Organic photovoltaic devices based on a blend of poly(3-hexylthiophene) and a fullerene have been studied by inserting oriented zinc oxide nanopillars which were fabricated by a new method at low temperature (343 K). The dependence of the photovoltaic performance on the zinc oxide morphology was investigated, and it is concluded that the oriented zinc oxide nanopillar array plays an important role in collecting photogenerated electrons and acts as a conducting path to the electrode. Insertion of the oriented zinc oxide nanopillars in the photovoltaic cells produced enhanced performance with a power conversion efficiency of 1.22% under AM1.5 illumination.

It is shown experimentally that the absorbance change observed in the ‘‘negative’’ time range, where probe pulse precedes pump pulse in real-time vibrational spectroscopy is induced only by the excited-state wave-packet motion as theoretically expected. Coherent molecular vibration of a polymer in the excited state was observed in the real-time trace without the effect of wave-packet motion in the ground state, which usually makes it difficult to ascribe the signal either to the ground state or to the excited state.

Naphthalocyanine-sensitized multi-walled carbon nanotube (NaPc–MWNT) composites have been synthesized through the π-stacking between naphthalocyanine (NaPc) and carbon nanotubes. The resultant nanocomposites were characterized with a scanning electron microscope (SEM), a transmission electron microscope (TEM), and by UV–vis absorption and photocurrent spectra. The long-range ordering was observed in the NaPc–MWNT composites by using a TEM. The enhancement in the absorption intensity and the broadening of the absorption wavelength observed in the composite films, which were due to the attachment of NaPc on the MWNT surface, is discussed based on the measured UV–vis absorption spectra. Furthermore, the photoconductivity of the poly(3-hexylthiophene)(PAT6)–NaPc–MWNT composite film was found to increase remarkably in the visible region and broaden towards the red regions. These new phenomena were ascribed to the larger donor/acceptor (D/A) interface and the formation of a biconsecutive D/A network structure, as discussed in consideration of the photoinduced charge transfer between PAT6 and NaPc–MWNT.

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