Observation of size-dependent thermalization in CdSe nanocrystals using time-resolved photoluminescence spectroscopy

Daniel C. Hannah, Nicholas J. Dunn, Sandrine Ithurria, Dmitri V. Talapin, Lin X. Chen, Matthew Pelton, George C Schatz, Richard D Schaller

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

We report heat dissipation times in semiconductor nanocrystals of CdSe. Specifically, a previously unresolved, subnanosecond decay component in the low-temperature photoluminescence decay dynamics exhibits longer decay lifetimes (tens to hundreds of picoseconds) for larger nanocrystals as well as a size-independent, ∼25-meV spectral shift. We attribute the fast relaxation to transient phonon-mediated relaxation arising from nonequilibrium acoustic phonons. Following acoustic phonon dissipation, the dark exciton state recombines more slowly via LO-phonon assistance resulting in the observed spectral shift. The measured relaxation time scales agree with classical calculations of thermal diffusion, indicating that interfacial thermal conductivity does not limit thermal transport in these semiconductor nanocrystal dispersions.

Original languageEnglish
Article number177403
JournalPhysical Review Letters
Volume107
Issue number17
DOIs
Publication statusPublished - Oct 20 2011

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nanocrystals
photoluminescence
decay
spectroscopy
acoustics
shift
thermal diffusion
phonons
thermal conductivity
dissipation
relaxation time
excitons
cooling
life (durability)

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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Observation of size-dependent thermalization in CdSe nanocrystals using time-resolved photoluminescence spectroscopy. / Hannah, Daniel C.; Dunn, Nicholas J.; Ithurria, Sandrine; Talapin, Dmitri V.; Chen, Lin X.; Pelton, Matthew; Schatz, George C; Schaller, Richard D.

In: Physical Review Letters, Vol. 107, No. 17, 177403, 20.10.2011.

Research output: Contribution to journalArticle

Hannah, Daniel C. ; Dunn, Nicholas J. ; Ithurria, Sandrine ; Talapin, Dmitri V. ; Chen, Lin X. ; Pelton, Matthew ; Schatz, George C ; Schaller, Richard D. / Observation of size-dependent thermalization in CdSe nanocrystals using time-resolved photoluminescence spectroscopy. In: Physical Review Letters. 2011 ; Vol. 107, No. 17.
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