Electrochemically fabricated electrochromic films from 4-(N-carbazolyl)triphenylamine and its dimethoxy derivative

A carbazolyl-substituted triphenylamine derivative, 4-(N-carbazolyl)triphenylamine (TPACz), was synthesized and used to build a fluorescent and electrochromic polymeric film (PTPACz) on the ITO-glass surface by electrochemical oxidative coupling reactions. The electrodeposited PTPACz film showed blue emission (λmax = 424 nm) and exhibited reversible electrochemical redox processes and stable color changes upon electro-oxidation, which can be switched by potential modulation. The remarkable electrochromic behavior of the film is clearly interpreted on the basis of spectroelectrochemical studies. A dimethoxy-substituted derivative of TPACz, namely 4,4′-dimethoxy-4′′-(N-carbazolyl)triphenylamine (MeOTPACz), was also synthesized and characterized for a comparative study. Repetitive cyclic voltammetry scanning of MeOTPACz in an electrolyte/acetonitrile solution resulted in an electroactive dimeric film of (MeOTPACz)2 on the electrode surface. Electrochromic devices using PTPACz or (MeOTPACz)2 as an active layer were also fabricated as preliminary investigations for electrochromic applications.