Two New Near-Infrared Switchable Electrochromic Bithiophenes Derivatives Based on 4-Methoxytriphenylamine Unit and Their Application for Electrochromic Devices

Abstract

Two novel triphenylamine-containing thiophene derivative monomers, 4-methoxy-4′,4″-di(thiophen-2-yl)triphenylamine (MTTPA) and 4-methoxy-4′,4″-di(2,3-dihydrothieno[3,4-b][1,4]dioxin-7-yl)triphenylamine (METPA), were successfully synthesized. The corresponding polymers including PMTTPA and PMETPA were electrochemically synthesized and characterized by cyclic voltammetry (CV), UV–vis–NIR spectroscopy and scanning electron microscopy (SEM). Electrochemical and spectroelectrochemical analysis showed that two polymers had reversible redox behavior and multi-electrochromic property. Dynamic electrochromic experiments suggested that both the polymers had rapid switching time, high coloration efficiency, and high contrast of optical transmittance changes (ΔT%) in the NIR region (55.5% at 1280 nm for PMTTPA, 77.6% at 1200 nm for PMETPA). The dual-type electrochromic device based on PMTTPA film (or PMETPA film) was constructed and characterized as well. Both of them revealed excellent properties.