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We have prepared organic photovoltaic (OPV) cells possessing an ideal bulk heterojunction (BHJ) structure using the self-assembly of copper phthalocyanine (CuPc) as the donor material and fullerene (C(60)) as the acceptor. The variable self-assembly behavior of CuPc on a diverse range of substrates (surface energies) allowed us to control the morphology of the interface and the degree of carrier transportation within the active layer. We observed rod-like CuPc structures on indium-tin oxide (ITO), poly(3,4-ethylenedioxythiophene)-poly(4-styrenesulfonate) (PEDOT:PSS) and Au substrates. Accordingly, the interfaces and continuing transport path between CuPc and fullerene domains could be greatly improved due to the ideal BHJ structure. In this paper, we discuss the mechanisms of producing CuPc rod-like films on ITO, PEDOT:PSS and Au. The OPV cell performance was greatly enhanced when a mixture of horizontal and vertical CuPc rods was present on the PEDOT:PSS surfaces, i.e. the power conversion efficiency was 50 times greater than that of the corresponding device featuring a planar CuPc structure.

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Carbon nanofibers (CNFs) with diameter ∼66 nm have been synthesized from coronene by low-temperature (∼45 °C) vacuum sublimation without the aid of a catalyst. Our method makes use of the property of polycyclic aromatic hydrocarbon (PAH) molecules, which can self-assemble into columnar aggregates. This polycyclic aromatic hydrocarbon-carbon nanofibers (PAH-CNFs) reveal much better thermal stability than commercial carbon nanotubes and exhibit field-emission characteristics with the onset of an electric field of 5.4 V/μm and field enhancement factor of 1326 cm−1 for 100 μm interelectrode distance. The relative high thermal stability and easier process open up a possibility to fabricate large-scale field-emission devices in an efficient way and to provide a broad range of applications in nanoscience and technology.

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