LAUSR

This paper aims to develop a multi-colored electrochromic device based on mixed mono- and bi-substituted 4,4′-bipyridine derivatives containing an ester group. A series of these derivatives were synthesized, and their electrochemical and electrochromic properties were studied through cyclic voltammetry and ultraviolet–visible spectroscopy. The mono- and bi-substituted 4,4′-bipyridine derivatives containing an ester group displayed different onset bias and colored state. Mono-substituted 4,4′-bipyridine derivatives showed a magenta colored state at an onset bias of − 1.3 V; bi-substituted 4,4′-bipyridine derivatives showed violet colored states at an onset bias of − 0.8 V. A multi-colored electrochromic device was achieved by mixing mono- and bi-substituted 4,4′-bipyridine derivatives as the electrochromic layer.Graphical Abstract