Monodisperse Oligo(phenylene vinylene) Ligands on CdSe Quantum Dots: Synthesis and Polarization Anisotropy Measurements

Well-defined oligo(phenylene vinylene) (OPV) molecules with phosphine oxide chain-ends were prepared and used for surface functionalization of CdSe quantum dots. Interestingly, OPV-covered CdSe nanostructures exhibit photoluminescence emission properties characteristic of linear dipoles, similar to those found in organic dyes and collapsed polymer chains. This is seen in the spatial photon distribution from a single OPV-covered CdSe nanostructure under slight defocusing in a high numerical aperture (NA) optical system (Inverted Nikon TE300 microscope, 1.4NA), excited in epi-illumination geometry using a 405 nm GaN diode laser. We speculate that the appearance of linear polarization in the QD emission is associated with photoinduced charge transfer from the ligand to the QD surface.