Photoinduced ultrafast electron transfer from CdSe quantum dots to Re-bipyridyl complexes.

Ultrafast dissociation of excitons in CdSe quantum dots via electron transfer to adsorbed Re-bipyridyl complexes was demonstrated. The dissociation pathway was determined by the observation of reduced adsorbate using femtosecond IR spectroscopy. The rate of electron transfer was shown to increase at smaller QD sizes. Electron transfer time as fast as 2.3 ps was observed, faster than the exciton annihilation time in CdSe. The ultrafast charge separation in this quantum dot-adsorbate donor-acceptor complex provides a potential approach for separating multiple excitons in quantum dots.