exciton relaxation in Cd 33Se 33 semiconductor quantum dots passivated by either trimethylphosphine oxide or methylamine ligands using explicit time-dependent modeling. The large extent of hybridization between electronic states of quantum dot and ligand molecules is found to strongly facilitate exciton relaxation. Our computational results for the ligand contributions to the exciton relaxation and electronic energy-loss in small clusters are further extrapolated to larger quantum dots.

Original languageEnglish
Pages (from-to)6515-6524
Number of pages10
JournalACS Nano
Volume6
Issue number7
DOIs
Publication statusPublished - 24 Jul 2012
Externally publishedYes

Keywords

  • electron-phonon couplings
  • excitation relaxation
  • nanocrystals
  • phonon-bottleneck
  • surface effects

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