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

Abstract

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 (λ_max = 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.