posted on 2021-02-08, 13:05authored byLars Dworak, Anne Bottin, Sina Roth, Phuong Thao Trinh, Klaus Müllen, Thomas Basché, Josef Wachtveitl
Excitation energy
and charge transfer processes in perylene diimide
dye–CdSe quantum dot complexes have been studied by femtosecond
transient absorption spectroscopy. After excitation of the quantum
dots high above the band edge, the electronically excited perylene
diimide forms on a timescale similar to the ultrafast quantum dot
intraband relaxation. An extraordinarily fast energy transfer time
of <300 fs is determined, indicating that the transfer from the
hot excitonic state competes with quantum dot intraband relaxation.
A much slower kinetic component is attributed to the energy transfer
from the quantum dot’s lowest excitonic state to perylene diimide.
At high dye–quantum dot ratios, the electronically excited
dye generated in the energy transfer reaction is reduced by an electron
transfer from the quantum dot ground state. This study demonstrates
the potential of the investigated organic–inorganic hybrid
for the design of tailor-made energy transfer systems, which can be
applied in the emerging field of hot exciton utilization.