Different effects of alkyl sulfate and alkylbenzene sulfonate surfactants on the synthesis and properties of CuPc/TiO2 composite films by the liquid-phase deposition (LPD) method

The insoluble copper phthalocyanine (CuPc)/TiO2 composite thin film has been successfully prepared in an aqueous solution by liquid-phase deposition (LPD) method, applying two surfactants as the solubilizing agents. The two surfactants are sodium dodecyl benzylsulfonate (SDBS) and sodium lauryl sulfate (SDS), selected as the representative of their groups. The deposited films were characterized by UV-vis, SEM, FT-IR, XRD and ICP-AES. Comparing the two composite thin films, it revealed a series of interesting facts. The films showed excellent adherence to the substrate with particle diameter ranging from 20-50 nm in, and 90 and 280 nm in thickness. It is identified that CuPc is coexisting of dimers, and monomers form, mainly in dimeric form for both the composite thin films by UV-vis spectroscopy, illustrating that the CuPc is not further aggregated by LPD process. The dependences of deposited amount of Ti and Cu with the reaction time suggested the growing of the films can be easily controlled, the SDBS seems to be hindrance to the growing of the films. After heat treatment at 250degreesC for 2 h, the SDS-CuPc/TiO2 thin film becomes crystallized, but no obvious XRD peak is observed in the SDBS-CuPc/TiO2 composite thin film. (C) 2004 Elsevier B.V. All rights reserved.