Photoinduced energy transfer in dye encapsulated polymer nanoparticle-CdTe quantum dot light harvesting assemblies

Here, we have designed organic-inorganic light harvesting assemblies in which highly efficient resonance energy transfer occurs from CdTe quantum dots (donors) to Nile Red dye (acceptor) encapsulated polymer nanoparticles. Our motivation is to develop an assembly where the quantum dots (QDs) will absorb visible light as an antenna material, followed by the funneling of the exciton to an acceptor molecule (the Nile Red dye), which is confined in polymer nanoparticles in order to enhance their energy transfer efficiency. An ionic liquid is used to prepare the positively charged Nile Red (NR) dye encapsulated poly(methyl methacrylate) (PMMA) polymer nanoparticles. Then, negatively charged thioglycolic acid capped CdTe QDs are attached to the surface of the polymer nanoparticles by electrostatic interaction. The drastic quenching of the photoluminescence (60%) and the shortening of the decay time of the CdTe QDs imply an efficient energy transfer (73%) from the CdTe QDs to the NR dye doped PMMA nanoparticles. Time resolved anisotropy decay measurements reveal the rotational motion of the dye molecules inside the PMMA nanoparticles. Interesting findings reveal that the efficient energy transfer in the organic-inorganic assemblies may open up new possibilities for the design of an artificial light harvesting system for future applications.