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

A phenothiazine-functionalized\ntriazine derivative <b>TAZ-3PTZBr</b> was designed and synthesized\nvia a cyclization reaction with trifluoromethanesulfonic\nacid in good yield. The photophysical, electrochemical, and computational\nstudies of the synthesized compound <b>TAZ-3PTZBr</b> were systematically\ninvestigated. The phenothiazine-functionalized triazine derivative <b>TAZ-3PTZBr</b> exhibits an absorption maximum at 393 nm due to\nthe ICT transition from the donor phenothiazine to the acceptor triazine\nmoiety. The electrochemical analyses reveal that <b>TAZ-3PTZBr</b> exhibits one reversible oxidation wave on the anodic side assigned\nto the phenothiazine moiety and one reduction wave on the cathodic\nside corresponding to the triazine moiety. The electrochromic device\nof <b>TAZ-3PTZBr</b> displays fast switching in less than a\nsecond with a coloration efficiency of 514 and 407 cm<sup>2</sup>/C\nunder an external bias of ±1.6 V at 500 and 670 nm, respectively.