Multicolored and high contrast electrochromic devices based on viologen derivatives with various substituents

A series of viologen derivatives, 1,1 '-bistriphenylamine-4,4 '-bipyridine (2TPAV2+(PF6-)(2)), 1,1 '-bis(N-phenylpyrrole)- 4,4 '-bipyridine (2PPV(2+)(PF6-)(2)), and 1,1 '-bis(N-phenylcarbazole)- 4,4 '-bipyridine (2PCV(2+)(PF6-)(2)), were synthesized. The electrochemical and electrochromic properties of these viologen derivatives were investigated. Electrochromic devices (ECDs) based on these viologen derivative exhibited reversible, multicolored changes under applied voltages. Among them, the optical contrast of ECD based on 2PCV(2+)(PF6-)(2) reached 62.1% and 62.5% at 617 nm and 716 nm, respectively.