Ultrafast charge separation in multiexcited CdSe quantum dots mediated by adsorbed electron acceptors.
Ultrafast ET with a characteristic time constant of approximately 70 fs between CdSe QDs (mean radii of 1.4 nm) photoexcited in the lowest 1S electron state (lambda(exc) = 539 nm), and the molecular electron acceptor MV(2+) adsorbed on the QD surface was observed. The photophysics of such a system was investigated by time-resolved transient absorbance spectroscopy in the UV-visible spectral region. Our studies for the coupled system as a function of excitation intensity at lambda(exc) = 387 nm show that the ET processes compete efficiently with Auger recombination in CdSe QDs and at least 4 e-h pairs can be separated by ET to the electron acceptor MV(2+).
Matylitsky
Victor V
VV
Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt/M., D-60438 Frankfurt/M, Germany. matylitsky@chemie.uni-frankfurt.de
Dworak
Lars
L
Breus
Vladimir V
VV
Basché
Thomas
T
Wachtveitl
Josef
J