Design, Synthesis, and Characterization of a Phenothiazine-Functionalized Triazine Derivative for Electrochromic Devices

A phenothiazine-functionalized triazine derivative TAZ-3PTZBr was designed and synthesized via a cyclization reaction with trifluoromethanesulfonic acid in good yield. The photophysical, electrochemical, and computational studies of the synthesized compound TAZ-3PTZBr were systematically investigated. The phenothiazine-functionalized triazine derivative TAZ-3PTZBr exhibits an absorption maximum at 393 nm due to the ICT transition from the donor phenothiazine to the acceptor triazine moiety. The electrochemical analyses reveal that TAZ-3PTZBr exhibits one reversible oxidation wave on the anodic side assigned to the phenothiazine moiety and one reduction wave on the cathodic side corresponding to the triazine moiety. The electrochromic device of TAZ-3PTZBr displays fast switching in less than a second with a coloration efficiency of 514 and 407 cm2/C under an external bias of ±1.6 V at 500 and 670 nm, respectively.