Acceptor concentration dependent Fo?rster resonance energy transfer in nanocrystal-molecule complexes revealed by spectral analysis*

Abstract:

A nanocrystal-molecule complex composed of CdSe donor and Rhodamine B (RhB) acceptor is prepared to investigate the effect of accepter-donor ratio on the Fo?rster resonance energy transfer (FRET) process. To highlight the FRET process, the energy level alignment between CdSe and RhB is purposefully designed and CdSe nanocrystal is coated with a wide band-gap ZnS shell. The carrier dynamics is observed via combined spectral analysis. The results reveal clear FRET process between the CdSe donor and RhB acceptor. The FRET is enhanced by increasing RhB/CdSe ratio and a gradual saturation will be present at high RhB concentration.

Key words:Fo?rster resonance energy transfer;Carrier dynamics; Ultrafast spectra; CdSe nanocrystals