Dye-fluoropolymer nanocomposite film deposition in vacuum

Dye-filled fluoropolymer nano-composite films were deposited by means of vacuum co-deposition using either thermal evaporation of bulk material both of dye and polymer or by using laser beam evaporation of composite targets prepared as mixture of dye and polymer. We studied optical properties of two types of dyes, phthalocyanines (Pc) and 1,2-dihydroxyantraquinone (Aq) in polytetrafluoroethylene (PTFE) and polychlorotrifluoroethylene (PCTFE) matrix. Absorption spectra of the films composed of PTFE and metal-free phthalocyanine (H2Pc) revealed that the chromophores form aggregates in the polymer matrix. A gradual change of dye concentration in the PTFE matrix towards lower values is connected with a change in structure of H2Pc aggregates. At high dye concentration, the 615 nm absorption band is more pronounced, while at low dye concentration the absorption band at 686 nm dominates. This effect is due to different size and structural states of dye nano-particles. Laser beam evaporation of pure VOPc and of dye with polymer leads to formation of phase 2 aggregates, usually formed only at high temperature, but here even at ambient substrate temperature. Using various evaporation methods and deposition conditions, it is possible to control dye aggregation in the polymer matrix and, therefore, optical film properties.