Electrosynthesis and characterization of an electrochromic material from poly(1,4-bis(3-methylthiophen-2-yl)benzene) and its application in electrochromic device

1,4-Bis(3-methylthiophen-2-yl)benzene monomer was successfully synthesized via Suzuki coupling reaction. Poly(1,4-bis(3-methylthiophen-2-yl)benzene) (PBMTB) was electrochemically synthesized and characterized. Characterizations of the resulting polymer PBMTB were performed by cyclic voltammetry (CV), UV–vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Moreover, the spectroelectrochemical and electrochromic properties of the polymer film were investigated. The resulting polymer film has distinct electrochromic properties and shows three different colors (yellow, yellowish green and blue) under various potentials. The PBMTB film shows a maximum optical contrast (ΔT%) of 58% at 630 nm with a response time of 1.11 s. The coloration efficiency (CE) of PBMTB film was calculated to be 107 cm2 C−1. An electrochromic device (ECD) based on PBMTB and poly(3,4-ethylenedioxythiophene) (PEDOT) was also constructed and characterized. The optical contrast (ΔT%) at 606 nm was found to be 50% and response time was measured as 0.41 s. The CE of the device was calculated to be 365.6 cm2 C−1. This ECD has satisfactory optical memories and redox stability.