The film formation behaviors of the photocatalytic deposition method are investigated using copper phthalocyanines (alpha, beta, and is an element of forms of CuPc), metal-free phthalocyanines (alpha, beta, and x forms of H2Pc), and N,N'-3,5-xylyl-3,4,9,10-perylene tetracarboxylic diimide. The detailed analyses based on a diffusion equation reveal that the film deposition is controlled by the diffusion of pigment particles from the dispersion bulk to the substrate. This leads to the finding that the average size of the pigment particles composing the films is smaller than that of the particles composing the dispersions. An additional finding is the fact that the packing density of the films remains constant during their growth. These features of fundamental importance enable the preparation of two types of composite films. One is a double-layered structure with a graded junction profile, and the other is a mixed film with a homogeneously blended concentration profile along the thickness. These structures are characterized by scanning electron microscopic analysis, X-ray photoelectron spectroscopy, and UV-vis spectroscopy.