A novel multiplayer film was assembled from poly[(4 carboxyphenyl)acetylene](PCPA) and diazoresin(DR) in aqueous solution via electrostatic attraction. Under UV irradiation, following the decomposition of diazonium group between the adjacent interfaces of the multiplayers, the ionic bonds of the self assembly film convert to covalent bonds and the film becomes very stable toward electrolyte solutions. Thus the photoelectric conversion property of poly[(4 carboxyphenyl)acetylene] containing film can be measured in conventional three electrode photoelectrochemical cell, and 0.5 mol/L KCl solution can be used as the supporting electrolyte. The photocurrent spectroscopy responses coincide with the absorption spectrum of the irradiated self assembly film, which indicates that the irradiated DR/PCPA film is responsible for the photocurrent generation. Under UV irradiation, the following decomposition of diazonium group between the adjacent interfaces of the multiplayers, the ionic bonds of the self assembly film convert to covalent bonds and the film becomes very stable toward electrolyte solutions. Thus the conversion property of poly [(4 carboxyphenyl) acetylene] containing film can be measured in conventional three electrode photoelectrochemical cells, and 0.5 mol / The photocurrent spectroscopy responses coincide with the absorption spectrum of the irradiated self assembly film, which indicates that the irradiated DR / PCPA film is responsible for the photocurrent generation.