Electrochromism in the transition-metal phthalocyanines. Part 2.—Structural changes in and properties of [Cr(pc)] and [Mn(pc)] films

Abstract

The electrochromic properties observed in manganese and chromium phthalocyanine thin films are reported. Schemes are proposed to explain the chemistry involved in the electrochromic changes. Both chromium and manganese are shown to undergo changes in their valence states during oxidation and reduction of the phthalocyanine films. The phthalocyanine rings also undergo oxidation and reduction with cycling between reduced and oxidised states but the latter were not stable. Although changes in colour were observed in both materials on oxidation, the films degraded and so the results were not useful. The films have been found to cycle reversibly a few thousand times between neutral and reduced states. However, their cycling properties and colour range are greatly inferior to the metal bisphthalocyanine films.