Effect of bridging group in poly(titanyloxo-phthalocyanine)s on photocurrent generation

Photoelectric properties of soluble poly(titanyloxo-phthalocyanine)s, PTiOPc, in which phthalocynaine rings were bridged by carbonyl, sulfur dioxide, or alkylene groups, were investigated by using a photoelectrochemical techniques. Soluble poly(titanyloxophthaloeyanine) s were synthesized by the condensation of phthalic anhydride, dianhydrides, Ti(OBu)4, and urea in tetramethylene sulfone, followed by hydrolysis in an aqueous solution of KOH containing NaCl. Thin films of PTiOPc showed photocurrent of 2 ~ 10 μA/cm2 upon excitation with a light above 560 nm under external potential of 0.6 V (vs Ag/AgCl). The intensity of the photocurrent was highly dependent on the polymer structure. Thin film of PTiOPc with carbonyl bridging groups showed highest photocurrent generation, whereas that with hexafluoroisopropylidene groups showed lower photocurrent. XRD of PTiOPc indicated that ordering of the polymer, induced by the bridging group, relates to the photocurrent.