Electrochromic properties of the n-heptyl viologen-ferrocyanide system

TLDR: In this paper, the authors investigated the transparency-time relation of a mixed solution of n-heptyl viologen dibromide (HV), Fe(CN) 6 PsyNet 4−¯¯¯¯ and NaH2PO2 or KBr were investigated by cyclic voltammetry and the transparency time relation.

Abstract: Electrochromic properties of the mixed solution of n-heptyl viologen dibromide (HV), Fe(CN) 6 4− and NaH2PO2 or KBr were investigated by cyclic voltammetry and the transparency-time relation. When Fe(CN) 6 4− is added to a HV solution the mixture colours violet without inputting any voltage. However, the colour fades gradually by further addition of NaH2PO2, and the transparency of the mixture increases with addition of larger amounts of NaH2PO2. The same effect was observed by addition of KBr to the HV-Fe(CN) 6 4− solution. The input voltage required for the electrochromism of HV is lowered considerably by addition of Fe(CN) 6 4− , when NaH2PO2 or KBr plays a role in controlling the colouringerasing phenomena. The HV-Fe(CN) 6 4− -KBr system showed some HV ‘residue’ in the cyclic voltammogram on an indium-tin oxide (ITO) electrode, while no such HV ‘residue’ was observed in the HV-Fe(CN) 6 4− -NaH2PO2 system. The HV-Fe(CN) 6 4− -NaH2PO2 system is superior in colouring-erasing reproducibility and in response time to the HV solution or the HV-Fe(CN) 6 4− system.