Synthesis and optical properties of two new PPV derivatives embedded on the surface of PbS nanocrystals

In this work we present the optical characteristics of three PPV derivatives, pure and conjugated with PbS nanocrystals (NCs). Our results exhibit strong dependence of the fluorescence lifetime of the polymers on the PbS concentration. It appears that the fluorescence lifetimes increase with the PbS NCs concentration. This is a surprising result because the presence of the quantum dots, which create new nonradiative pathways, should cause a shortening of the exciton lifetime. The observed phenomenon indicates that the surface of the PbS NCs strongly affects the excited polymer, leading to the stabilization of the emerging exciton.