Synthesis and Characterization of Novel Triarylamine Derivatives with Dimethylamino Substituents for Application in Optoelectronic Devices

Two novel triphenylamine-based derivatives with dimethylamino substituents, N,N′-bis­(4-dimethylaminophenyl)-N,N′-bis­(4-methoxyphenyl)-1,4-phenylenediamine (NTPPA) and N,N′-bis­(4-dimethylaminophenyl)-N,N′-bis­(4-methoxyphenyl)-1,1′-biphenyl-4,4′-diamine (NTPB), were readily prepared for investigating the optical and electrochromic behaviors. These two obtained materials were introduced into electrochromic devices accompanied with heptyl viologen (HV), and the devices demonstrate a high average coloration efficiency of 287 cm²/C and electrochemical stability. Besides, NTPB/HV was further used to fabricate electrofluorochromic devices with a gel type electrolyte, and exhibit a controllable and high photoluminescence contrast ratio (I_off/I_on) of 32.12 from strong emission to truly dark by tuning the applied potential in addition to a short switching time of 4.9 s and high reversibility of 99% after 500 cycles.