PHOTOLUMINESCENCE STUDIES ON POLY(1,4-PHENYLENE 1'-PHENYL VINYLENE) DOPED WITH FLUORENYLIDENE MALONONITRILE

The results of steady-state and transient photoluminescence (PL) studies on poly(1,4-phenylene 1'-phenyl vinylene) (PPV-P) thin films doped with an electron acceptor, fluorenylidene malononitrile (BCFM), are presented. The steady-state PL of undoped PPV-P is characterized by a broad band with a maximum at 505 nm and a fairly long tail extended to the near-infrared. The main PL band, peaked at 505 nm (A band), was strongly quenched by BCFM, while the intensity of the far-red PL emission tail (B band) was not affected by BCFM. By contrast the lifetime of the B band increased with BCFM doping. A photoinduced electron transfer, followed by charge separation, is proposed as the mechanism for the observed PL quenching, The observed long-lived red PL emission is associated with exciplex formation.