Room-temperature exciton storage in elongated semiconductor nanocrystals.
The excited state of colloidal nanoheterostructures consisting of a spherical CdSe nanocrystal with an epitaxially attached CdS rod can be perturbed effectively by electric fields. Field-induced fluorescence quenching coincides with a conversion of the excited state species from the bright exciton to a metastable trapped state (dark exciton) characterized by a power-law luminescence decay. The conversion is reversible so that up to 10% of quenched excitons recombine radiatively post turn-off of a 1 micro s field pulse, increasing the delayed luminescence by a factor of 80. Excitons can be stored for up to 10(5) times the natural lifetime, opening up applications in optical memory elements.
Kraus
R M
RM
Photonics and Optoelectronics Group, Physics Department and CeNS, Ludwig-Maximilians-Universität, Amalienstrasse 54, 80799 München, Germany.
Lagoudakis
P G
PG
Rogach
A L
AL
Talapin
D V
DV
Weller
H
H
Lupton
J M
JM
Feldmann
J
J