Light-Triggered Switching of Quantum Dot Photoluminescence through Excited-State Electron Transfer to Surface-Bound Photochromic Molecules

This
paper describes reversible “on–off” switching
of the photoluminescence (PL) intensity of CdSe quantum dots (QDs),
mediated by photochromic furylfulgide carboxylate (FFC) molecules
chemisorbed to the surfaces of the QDs. Repeated cycles of UV and
visible illumination switch the FFC between “closed”
and “open” isomers. Reversible switching of the QDs’
PL intensity by >80% is enabled by different rates and yields of
PL-quenching
photoinduced electron transfer (PET) from the QDs to the respective
isomers. This difference is consistent with cyclic voltammetry measurements
and density functional calculations of the isomers’ frontier
orbital energies. This work demonstrates fatigue-resistant modulation
of the PL of a QD-molecule complex through remote control of PET.
Such control potentially enables applications, such as all-optical
memory, sensing, and imaging, that benefit from a fast, tunable, and
reversible response to light stimuli.