Electrochromism in mixed Langmuir-Blodgett films containing rare earth bisphthalocyanines

Abstract Although good deposition ratios have been obtained for the deposition of rare earth bisphthalocyanine, notably [Yb(pc)(ṗc)], provided suitable Z-type deposition is used, the phthalocyanines have not proved ideal materials for LB deposition as they do not contain a polar head group. In order to decrease collapse rate and to improve film quality, the bisphthalocyanines have been mixed with stearic acid or cadmium stearate. The paper discusses the electrochromic behaviour of alternate layer films using different fatty acids plus bisphthalocyanines, and the electrochromic behaviour of films which consist of a mixture of rare earth bisphthalocyanines. It is shown that there is molecular self-reorganization in the films and that electrochromic behaviour is suppressed using fatty acid salts when the number of carbon atoms in the acid chain is greater than 21.