Preparation Of The Electrochromic Materials Containing Bipyridine Derivatives And Properties Of The Solid-state Devices

Organic electrochromic materials with bipyridine group are the hot issue of focus in greenphotovoltaic materials due to its rich colors and fast color conversion speed. In this paper,four kinds of different bipyridine-based compounds, totaling13target compounds, weresynthesized using4,4’-bipyridine and substituted terpyridine as precursors, and theirstructures were characterized. The optical performance and electrochromic mechanism ofthe compounds were tested via UV-visible spectrophotometry and cyclic voltammetry. Theresults showed that: the small molecule viologen achieves electrochromic when itsmolecule structure change between benzene and quinone by redox, while theelectrochromic of bipyridine metal complexes are achieved through charge transferringbetween the metal ions and the ligands.Electrochromic films of bipyridine compounds were prepared by spin coating andelectrochemical deposition on ITO conductive glass respectively, and their opticalperformance were tested. All-solid-state electrochromic devices based on conductive ITOglass were fabricated using LiClO4-PMMA/PEO polymer electrolyte as PE layer, and theperformances of the devices were tested. The results showed: the electrochromic device of4,4’-bis-triphenylamine viologen has reversible color change from colorless to blue-greenbetween0V and-0.8V; while the devices of Fe(Ⅱ) bipyridine metal complexes and Ru(Ⅱ)bipyridine metal complexes have reversible color change from purple to blue-green andorange to green respectively under the potential of0~3V. All the devices can stably shiftin two states of coloring and fading under a driving potential which is not higher than3V.All the devices response fast while coloring and fading. And the open memory time of theECD is as long as300min. All of these proved that the ECDs have excellentelectrochromic properties, which are expected to produced to practical electrochromicdevices.