We describe here the facile methods for the stepwise regulation of the formation of tetrathiafulvalene (TTF) radical cation and the self-assembly to the mixed-valence state of TTF in various polymer films. The homogeneous polymer composites containing TTF and (1R)-3,3-dimethylbicyclo[2.2.1]hepta-2-one-1-triflate as a photoinduced acid generator in several kinds of conventional polymers were prepared, and the phototriggered conversion of TTF to radical cation via protonation in the films was executed. The amount of the TTF radical species can be controlled by the length of UV-irradiation time to the polymer composite films. In addition, the formation of the mixed-valence TTF can be observed in the composite films by annealing after UV irradiation when the glass transition temperature of the matrices was sufficiently higher than the reaction temperature during the photoirradiation. Finally, we presented the facile patterning method for preparing the composite with the concentration gradient of TTF radical and the mixed-valence TTF.