Synthesis of a new star-shaped 4,4′-bipyridine derivative and its multicolor solid electrochromic devices

A new star-shaped 4,4′-bipyridine derivative (1,3,5-tri(1-methyl-4,4′-bipyridinium bromide)-2,4,6-trimethyl benzene) TBTB was synthesized and characterized. The electrochromic behavior, electrochromic mechanism and electro-optical properties of the new type of monosubstituted 4,4′-bipyridine derivative were investigated by cyclic voltammetry and UV–vis absorption spectra. Moreover, a serial of environmentally friendly solid electrochromic devices (ECD) based on TBTB were constructed successfully and their electrochromic performance were further studied. The ECD presented a stable as well as multicolor electrochromic change from blue to violet–blue and then to violet–red between 0 V and +3.0 V. They exhibited a fast switching time (∼0.3 s for coloring and ∼0.5 s for bleaching) between the violet–blue (+2.0 V) reduced state and the transparent light blue oxidized state (−2.0 V), with a contrast ranging from 25% to 40% at 530 nm and a coloration efficiency of 279 cm2 C−1.

The ECD based on TBTB presented multicolor electrochromic change from blue to violet–blue and then to violet–red between 0 V and +3.0 V, corresponding to the four redox states, respectively.Figure optionsDownload as PowerPoint slideHighlights
► A new star-shaped 4,4′-bipyridine derivative was synthesized and characterized.
► The solid ECD presented a stable as well as multicolor electrochromic change.
► The accepting-donating electron mechanism of the ECD was proposed and discussed.
► The ECD exhibited a fast switching time, with good contrast and coloration efficiency.