We have investigated the photovoltaic properties of organic p-n heterojunction photovoltaic cells consisting of p-type zinc (or copper) phthalocyanine (ZnPc, CuPc) and various dye materials, such as tetrapyridyl porphyrin (H2TPyP), DCM, Coumarin6, perylene derivative (BP-PTCDI), and Buckminsterfullerene (C-60), evaporated on an n-type anatase TiO2 film. The open circuit voltage (V-oc) of ITO/TiO2/dye/ZnPc/Au devices lined up in order of DCM > BP-PTCDI > H2TPyP > C-60 which corresponds to the order of the energy difference between the Lowest Unoccupied Molecular Orbital (LUMO) values of dye material and the ionization potential of ZnPc. The quantum efficiency also increased effectively by inserting the very thin dye layer (similar to 10 nm) between phthalocyanine (Pc) and TiO2 layer compared to TiO2/pc double layered device, except Coumarin6, whose LUMO locates higher than Pc, corresponding to the concept of donor-acceptor system. The largest short circuit current density (J(sc)) was obtained for the ITO/TiO2/C-60/CUPc/Au multilayered structure. Higher values of V-oc and J(sc) of 0.49 V and 5.42 mA/cm(2), under 130 mW/cm(2) white light illumination, were obtained by substituting coevaporated layer Of C-60 and CuPc by C-60 layer and by heating the substrate at 120 degrees C during the deposition. (c) 2005 Elsevier B.V. All rights reserved.