Plastic Electrochromic Devices: Electrochemical Characterization and Device Properties of a Phenothiazine-Phenylquinoline Donor−Acceptor Polymer

We describe the morphological, electrochemical, spectroelectrochemical characterization, and electrochromic device properties of films of poly(2,2‘-[10-methyl-3,7-phenothiazylene]-6,6‘-bis[4-phenylquinoline]) (PPTZPQ). Cyclic voltammograms of PPTZPQ polymer films showed reversible electrochemical oxidation accompanied with a color change that was switchable as a function of the potential. However, the reduction behavior of PPTZPQ was unstable and caused a loss of the electrochromic effect. The spectroelectrochemical behavior of PPTZPQ was interpreted as the combination of the properties of the constituent donor and acceptor moieties. Two PPTZPQ solid-state electrochromic devices were constructed using indium tin oxide (ITO) deposited on polyester and poly(ethylene oxide) as a polymeric electrolyte. The electrochromic active materials were PPTZPQ as the primary electrode and ladder poly(benzobisimidazobenzophenanthroline) (BBL) or vanadium pentoxide (V 2 O 5 ) as the secondary electrode. The PPTZPQ−BBL and PPTZPQ−V 2 O 5 devices showed black-red and yellow-red color changes, respectively, during potential cycling.