Fabrication and electrochromic properties of layer-by-layer self-assembled ultrathin films containing water-soluble phthalocyanine

Alternate ultrathin films of water-soluble copper (II) phthalocyanine-3,4′ ,4″ ,4‴-tetrasulfonic acid (CuPcTs) and poly(diallyldimethylammonium chloride) (PDADMAC) were fabricated using the electrostatic layer-by-layer self-assembly technique. Linear depositions of the bilayers were observed from the UV-vis absorption spectra and ellipsometry. The average thickness of the CuPcTs monolayer obtained from ellipsometry was about 1.2nm and CuPcTs molecules were estimated to be tilted to the film surface. The cyclic votammogram (C-V) of the fabricated films in aqueous solution containing 0.1 M KCl suggested the oxidation and reduction of the CuPcTs at around +0.9 V and 0.05 V respectively. UV-vis absorption spectra were observed for the films at applied voltages of 0.8Vand 0V in the KCl aqueous solution and reversible absorption changes were observed.