Abstract: In this paper, a modifcation of the procedure reported by Barret was applied to synthesize vanadyl phthalocyanine(VOPc) which gave higher yield and easier to carry out. The purified VOPc was employed to Al\VOPc\ITO sandwich cell by vacuum deposition. Three phases of VOPc films have been discovered and their absorption spectrum, the steady-state cw(continious wavelength) photovoltage response of the cells have been investigated. It has been found that the structure of the VOPc film influences the absorption and photoelectronic properties remarkably. Two of the three phases of VOPc films, phase I and phase Ⅱ gave obvious positive photovoltage response which was abnormal from the α-form film that gave only negative photovoltage response. This abnormal phenomenon could be explained by assuming that the negative and positive photovoltage response might be related to Q-excitation and nonlinear effects respectively.

Key words: vanadyl phthalocyanine, photovoltage, organic dye film, sandwich cell