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 NPs ) of 100 nm as core and semiconducting CdTe quantum dots (CdTe QDs ) 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 QDs /P3HT NPs nanoensembles were confirmed by high-resolution scanning transmission microscopy and dynamic light-scattering studies. Intimate interface contact between the CdTe QDs shell and the P3HT NPs core leads to the stabilization of the CdTe QDs /P3HT NPs nanoensemble as probed by the steady-state absorption spectroscopy. Effective quenching of the characteristic photoluminescence of CdTe QDs at 555 nm, accompanied by simultaneous increase in emission of P3HT NPs at 660 and 720 nm, reveals photoinduced charge-transfer processes. Probing the redox properties of films of CdTe QDs /P3HT NPs further proves the formation of a stabilized core–shell system in the solid state. Photoelectrochemical assays on CdTe QDs /P3HT NPs films show a reversible on–off photoresponse at a bias voltage of +0.8 V with a 3 times increased photocurrent compared to CdTe QDs . The improved charge separation is directly related to the unique core–shell configuration, in which the outer CdTe QDs shell forces the P3HT NPs 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.