Radiative and nonradiative pathways in multiexciton recombination in giant nanocrystal quantum dots
Abstract
Recently,
footnotetextY. Chen et al., JACS 130, 5026 (2008) we developed ``giant'' nanocrystal quantum dots (g-NQDs), in which a small emitting core of CdSe is overcoated with a thick shell of a wider-gap CdS. We conduct room-temp measurements of photoluminescence (PL) lifetimes in such g-NQDs as a function of excitation power and a number of shell monolayers. At low pump levels, corresponding to excitation of less than 1 exciton per dot on average (<N>< 1), we observed excitonic radiative lifetimes of ∼100 ns and a linear scaling of the PL signal with pump intensity. At powers corresponding to <N>>1, fast (∼1ns) PL component appeared, accompanied by a transition to a sub-linear scaling of PL intensity with <N>. Our findings indicate that while g-NQDs indeed produce suppression of nonradiative Auger recombination,
footnotetextF. Garcia-Santamaria et al., Nanoletters 9, 3482 (2009) this suppression is incomplete. We conduct systematic studies of relative efficiencies of nonradiative and radiative processes in these nanostructures.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2010
- Bibcode:
- 2010APS..MAR.A9009M