Charge Transfer in CdSe Nanocrystal Complexes with an Electroactive Polymer

A better understanding of the essential interaction of semiconductor nanocrystals with their adsorbates and surrounding media can be used for controlling and optimizing the energy or charge transfer reactions found in these systems and also for comparing a diverse assortment of photoexcited charge transfer systems found in the latest materials research. In this study, the photoinduced interfacial charge transfer system, a complex of CdSe semiconductor nanocrystals and electroactive polymers containing ruthenium(II)tris(bipyridine), is characterized and then investigated in a comprehensive range of dielectric solvents from toluene to water. The effects of the solvent on the nanocrystal and adsorbate/ligand as well as the charge transfer dynamics of the system are explored through the fluorescence lifetime of the nanocrystal. Through this investigation it was found that fluorescence decays showed the presence of two decay components, which are influenced by solvent dielectric contributions on nanocrystal passivation and surface traps, and charge transfer processes present in the system. The results of the fluorescence decays were put into perspective using Marcus theory, providing some general insight on QD-based charge transfer systems and the effects of solvent polarity.