Ultrafast Photoluminescence from the Core and the Shell in CdSe/CdS Dot-in-Rod Heterostructures.
With an ultrafast time-resolved photoluminescence system utilizing a Kerr gate, the time-resolved photoluminescence of core and shell constituents within CdSe/CdS dot-in-rod heterostructures is studied as a function of heterostructure size. Measurements performed at low excitation fluence generating, on average, less than one exciton per nanorod, reveal photoluminescence from direct recombination of carriers in the CdS heterostructure rod with lifetime generally increasing from 0.4 ps to 1.3 ps as the rod length increases. Decay of the CdS rod photoluminescence is accompanied by an increase in emission from the CdSe core on comparable time scales, also trending towards larger values as the rod length increases. The observed kinetics can be explained without invoking a non-radiative trapping mechanism. We also present alloying as a mechanism for enhancing electron confinement and reducing fluorescence lifetime at nanosecond time scales.
Department of Chemistry, University of Pennsylvania, USA.
Benjamin T
BT
Diroll
Department of Physics, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, USA.
Michael E
ME
Turk
Department of Materials Science and Engineering, University of Pennsylvania, USA.
Natalie
N
Gogotsi
Department of Chemistry, University of Pennsylvania, USA.|Department of Materials Science and Engineering, University of Pennsylvania, USA.
Christopher B
CB
Murray
Department of Physics, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, USA. kikkawa@physics.upenn.edu.
James M
JM
Kikkawa
D019187:Cadmium Compounds / Q000737:chemistry*; D049449:Luminescence; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry*; D013440:Sulfides / Q000737:chemistry*
D019187:Cadmium Compounds; D018036:Selenium Compounds; D013440:Sulfides; C034939:cadmium sulfide; C058667:cadmium selenide
CdSe/CdS; Kerr gate; dot-in-rod; fluorescence; nanostructures