The objective of this work is to demonstrate that

conjugated polymer:fullerene hybrid nanoparticles encapsulated in the

hydrophobic cores of triblock copolymer micelles may successfully act as

spatially confined donor−acceptor systems capable of facilitating

photoinduced charge carrier separation. To this end, aqueous

dispersions of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]

(MEH-PPV) nanoparticles were first prepared by solubilization

of the polymer in the cores of poly(oxyethylene)−poly(oxypropylene)−

poly(oxyethylene) triblock copolymer, Pluronic F-127

micelles. A number of significant optical spectroscopic changes were

observed on transfer of the conjugated polymer from a nonaqueous

solvent to the aqueous micellar environment. These were primarily

attributed to increased interchain interactions due to conjugated

polymer chain collapse during encapsulation in the micellar cores.

When prepared in buffer solution, the micelles exhibited good long-term collodial stability. When MEH-PPV micelles were

blended by the addition of controlled amounts of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), the observed

correspondence of photoluminescence emission quenching, quantum yield decreases, and emission lifetime shortening with

increasing PCBM concentration indicated efficient photoinduced donor-to-acceptor charge transfer between MEH-PPV and the

fullerenes in the cores of the micelles, an assignment that was confirmed by transient absorption spectroscopic monitoring of

carrier photogeneration and recombination.