Unusual photoinduced changes in the electrical conductivity of ferrocene-doped poly(methyl methacrylate) thin films prepared under different relative humidity condition

Electrical conductivity in solution cast (using chloroform as solvent) ferrocene-doped poly(methyl methacrylate) (PMMA) thin films were studied under photoexcitation by using surface-type sample cells at various temperatures. Photoinduced enhancement in current followed by a quenching in photocurrent during photoexcitation was noticed and this effect was studied as a function of duration of photoexcitation as well as sample cell temperature. Persistence of the photoinduced effects for a longer time was observed in some cases. Our study suggests that the quenching in photocurrent and the persistence of the photoinduced effects depend on the temperature at which the measurements were carried out and the humidity of the environment at which the films were prepared. The role of water molecules present in the films for controlling the photoconductivity change of ferrocene-doped PMMA films has been discussed. (C) 2004 Elsevier B.V. All rights reserved.