Photo-induced electron transfer in CdSe nanocrystals passivated by quinone derivatives

摘要

The directed surface passivation of semiconductor CdSe, CdSe/ZnS nanocrystals (NC) by di-meso-pyridyl substituted porphyrins (H2P) as well as quinone and his derivatives with increasing electron accepting abilities has been realized via the reversible non-covalent self-assembly interaction of organic and inorganic subunits. The formation of "NC-organic ligand" composites leads to the observed NC luminescence quenching (intensity decrease and decay shortening). It was shown that NC luminescence quenching by directly attached porphyrin ligands is due to the exciton non-radiative deactivation via processes realized in CdSe core interface. In this case, strong exciton-phonon interactions and charge localization depend essentially on physico-chemical and electronic properties (inductive and mesomeric effects) of the ligand and linker group. In NCs capped with quinones, using steady-state and picosecond transient spectroscopy it was found that the luminescence quenching is due to the photoinduced electron transfer and strongly depends on redox properties of quinone and its derivatives.