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Picosecond time-resolved photoluminescence measurements were performed on CdSe core and CdSe/ZnS core/shell colloidal quantum dots (QDs). Photoluminescence (PL) emission is observed to originate from intrinsic ±1U and ±1L bright states with lifetimes of 60 and 450 ps, respectively, and from a long living component with nanosecond lifetimes. The latter is attribuited to the emission from surface states (ss) approximately 16 and 13 meV below the ±1L state for core and core/shell QDs, respectively. We show that in the temperature range between 15 and 70 K the three recombination processes compete and they are thermally populated through different pathways (±1L → ±1U and ss → ±1L).
American Chemical Society
Publication date: 
19 Jul 2007

Giovanni Morello, Marco Anni, Pantaleo Davide Cozzoli, Liberato Manna, Roberto Cingolani, Milena De Giorgi

Biblio References: 
Volume: 111 Issue: 28 Pages: 10541-10545
The Journal of Physical Chemistry C