Anisotropic photoconduction in novel photoconductive (oligo phenylene sulfide)ndash;polyimide films cast on a Langmuirndash;Blodgett polyimide underlayer

摘要

Two methods for preparing highly oriented crystalline polyimide films comprised of oligohyphen;phyphen;phenylene sulfide lsqb;ndash;(C6H5S)nminus;1ndash;C6H4ndash;:n=3,4,5...rsqb; monomers have been developed, which show novel photoconductivity. The first method is using modified terminals of the polymer chains for carboxylic anhydrides as crystallization nuclei in order to enhance the crystallization of the (oligo phenylene sulfide)ndash;polyimides (OPShyphen;PIs). The second uses a Langmuirndash;Blodgett polyimide underlayer to prepare oriented OPShyphen;PI films parallel to the substrate, extending up to several microns. The Langmuirndash;Blodgett polyimide underlayer introduces an oriented epitaxial crystallization of the OPShyphen;PIs. Anisotropic photocurrent measurements on these films revealed an anisotropic photoconduction mechanism in which carriers were transported perpendicular to the polymer chain axis.