Prevailing Photocurrent Generation of D-π-A Type Oligo(phenyleneethynylene) in Contact with Gold over Dexter-Type Energy-Transfer Quenching.

Photocurrent generation is observed with D-π-A type oligo(phenyleneethynylene) (OPE) physically contacting gold substrate. The OPE is conjugated with helical peptides, which helps the OPE moiety orient vertically on gold surface. This configuration makes the Dexter energy transfer difficult to occur even though one end of the D-π-A type OPE physically contacts gold. The anodic photocurrent continuously increases with increment of applying bias voltage from -0.3 to 0.5 V. The first principle calculations reveal that the increase in photocurrent generation is attributed partly to the change in the electron distributions of HOMO and LUMO of the D-π-A type OPE to be more localized with applying the positive potential.