Self-Assembled Core-Shell CdTe/Poly(3-hexylthiophene) Nanoensembles as Novel Donor-Acceptor Light-Harvesting Systems.

The self-assembly of novel core-shell nanoensembles consisting of regioregular poly(3-hexylthiophene) nanoparticles (P3HT) of 100 nm as core and semiconducting CdTe quantum dots (CdTe) as shell with a thickness of a few tens of nanometers was accomplished by employing a reprecipitation approach. The structure, morphology, and composition of CdTe/P3HT nanoensembles were confirmed by high-resolution scanning transmission microscopy and dynamic light-scattering studies. Intimate interface contact between the CdTe shell and the P3HT core leads to the stabilization of the CdTe/P3HT nanoensemble as probed by the steady-state absorption spectroscopy. Effective quenching of the characteristic photoluminescence of CdTe at 555 nm, accompanied by simultaneous increase in emission of P3HT at 660 and 720 nm, reveals photoinduced charge-transfer processes. Probing the redox properties of films of CdTe/P3HT further proves the formation of a stabilized core-shell system in the solid state. Photoelectrochemical assays on CdTe/P3HT films show a reversible on-off photoresponse at a bias voltage of +0.8 V with a 3 times increased photocurrent compared to CdTe. The improved charge separation is directly related to the unique core-shell configuration, in which the outer CdTe shell forces the P3HT core to effectively act as electron acceptor. The creation of novel donor-acceptor core-shell hybrid materials via self-assembly is transferable to other types of conjugated polymers and semiconducting nanoparticles. This work, therefore, opens new pathways for the design of improved optoelectronic devices.